Download Femoral Nerve

Anterior Thigh
Details
Background &
joint movement
-The lower limb consists of several named regions, and
proximally, it is contiguous with the back, the
abdomen, and the perineum
*The lower limb is designed for bipedal locomotion,
and to support and balance the weight of the body
-The hip joint is multiaxial, and thus capable of rotation,
flexion/extension, and abduction/adduction
*In concert, these actions produce circumduction
-The knee joint is essentially only capable of flexion and
extension
*Ankle and foot joints are more complex, and will be
discussed in further detail in upcoming lectures
-In many instances the actions mentioned occur with
the lower limb fixed on the ground
*In such cases, movement of the pelvis occurs
relative to the fixed limb
Pictures
Details
LE plexuses
-Somatic motor and general sensory innervation of the
lower limb are supplied by two somatic plexuses (which
are hidden from our view until block 5)
-The lumbar plexus
*which primarily serves the anterior aspect of the
lower limb
*is located on the posterior abdominal wall and is
formed by the anterior rami of T12-L4
-The sacral plexus
*which primarily serves the posterior aspect of the
lower limb
*is located on the posterior pelvic wall and is formed
by the anterior rami of L4-S3
Pictures
Details
Fascial
compartments
-The deep fascia of the thigh (fascia lata) gives rise to
lateral and medial intermuscular septa, which create
anterior and posterior osteofascial compartments
*It is customary to add a third compartment—the
medial compartment
*However, the medial compartment is not
delineated posteriorly by a septum, and thus is truly a
part of the posterior compartment
Pictures
Details
Innervation
Muscle groups
-All anterior compartment muscles are supplied by the
femoral nerve
*with the exception of psoas major and minor
(innervated by anterior rami of L1-L2), and pectineus
(sometimes additionally innervated by the obturator
nerve)
-The anterior compartment of the thigh contains two
groups of muscles
*The flexors of the hip/thigh
*The extensors of the knee/leg
Pictures
Details
Flexors
-The flexors of the hip (of the anterior compartment)
consist of three muscles—pectineus, iliopsoas, and
Sartorius
*All of these cross the anterior aspect of the hip joint,
thus producing flexion at the hip
-Iliopsoas
*Acts as a single muscle (it is sometimes referred to
as a functional unit) but truly consists of three
individual muscles:
*iliacus, psoas major, and psoas minor
-Iliacus originates in the iliac fossa, while psoas major
and minor originate from the lumbar vertebrae
*Iliacus and psoas major have a common insertion on
the lesser trochanter, while psoas minor inserts on the
iliopubic ramus and iliac fascia
-Function of Iliopsoas
*One of the body’s most powerful muscles, and the
only one attaching at once to pelvis, vertebral column,
and femur
*It is the chief flexor of the thigh, and has the most
range amongst flexors
*With the thighs fixed it is the main flexor of the
trunk
*Iliopsoas is an important postural muscle, stabilizing
the trunk and helping to maintain normal lumbar
lordosis
-Psoas Abscess
*Abdominopelvic infections—such as spinal
tuberculosis, or enteritis of the ileum—can be
transmitted to the proximal part of iliopsoas, between
the covering (deep) fascia and the muscle
*The infection may then drain inferiorly to the
inguinal and proximal thigh regions, referring severe
pain to the hip, thigh, or knee joint
Pictures
Details
*May be palpated in the inguinal region, and thus
mistaken for a femoral, or inguinal hernia
-Pectineus
*Because pectineus is located in a transitional area
between anterior and medial compartments it may
receive dual innervation (obturator nerve in addition to
the femoral nerve)
*Flexes, adducts, and laterally rotates the thigh, but
studies have shown it to be most active in flexion
-Sartorius
*A long, strap-like muscle that passes across the
length of the anterior thigh, originating on the ASIS and
inserting on the medial tibia
*B/c crosses both hip and knee joints, it has several
actions, which together produce a cross-legged sitting
position, formerly used by working tailors, from which
Sartorius got its name (Sartus, L., means patched or
repaired)
*The relatively small size of Sartorius suggests it acts
as a synergist, and in practical terms probably keeps
the knee in line
-Hip flexion:
*translates into acceleration of the thigh at the
beginning of the swing phase of walking!
Pictures
Details
Extensors
-The quadriceps are the extensors of the knee and the
largest muscle group in the body, covering most of the
anterior and lateral part of the femur
*Consists of four parts—rectus femoris, vastus
medialus, vastus intermedius, and vastus lateralis—
which converge to form the common quadriceps
tendon
*The quadriceps tendon envelops the patella, and
continues as the patellar ligament, which inserts on the
tibial tuberosity
*Vastus medialis & vastus lateralis originates on the
posterior femur and wraps around to anterior side!
-Practical Function
*The quadriceps are powerful extensors of the knee,
but in practical terms, the most important function of
the quadriceps is to accept weight during the loading
response (flat foot) of the stance phase
*Quadriceps are important in projection (running and
jumping) and thus may be ~3X as strong as the
hamstrings
*For the above reasons, atrophy of the quadriceps is
particularly great when they are not in use
-Rectus Femoris
*Runs straight down the anterior part of the thigh,
crossing both hip and knee joints
*It originates on the AIIS and inserts with all
quadriceps on the tibial tuberosity
*It flexes the thigh and extends the leg (soccer kick)
*In terms of locomotion it works with hip flexors in
accelerating the thigh during the swing phase
*strain at the muscle’s origin (often subsequent to
rapid contraction following stretch) may lead to
anterior hip pain!
Pictures
Details
Pictures
Medial Thigh
Details
“Adductor”
compartment
-The medial compartment of the thigh consists of
adductor muscles, which generally originate on the
anteroinferior surface of the pubis and insert on the
linea aspera of the femur
-With the exception of obturator externus, all
muscles of the medial compartment adduct the thigh
(i.e., in the anatomical position they return the thigh
to the midline)
-The adductors are mainly innervated by the
obturator nerve
-The adductors play a secondary role in maintaining
posture (by balancing the trunk on the legs) and in
regular gait (where they function as synergists)
-In certain activities, forcible adduction is very
important
*Side-to-side motions (shuffling feet in many
sports)
*Sweeping thigh motions such as a soccer kick
Muscle groups
-Though they are termed “adductors”, the muscles of
the medial compartment are important contributors
to flexion and extension of the femur (thigh) against
resistance
*Running
*Weight-training
-Adductor Longus and Brevis
*Primarily flexors of the thigh
*However, when the insertion of either muscle rises
above the origin, their action is reversed, and they
become extensors of the thigh
*The adductors flex the thigh from neutral to ~70°,
and they extend from >70° back to ~70°
Pictures
Details
-Adductor magnus
*the largest, most powerful, and most posterior
muscle of the adductor group
*consists of two parts:
-The adductor part flexes the thigh and is
innervated by the obturator nerve
-The hamstrings part extends the thigh and is
innervated by tibial division of the sciatic nerve
-Obturator externus is primarily a lateral/external
rotator of the femur
-Gracilis is a medial/internal rotator of the femur
(recall that it also adducts the femur)
-Both lateral and medial rotation of the hip are
crucial to minimizing vertical shifts in the center of
gravity during walking
Pictures
Details
Neurovascular
structures and
relationships
-Femoral Triangle
*Like the popliteal fossa and the tarsal tunnel,
which we will see later—is an important area of
transition between the abdomen and the thigh
* A subfascial (i.e., deep to the fascia lata)
formation of the superior, anteromedial thigh
*In muscular individuals—in which the thigh is
flexed, abducted, and laterally/eternally rotated—
the femoral triangle is visible as an intermuscular
depression
-Areas of transition
*Often clinically important for two related reasons
*They represent a passageway, from region to
region, for important neurovascular structures
*Such a passageway is often the only available
route, so structures within are often grouped tightly
together
*Lesions can compress the structures, and injury
can affect multiple structures at once
- Femoral Sheath
*The femoral sheath is a fascial tube within the
femoral triangle, ~3-4 cm long, containing blood and
lymphatic vessels
*Divided into three compartments:
-The lateral compartment contains the femoral
artery
-The intermediate compartment contains the
femoral vein
-The medial compartment (AKA femoral canal)
contains lymphatic vessels
Pictures
Details
Femoral Canal
-Unlike in the other two compartments, the contents
of the medial compartment (the lymphatic vessels)—
do not fill out the compartment, & are not adherent
to the compartment walls
*This leaves space within the femoral canal
Pictures
Details
Femoral Ring
-The femoral ring
*on the inside of the abdominal wall
*represents a potential opening into the femoral
canal
*This opening is covered by the femoral septum,
which consists of peritoneum and extraperitoneal
fascia
Femoral hernias
-Femoral ring is the usual originating site of a
femoral hernia, which appears as a tender mass in
the femoral triangle
*In the early stage, the hernia is contained within
the femoral sheath, but it may eventually pass
through the saphenous opening into the
subcutaneous tissue of the thigh
*The hernia can get strangulated by the tough
lacunar ligament
*Femoral hernias are more prominent in females
because of their wider pelves
Pictures
Details
Femoral Artery
-The continuation of the external iliac artery inferior
to the inguinal ligament
*is the primary artery of the lower limb
-It enters the femoral triangle at the midpoint of the
inguinal ligament, bisects the triangle, and is
relatively superficial
*Its pulse can be taken, and it is commonly
catheterized, but as well, it is easily lacerated
-Has one major branch
*The deep artery of the thigh (profunda femoris),
which arises ~5 cm inferior to the inguinal ligament
and passes deeply between pectineus and adductor
longus
-In turn, the deep artery of the thigh usually gives
rise to medial and lateral circumflex femoral
arteries
*These branches sometimes arise from the femoral
artery
Pictures
Details
Veins
-Venous drainage is both deep and superficial
-The principal deep vein of the lower limb is the
femoral vein
*Becomes the external iliac vein at the inguinal
ligament
-The main superficial veins of the lower limb are the
great and small saphenous veins
*The great saphenous vein enters the saphenous
opening and drains into the femoral vein
Femoral Nerve
-8 cm inferior to the inguinal ligament the femoral
nerve divides into multiple cutaneous and muscular
branches
-The anterior cutaneous branches of the femoral
nerve supply the anteromedial aspect of the thigh
-Cutaneous supply to the anterolateral thigh is from
the lateral femoral cutaneous nerve
Pictures
Details
Obturator Nerve
-The obturator nerve is not considered to be a part
of the femoral triangle, but it does innervate certain
muscles in the area
-Upon exiting the pelvis and entering the thigh, the
obturator nerve (L2-L4) splits into two divisions:
*anterior and posterior—which pass anterior and
posterior to adductor brevis
-Cutaneous branches of the obturator nerve supply a
part of the medial thigh
Pictures