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Transcript
University of Alberta
PEDS 400: Human Gross Anatomy
Fall 2008 Semester
Dissection Guide & Laboratory Materials
Authors:
George J. Salem, Ph.D.
Phu Tranchi, M.S.
and
Rikalla Zakhary, Ph.D.
Revisions:
Loren Z.F. Chiu, Ph.D.
Alex Game
© 2008
Students are permitted to have a maximum of three copies of the Dissection Guide &
Laboratory Materials at any given time: 1) 1 Electronic Copy, 2) 1 Printed Copy for
Home/Study Use and 3) 1 Printed Copy for Laboratory Use
LABORATORY POLICIES PROCEDURES
1. Preparation: Do not begin dissection before reviewing your dissection manual. Each
dissection procedure has been carefully designed to provide you with a comprehensive
review of the relevant structures. You must not deviate from these dissection guidelines.
2. Uniform: Each participant will provide his/her own lab coats. Your clothing will also absorb
the odor from the lab so you may also want to purchase scrubs or bring a change of cloths to
the lab to wear under your lab coat. Always wear your lab coat in the laboratory. Do not
wear them outside of the laboratory. Students will be provided latex gloves. If you have an
allergy to latex please contact Alex Game as soon as possible so he can purchase Nitrile
gloves for lab use.
3. Tools: Each group will be provided thier own dissection tools. These tools will include
serrated forceps, a scalpel blade holder, and scissors. Each group will be responsible for
purchasing scalpel blades (No. 21 blades). It would be best to start with 12 blades to start the
year. After each class, you must clean your dissection tools and replace in the provided tool
cases. Any tools left on the dissection tables may disappear as other groups use the
laboratory.
4. Waste Disposal: All tissues, fluids, supplies, and gloves must be disposed of in the
appropriate containers. Any fluid or cadaver part dropped on the floor should be removed
immediately and the floor cleaned. This is necessary to avoid accidents on slippery surfaces.
5. Cadavers: All tissue pieces (e.g. skin flaps) should remain with the cadavers or be placed in
the appropriately labeled container (bucket) to be returned with the cadaver at the end of the
year.
6. Fluid Collection Pails: Fluids from the cadavers should be collected in the pails beneath the
tables. Please ensure that the drain on the table is never blocked or plugged. Once the pail is
1/3 full, bring it to the attention of Alex Game or Tom Wu for disposal.
7. Sinks: You notice two styles of sinks in the laboratory. The half moon (crescent shaped)
sinks are for washing of hands only. Do not wash tools in these sinks. The regular kitchen
sinks are for washing of tools.
8. Sharps Containers: Used scalpel blades should be placed in the sharps' containers. (Ask
for assistance from either Tom Wu or Alex Game regarding proper blade disposal your
first time)
9. Cadaver Preservation: Each cadaver must last for the entire semester. You are in charge
of protecting and maintaining the condition of your cadaver. If there appears to be a
problem with your cadaver (e.g. mold), please contact Jason Papriny by leaving a note on
the white board with your table number. Excessive drying of the specimens must also be
prevented. Be sure to frequently hydrate your cadaver with the provided wetting solution.
Additionally, be sure to preserve your skin flaps and replace them over the exposed
tissues before leaving the laboratory. Lastly, all specimens must be covered and enclosed
within the body bags prior to leaving the laboratory. If your bag develops a tear or you
lose a limb bag inform a faculty member as soon as possible.
10. Lab Period and Access: The PEDS 400 lab will be different from your previous lab
experiences in Phys Ed. Using your One card you’ll have 24 hour access to the anatomy
lab unless it has been locked for the preparation of an exam. The lab instructors will
advise if the lab will be closed for any reason.
11. Laboratory Examinations: Typically the lab will be closed the night before the
examinations in order to prepare the exam. The lab instructors will inform you of the
exact closing time of the lab for each exam.
FAQs
Over the years, students raise similar questions. Hopefully these tips and tricks will make your
dissections easier and more enjoyable.
 How do I tell an artery from a vein?
 Generally, veins will have some amount of coagulated blood in them, therefore they will
feel hard.
 Arteries are much rounder in shape than veins as they have muscular components to
maintain blood pressure. Also, arteries will have tiny blood vessels on the vessel.
 Veins will collapse when they are empty. Arteries will stay round/open.
 Veins are darker in color.
 How do I tell a nerve from an artery or connective tissue?
 Nerves do not have small blood vessels on them.
 Nerves are generally whitish/opaque.
 Connective tissue in fat and fascia will generally break fairly easily with your fingers,
nerves will be more difficult, but be careful!
 Nerves will follow a clear pathway; connective tissue generally will be more
disorganized.
 Nerves are flatter when compared to arteries.
 How do I prepare tissues for easy identification?




Use the back of your scalpel
Use the blade portion gently!
Use your forceps
Use paper towels to dry the area out
 Help! I did a great job of just taking off the skin, but now there’s fat and connective
tissue everywhere and I can’t get it off!
 Don’t let this happen to you! Once you know where you are dissecting and have an idea
of what structures to follow, try to make your cuts close to the structure. Make short,
deliberate strokes and take your time. This is a time consuming method, but much less so
if you have to go back and pick off the fat and connective tissue with your forceps!
 What is an easy way to dissect out small structures?
 Pointed scissors are the key. This method is a little awkward to begin with, but is
wonderful! Begin by placing your scissors in a location closed so that you have one
“point”. Gently spread apart the scissors while in place. You may feel something
blocking them from opening. That’s ok, don’t force it. Slowly bring them out while
open, giving to pressure of structures as you feel them. Take some time to practice with
the method and you will be pleased with the results.
 There are too many things to remember! Help!
 Try flash cards with the muscle and identify the nerve and artery that feeds it and their
origins.
 Try to palpate the structures on yourself or your classmate.
 Spend extra time in the lab, it’s open to you 24/7.
 Come to your TA’s prepared to ask questions.
 Perform identification exam practice with your group.
 Try to relate the structure to a task or location. (What muscles do you use to lift a book?
How many muscles cross the shoulder? What are they? Think of the muscles and nerves
you use while preparing dinner….)
INTRODUCTION AND OVERVIEW
OF THE LOWER EXTREMITY
LOWER EXTREMITY STRUCTURE LIST
Anterior and Medial Thigh
Structures:
Fascia lata
Femoral triangle
Iliotibial band
Adductor canal
Adductor hiatus
Lateral intermuscular septum
Nerves and Arteries:
Femoral Sheath, with:
 Femoral nerve
 Femoral artery
 Femoral vein
Profunda femoris artery
Medial femoral circumflex artery
Lateral femoral circumflex artery
Perforating arteries (4)
Obturator artery
Obturator nerves (anterior & posterior)
Saphenous nerve
Muscles, Tendons and Ligaments:
Inguinal ligament
Tensor fascia latae muscle
Gracilis muscle
Adductor longus muscle
Pectineus muscle
Sartorius muscle
Adductor longus muscle
Adductor brevis muscle
Iliopsoas muscle
Rectus femoris muscle
Vastus lateralis muscle
Vastus intermedius muscle
Vastus medialis muscle
Quadriceps tendon
Patellar ligament
Gluteal Region
Nerves, Arteries and Structures:
Greater sciatic foramen
Superior gluteal nerve
Superior gluteal artery
Lesser sciatic foramen
Inferior gluteal nerve
Inferior gluteal artery
Sciatic nerve
Sacrotuberous ligament
Muscles:
Gluteus maximus muscle
Gluteus medius muscle
Gluteus minimus muscle
Piriformis muscle
Superior gemellus muscle
Obturator internus muscle
Inferior gemellus muscle
Obturator externus muscle
Quadratus femoris muscle
Posterior Thigh
Nerves and Structures:
Sciatic nerve
Pes anserinus
Muscles:
Semitendinosus muscle
Semimembranosus muscle
Biceps femoris muscle (long and short
heads)
Popliteal Fossa
Nerves and Arteries:
Politeal artery
 Superior lateral genicular artery
 Superior medial genicular artery
 Inferior lateral genicular artery
 Inferior medial genicular artery
Popliteal nerve
 Tibial nerve


Common fibular nerve (peroneal)
Sural nerve
Muscles:
Gastrocnemius muscle
Plantaris muscle
Soleus muscle
Posterior Leg
Nerves, Arteries and Structures:
Tibial nerve
Posterior tibial artery
Fibular artery (peroneal)
Anterior tibial artery
Flexor retinaculum
Achilles tendon
Muscles:
Gastrocnemius muscle
Plantaris muscle
Soleus muscle
Popliteus muscle
Flexor hallucis longus muscle
Flexor digitorum longus muscle
Tibialis posterior muscle
Sole of the Foot
Nerves, Arteries and Structures:
Medial plantar nerve
Medial plantar artery
Lateral plantar nerve
Lateral plantar artery
Plantar aponeurosis
Muscles of the First and Second Layer:
Abductor hallucis muscle
Abductor digit minimi muscle
Flexor digitorum brevis muscle
Quadratus plantae muscle
Lumbrical muscles
Distal tendons of flexor digitorum longus
and flexor hallucis longus
Muscles of the Third Layer:
Flexor Digiti Minimi
Adductor Hallucis
Flexor Hallucis Brevis
Muscles of the Fourth Layer:
3 plantar interossei
4 dorsal interossei
Tendon of fibularis longus
Tendon of tibialis posterior
Lateral Compartment of the Leg
Nerves and Structures:
Superficial fibular nerve
Superior fibular retinaculum
Muscles:
Fibularis longus muscle
Fibularis brevis muscle
Anterior Compartment of the Leg
Nerves, Arteries and Structures:
Deep fibular nerve
Anterior tibial artery
Superior extensor retinaculum
Inferior extensor retinaculum
Muscles:
Tibialis anterior muscle
Extensor hallucis longus muscle
Extensor digitorum longus muscle
Fibularis tertius muscle
Dorsum of the Foot
Artery:
Dorsalis pedis artery
Muscles:
Extensor digitorum brevis muscle
Extensor hallucis brevis muscle
The lower extremity may be considered with two major divisions: the upper and lower
limb. The upper limb is referred to as the thigh, while the lower limb is simply referred to as the
leg. These regions can be further divided into separate compartments, such as posterior or
lateral.
Blood Supply to the Thigh (Refer to Fig. 1.1)
The abdominal aorta is the continuation of the descending aorta into the abdomen. After
giving several branches off to supply the organs of the abdomen, it continues down to bifurcate
into the two common iliac arteries (right and left) which supply the lower extremity. Each
common iliac artery bifurcates into an internal iliac artery and external iliac artery. The
internal iliac artery supplies the pelvic region and gives off a branch, the obturator artery, which
supplies the adductor muscles. The external iliac artery continues on to the lower limb, crosses
the inguinal ligament, and is renamed the femoral artery. Thus, two cases have been illustrated
whereby an artery may change its name: by branching to form new vessels or by passing a
particular landmark.
The femoral artery is not the main blood supply to the thigh, but it does give off muscular
branches to supply some aspects.
It continues down the thigh within the adductor canal,
bordered between the adductor muscles and the vastus medialis muscles, and then pierces the
adductor hiatus - a gap in the adductor magnus muscle. Thereafter, it becomes the popliteal
artery, and supplies the lower leg. The major branch of the femoral artery is the profunda
femoris artery, which is the main supply of blood to the thigh.
The profunda femoris artery branches from the femoral artery within the femoral
triangle. Both vessels descend the thigh in parallel, with the profunda femoris artery running
deep to the adductor longus muscle. It gives off three major branches to supply the different
regions of the thigh: the medial and lateral femoral circumflex arteries and the perforating
arteries. The lateral circumflex artery branches most often from the upper lateral portion of the
profunda femoris artery, traveling laterally, deep to the rectus femoris muscle. It has three major
branches: ascending, transverse, and descending. The medial circumflex artery branches from
the upper medial portion of the profunda femoris artery, traveling medially briefly, and then
descends posteriorly between the pectineus muscle and the iliopsoas tendon. These two arteries
circumflex the femur below the lesser trochanter, then anastamose with each other.
The
perforating arteries are a set of four branches from the profunda femoris artery, which
“perforate” the adductor muscles to enter the posterior compartment of the thigh, and supply
these muscles. Generally, the upper two arteries will penetrate adductor brevis, while all four
will penetrate adductor magnus and longus. Blood supply to each of the specific compartments
of the thigh will be discussed in detail later.
Remember that a vein of the same name accompanies each artery discussed. The only
exception is the abdominal aorta, which is accompanied by the inferior vena cava. Still, veins
are very likely to vary in location with respect to their corresponding arteries. Some major veins
also exist superficially and do not accompany an artery. One such vein that will be encountered
in the lower limb is the great saphenous vein. In discussing veins, remember that their function
is to carry blood back toward the heart, so that their flow is in reverse of the arteries. In that
case, the great saphenous vein begins in the foot at the dorsal venous arch, and ascends, more or
less, along the medial aspect of the entire leg before emptying into the femoral vein at the
saphenous opening.
Figure 1.1 – Arterial supply to the thigh.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Figure 1.2 – The Great saphenous vein and its course through the lower limb.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Peripheral Innervation of the Thigh
The spinal nerves are the origin of the peripheral nervous system. Each is composed of
sensory and motor fibers. The sensory fibers enter the dorsal horn of the spinal cord gray matter,
forming dorsal roots, which carry in sensory information from all parts of the body. The motor
fibers exit from the ventral horn of the spinal cord to form ventral roots and carry motor impulses
throughout the body. There are 31 pairs of spinal nerves which branch off along the length of
the spinal cord, in five regions: cervical, thoracic, lumbar, sacral, and coccygeal. The spinal
nerves organize into plexuses to form the major peripheral nerves, which innervate the
appendages of the body. A plexus is a protective mechanism whereby damage to or compromise
of a particular spinal nerve will not completely halt the functioning of a particular muscle or
group of muscles. Instead, it may be compensated for by the contributions of other spinal nerves
to the peripheral nerve in question.
There are three types of peripheral nerves, which branch from a major peripheral nerve.
While the major peripheral nerves are mixed, containing both sensory and motor fibers, their
branches may not carry all such information. Muscular peripheral nerves are the only type that
carry both motor and sensory signals, delivering motor information to the motor end plates, and
carrying sensory information from the muscle spindle receptors. Cutaneous peripheral nerves
are sensory only, bringing in sensory information from skin receptors. Articular peripheral
nerves also have only sensory function, delivering information from joint receptors.
Innervation of the lower limb originates in the lumbosacral plexus, which consists of
spinal nerves L1 - S4. Anteriorly, the lumbosacral plexus gives off the femoral and obturator
nerves. Both are major peripheral nerves, originating from spinal nerves L2 - L4. Posteriorly, the
sciatic nerve, the largest nerve in the body, descends from spinal nerves L4 - S3, before
bifurcating into the common fibular and tibial nerves. The specific innervations of these nerves
will be discussed in further detail in following sections.
Fascia
Fascia is fibrous connective tissue, typically arranged in a sheet or tube. There are two
types encountered in dissection:
superficial and deep fascia.
Superficial fascia is a
subcutaneous layer of loose areolar tissue, found just deep to the skin. It is also referred to as the
tela subcutanea, meaning “subcutaneous web,” which describes its appearance.
This
subcutaneous layer is composed of about 90% adipose tissue, held together by the collagen web.
Cutaneous nerves and superficial blood vessels may be found housed within this layer of fatty
tissue. Beneath the superficial fascia is the deep fascia.
Deep fascia is a layer of dense connective tissue found in three places: enveloping limbs,
enveloping muscles, and forming the intermuscular septa. Its main functions are to separate
muscles and to serve as sites of muscle attachment. The fascia is thickened and much stronger
than in other regions at sites of muscle attachment. A prime example is the iliotibial band, which
is significantly thickened compared to the rest of the fascia lata of the thigh. In some areas, the
deep fascia may be so thin that it appears to be absent, or it may be absent all together. In such
thinner regions, it may serve merely as a separation between muscles.
In forming the
intermuscular septa, the fascia blends in with the periosteum of the bony surface. The collagen
fibers are typically interwoven in a longitudinal and transverse manner. At sites of muscle
attachment, the fibers are arranged primarily in one direction, similar to the composition of a
tendon, where the fibers are parallel to each other and in relation to the line of pull of the
muscles, providing the necessary tensile strength to anchor them.
Introduction to Dissection
The goal of the dissection is to isolate and clean structures within the upper and lower
extremities. The structures to be isolated are muscles, nerves, vessels, and various connective
tissue structures. The most important aspect of an effective dissection is preparation. Many
times, structures will be encountered, bringing up the dilemma of whether to preserve or to
remove the structure. This question is easily answered by reading the materials beforehand to
become prepared for what to expect from the specimens at each step of the dissection. Also
bear in mind that there will be many variations and anomalies, which deviate from the
information presented in lecture and the dissection guides.
The only required tools for the dissection are a scalpel with replacement blades, forceps,
and scissors. A probe may be useful in exposing deep structures, but is not required for the
actual procedures. The two techniques that will be most widely employed are blunt and sharp
dissection. In blunt dissection, the dissector uses a blunt edge - typically the reverse end of the
scalpel, or even your hand - to remove the loose superficial fascia and adipose, and separate
larger structures. In sharp dissection, the blade is used to remove deep fascia, which binds
tightly to structures below. By each method, the superficial tissue is removed by applying
moderated tension, while the blunt or sharp edge is used to actually separate the layers. The key
to both techniques is to use the proper tension to pull on the layer to be removed. At this point,
light strokes of the blade or dull end will easily separate the two layers. This will be evident in
your dissections. Another technique applied uses scissors to clean more delicate structures such
as the nerves and vessels. With the scissors in the “closed” position, approach the connective
tissue surrounding the structure, and gently force the blades apart in a direction parallel to the
structure to achieve separation.
Dissection Guide I
The objective of the first dissection is to remove the skin and superficial fascia from both thighs,
and to isolate the great saphenous vein.
Make the following skin incisions according to Figures 1a and 1b. These incisions should
initially be relatively shallow, just piercing the skin (depth of approximately 1/8”). After
determining the thickness of the superficial fascia, the cuts may be made deeper, but be careful
not to sever the great saphenous vein (dotted line in fig. 1a). The great saphenous vein lies in the
medial portion of the thigh and is very superficial. If you cut too deeply, you may remove it with
the fat and skin. (See more detail below)
A
E
E
F
G
F
C
D
B
A
C
D
H
B
Figure 1 A & B – Anterior and Posterior cuts for skinning the lower extremity.
The small dotted line represents the greater saphenous vein and the triangle
represents the femora triangle.
 From a point midway between the anterior superior iliac spine and the pubic crest (Pt. A),
make an incision down the middle of the thigh to a point about two inches below the tibial
tuberosity (Pt. B).
 Make a horizontal incision to intersect with point B, around the proximal shank, from the
lateral aspect of the leg to medial (Pt. C to Pt. D). This cut should not be made deeply,
piercing only the skin.
 Locate the ASIS again and make an incision from the ASIS toward the midline (Pt. E to Pt.
A). Again, this cut should be very superficial until the great saphenous vein is located.
 From the midline point make another incision down towards the medial thigh (Pt. A to Pt. F).
 From the anterolateral side of the thigh, reflect laterally, the skin and superficial fascia,
which will be primarily adipose. This will expose the deep fascia lata. Proceed carefully to
preserve the iliotibial band and the joint capsule of the knee. The superficial fascia at the
knee is thin, so cutting any deeper than the skin will damage the joint capsule or tendons in
the area.
 From the anteromedial side of the thigh, remove only the skin.
The area marked with a triangle in Figure 1a. houses the great saphenous vein and the
saphenous opening (proximally). The vein may be located inferiorly at the knee at about a
hand’s width medial to the medial border of the patella. From there it ascends vertically,
emptying into the femoral vein at the saphenous opening or hiatus. Try to separate the vein
beginning inferiorly, and follow its course up to the opening near the pubis. In tracing this
course, pass the handle of the scalpel behind the vessel to separate it from the superficial fascia.
Study the valve arrangement of a typical vein, by slitting open a segment of the vessel
longitudinally.
Also located within the superficial fascia near the superior end of the great saphenous vein are
the superficial inguinal lymph nodes which serve as the drainage point for the lower limb, and
some parts of the pelvic region. There may be approximately 12-20 of these nodes, ranging in
size from invisible to the unaided eye to about the size of a peanut. Remove these from the
fascia and observe them before discarding.
STRUCTURES OF THE
ANTERIOR AND MEDIAL THIGH
Fascia Lata
The fascia lata is the deep fascia of the thigh enveloping the limb like a stocking.
Proximally, it attaches to all the bones of the pelvic girdle, including the sacrum and the inguinal
ligament. This structure is not actually a ligament, rather the tendinous inferior edge of the
external oblique muscle, extending between the pubis and the anterior superior iliac spine. The
complete proximal attachment of the fascia lata from the anterior midline and moving
posteriolaterally is as follows: from the inguinal ligament, spanning the iliac crest, the posterior
sacrum and sacrotuberous ligament, the ischial tuberosity and ischial ramus, to the inferior pubic
ramus and pubic body. Distally, the fascia lata blends in with other fascial structures of the knee
joint. Anteriorly, it blends with the tendinous expansions of the quadriceps muscles to form the
patellar retinacula. Laterally, it attaches to the lateral tibial condyle as the distal attachment of
the iliotibial band. Posteriorly, it contributes to the fibrous capsule of the knee joint, blending
with the tendinous expansions of the semimembranosus muscle, and continues inferiorly to
become the deep fascia of the knee. Medially, the fascia lata becomes thin and does not
contribute to any significant structures.
The fascia lata varies in thickness about the thigh. On the medial aspect, covering the
adductor muscles, it is relatively thin. Laterally, it forms the iliotibial band, a thick aponeurosis
which attaches from the iliac crest to the lateral tibial condyle. Serving as a site of attachment
for the tensor fascia latae and gluteus maximus muscles, it forms the thickest part of the fascia
lata.
Three intermuscular septa are found in the thigh which may be considered extensions of
the fascia lata, separating the thigh into three compartments. Each compartment contains a
functionally related group of muscles, and the nerve which innervates them.
The lateral
intermuscular septum is the thickest of the three septa, found between the vastus lateralis and
biceps femoris muscles.
The medial intermuscular septum is located between the vastus
medialis and adductor magnus and adductor longus muscles. This is a thinner structure which
thickens noticeably at its inferior end. The posterior intermuscular septum is so thin it may
appear to be nonexistent, but is found between the adductor magnus and semimembranosus and
semitendinosus muscles.
Figure 2.1 – Transverse cross-section of the thigh displaying its three compartments and contents.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
All three compartments of the thigh are bordered on one side by the fascia lata, as
it envelops the limb (Fig 2.1). The anterior compartment is also bordered by the medial
and lateral intermuscular septa. It contains the quadriceps and iliopsoas muscles,
functionally related by knee extension and hip flexion. The femoral nerve innervates this
muscle group. The medial and posterior intermuscular septa and the fascia lata border the
medial compartment. The obturator nerve innervates its contents which are the adductors
of the hip. The posterior compartment contains the hamstring muscles which are
innervated by the sciatic nerve, and surrounded by the lateral and posterior intermuscular
septa and fascia lata.
Figure 2.2 – The contents and borders of the femoral triangle.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Femoral Triangle
The femoral triangle is an anatomical space found on the superior anteromedial aspect of
the thigh (Fig 2.2). Its borders are: the inguinal ligament superiorly, the lateral edge of the
adductor longus muscle medially, and the medial edge of the sartorius muscle laterally.
Anteriorly, the fascia lata constitutes the “roof” of the femoral triangle, while posteriorly, the
iliopsoas and pectineus muscles form the “floor.” Inferiorly, the apex of the triangle results from
the intersection of its medial and lateral borders. The femoral nerve enters the lower limb deep
to the inguinal ligament, through the femoral triangle. The femoral sheath, a continuation of the
abdominal fascia, is located within the triangle, forming a pouch-like structure which houses the
femoral vessels.
It is divided into three longitudinal compartments, with the most lateral
containing the femoral artery. The middle compartment contains the femoral vein, and the
medial compartment is actually an empty space called the femoral canal, which allows for
expansion of the femoral artery and vein within the sheath. Also found within the femoral
triangle are the deep inguinal lymph nodes, which are located medial to the femoral sheath.
These are fewer in number and much smaller than the superficial inguinal lymph nodes. A
convenient mnemonic device may be used to learn these structures and their relative locations.
From lateral to medial, the first letters of the structures form the word, NAVEL, as follows:
Nerve (femoral), Artery (femoral), Vein(femoral), Empty space(femoral canal), and Lymph
nodes (deep inguinal).
The femoral triangle is an origin and termination point for several other vessels. The
most prominent artery origin is of the profunda femoris artery, which branches off of the femoral
artery. The medial and lateral femoral circumflex arteries also branch within the femoral triangle
off of the profunda femoris artery. The terminations of the veins associated with these arteries
obviously occur within this space as well. The most prominent vein termination is of the great
saphenous vein which enters the femoral sheath through the saphenous opening, before joining
the femoral vein.
Figure 2.3 –Anterior view of the femoral artery and vein coursing through the adductor canal.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Adductor Canal
The adductor canal is a triangular-shaped tunnel which runs longitudinally along the
anteromedial portion of the thigh. The triangle is readily apparent in a transverse cross-section
of this anatomical space.
The superior point of the adductor canal is the apex of the femoral
triangle, where the adductor longus and sartorius muscles intersect.
As sartorius courses
inferiorly, it forms the roof. At the inferior end is the adductor hiatus, where the contents of the
adductor canal exit into the popliteal region of the leg. The lateral border is vastus medialis, and
the medial border is formed by adductor longus proximally and adductor magnus distally. These
muscles meet posteriorly so that the adductor canal has no distinct floor. The femoral artery and
vein enter and course through the canal from the femoral triangle (Fig 2.3). The saphenous
nerve, which is a cutaneous branch of the femoral nerve and its muscular branch to vastus
medialis are also found here.
Figure 2.4 – Anterior view of the quadriceps femoris, adductors and iliopsoas muscles.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Anterior Compartment of the Thigh
The muscles of the anterior compartment generally function in hip flexion and knee
extension. The bulk of this compartment is composed of the quadriceps, which are the only knee
extensors of the body (Fig 2.4). Most anterior and superficial is the rectus femoris muscle. It
attaches proximally at the anterior inferior iliac spine, and the acetabular roof of the hip. Rectus
femoris actually has two heads - a “straight” head, and a “reflected” head - with the reflected
head attaching from the acetabulum. Distally, the muscle attaches to the superior border of the
patella, then the tibial tuberosity with the other quadriceps muscles, via the patellar ligament.
Rectus femoris is biarticular, crossing the hip and knee joints, thus functioning in hip flexion and
knee extension, during shortening contractions.
The three uniarticular vastus muscles are the remaining muscles of the quadriceps group.
Vastus intermedius lies directly posterior to rectus femoris, attaching from the anterior surface
of the femur to the superior border of the patella, beneath the rectus femoris attachment, and the
tibial tuberosity. Vastus lateralis is a partially superficial muscle, originating from the lateral
aspect, or lip, of the linea aspera and the lateral intermuscular septum, before wrapping around
the femur, and terminating at the lateral border of the patella, then the tibial tuberosity. Vastus
medialis is analogous to vastus lateralis, attaching from the medial lip of the linea aspera to the
medial border of the patella and the tibial tuberosity. Remember that this muscle forms the
lateral wall of the adductor canal.
Sartorius is the longest muscle of the body, beginning at the anterior superior iliac spine,
and extending to the medial tibial condyle. The distal tendon merges here with the distal tendons
of two other muscles to form a distinct anatomical structure called the pes anserinus, or “goose’s
foot.” Sartorius crosses the thigh from lateral to medial as it descends and passes posterior to the
knee before attaching more anteriorly on the tibia. At the hip, sartorius contributes to flexion,
external rotation, and weakly to abduction. Passing posterior to the knee joint, it functions in
flexion. Sartorius will form borders for the femoral triangle and the adductor canal.
The majority of iliacus and psoas major are found in the abdomen, but distally, they
attach in the anterior compartment of the thigh. Iliacus originates at the iliac fossa, while psoas
major attaches proximally from the transverse processes and intervertebral discs of vertebrae T12
–L4. These two muscles are often described as the singular iliopsoas muscle due to their
common insertion site at the lesser trochanter of the femur. These are the primary flexors of the
hip, crossing the joint anteriorly, and passing deep to the inguinal ligament. They form the floor
of the femoral triangle.
The last muscle to be discussed in this group is technically not found in the anterior
compartment. The tensor fascia latae muscle is actually encased within the fascia lata on the
lateral aspect of the thigh. Proximally, TFL attaches to the lateral aspect of the anterior superior
iliac spine. Distally, it attaches to the lateral tibial condyle due to its insertion into the iliotibial
band. The primary function of tensor fascia latae is to stabilize the knee joint. However, due to
its anterolateral position at the hip, it will contribute to flexion, internal rotation, and abduction
at this joint.
The main blood vessel found in the anterior compartment is the femoral artery, which
begins at the inguinal ligament before entering the femoral triangle and proceeding through the
adductor canal. However, as you may recall, this artery does not provide the main supply of
blood to the muscles of the thigh (Refer to Fig 1.1). Its major branch, the profunda femoris
artery, nourishes the quadriceps and sartorius, but the femoral artery may also contribute. The
medial and lateral femoral circumflex arteries originate in the anterior compartment, as they
branch from profunda femoris to supply the hip joint. The descending branch of the lateral
femoral circumflex artery contributes to the supply of the lateral quadriceps muscles. Along the
length of the thigh, the four perforating arteries also branch off before penetrating into the
posterior compartment.
The femoral nerve provides innervation for the entire anterior thigh, originating from
spinal nerves L2-L4 of the lumbosacral plexus. Its muscular branches innervate all four of the
quadriceps muscles, sartorius, iliacus, psoas major, and pectineus - a muscle of the medial
compartment.
Figure 2.5 – The muscles of the medial compartment with pectineus and adductor longus sectioned to expose
underlying muscles and innervation by the obturator nerve.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Medial Compartment of the Thigh (Fig 2.5)
All five of the muscles within the medial compartment function in hip adduction, flexion,
and medial rotation. Pectineus is a small muscle located immediately medial to the iliopsoas
muscle. It attaches proximally to the superior pubic ramus and distally to the proximal linea
aspera, just inferior to the lesser trochanter. Adductor longus is found immediately medial to
pectineus, originating from the anterior surface of the pubic symphysis and superior pubic ramus
and fanning out before reaching its extensive distal attachment at the linea aspera of the femur.
It contributes to the borders of the femoral triangle and adductor canal. Adductor brevis is
located posterior to adductor longus. It arises from the inferior pubic ramus and then attaches
distally to the medial lip of the linea aspera. Adductor magnus is the largest of this group of
muscles, found posterior to adductor longus and adductor brevis. Proximally, it begins at the
ischial tuberosity, ischial ramus, and inferior pubic ramus then continues inferiorly to insert
along the entire linea aspera, and the adductor tubercle of the medial femoral condyle. The
posterior fibers of adductor magnus may be considered as a part of the posterior compartment of
the thigh, functioning in hip extension, and receiving separate innervation. There is a gap in its
distal attachment which is the adductor hiatus, through which the femoral artery passes into the
popliteal region. Gracilis, the last muscle in this compartment, is the most medial muscle of the
thigh. It attaches from the inferior pubic ramus to the medial tibial tuberosity, contributing to the
pes anserinus with sartorius.
The medial compartment is supplied vascularly by the profunda femoris artery, the
perforating arteries, and the obturator artery - a branch of the internal iliac artery. Innervation
comes from the obturator nerve originating from spinal nerves L2-L4 of the lumbosacral plexus.
This nerve bifurcates into anterior and posterior segments which flank the adductor brevis
muscle. It innervates gracilis, adductor brevis, adductor longus, the anterior fibers of adductor
magnus, and obturator externus - an external rotator muscle to be discussed later. Remember
that pectineus is supplied by the femoral nerve, although it lies in the medial compartment.
Dissection Guide II
In the second dissection, we will examine the following structures of the anterior, medial and
lateral thigh:
Structures:
Fascia lata
Femoral triangle
Iliotibial band
Saphenous nerve
Adductor canal
Adductor hiatus
Lateral intermuscular septum
Nerves Arteries:
Femoral sheath, with:
 Femoral nerve
 Femoral artery
 Femoral vein
Profunda femoris artery
Medial femoral circumflex artery
Lateral femoral circumflex artery
Perforating artery
Obturator artery
Obturator nerves (ant. & post.)
Muscles, Tendons and Ligaments:
Inguinal ligament
Tensor fascia latae muscle
Gracilis muscle
Adductor longus muscle
Pectineus muscle
Sartorius muscle
Adductor longus muscle
Adductor brevis muscle
Iliopsoas muscle
Rectus femoris muscle
Vastus lateralis muscle
Vastus intermedius muscle
Vastus medialis muscle
Patellar tendon
Quadriceps tendon
Before beginning this dissection, be sure to have reviewed all of the procedures so that the
structures listed above may be preserved. Always be cautious, when separating and isolating
structures, to smaller details such as vascular and nervous branching.
 Relocate the great saphenous vein and the saphenous opening. Remove a portion of fascia
lata from around the saphenous opening to expose the femoral triangle. Find a free edge of
the fascia lata then use sharp and blunt dissection to begin to define and clean the borders of
the femoral triangle. These borders are: the inguinal ligament, the medial edge of
sartorius, the lateral edge of adductor longus, iliopsoas and pectineus (the floor), and
the fascia lata (the roof).
 Within the femoral triangle, the femoral sheath should be somewhat visible. Remove as
much adipose as possible to clean the sheath, which will not be clearly defined. The femoral
artery and vein located within the sheath will be visible. Now separate and clean the artery
from the sheath and remove the vein. Do not remove the nerve during this process. Remove
all veins distal and deep to the femoral vein at the intersection with the Great
saphenous vein.
Some variations of the femoral artery that may occur include a doubling of the artery or that it
may arise from the internal iliac artery then exit the pelvis to travel down the posterior aspect of
the thigh with the sciatic nerve.
Three other arteries commonly originate in the femoral triangle:

Profunda femoris artery runs parallel to the femoral artery, entering the gap between
pectineus and adductor longus, running posterior to adductor longus down the thigh. It
has also been seen to penetrate an opening in the femoral vein before beginning its
descent.

The medial and lateral femoral circumflex arteries usually branch from profunda
femoris artery, but may also branch from the femoral artery. These branches will become
more fully exposed as dissection continues along the thigh.

The lateral femoral circumflex runs laterally, deep to sartorius and rectus femoris, with
branches found on the surface of or piercing vastus lateralis. It may be doubled with one
branch from the femoral artery and one from profunda femoris artery, or both from either.

The medial femoral circumflex typically runs posteromedial between pectineus and
iliopsoas, but may arise from the external iliac artery or one of its branches.
Note: You may not be able to identify these arteries until we reflect sartorius and rectus
femoris.
Lateral to the artery is the femoral nerve. Try to trace its muscular branches to sartorius and
rectus femoris, and clean the nerve without severing these innervations, if possible. You may be
able to observe other branches of the nerve within the femoral triangle. In some cases, the
femoral nerve may enter the thigh between the artery and vein, or pierce through iliacus. There
have also been instances in which it sends branches to tensor fascia latae and adductor longus.
The largest branch follows the femoral artery into the adductor canal and is called the
saphenous nerve.
The next step is to remove the fascia lata from the anterior and medial thigh. Observe its
attachments to the pelvic girdle and the inguinal ligament, and notice the changes in thickness
from the lateral to medial. This thick lateral portion is the iliotibial band.
 Palpate the proximal attachment of sartorius at the anterior superior iliac spine, and then
carefully cut the fascia lata from the saphenous opening to this point, just inferior to the
inguinal ligament.
 Lateral and inferior to the proximal sartorius attachment, the bulge of the tensor fascia latae
should be palpable. To separate and define the iliotibial band, make an incision medial to
this muscle, beginning from the end of the last cut and proceeding down the thigh to the tibia.
Be careful to preserve the distal attachment of the iliotibial band. This cut should be very
superficial and only through the deep fascia layer. The fascia lata may now be removed from
the anterior and medial thigh by blunt and sharp dissection, exposing the muscles of these
regions.
 On the anterior surface of the thigh, separate and clean sartorius throughout its length by
blunt dissection, and careful sharp dissection as required. In very rare cases, this muscle may
be divided in two, or absent. Stop just above the knee joint to preserve its distal attachment.
 Lifting sartorius laterally will expose the fascial roof of the adductor canal, bordered
laterally by vastus medialis and medially by adductor longus and adductor magnus.
Open the roof so as not to damage the underlying femoral vessels and saphenous nerve.
Remove any fascia to clean out the canal and define the vessels by the scissors technique.
Trace the course of the femoral artery as it passes down into the adductor hiatus. This space
will be more clearly defined during the dissection of the posterior thigh.
 Choose one limb to perform the following dissection: Carefully cut and reflect the sartorius
m. as close to it’s proximal attachment as possible. Carefully cut the rectus femoris as close
to it’s proximal attachment as possible. Reflect the rectus femoris to expose the lateral
femoral circumflex.
 Clean and define rectus femoris. Then continue to clean and define the three vasti muscles.
The simplest way to initiate separation of these muscles is to use your hand to effect blunt
dissection. In separating vastus lateralis, slip your blunt edge between the muscle and the
iliotibial band as far as possible. You will be stopped by the lateral intermuscular septum,
to which the iliotibial band and the muscle are attached. The iliotibial band will be fully
defined in the next dissection. Vastus intermedius, lying below vastus lateralis and vastus
medialis, may be isolated by blunt and sharp dissection, but in rare cases, these muscles have
been found as a single fleshy mass. If sharp dissection is attempted, proceed carefully to
separate the fibers. Follow the quadriceps to their distal insertion on the patella via the
quadriceps tendon. Examine the patellar tendon joining the patella and tibial tuberosity.
 Remove any deep fascia from the medial thigh to expose the adductor muscles.
 Find gracilis from its attachments at the inferior pubic ramus. Clean and separate it from the
other adductor muscles, preserving its distal attachment.
 Trace pectineus and adductor longus and their distal attachment along the length of the linea
aspera. Observe the profunda femoris artery and its vessels as they run between these
muscles. Clean the main vessels and locate the perforating arteries as they branch in this
region, penetrating the adductors.
 Clean and separate adductor brevis anteriorly from adductor longus, and posteriorly from
adductor magnus. The brevis muscle may be hard to distinguish from the magnus at first, so
locate the medial edge of the muscle and then separate by blunt dissection. Anomalies have
been observed where the adductors occur as more than or less than the usual number of
muscle bellies.
 Locate the obturator nerve which pierces through the obturator foramen into the medial
compartment, passing deep to pectineus. It divides into the anterior and posterior obturator
nerves just superior to adductor brevis. The anterior branch will pass anterior to adductor
brevis, while the posterior branch passes posteriorly.
 Choose one limb to perform the following dissection: Carefully dissect the knee joint
capsule, preserve the collateral ligaments, and clean the patellar ligament. Do not cut any
muscular attachments about the knee. Then carefully cut the patellar ligament near the tibial
tuberosity. Reflect the patella superiorly and inspect the articulating surfaces of the patella
and femur. Continue to inspect the tibiofemoral articulation and note the structure and
location of the menisci and cruciate ligaments. Move the knee through flexion and extension
and note the motions of these structures.
STRUCTURES OF THE GLUTEAL
REGION, POSTERIOR THIGH, AND
POPLITEAL FOSSA
Figure 3.1 – The muscles of the posterior thigh.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Figure 3.3 – Muscles for the gluteal region.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Gluteal Region
The gluteal region spans the area on the posterior aspect of the pelvic girdle, superior to
the thigh (Fig 3.3). All muscles in this region are uniarticular, functioning only at the hip. The
three gluteal muscles are layered, each one deeper than the previous. The largest and most
superficial of these is gluteus maximus, which originates along the posterior ilium, sacrum, and
thoracolumbar fascia.
It is also attached to a large portion of the external surface of the
sacrotuberous ligament, which will be discussed later. Distally, 3/4 of gluteus maximus attaches
into the iliotibial band, and 1/4 into the gluteal tuberosity of the femur. The latter, deep and
inferior portion of the muscle is the only part attaching directly into bone. All fibers of gluteus
maximus control hip extension and external rotation, while the inferior fibers adduct the hip and
the superior fibers abduct the hip. Gluteus medius lies in the next layer, attaching proximally to
the gluteal surface of the ilium, and to an aponeurosis which covers its external surface. Distally,
it inserts into the superior aspect of the greater trochanter. With this positioning, it serves as the
primary hip abductor, but the anterior fibers contribute to flexion, pelvic stabilization, and
slightly to internal rotation. The posterior fibers contribute to extension and external rotation of
the hip. Gluteus medius is palpable just inferior to the anterior portion of the iliac crest. It is
most noticeable while standing on one leg, as it prevents contralateral tilt of the pelvis. Gluteus
minimus is the deepest of the three gluteal muscles, attaching from the anterior ilium to the
anterior aspect of the greater trochanter. The anterior fibers contribute to hip flexion, abduction,
internal rotation and pelvic stabilization and the posterior fibers contribute to hip abduction,
extension and external rotation.
The remaining six muscles of this region are the small external rotators. These muscles
will be discussed in order of their position, from superior to inferior. Piriformis lies immediately
inferior to gluteus medius. Proximally, it attaches to the anterior surface of the sacrum, then
inserts into the greater trochanter through the greater sciatic foramen, which will be discussed
later. The piriformis is often referred to as the “key” to the gluteal region because a number of
structures enter this region by passing either superior or inferior to it - as the rest of the external
rotators do. The next three muscles blend together to form a tricipital tendon attaching distally
on the medial aspect of the greater trochanter. Alternatively, they will present as one muscle
belly. They are found immediately inferior to piriformis, and just deep to the sciatic nerve.
Obturator internus is the middle muscle of the three. It derives its name from its proximal
attachment at the internal surface of the membrane covering the obturator foramen and the bone
surrounding it. From here, it travels posteriorly to enter the gluteal region through the lesser
sciatic foramen, where it loops around the lesser sciatic notch to attach to the greater trochanter.
On its deep surface, the muscle is entirely tendinous - allowing it to slide undamaged through the
notch. The surrounding muscles are the superior and inferior gemelli. The superior gemellus
attaches from the posterior surface of the ischial spine to the greater trochanter - blending with
the other two muscles. The inferior gemellus attaches from the posterior surface of the ischial
tuberosity to the greater trochanter. Obturator externus lies deep between the inferior edge of
the inferior gemellus and the superior edge of quadratus femoris. It attaches from the external
surface of the obturator foramen, and its membrane to the trochanteric fossa of the femur.
Quadratus femoris, the largest and most inferior of the external rotators, is named for its
quadrangular shape. It originates at the ischial tuberosity and inserts into the intertrochanteric
crest. The external rotators will all be visible in dissection, deep to gluteus maximus.
Fi
gure 3.4 – Lateral view of the pelvic girdle displaying the lesser and greater sciatic foramina.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Two ligaments, also found in this area, are important landmarks defining the two
anatomical spaces of the gluteal region (Fig 3.4). The sacrotuberous ligament lies deep to
gluteus maximus, serving also as a partial proximal attachment for this muscle. The ligament
itself, attaches from the posterior superior iliac spine, along the lateral edge of the sacrum and the
tip of the coccyx to the ischial tuberosity.
The sacrospinous ligament lies deep to the
sacrotuberous ligament, attaching from the sacrum to the ischial spine. The greater sciatic
foramen is bordered by the greater sciatic notch, the sacrotuberous, and the sacrospinous
ligaments. It contains piriformis, the superior and inferior gluteal nerves and arteries, and the
sciatic nerve.
The lesser sciatic foramen is defined by the lesser sciatic notch and the
sacrospinous and sacrotuberous ligaments. It contains the tendon of obturator internus, and
lesser nerves and arteries which will not be discussed.
A number of peripheral nerves may be found in the gluteal region, but only those which
innervate the lower limb will be discussed. The sciatic nerve, as discussed within the context of
the posterior thigh, originates from spinal nerves L4 - S3 of the lumbosacral plexus. It typically
enters the gluteal region inferior to piriformis through the greater sciatic foramen, passing above
the surfaces of the external rotators before entering the posterior thigh. In other cases, the sciatic
nerve may pass through piriformis, and more rarely, above the muscle. Also, the sciatic nerve
may have already divided into the tibial and common fibular nerves in this region. In this case,
the tibial nerve will still usually enter below the piriformis, while the common fibular nerve will
enter superior to or through the muscle.
Figure 3.5 – Posterior view of the gluteal region with the superior and inferior gluteal arteries and nerves exposed.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Innervation of the gluteal muscles occurs by the superior and inferior gluteal nerves (Fig
3.5). The superior gluteal nerve originates from spinal nerves L4 - S1 of the lumbosacral plexus,
and enters the gluteal region superior to piriformis through the greater sciatic foramen. It
supplies gluteus medius, gluteus minimus, and tensor fascia latae. The inferior gluteal nerve
originates from spinal nerves L5 - S2, entering inferior to piriformis, also through the greater
sciatic foramen. This nerve innervates gluteus maximus only. All of the external rotators
receive innervation directly from the lumbosacral plexus, except for obturator externus, which is
supplied by the obturator nerve. Obturator internus and piriformis are innervated by spinal
nerves L5 - S2. The superior and inferior gemelli, and quadratus femoris are innervated by spinal
nerves L5 - S1.
Blood supply to the gluteal region occurs by the superior and inferior gluteal arteries,
which accompany the nerves of the same name. The superior gluteal artery branches after
entering the gluteal region, sending one branch deep to and one branch superficial to gluteus
medius, supplying all three gluteal muscles and tensor fascia latae. The inferior gluteal artery
primarily supplies gluteus maximus.
Posterior Thigh
The muscles of the posterior thigh are often referred to as the hamstring muscles (Fig
3.1).
The common definition for the hamstrings involves three criteria:
1) the proximal
attachment is the ischial tuberosity, 2) the distal attachment is on either of the bones of the lower
leg, and 3) innervation occurs from the tibial division of the sciatic nerve. Thus, the hamstrings
are biarticular, functioning as extensors of the hip, and flexors of the knee. By this definition,
only three of the muscles of the posterior thigh are considered hamstrings. Semimembranosus
is the most medial muscle, named for its proximal aponeurotic tendon. Distally, it attaches to the
posterior aspect of the medial tibial condyle. In the popliteal fossa, of the posterior knee, it
blends with the oblique popliteal ligament and fascia which covers the joint capsule and the
popliteus muscle. Semitendinosus, lying superficial to semimembranosus, is named for its cordlike distal tendon which may be palpated on the medial aspect of the posterior knee joint. It
inserts at the anteromedial aspect of the tibia, joining sartorius and gracilis to form the pes
anserinus. Biceps femoris is named for its two heads, but only the long head is considered a
hamstring muscle. Proximally, the long head of biceps femoris blends with semitendinosus near
the ischial tuberosity, then runs laterally across the thigh to attach to the head of the fibula.
The short head of biceps femoris does not belong to the hamstrings. It originates at the
lateral lip of the linea aspera, and then blends with the long head, terminating at the head of the
fibula. Crossing only the knee joint, it is uniarticular, flexing the knee during a shortening
contraction. The posterior fibers of adductor magnus are discussed as a part of the posterior
compartment, due to its hamstring characteristics. Adductor magnus attaches from the ischial
tuberosity and receives dual innervation, with its posterior fibers being controlled by the tibial
portion of the sciatic nerve, while the anterior fibers are innervated by the obturator nerve.
Distally, posterior adductor magnus attaches to the adductor tubercle of the femur, and thus
functions in hip extension only.
Figure 3.2 – The origin of the tibial and common fibular nerves, forming the sciatic nerves from spinal nerves L4S3. Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
The structures of the posterior thigh receive their blood supply from the perforating
arteries, which branch transversely and posteriorly from the profunda femoris artery. The main
peripheral nerve running through this region is the sciatic nerve, originating from the
lumbosacral plexus, specifically, spinal nerves L4 - S3 (Fig 3.2).
This is actually two separate
nerves, the tibial nerve and common fibular nerve, wrapped together in a connective tissue
sheath. The sciatic nerve begins its course down the thigh in the gluteal region, entering
subcutaneously at the lower edge of gluteus maximus, between the ischial tuberosity and the
greater trochanter. Prolonged pressure at this point, perhaps by sitting for an extended period,
may constrict nerve supply to the leg and cause numbness, or cause the leg to “fall asleep.”
From here it dives deep to the hamstrings, then presents its typical bifurcation just superior to the
popliteal fossa into the tibial and common fibular nerves. Only a small initial length of sciatic
nerve may be present in the thigh, however the nerves may divide early in the gluteal region and
run separately through the posterior compartment. As previously mentioned, the tibial nerve is
responsible for innervation of the hamstrings and posterior adductor magnus, sending branches
medially from the sciatic nerve. The common fibular nerve innervates only the short head of
biceps femoris, branching laterally from the sciatic nerve.
Popliteal Fossa
The popliteal fossa is the diamond-shaped posterior region of the knee joint (figure 3.6).
It is filled with adipose, nerves and vessels.
The superior borders of the fossa are the
semimembranosus and semitendinosus muscles medially, and biceps femoris laterally. The
heads of the gastrocnemius muscle form the lateral and medial borders inferiorly. The anterior
floor is composed mainly of the posterior joint capsule of the knee, while the posterior roof is
composed of the fascia lata. The contents of the popliteal fossa from medial to lateral are the
popliteal artery then vein, the tibial nerve, and the common fibular nerve.
Figure 3.6 – The popliteal fossa of the right leg (posterior and transverse sections).
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
The popliteal vessels are the deepest lying structures of the fossa, with the artery lying
nearly on the popliteal surface of the femur at the superior end. Wrapped together within a
connective tissue sheath, the two vessels travel down the midline of the fossa along its length as
the femoral artery and vein. Passing through the adductor hiatus in the adductor magnus muscle
from anterior to posterior, the vessels change their name to the popliteal artery and vein. At their
distal end, the vessels bifurcate into the anterior and posterior tibial arteries and veins. This
division occurs just as the vessels run deep to the soleus muscle through a gap in its superior
border.
Four small arteries branch off the popliteal artery to supply the knee joint: the superior
medial, superior lateral, inferior medial, and inferior lateral genicular arteries (Figure 3.7).
These arteries course anteriorly where they anastomose, forming a system of collateral
circulation. Anastomoses occur around all joints to protect against the reduction in blood flow
which may occur as a result of muscular pressure or extreme ranges of joint movement. Blood
vessels will enlarge as more blood tries to flow through them. By this mechanism, collateral
circulation may take over blood supply to a region if the primary vessel becomes occluded. Such
a system of anastomoses also occurs in the hip by the inferior gluteal arteries and the medial and
lateral femoral circumflex arteries, which intersect posteriorly.
The tibial nerve is located
superficial to the popliteal vessels, in the midline of the fossa. It descends deep between the
heads of the gastrocnemius muscle, passing through the gap in soleus with the popliteal artery
and nerve, where it enters the lower leg. The tibial nerve has one cutaneous branch, the sural
nerve, which descends superficially halfway down the leg before piercing the deep fascia (Fig
3.7). The common fibular nerve is located along the superior lateral border of the fossa, just
medial to the tendon of biceps femoris. It leaves the fossa by superficially crossing the lateral
head of gastrocnemius, and diving toward the head of the fibula where it may be palpated.
Figure 3.6 – The popliteal fossa of the right leg (frontal section).
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Figure 3.7 – The courses of the medial (tibial N) and lateral (common fibular N) sural nerves.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Dissection Guide III
During this dissection session, the structures of the posterior thigh, gluteal region and popliteal
fossa will be explored.
Gluteal Region
Nerves, Arteries and Structures:
Greater sciatic foramen
Superior gluteal nerve
Superior gluteal artery
Lesser sciatic foramen
Inferior gluteal nerve
Inferior gluteal artery
Sciatic nerve
Sacrotuberous ligament
Muscles:
Gluteus maximus muscle
Gluteus medius muscle
Gluteus minimus muscle
Piriformis muscle
Superior gemellus muscle
Obturator internus muscle
Inferior gemellus muscle
Obturator externus muscle
Quadratus femoris muscle
 On the posterior aspect, remove the skin and superficial fascia from the gluteal region. The
easiest approach will be to begin from the medial edges, near the sacral attachment of
gluteus maximus, and proceed laterally. Attempting to skin the gluteal region from a lateral
approach will lead to the fibers of gluteus maximus entering the iliotibial band and cause
some severing of the muscle.
Examine the superior and inferior borders of the gluteus maximus. A portion of gluteus medius
will be visible superior to gluteus maximus and the sciatic nerve should be seen emerging from
beneath its inferior border. The superior border of gluteus maximus will be located below the
fascia lata which covers it and gluteus medius.
 By palpation, locate the bulge of gluteus maximus at the superior edge. Lift the fascia with
forceps and incise it along this edge. Insert your hands beneath the superior and inferior
borders and by blunt dissection, separate the muscle from those deep to it. Be aware that the
inferior gluteal nerve and artery are located in this area on the deep surface of the gluteus
maximus. You will be able to palpate them during your blunt dissection. Be careful not to
sever their attachments to this and the underlying structures.
 Now make a longitudinal cut perpendicular to the muscle fibers near the medial border of
gluteus maximus along the sacrum. Do not cut deep enough to damage the structures beneath
the muscle. Reflect the muscle laterally, and identify the inferior gluteal nerve and artery.
Cut these structures so that they may be identified on either end of their insertions inferior to
piriformis and into gluteus maximus. Clean and distinguish the artery from the nerve.
Detach the medial portion of gluteus maximus from the sacrotuberous ligament in order to
more fully expose the underlying structures.
The inferior border of piriformis may be located by tracing the sciatic nerve up to this point.
where it typically enters the gluteal region. Remember that the nerve may enter through or
superior to piriformis as well. Geometrically, the inferior border of piriformis should be found
along a line from the greater trochanter to the midpoint of a line between the posterior superior
iliac spine and the tip of the coccyx. The inferior gluteal nerve and artery should also have been
traced to this origin previously.
Emerging from between the superior border of piriformis and the inferior border of gluteus
medius should be the superior gluteal nerve and artery. Observe the fascia covering the gluteus
medius, and how some of its superficial fibers arise from this fascia. Notice the anterior extent of
the gluteus medius beneath the iliotibial band, which is responsible for internal rotation by this
muscle.
 Sweep your fingers deep to this muscle to separate it from gluteus minimus. Cut gluteus
medius near its proximal attachment perpendicular to its fibers and reflect the muscle to
expose the gluteus minimus and the superior gluteal nerve and artery on its surface. Note
the space from which these structures enter this region. This is the greater sciatic foramen.
Try to clean the sacrospinous and sacrotuberous ligaments which border this opening to
better define this space. These ligaments will bear the idealized, striking white appearance
of connective tissue.
Immediately inferior to the piriformis will be the superior gemellus, the obturator internus and
the inferior gemellus muscles. These three will blend as they insert into the greater trochanter.
The superior gemellus may be traced proximally to the ischial spine, and the inferior gemellus to
the ischial tuberosity. The proximal attachment of obturator internus on the internal surface of
the obturator foramen will not be visible, but notice its course through a small opening inferior to
the greater sciatic foramen. This is the lesser sciatic foramen, and the lesser sciatic notch on
which obturator internus slides.
Inferior to the inferior gemellus is the rectangular-shaped quadratus femoris muscle, attaching
from the ischial tuberosity to the posterior aspect of the greater trochanter. Separate these two
muscles and search deep between these two muscles to locate the obturator externus tendon.
Posterior Thigh
Nerves and Structures:
Sciatic nerve
Pes anserinus
Muscles:
Semitendinosus muscle
Semimembranosus muscle
Biceps femoris muscle (1ong and short
heads)
 Complete the removal of the skin from the posterior thigh from Dissection # 1.
 First, the fascia lata must be removed from the posterior thigh, and the iliotibial band must
be defined. Locate the most inferior portion of gluteus maximus where it inserts into the
iliotibial band. From this point make a longitudinal incision to a point below the knee joint.
Be careful to preserve its distal attachment. Remove all the fascia lata from the posterior
thigh, leaving the IT band intact. Separate the IT band from the lateral intermuscular septum
along its length by sharp dissection.
Clean the sciatic nerve and preserve its muscular branches if possible. Define and separate the
hamstring muscles, thereby exposing the length of the nerve. Verify their common origin at the
ischial tuberosity, and note how semitendinosus and biceps femoris long head blend at this
proximal attachment. Observe the separate membranous tendon of semimembranosus at the
ischial tuberosity.
Define the short head of biceps femoris, with its proximal attachments at the linea aspera, and
the lateral intermuscular septum. It may be difficult to separate this muscle proximally from
vastus lateralis which shares the same proximal attachment. Clean the distal attachment of
biceps femoris at the head of the fibula.
The distal attachment of semimembranosus at the medial tibial condyle will not be defined at
this stage. It has posterior expansions which are covered by the superficial fascia of the popliteal
fossa which will be removed later.
Clean the distal attachment of semitendinosus and its distinct cord-like distal tendon, on the
medial aspect of the tibia. Do not separate it from sartorius and gracilis as it crosses the knee
joint. Now the pes anserinus will be fully defined as the distal attachment of these three
muscles, resembling a goose's foot.
Within the posterior thigh, try to locate the perforating arteries of profunda femoris, which
supply the hamstrings. Look on the medial side at the posterior surface of adductor magnus. Try
to clean and define these branches as they insert into the muscles. They may be difficult to locate
without damaging them so do not spend a large amount of time trying to accomplish this.
Popliteal Fossa
Nerves and Arteries:
Popliteal artery
 Superior lateral genicular artery
 Superior medial genicular artery
 Inferior lateral genicular artery
 Inferior medial genicular artery
Popliteal nerve
 Tibial nerve


Common fibular nerve (peroneal)
Sural nerve
Muscles:
Gastrocnemius muscle
Soleus muscle
Plantaris muscle
Within the superficial fascia between the two heads of gastrocnemius, the sural nerve will be
found. Incise the fascia and trace the nerve proximally to its origin on the tibial nerve. Remove
the fat and fascia to expose the tibial nerve. Trace its descent into the gap in soleus. This will be
examined more closely in the following dissections. In the lateral portion of the popliteal fossa,
find and isolate the common fibular nerve running along the medial border of biceps femoris.
Within the fossa, displace the tibial nerve to expose the dense vascular sheath containing the
popliteal vessels.
 Open the sheath and remove the vein to more closely observe the artery and its branches, the
genicular arteries. Be careful to preserve all arterial branches as you remove the veins.
 Locate the lateral superior genicular artery and medial superior genicular artery. They
are located deep in the popliteal fossa, proximal to the attachments of the gastrocnemius
muscle (proximal to the knee joint). To assist with identification of the genicular arteries;
trace the arteries until they disappear deep to the heads of gastronemius and the hamstring
muscles. If the arteries stop and pierce the muscle they probably are muscular branches as
opposed to the genicular.
 Locate the lateral inferior genicular artery and medial inferior genicular artery. The
lateral inferior genicular artery is often located deep to the plantaris and the lateral head of
the gastrocnemius. The medial inferior genicular artery can be traced under the medial
head of gastrocnemius in a space between it’s proximal attachment and the soleus.
Trace the popliteal artery proximally to its origin at the adductor hiatus in adductor magnus.
Delicately define this gap and establish the continuity of the femoral and popliteal artery.
Clean the popliteal fossa of fat and fascia and observe its borders and diamond shape. Expose the
posterior surface of the knee joint capsule which defines the floor of the fossa. Notice the distal
attachment of semimembranosus and its contribution to the oblique popliteal ligament of the
joint capsule.
COMPARTMENTAL ORGANIZATION
OF THE LEG,
POSTERIOR COMPARTMENT
STRUCTURES, AND
STRUCTURES OF THE FOOT SOLE
Figure 4.1 – Transverse section of the leg displaying compartments, nerves, and vessels.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Compartmental Organization of the Leg
The leg is divided into three compartments by a combination of bones, intermuscular
septa, the interosseus membrane, and the deep fascia of the leg (Fig 4.1). These structures also
serve as important sites of attachment, increasing the overall surface area available in the leg.
There are two intermuscular septa in the leg, both of which branch laterally off the fibula. The
anterior intermuscular septum extends from the anterior aspect of the fibula to the deep surface
of the deep fascia.
It separates the lateral and anterior compartments.
The posterior
intermuscular septum branches from the lateral fibula to the deep fascia, separating the lateral
and posterior compartments. The interosseus membrane separates the anterior and posterior
compartments, connecting between the tibia and fibula. Its fibers run diagonally inferiorly from
tibia to fibula, lending support to the fibula which is pulled inferiorly by many of the muscles
which attach to it. The deep fascia of the leg envelops the entire lower leg, except for the
anteromedial surface of the tibia which is subcutaneous. It serves as a major site of muscle
attachment, particularly in the anterior and lateral compartments, which will be apparent in
dissection.
The anterior compartment is bordered anteriorly by the deep fascia, posteriorly by the
interosseus membrane, medially by the tibia and laterally by the anterior intermuscular septum.
In general, the muscles of this compartment function in ankle dorsiflexion and extension of the
toes. Innervation occurs from the deep fibular nerve, and blood supply from the anterior tibial
artery. The triangular lateral compartment is the smallest of the three, bordered by the deep
fascia laterally, the anterior intermuscular septum medially, and the fibula and posterior
intermuscular septum posteriorly. The superficial fibular nerve runs through this compartment
which does not contain a major blood vessel. The posterior compartment is the largest of the
three, bordered anteriorly by the tibia, fibula, interosseus membrane, and posterior intermuscular
septum.
The deep fascia borders this compartment posteriorly.
The muscles of this
compartment are typically ankle plantar flexors and toe flexors. The nerve of this compartment
is the tibial nerve, and the major arteries are the posterior tibial and fibular arteries.
Posterior Compartment of the Leg
The muscles of the posterior compartment are arranged in three layers: superficial,
middle, and deep. The superficial layer contains three muscles collectively known as the triceps
surae. They all attach distally to the calcaneus via the Achilles tendon, and cause ankle plantar
flexion, and inversion at the intertarsals joint. Gastrocnemius is most superficial, with two
heads, each attaching proximally from the posterior superior surface of the femoral epicondyles.
The gastrocnemius is triarticular, crossing the knee joint which it flexes. Soleus is the deepest of
the three, with an extensive proximal origin spanning the soleal line of the tibia, and the
head/neck of the fibula. A gap between these attachments occurs where the tibial nerve and
popliteal vessels pass as they descend into the leg (Fig 4.2). Plantaris is a small vestigial
muscle, which has a small belly located just deep to the lateral head of the gastrocnemius and its
attachment to the lateral femoral condyle. A small, thin tendon extends from the muscle to the
calcaneus between gastrocnemius and soleus. Plantaris is technically triarticular, serving the
same functions as gastrocnemius, but its actual contributions are minimal.
Figure 4.2 – The superficial layer of the posterior compartment with gastrocnemius and plantaris removed. The
popliteal vessels and tibial nerve descend into the leg from the popliteal fossa.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
The middle layer contains two muscles which control flexion of the digits. Flexor
digitorum longus is located medially within the middle 1/3 of the posterior surface of the tibia
and inserting into the second through the fifth distal phalanges. Flexor hallucis longus lies
lateral in the middle layer, attaching to the distal 2/3 posterior surface of the tibia and passing
under the sustentaculum tali of the talus to the first distal phalanx. The larger muscle belly of
flexor hallucis longus indicates its importance in locomotion as it affects the push-off of the first
toe by controlling flexion. Both muscles plantar flex the ankle and flex the digits.
The deep layer of the posterior compartment contains one muscle, the tibialis posterior.
This muscle attaches along the tibia, fibula, and interosseus membrane, then sends its tendon
posterior to the medial malleolus before it inserts into the navicular tuberosity, medial/mid/lateral
cuneiform and base of metatarsals 2-4 of the foot. Tibialis posterior acts in plantar flexion, and
inversion.
Figure 4.3 - The tendons of the muscles of the middle and deep layers of the posterior compartment as they cross
the ankle joint to the medial malleolus.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
The relative positions of the muscles of the middle and deep layer vary as they descend
the leg. Proximal to the ankle joint, the flexor digitorum longus is most medial, the tibialis
posterior is in the middle, and the flexor hallucis longus is lateral. As they cross the ankle joint,
the tendons of all three pass posterior to the medial malleolus along with the posterior tibial
artery and the tibial nerve, and their positioning may be recognized by the mnemonic, “Tom,
Dick, and not Harry,” which stands for, from medial to lateral:
tibialis posterior, flexor
digitorum longus, posterior tibial artery, tibial nerve and flexor hallucis longus (Fig 4.3).
Tibialis posterior has passed deep to flexor digitorum longus just before the medial malleolus. In
the foot, flexor hallucis longus crosses deep to flexor digitorum longus to lie medial and continue
to its distal attachment on the plantar surface of the first distal phalanx. Flexor digitorum longus
ends up lateral and extends to its distal attachment on digits 2-5. Tibialis posterior remains
somewhat medial, but also spreads laterally across the sole of the foot in its extensive distal
attachment.
The last muscle of the posterior compartment is popliteus, which may be considered a
part of the deep layer. It is a triangular muscle located posterior to the knee joint, crossing only
this joint (Fig 4.2). Proximally, it attaches to the lateral aspect of the lateral femoral condyle
within the fibrous joint capsule. Distally, it fans out to attach to the posterior surface of the tibia,
just above the soleal line. Popliteus serves an important function at the knee, internally rotating
the tibia, and externally rotating the femur to unlock the joint and allow flexion to occur.
Extending from the medial malleolus posteroinferiorly to the medial surface of the
calcaneus is the flexor retinaculum. This thickening of the deep fascia holds the tendons,
arteries and nerves which pass behind the medial malleolus. This is the thickest and most
complex of the ankle retinacula, sending three septa from its deep surface to the tibia and
calcaneus. This divides the area deep to the retinaculum into four compartments, each housing
one of the tendons or the nerve and artery which pass beneath it.
The tibial nerve innervates all seven muscles of the posterior compartment.
As
previously mentioned, it passes deep through the gap in soleus, and then travels down on the
surface of the flexor digitorum longus (Fig 4.4). The tibial nerve terminates after passing
posterior to the medial malleolus by bifurcating into the medial and lateral plantar nerves which
supply the sole of the foot. Throughout its length, it sends muscular branches into the muscles of
the posterior compartment.
Figure 4.4 – View of the tibial nerve as it travels down the surface of flexor digitorum longus to supply the muscles
of the posterior compartment.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Blood supply to the posterior compartment is primarily via the posterior tibial artery.
This is a branch of the bifurcation of the popliteal artery which typically occurs just superior to
the gap in soleus. It courses down the leg, deep to soleus, on the surface of flexor digitorum
longus with the tibial nerve. The termination of the posterior tibial artery is analogous to that of
the tibial nerve, as the artery bifurcates into the medial and lateral plantar arteries, which supply
the sole of the foot. The fibular artery branches from the posterior tibial artery just inferior to
the gap in soleus. It runs across the surface of tibialis posterior, then passes deep to flexor
hallucis longus at the muscle’s most proximal portion. The fibular artery supplies the lateral
compartment and the lateral part of the posterior compartment before ending as a series of small
branches at the ankle.
Sole of the Foot
The sole of the foot is divided into four muscular layers, containing both extrinsic and
intrinsic musculature. Intrinsic muscles have both attachments within the bones of the foot,
while extrinsic muscles attach proximally outside of the foot. These layers are covered by
superficial structures, including the skin and the superficial and deep fasciae. The skin of the
sole of the foot is thick and callous, particularly at points of contact with the ground. The skin at
the heads of the metatarsals, the distal plantar surfaces of the toes, and the heel are such points,
with the heel having the thickest layer. The superficial fascia is of a different quality than in the
rest of the lower limb. The primary component is still fat, but it tends to be more densely
packed, especially in the areas just mentioned. The connective tissue fibers of the superficial
fascia are bound very tightly to the deep fascia below.
The deep fascia of the midline of the
sole is called the plantar aponeurosis and differs from that at the medial and lateral aspects. It
is more tendinous in appearance, and is thicker than the medial and lateral deep fascia.
Proximally, it attaches to the calcaneus, then extends toward the toes, where it fans out, and then
divides into digitations to attach to each toe. Its complex distal attachments actually include the
flexor tendon sheaths, the deep transverse metatarsal ligament, the bases of the proximal
phalanges, and the skin through some superficial fibers. The plantar aponeurosis functions as
support for the arch of the foot, where it is easily palpable. On the medial and lateral aspects, the
deep fascia serves mainly to cover the small intrinsic muscles.
Figure 4.5 – Blood supply and innervation to the first layer of muscles of the foot.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
The first layer consists of three intrinsic muscles, and two sets of nerves and arteries
which will be discussed later (Fig 4.5). Flexor digitorum brevis attaches from the calcaneal
tuberosity and plantar aponeurosis and sends tendons to the middle phalanges of digits 2-5.
These tendons split near their distal ends and attach at either side of the phalanges. This allows
the tendons of flexor digitorum longus, which lie deep to the tendons of flexor digitorum brevis,
to pass through, reaching their attachment at the distal phalanges. The tendons of both muscles
are enveloped in flexor or digital tendon sheaths from the heads of the metatarsals to the bases
of the distal phalanges. These bilayered fibrous sheaths attach to the medial and lateral portions
of the plantar aspect of the bones, forming tunnels which hold the tendons close to the bone
while they function in metatarso-phalangeal, and proximal interphalangeal flexion. Abductor
digiti minimi originates from the plantar surface of the calcaneus and plantar aponeurosis and
inserts into the lateral aspect of the base of the fifth proximal phalanx, serving to abduct the fifth
digit. Abductor hallucis attaches from the medial process of the calcaneal tuberosity to medial
aspect of the base of the first proximal phalanx, and abducts the first digit. Often, its proximal
attachment is much more extensive, spanning to the talus and possibly, the navicular.
The second layer of the foot consists of two intrinsic muscles and the extrinsic muscle
tendons of flexor hallucis longus and flexor digitorum longus (Fig 4.6). Recall that in the foot,
flexor hallucis longus is medial to flexor digitorum longus. After these tendons penetrate the
abductor hallucis muscle, flexor hallucis longus crosses deep to flexor digitorum longus to
assume a more medial position. The tendon of flexor hallucis longus is held in place by a flexor
tendon sheath as it attaches to the distal phalanx, but it does not pass deep to a split tendon as do
the tendons of flexor digitorum longus. The tendons of flexor digitorum longus serve as an
attachment site for the intrinsic muscles of this layer. The flexor accessorius or quadratus
plantae muscle attaches proximally to the calcaneal tuberosity and distally to the lateral aspect of
the tendon of flexor digitorum longus, just before it divides. It aids this extrinsic muscle by
aligning the pull of its tendons with the sagittal plane. The other intrinsic muscles of this layer
are a group of four small muscles called the lumbricals. These muscles attach proximally from
the sides of the flexor digitorum longus tendons. The first lumbrical attaches to the medial side
of the first tendon, while the lateral three lumbricals attach from both of the tendons which they
lie between. Distally, they insert at the medial aspect of the extensor expansions at the proximal
phalanges, which will be discussed with the dorsum of the foot. By this arrangement, the
lumbricals have the unique ability to flex the metatarso-phalangeal joints and extend the
interphalangeal joints.
Figure 4.6 – Muscles of the third layer of the foot.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
In the third layer are three small intrinsic muscles confined to the metatarsal region of the
foot (Fig 4.6). Flexor hallucis brevis originates from the cuboid and cuneiforms before it splits
and inserts into the medial and lateral portions of the plantar aspect of the first proximal phalanx.
It flexes the first proximal interphalangeal joint. Adductor hallucis has a large oblique head and
a small transverse head, both of which adduct the first digit.
The oblique head attaches
proximally from the long plantar ligament and the bases of metatarsals 2-4, while the transverse
head attaches from the transverse ligament. The two heads merge distally and blend with the
distal attachment of the lateral portion of flexor hallucis brevis at the first proximal phalanx.
Flexor digiti minimi brevis originates from the base of the fifth metatarsal and inserts into the
base of the proximal phalanx of the same toe, contributing to its flexion.
In the fourth layer of the sole of the foot, we will be most concerned with the extrinsic
tendons which insert in this layer. The intrinsic muscles found in this layer are the plantar and
dorsal interossei muscles. Also located here are the long plantar and spring ligaments. The
long plantar ligament attaches from the calcaneal tuberosity to the bases of the metatarsals. The
spring ligament connects the sustentaculum tali and the navicular. Both ligaments serve to
anchor the bones of the foot and support the arch. The tendons of tibialis posterior and fibularis
longus insert distally in the fourth layer of the foot. Tibialis posterior enters deep to abductor
hallucis and attaches primarily to the navicular, but may spread out to span the cuneiforms, the
cuboid, and the bases of the metatarsals. In dissection, this will be visible deep to flexor hallucis
longus and flexor digitorum longus. Fibularis longus passes behind the lateral malleolus then
passes deep to abductor digiti minimi to enter the sole, where it fits into a groove on the cuboid.
The long plantar ligament covers this groove, and forms a tunnel in which the tendon of fibularis
longus actually sits. From the tunnel, it travels medially to attach on the plantar surface of the
medial cuneiform and the base of the first metatarsal.
The blood supply and innervation to the sole of the foot come from the medial and lateral
plantar arteries and the medial and lateral plantar nerves of the first layer (Fig 4.7). These
nerves and arteries are considered together because their courses are practically identical. They
result from the bifurcation of the tibial nerve and posterior tibial artery occurring deep to the
abductor hallucis muscle. The lateral plantar nerve and artery cross the sole immediately deep to
flexor digitorum brevis to supply the structures of the middle and lateral aspect of the sole. The
nerve innervates the abductor digiti minimi, quadratus plantae, and the lateral three lumbricals.
The medial plantar artery supplies medial and midline structures, and the medial plantar nerve
innervates abductor hallucis, flexor digitorum brevis, and the first lumbrical.
Figure 4.7 – Muscles of the third layer of the foot.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Dissection Guide IV
During this dissection period, the entire lower leg or shank and foot will be skinned, and the
structures of the posterior leg and of the sole of the foot will be examined.
 To skin the leg, begin by making a vertical incision along the medial surface of the tibia,
stopping just above the medial malleolus.
 From this point, make an oblique cut on the medial surface to the point of the heel.
 Make a similar cut laterally to the heel, crossing the lateral malleolus.
 Remove the skin and superficial fascia from the leg. Be cautious of the deep fascia and its
retinacula around the ankle.
 On the dorsum of the foot, make a longitudinal cut at the midline from the ankle, then make
a transverse cut across the base of the toes and intersect this with. Both of these cuts should
be very superficial, just deep enough to penetrate the skin.
 Reflect the skin and remove the thin layer of superficial fascia to expose the extensor
tendons. On the sole of the foot (plantar surface), make a similar transverse cut at the base of
the toes and longitudinal cut to the heel.
 Remove the skin and superficial fascia to the level of the plantar aponeurosis. The skin and
superficial fascia here will be very densely packed, and difficult to remove.
Scalpel blades will dull quickly, so more than one change may be necessary to complete this
region.
Posterior Leg
Nerves, Arteries and Structures:
Tibial nerve
Posterior tibial artery
Fibular artery (peroneal)
Anterior tibial artery
Flexor retinaculum
Achilles tendon
Muscles:
Gastrocnemius muscle
Plantaris muscle
Soleus muscle
Popliteus muscle
Flexor hallucis longus muscle
Flexor digitorum longus muscle
Tibialis posterior muscle
 Clean the deep fascia from the back of the leg and cut it vertically from the popliteal fossa to
the calcaneus to remove it. Clean the Achilles tendon of fat and fascia then sever its
attachment about 2 inches above its distal attachment on the calcaneus. Clean the proximal
attachments of the gastrocnemius and separate the heads longitudinally as far inferiorly as
blunt dissection will allow.
 Using your fingers, separate gastrocnemius from soleus by blunt dissection as close as
possible to the Achilles tendon. Look for the tiny tendon of the plantaris between
gastrocnemius and soleus. Remember that this muscle may be absent in your specimen, but
be aware that there are many variations reported for its distal insertion which may not occur
in the Achilles tendon at all. You can now reflect both heads of gastrocnemius and planatais
to expose the deeper structures of the Popliteal fossa. Make the cut approximately half way
between the proximal attachment and the point where the two heads join together. Locate
the popliteus deep to the heads of the gastrocnemius and clean its surface.
 Soleus will now need to be reflected to examine the middle and deep layers of the posterior
leg. Lift the muscle and separate it from the structures below up to its proximal attachments
with your fingers. Be careful to separate the tibial nerve and posterior tibial vessels which
exit the popliteal fossa passing deep to the tendinous arch of the soleus muscle. The belly of
flexor hallucis longus will be visible covering the lower half of the fibula. Reflect the soleus
by carefully cutting the muscle from it’s proximal attachements.
 Flexor digitorum longus will be covering the medial side of the compartment. Locate on its
surface the tibial nerve and posterior tibial artery. Separate and clean these structures and
trace them proximally distally, as they descend into the foot behind the medial malleolus.
This will be examined with the sole of the foot.
 Trace the posterior tibial artery proximately to find a branch traveling towards the anterior
surface. This branch is the anterior tibial artery which will pass between the tibia and
fibula to supply the anterior compartment. The second branch you’ll find is the fibular
artery which will supply the fibular muscles in the lateral compartment
 Tibialis posterior lies deep to the muscles of the middle layer. To view this muscle, reflect
the medial edge of flexor hallucis longus, which should be done easily. Flexor digitorum
longus will be more difficult because some of its fibers attach to the fibers of tibialis
posterior. They may need to be separated by careful sharp dissection.
Find the tendons of these three muscles near the medial malleolus where they are held in place
by the flexor retinaculum, which should be left intact. Try to observe the four compartments of
the flexor retinaculum within which these tendons, the tibial nerve, and posterior tibial artery lie.
Trace the course of flexor hallucis longus, flexor digitorum longus, and tibialis posterior from
proximal to distal. Notice how they change positions, as tibialis posterior passes deep to flexor
digitorum longus just superior to the medial malleolus, to assume their final positions on the sole
of the foot. Remember that flexor hallucis longus will course under the sustentaculum tali of the
calcaneus.
Sole of the Foot
Nerves, Arteries and Structures:
Medial plantar artery
Medial plantar nerve
Lateral plantar artery
Lateral plantar nerve
Plantar aponeurosis
Muscles:
Abductor hallucis muscle
Abductor digit minimi muscle
Flexor digitorum brevis muscle
Quadratus plantae muscle
Lumbrical muscles
Distal tendons of flexor digitorum longus
and flexor hallucis longus
The plantar aponeurosis should already be exposed. Clean its surface and examine its proximal
and distal attachments.
 Relocate the posterior tibial artery and tibial nerve as they pass behind the medial malleolus.
They will each divide and enter the sole of the foot deep to the abductor hallucis as the
medial and lateral plantar arteries and nerves. The proximal attachments of abductor
hallucis and abductor digiti minimi must be severed and the muscles reflected in order to
see these structures more clearly.
 To further trace the paths of the arteries and nerves we will need to remove the plantar
aponeurosis. To expose the muscles below it, split the plantar aponeurosis down the center
of its length. Then carefully cut it close to the calcaneus and the base of the toes. Reflect
these flaps to reveal the underlying muscles. The plantar aponeurosis will adhere tightly to
these muscles, so sharp dissection will be necessary. Now completely remove the
aponeurosis.
Flexor digitorum brevis will be the muscle lying in the middle of the foot.
 Now cut the proximal attachment of flexor digitorum brevis at the calcaneus to expose the
muscles of the second layer. This will also expose the the lateral plantar nerves and artiers as
the traverse from the medial malleolus to the lateral aspect of the foot.
The tendons of flexor digitorum longus and flexor hallucis longus should be visible. Locate the
quadratus plantae, or flexor accessorius, which attaches to the calcaneus and lateral aspect of
flexor digitorum longus. Realize the function of this muscle and visualize how it serves this
function, aligning the pull of flexor digitorum longus. The lumbricals also attach to the tendons
of flexor digitorum longus, coming off between them. Notice their path toward the toes where
they will attach to the medial aspect of the extensor expansions. Clean and clearly identify all the
structures of the sole of the foot.
Muscles of the third and fourth layers can be studied via the course prosections. Identify the
following prosected structures:
Muscles of the Third Layer:
Flexor Digiti Minimi
Adductor Hallucis
Flexor Hallucis Brevis
Muscles of the Fourth Layer:
3 plantar interossei
4 dorsal interossei
Tendon of fibularis longus
Tendon of tibialis posterior
ANTERIOR AND LATERAL
COMPARTMENTS OF THE LEG AND
DORSUM OF THE FOOT
Figure 5.1 – The muscles of the lateral compartment of the leg and their innervation by the common fibular
(peroneal)
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Lateral Compartment of the Leg
The lateral compartment is the smallest of the three compartments of the leg, containing
only two muscles and one nerve (Fig 5.1). Fibularis brevis (peroneus) attaches proximally
from the lower 2/3 of the lateral aspect of the fibula and from the lateral and posterior
intermuscular septa. Distally, its broad tendon descends posterior to the lateral malleolus, then
rounds to the base of the fifth metatarsal where it attaches on its dorsolateral aspect. It has also
been seen to insert more proximally onto the cuboid bone. Fibularis brevis functions in eversion
at the intertarsals joint and in plantar flexion at the ankle joint. Fibularis longus (peroneus)
originates at the upper 2/3 of the lateral aspect of the fibula and deep fascia, lying superficial to
fibularis brevis, covering most of its muscle belly. Its narrower tendon also passes posterior to
the lateral malleolus, extending to the cuboid where it turns medially and crosses the sole of the
foot. This traverse begins in the tunnel formed by the groove on the plantar aspect the cuboid
and the long plantar ligament. Distally, fibularis longus inserts into the plantar surfaces of the
medial cuneiform and the base of the first metatarsal. It shares the same functions as fibularis
brevis in eversion and plantar flexion. Both tendons are held in place by the fibular retinacula.
At the lateral malleolus, the superior fibular retinaculum secures these tendons, as a band of
thickened fascia extending from the malleolus to the calcaneus.
The inferior fibular
retinaculum is more difficult to locate, holding in the tendons on the lateral aspect of the
calcaneus. They are continuous with the superior and inferior extensor retinacula, respectively.
The common fibular nerve enters the lateral compartment, curving anteriorly around the
neck of the fibula and then penetrates the fibers of fibularis longus. Within this muscle, it
bifurcates into the deep fibular nerve and the superficial fibular nerve, which supplies the
lateral compartment. The deep fibular nerve continues on to the anterior compartment through
the anterior intermuscular septum. The superficial fibular nerve descends within the muscle
belly of fibularis longus before emerging near the attachment for fibularis brevis.
It then
continues between these muscles and the anterior intermuscular septum before dividing into two
cutaneous branches within the superficial fascia. The lateral compartment has no major artery,
receiving blood supply primarily from the fibular artery of the posterior compartment, and
anterior tibial artery of the anterior compartment.
Figure 5.2 – The muscles of the anterior compartment of the leg and their innervation by the deep fibular (fibular)
nerve and vasculature by the anterior tibial artery.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Anterior Compartment of the Leg
The four muscles of the anterior compartment run a straight course, unlike the muscles of
the posterior compartment, and are divided by a gap which separates the muscles attaching to the
tibia and fibula (Figure 5.2). This gap contains the major artery and nerve for this compartment.
Tibialis anterior attaches proximally from the anterolateral portion of the tibia and interosseus
membrane and distally to the dorsal surface of the medial cuneiform and base of the first
metatarsal. These are the same attachments as for fibularis longus, which antagonizes the actions
of tibialis anterior, which are dorsiflexion and inversion. Extensor hallucis longus originates at
the distal 2/3 of the fibula and the interosseus membrane. Terminating on the distal phalanx of
the first toe, it controls extension of the first toe, dorsiflexion at the ankle, and contributes
minimally to eversion at the intertarsals joint.
Extensor digitorum longus attaches from the head of fibula and a small portion of the
lateral side of the lateral condyle of the tibia. It functions in extension of the toes, dorsiflexion,
and eversion. The insertion of this muscle consists of special structures called the extensor
expansions or hoods, which span the metatarsophalangeal joint of toes 2-5, and tendinous slips
which insert into the phalanges (Fig 5.3). As the tendons of extensor digitorum longus pass over
the metatarsophalangeal joint, they expand to cover the sides of this joint, and serve as the
attachment for several of the intrinsic muscles of the foot. The lumbricals of the second layer of
the foot insert into the medial aspects of the expansions of digits 2-5.
A muscle still to be discussed, extensor digitorum brevis, sends its three tendons into
the lateral aspects of the expansions of digits 2-4. The extensor expansions do not attach to the
proximal phalanges, so they slide over the metatarsophalangeal joints during flexion and
extension. After crossing the proximal interphalangeal joints, the expansions divide into three
tendinous slips, with a central tendon attaching to the dorsal surface of the middle phalanges, and
two flanking tendons inserting into the dorsal surface of the distal phalanges. The final muscle
of the anterior compartment, fibularis tertius, typically arises from the muscle belly of extensor
digitorum longus. Its actual attachment is on the distal 1/3 of the fibula. Distally, fibularis
tertius attaches to the dorsolateral aspect of the base of the fifth metatarsal. It functions only in
dorsiflexion and eversion.
Figure 5.3 – Retinacula across the ankle joint and aponeurosis attachment of extensor digitorum longus.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
The tendons of the four muscles of the anterior compartment are held in place by the
extensor retinacula (Figure 5.3) as they cross anterior to the ankle joint. The retinacula are
formed from thickenings of the deep fascia. The fibers of the superior extensor retinaculum run
horizontally across from the tibia to the fibula, just superior to the malleoli. The inferior
extensor retinaculum forms a Y-shaped band from the lateral surface of the calcaneus to medial
malleolus and to the deep fascia of the medial side of the sole of the foot.
As stated earlier, the nerve and artery of the anterior compartment lie in a gap which is
defined medially by the muscle attaching from the tibia, tibialis anterior, and laterally by the
muscles attaching from the fibula, the extrinsic toe extensors (Fig 5.4). Innervation comes from
the deep fibular nerve which enters this compartment by piercing the anterior intermuscular
septum and the most proximal portion of extensor digitorum longus. In this proximal region of
the compartment, it lies between this muscle and tibialis anterior, then descends to lie between
tibialis anterior and extensor hallucis longus distally. Just before crossing the ankle, the deep
fibular nerve crosses deep to extensor hallucis longus, entering the dorsum of the foot between
this tendon medially, and those of extensor digitorum longus laterally, then terminates as small
branches. Blood supply is from the anterior tibial artery, which results from the bifurcation of
the popliteal artery below the popliteal fossa. Originating in the posterior compartment, it
pierces the interosseus membrane to enter the anterior compartment, where it joins the deep
fibular nerve, tracing the same course down the leg. As the anterior tibial artery crosses the
ankle and enters the foot, it is renamed the dorsalis pedis artery.
Figure 5.4 – Structures of the dorsum of the foot.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Dorsum of the Foot
As discussed earlier, the four extrinsic muscle tendons attach within the dorsum of the
foot, as does the inferior extensor retinaculum. The remaining structures are two small intrinsic
muscles which share a common attachment from the anterolateral surface of the calcaneus (Fig
5.5). Extensor hallucis brevis inserts into the dorsal surface of the first proximal phalanx, and
extends the first toe. Extensor digitorum brevis has three distal tendons which attach to the
lateral aspects of the extensor expansions of toes 2-4, and serves to extend these digits. Blood
supply to this region is from the dorsalis pedis artery and innervation is from the deep fibular
nerve.
Figure 5.5 – Structures of the dorsum of the foot.
Reprinted with permission from Thieme Atlas of Anatomy, Thieme, 2006
Dissection Guide V
During the final dissection period for the lower limb, the structures of the lateral and anterior
compartments of the leg, and the dorsum of the foot will be examined.
Lateral Compartment of the Leg
Nerves and Structures:
Superficial fibular nerve
Superior fibular retinaculum
Muscles:
Fibularis longus muscle
Fibularis brevis muscle
 Remove the deep fascia from the lateral compartment by careful sharp dissection.
The more superficial muscle is fibularis longus, lying on fibularis brevis. The deep fascia may
be more difficult to remove at the proximal attachment of fibularis longus since it also inserts
into the deep fascia. It is not necessary to completely remove the deep fascia if the structural
integrity of the muscle may be damaged. Be careful not to cut the superficial fibular nerve
which is located on the surface of fibularis brevis.
Distally, locate the thin fibers of the superior fibular retinaculum, securing the tendons of
fibularis longus and brevis in place behind the lateral malleolus. The inferior fibular retinaculum
may not be visible, but search for it on the lateral aspect of the calcaneus, distal to the lateral
malleolus.
Locate the distal insertion of fibularis brevis at the base of the fifth metatarsal and clean this
attachment site. The distal tendon of fibularis longus travels with that of fibularis brevis to the
cuboid bone, where it then crosses within the groove on the plantar surface of this bone.
Traversing the sole of the foot, fibularis longus attaches distally to the medial cuneiform and
base of the first metatarsal.
 Clean the attachment site and the surrounding intrinsic muscles so that the distal tendon of
fibularis longus is clearly visible from the sole of the foot.
The superficial fibular nerve becomes visible in the distal half of the lateral compartment on the
anterior surface of fibularis brevis. It emerges after traveling deep to fibularis longus in the
proximal half of the compartment.
Anterior Compartment of the Leg
Nerves, Arteries and Structures:
Deep fibular nerve
Anterior tibial artery
Superior extensor retinaculum
Inferior extensor retinaculum
Muscles:
Tibialis anterior muscle
Extensor hallucis longus muscle
Extensor digitorum longus muscle
Fibularis tertius muscle
 Clean the deep fascia of the anterior leg, and cautiously search for the extensor retinacula.
The superior extensor retinaculum is located just superior to the medial and lateral malleoli.
Below this, the inferior extensor retinaculum may be distinguished by its Y-shaped band, with
its stem extending from the lateral calcaneus. These retinacula are thin and may be difficult to
see, but attempt to isolate and preserve these structures.
 Remove the remaining deep fascia.
As with the lateral compartment, be careful of proximal attachments which may encompass the
deep fascia. Tibialis anterior adheres tightly to the deep fascia, so sharp dissection is necessary
and the muscle may not be entirely cleaned.
The muscles of the anterior compartment will maintain the same relationship of position
throughout the length of the leg. Separate them by blunt and sharp dissection, tracing their
proximal and distal attachments.
Tibialis anterior is most medial. Trace its origin from the anterolateral tibia and interosseus
membrane to its insertion on the dorsal surface of the medial cuneiform. Extensor hallucis
longus lies lateral to tibialis anterior, attaching proximally from the distal 2/3 of the fibula, and
distally to the first distal phalanx. Its distal tendon forms an extensor expansion over the first
metatarsophalangeal joint.
Between tibialis anterior and extensor hallucis longus lies the gap within which lie the anterior
tibial artery and deep fibular nerve. These vessels are easily exposed upon separation of the
flanking muscles.
Lateral to extensor hallucis longus lies extensor digitorum longus, originating from the proximal
2/3 of the fibula. In the proximal half of the anterior compartment, this muscle actually lies next
to tibialis anterior. Distally, its tendons terminate at digits 2-5, forming extensor expansions at
the metatarsophalangeal joints. Beyond this joint, each tendon divides into three bands: the
central band inserts into the base of the middle phalanx, while the two lateral bands insert on the
sides of the distal phalanx.
 Carefully skin at least one toe in order to expose this structural arrangement.
The most lateral muscle is fibularis tertius. While it technically arises from the distal 1/4 of the
fibula, it usually presents from the distal belly of extensor digitorum longus, rather than as a
separate muscle. Distally, its attachment may span the dorsal surface of the cuboid to the base of
the fifth metatarsal.
Dorsum of the Foot
Artery:
Dorsalis pedis artery
Muscles:
Extensor digitorum brevis muscle
Extensor hallucis brevis muscle
Dorsalis pedis emerges as the continuation of the anterior tibial artery into the dorsum of the
foot. Beginning on the anterior surface of the ankle joint, it continues between the tendons of
extensor hallucis longus and extensor digitorum longus on the dorsum of the foot.
The belly of extensor digitorum brevis may be found on the lateral portion of the dorsum of the
foot, emerging proximally from the anterolateral portion of the dorsal surface of the calcaneus.
This proximal attachment is shared by extensor hallucis brevis which will then cross the dorsum
medially to attach on the first proximal phalanx. The three tendons of extensor digitorum brevis
insert into the extensor expansions of digits 2-4.
This completes the dissection for the entire lower limb.