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Anatomy Block 2 Test #2 Notes
Bony Pelvis, Hip and Femur
 Hip joint
o 3 main bones: ilium, ischium, pubis
 Ilium: superior “wing”
 Ischium: located inferior and posterior
 Pubis: located inferior and anterior
o Acetabulum: socket in the hip where the head of the femur sits
 Has contributions from all three hip bones
 The three hip bones in the acetabulum are separated by the
triradiate cartilage
 Lined with articular (lunate) cartilage
 Has a half-moon shape
 Gives rise to the labrum which in turn gives rise to the
transverse acetabular ligament
 Also contains synovial membrane
 Structurally contains a labrum (like that seen in the shoulder)
to help the stabilize the head of the femur in the acetabulum
 Labrum deepens the fossa where the femoral head sits
o Is a ball-and-socket joint (but unlike you may think, it is quite stable)
 Allows for the following actions:
 Flexion: bring leg forward
 Extension: bring leg backward
 Abduction: bring leg out to the side
 Adduction: bring leg back to midline
 Circumduction: moving leg in a circle (clockwise or
counter-clockwise)
 Medial rotation: rotating the leg inward (toward the
midline)
 Lateral rotation: rotating the leg outward (away from
the midline)
o Contains a strong joint capsule
 Allows for support during motion and at rest
 Contains three intrinsic (deep) ligaments
 From strongest to weakest
o Iliofemoral (two): connects the ilium to the femur
o Ischiofemoral: connects ischium to femur
o Pubofemoral: connects pubis to femur
o Contains hyaline cartilage
o Femoral fovea: point of attachment of the ligament of the head of
the femur (on the femoral head); no articular cartilage at this
location
o Arterial supply to the hip joint: circumflex femoral arteries
o Innervation at the hip joint:
 Femoral nerve
 Obturator nerve
 Superior gluteal nerves
o Points of articulation at the hip joint:
 Acetabular (lunate) cartilage w/articular cartilage of the
femoral head
 Remember no articular cartilage at the femoral fovea b/c this
is where the ligament of the head of the femur attaches
 Note that the entire acetabulum is not lined w/articular
cartilage
 There is a region at the bottom of the acetabulum that is
cartilage-free; this is the location of the transverse
acetabular ligament
o Muscles of the hip joint:
 Iliopsoas: flexion
 Sartorius: flexion
 Tensor fascia latae: flexion, abduction, medial rotation
 Rectus femoris: flexion
 Pectineus: flexion, adduction
 Adductor longus: flexion, adduction,
 Adductor brevis: flexion, adduction
 Adductor magnus: flexion (anterior part), adduction, extensor
(posterior part)
 Gracillus: flexion, adduction
 Obturator externus: adduction, lateral rotation
 Obturator internus: lateral rotation
 Gemelli: lateral rotation
 Piriformis: lateral rotation
 Quadratus femoris: lateral rotation
 Gluteus maximus: lateral rotation, extension
 Hamstrings (semitendinosus, semimembranosus, long head of
biceps femoris): extension
 Gluteus medius: abduction, medial rotation (anterior part)
 Gluteus minimus: abduction, medial rotation (anterior part)
 Knee joint
o Allows for the following motions:
 Flexion: bending the knee
 Extension: straightening the knee
 Moderate rotation
o A “stable” joint w/2 mensici
 Meniscus: a cartilaginous hemi-disc that prevents bone on
bone contact
 Serves as a shock absorber
o Knee joint contains numerous intrinsic and extrinsic ligaments
 Fibular (lateral) collateral ligament
 Tibial (medial) collateral ligament
 Oblique popliteal ligament
 Arcuate popliteal ligament
 Patellar ligament
o Anterior cruciate ligament (ACL) and posterior cruciate ligament
(PCL) are designed to restrict anterior and posterior motion between
the tibia and the femur
 Both are named for their attachment to the tibia
 Form a cross between the femur and tibia
o Knee joint consists of three main bones:
 Tibia, femur, patella
o Arterial supply to the knee:
 Genicular branches of the femoral, tibial and popliteal arteries
o Nerves in the knee:
 Femoral nerve, tibial nerve, common fibular nerve
o Knee also consists of an extensive network of bursa
 Bursae: fluid-filled synovial sac that serves as a cushion at
points of boney contact
o True knee joint is the articulation between the medial/lateral
condyles of the femur with the medial and lateral condyles of the
tibia
 Tibial plateau: superior surface of the tibia where the medial
and lateral condyles of the tibia are situated
 Note that a synovial membrane immediately surrounds
the tibial plateau and a joint capsule surrounds the
synovial membrane
 Or put another way: inward to outward
o Tibial plateau, synovial membrane, joint capsule
o All muscles that cross the knee joint help to contribute to joint
stability
 Ankle joint
o Is a hinge joint
 Also referred to as a mortise joint
 Is relatively stable due to the abundance of ligaments
o Borders of the ankle joint
 Tibia: roof, medial side
 Fibula: lateral side
 Talus: fits into the groove formed between the lateral
malleolus (of the fibula) and the medial malleolus (of the tibia)
 Supported by the calcaneus
o Movements at the ankle joint:
 Dorsiflexion: bring toes towards tibia
 Plantar flexion: point toes towards the ground
 Inversion: bring medial malleolus up
 Eversion: bring lateral malleolus up
o Deltoid ligament (consists of 4 parts)
 Anterior tibiotalar ligament
 Tibionavicular ligament
 Tibiocalcaneal ligament
 Posterior tibiotalar ligament
o Muscles that cross the ankle joint contribute to its stability
o Contains a thin joint capsule both anteriorly and posteriorly
 Is reinforced medially and laterally by collateral ligaments
o Arterial supply to the ankle: fibular and tibial arterial branches
o Nerves in the ankle joint: tibial nerve, deep fibular nerve
 Feet
o Bones of the foot
 Tarsal bones (ankle bones)
 Talus, calcaneus, cuboid, navicular, cuneiforms (lateral,
middle, medial)
o Talus consists of head, neck and body
 5 metatarsals (#1 starts w/big toe)
 Phalanges: digits 2-5 have proximal, middle and distal
 Digit #1 (big toe) just has proximal and distal
o Zones of the foot
 Hindfoot: calcaneus, talus
 Midfoot: cuboid, navicular, cuneiforms
 Forefoot: metatarsals, phalanges
 Transverse tarsal line separates the hindfoot from the midfoot
 Tarsometarsal line separates the midfoot from the forefoot
o There are NUMEROUS joints in the foot
 Intertarsal, tarsal-metatarsal, metatarsal-phlangeal,
interphalangeal
o The foot is primarily composed of hinge joints
 Allows for plantar flexion and dorsiflexion
 These joints usually undergo little movement
 Exceptions: talocalcaneal, calcaneocuboid, talonavicular
joints
o Allows for inversion/eversion
o Main ligaments in the foot (support the plantar arches)
 Plantar calcaneonavicular
 Long plantar
 Plantar calcaneocuboid
o Toe joints are hinge joints
 Digits 2-5 contain a PIP and DIP
 Digit 1 has a single IP joint
o Joint capsules in the feet are incredibly strong due to the stress your
feet take in everyday
o Arterial supply to the feet:
 Posterior tibial, fibular, lateral and medial tarsal arteries
o Nerves to the feet:
 Medial and lateral plantar nerves, deep fibular nerve, digital
nerves
 Review of joints
o Joint: a point of articulation between bones
 Most are of the synovial type
 Contains a capsule, cartilage, synovial fluid, articular
discs/menisci
o Hilton’s Law: joints receive innervation due to branches of nerves
that innervate the muscles that move the joint
o Arteries that pass by a joint will provide blood to that joint
 w/large joints you have arterial anastomoses
o venous drainage
 think “venae comitantes”
Anterior and Medial Thigh
 Lower limb consists of 6 regions:
o Gluteal (buttocks, hip), femoral (thigh), knee, leg (tibia,fibula), ankle,
foot
 Somatic motor and general sensory innervation of the lower limb is
provided via:
o Lumbar plexus:
 Located on posterior abdominal wall and consists of anterior
rami of L1-L4
o Sacral plexus:
 Located on the posterior pelvic wall and formed by anterior
rami of L4-S3
o Remember rami (dorsal and ventral) come off from the spinal nerve
and for the most part are mixed (have both sensory and motor)
o Note: the lumbar plexus is SUPERIOR to the sacral plexus
 Lumbar plexus innervates anterior portion of lower limb
 Sacral plexus innervates posterior portion of lower limb
 Fascia lata: the deep fascia of the thigh
o Gives rise to the lateral and medial intermuscular septa
 In turn forming the anterior and posterior osteofascial
compartments (contains the musculature of the thigh)
 Technically there is also a medial compartment but it is not
separated by fascial planes
 Fascia: the wrapping, packing and insulating material of the body
o Deep fascia is thought to help facilitate/enhance muscle movement
 Compartments of the thigh
o Each compartment contains muscles that perform similar functions
 Three compartments: anterior, posterior, medial
o Blood supply to the lower limb:
 Aorta gives rise to the common iliac artery which becomes the
external iliac artery which becomes the femoral artery
 It is the femoral artery that INDIRECTLY supplies the
entire lower limb
o Innervation to the compartments
 Anterior compartment: femoral nerve
 Posterior compartment: sciatic nerve
 Medial compartment: obturator nerve
 Anterior compartment of the thigh
o Contains the anterior thigh muscles
 Divided into:
 Flexors of the hip
 Extensors of the knee
o These muscles innervated by the femoral nerve
 EXCEPTION: psoas major and minor are innervated by the
anterior rami of L1-L2
o Flexors of the hip (in the anterior compartment)
 Pectineus:
 located in the anterior, superomedial thigh
 flexion, adduction, lateral rotation
 is a transition point between the anterior and medial
compartments
o therefore it may sometimes be innervated by a
branch of the obturator nerve
 Iliopsoas:
 Consists of iliacus, psoas major and minor
 Iliacus: originates on iliac fossa and inserts on lesser
trochanter of femur
 Psoas major: originates on lumbar vertebrae and inserts
on lesser trochanter of femur
 Psoas minor: originates on the lumbar vertebrae and
inserts on the iliopubic ramus
 Chief flexor of the thigh
o If thigh is fixed, allows flexion of the trunk
 Is an important postural muscle; stabilizes the trunk and
helps to maintain normal lumbar lordosis
 Sartorius:
 Originates on ASIS and inserts on medial tibia
 Crosses both hip and knee
 Allows for cross-legged sitting position
 Acts as a synergist; keeps the knee in line
 Flexion (thigh), abduction, external rotation (thigh),
medial rotation of tibia (if knee is bent)
 Hip flexion allows acceleration of the thigh needed for swing
phase of walking
o Extensors of the knee (in the anterior compartment)
 Quadriceps:
 Largest muscle group in the body
 Consists of four individual muscles:
o Rectus femoris, vastus medialis, vastus lateralis,
vastus intermedius
o Converge to form the quadriceps tendon, which
envelops the patella and continues as the patellar
ligament (inserting on the tibial tuberosity)
 Rectus femoris:
o Originates on the AIIS and inserts on tibial
tuberosity
o Flexes the thigh and extends the leg (soccer kick)
o Works w/iliopsoas during walking
 Vastus medialis/lateralis/intermedius
o All originate on the femoral shaft and insert on
the tibial tuberosity
o Vastus intermedius is DEEP to rectus femoris
 Are powerful knee extensors
o Most important function: to accept weight during
the loading response (flat foot) of the stance
phase
o When these muscles are not used, atrophy is
significant
 Medial compartment of the thigh
o Consists primarily of adductor muscles
 Exception: obturator externus
 Originate on the anteroinferior surface of the bony pelvis and
insert on the linea aspera of the femur
o Main innervation is via the obturator nerve
o These muscles also assist in flexion and extension of the thigh
AGAINST RESISTANCE
 Ex.) running, weight-training
o Obturator externus:
 Originates on the medial aspect of the obturator foramen (the
foramen formed by the three pelvic bones) and inserts on the
trochanteric fossa of the femur
 Stabilizes the femoral head in the acetabulum
 Also provides some flexion of and laterally rotates the
femur
o Adductor longus and brevis
 Flexion of the thigh
 NOTE: when the insertion of either rises above the origin, it’s
function transitions from flexion to extension of the thigh
o Adductor magnus
 The largest, strongest and most posterior of the medial
compartment thigh muscles
 Has two components:
 Adductor portion: flexes the thigh
 Hamstrings portion: extends the thigh
o Gracilis
 Adducts and medially rotates the femur
o When you walk, your pelvis undergoes rotation (one side externally
rotates while the other internally rotates), minimizing a drop in your
center of gravity
o Extensive or forcible adduction of the femur is typically not required
 Femoral triangle
o Is one of three key areas of transition in the lower limb (along
w/popliteal fossa and the tarsal tunnel)
 Transition areas are important b/c they conduct key structures
between adjacent regions
o Borders:
 Superior: inguinal ligament
 Lateral border: sartorius muscle
 Medial border: adductor longus muscle
 Floor: iliopsoas muscle (laterally) and pectineus (medially)
 Roof: fascia lata (deep fascia of the thigh)
o Inguinal ligament
 Forms the superior border of the femoral triangle
 Goes from the ASIS to the pubic tubercle
 Is the inferior border of the external oblique muscle
 It serves in part to retain soft tissue structures
 Such structures are said to pass through the retroinguinal space
o Retro-inguinal space
 Located deep to the inguinal ligament
 Inguinal ligament branches to form the iliopectineal arch and a
continuation of the inguinal ligament
 Serves to divide the retro-inguinal space into a muscular
compartment and a vascular compartment
 Muscular compartment: allows passage of iliopsoas muscle
and femoral nerve
 Vascular compartment: allows passage of major vessels that
run between the abdominopelvic cavity and the lower limb
 These vessels are surrounded by the femoral sheath
o Femoral sheath
 A funnel-shaped fascial tube that surrounds vessels contained
in the vascular compartment of the retro-inguinal space
 It allows said vessels to glide along the inguinal ligament during
hip movements
 Divided into 3 compartments
 Lateral: femoral artery
 Intermediate: femoral vein
 Medial: lymphatic vessels
 NAVeL: contents of the femoral triangle (lateral to medial)
 Femoral nerve, femoral artery, femoral vein, lymphatics
o Femoral canal = medial compartment of the femoral sheath
 Contains lymphatic vessels
 However these vessels do not fill the entire
compartment, thus leaving empty space
 Femoral ring is an opening into the femoral canal
 Represents a potential site of herniation
 However normally the femoral ring is covered by the femoral
septum
 Femoral septum derived from peritoneum and
extraperitoneal fascia
 Hernias
o The protrusion of a structure through the tissues that normally
contain it
o Abdominal hernias are common
 Typically involve loops of the small intestine protruding
through areas of the abdominal wall that are muscularly
deficient
o Femoral hernias
 Usually originate at the femoral ring and appear as a tender
mass in the femoral triangle
 The structure that is protruding (for example the small
intestine) can become compromised due to the tough,
inflexible lacunar ligament
 If the small intestines that are involved in the hernia
have their blood flow reduced/constricted by the
lacunar ligament, it can result in avascular necrosis
 Typically are more common in females due to the larger size of
their pelvis
 Femoral artery
o Aorta to common iliac artery to external iliac artery to femoral artery
 Note: the external iliac artery becomes the femoral artery
when it passes inferior to the inguinal ligament
o Bisects the femoral triangle and is RELATIVELY superficial
 Therefore its pulse can be taken by placing the palm of the
hand inferior to the inguinal ligament
 However, because it is superficial it can be easily lacerated
(cut)
o Femoral artery gives off one major branch:
 The profunda femoris (deep artery of the thigh)
 This passes deep between the pectineus and adductor longus
muscles in the femoral triangle
 It in turn gives off two branches:
 The lateral and medial circumflex femoral arteries
o Note that it is possible for these to arise from the
femoral artery itself rather than the profunda
femoris (varies among individuals)
o Note: the obturator artery (derived from the INTERNAL iliac artery)
will also provide blood supply, specifically to the medial
compartment of the thigh
 Veins
o Venous drainage in the lower limb consists of superficial and deep
veins
o Femoral vein: major DEEP vein of the lower limb
 Femoral vein becomes the external iliac vein upon passing
SUPERIOR (remember veins run up towards the heart) to the
inguinal ligament
o Great and small saphenous veins: major SUPERFICIAL veins of the
lower limb
 The great saphenous vein runs up the lower limb and merges
with the femoral vein at the saphenous opening
 Nerves
o Femoral Nerve
 Derived from L2-L4 of the lumbar plexus
 Innervates the anterior compartment muscles of the thigh
 Gives off multiple cutaneous and muscular branches
 Anterior cutaneous branches of the femoral nerve:
 Provides SENSORY information to the SKIN of the
anteromedial thigh
 Lateral cutaneous branches of the femoral nerve:
 Provides SENSORY information to the SKIN of the
anterolateral thigh
o Obturator nerve
 Derived from L2-L4 of the lumbar plexus
 Innervates the medial compartment muscles of the thigh
 Divides into anterior and posterior branches at the adductor
brevis
 Cutaneous branches of the obturator nerve
 Provides a small patch of SENSORY innervation to the
SKIN of the medial thigh
 Adductor canal
o A long, narrow intermuscular passageway in the middle third of the
thigh
o Extends from the apex (point) of the femoral triangle to the adductor
hiatus
 Adductor hiatus is situated near the inferior aspect of adductor
magnus
o Contains the femoral artery, femoral vein and the saphenous nerve
 Saphenous nerve innervates the medial aspect of the tibia
o Composed of tough vastoadductor fascia
Knee and Lower Leg
 Anatomical leg: the portion of the lower limb located between the knee
and the ankle
o Remember that the thigh is between the hip and the knee
 Bones of the leg
o Tibia: dominant, weight-bearing bone of the leg
o Fibula: subordinate (almost vestigial in nature), functions in muscle
attachment and closure of the ankle joint
 Gives rise to the lateral malleolus
 While the forearm of the upper limb was focused on mobility, the leg of the
lower limb is concerned with weight bearing
 Tibiofibular joint: 3 components
o Proximal tibiofibular joint
o Interosseous membrane (between the bones)
o Distal tibiofibular joint
 3 muscular compartments of the leg
o Anterior, posterior, lateral
 Separated by bones (tibia, fibula), interosseous membrane,
fascial septa
o Generally speaking, the muscles of each compartment have a similar
function and innervation
 Anterior leg
o Anterior compartment muscles are located lateral to the anterior
border of the tibia
o Muscles of the anterior compartment of the leg:
 Tibialis anterior
 Extensor digitorum longus
 Fibularis tertius
 Is actually an extra belly of the extensor digitorum
longus
 Extensor hallucis longus
 Hallucis implies the big toe
 These muscles cross the ankle joint (talocrural joint)
 Allow for dorsiflexion of the ankle and extension of the
toes (bring toes up to your chin)
 Dorsiflexion ROM: ~20 degrees
o Note that strength and ROM of dorsiflexion is LESS
than strength of plantarflexion
 Roles of dorsiflexion:
o Provides balance while standing
o Active during walking
 Keep foot flat to ground
 Permit smooth, eccentric lowering of foot
 Pull body forward over fixed foot
o Tibialis Anterior
 Most medial, superficial muscle of the anterior compartment
 Origin: superior half of the lateral tibia and adjoining surfaces
of the interosseous membrane
 Insertion: medial cuneiform and the base of the 1st metatarsal
 Actions: provides leverage for dorsiflexion and inversion,
supports medial longitudinal arch
o Compartment syndrome
 Fascial compartments are closed spaces ending at the joints
 Fascia in the leg (especially proximally) is strong and resistant
to expansion
 Compartment syndrome is increased pressure within a limited
anatomical space
 Example of a limited anatomical space is a fascial
compartment
 Example: fluid builds up in the leg, due to either infection or
injury; this accumulating fluid causes increased pressure in the
fascial compartment and hence the structures within said
compartment, i.e. blood vessels
 If these blood vessels become constricted, it can
diminish perfusion of tissues distal to the point of
compression, causing ischemia, hypoxia and possible
necrosis
 Treatment usually involves a fasciotomy, in which the fascia
overlying a compartment is incised, allowing the inherent
structure more freedom
 Shin splints are a mild form of compartment syndrome in the
anterior compartment of the leg
 Due to repetitive microtrauma of tibialis anterior
 Can occur with sudden overuse or intense training
 Treatment: rest, ice, strengthening
o Extensor digitorum longus
 The most lateral of the anterior compartment leg muscles
 Consists of four tendons (on digits 2-5)
 Origin: superior and medial border of the fibula and the
adjacent surfaces of the interosseous membrane
 Insertion
 Each tendon of extensor digitorum longus and extensor
digitorum brevis (located deep to EDL) form an extensor
expansion
 This extensor expansion divides into
o
o
o
o
o Central band located at the base of the middle
phalanx
o 2 lateral bands located at the base of the distal
phalanx
 Primary extensor of digits 2-5; also dorsiflexes the ankle
Extensor hallucis longus
 Located deep and in-between tibialis anterior and extensor
digitorum longus
 Extends digit #1 (big toe) and dorsiflexes the ankle
 Is the ONLY extensor of the hallux (big toe) and is critical
in making sure this toe is “cleared” from the ground
during walking
 Origin: medial anterior surface of the fibula
 Insertion: distal phalanx of the hallux (digit #1)
Fibularis tertius
 Is actually another belly of extensor digitorum longus
 Goes to the 5th metatarsal
 Weak dorsiflexion; eversion; possible protection of the
anterior tibiofibular ligament
Retinacula
 Superior extensor retinaculum and inferior extensor
retinaculum
 Two band-like thickenings of the deep (crural) fascia at
the inferior end of the anterior compartment of the leg
 Serves to bind the tendons of the anterior compartment
muscles and prevent anterior bowstringing during dorsiflexion
 Bowstringing during dorsiflexion would mean that the
tendons become taught in a straight line during the
action of dorsiflexion
Nerve supply
 Anterior compartment muscles of the leg are innervated via
the deep fibular nerve
 Located deep and in-between tibialis anterior, extensor
digitorum longus and extensor hallucis longus
o Blood supply
 Anterior compartment muscles derive their blood supply from
anterior tibial artery
 Femoral artery becomes the popliteal artery which
branches at the inferior border of the poplietus
o The small terminal branch is the anterior tibial
artery
 Lateral leg
o The lateral compartment of the leg is the smallest of the three
o Bordered by the anterior and posterior intermuscular septa
o Muscles of the lateral compartment of the leg are responsible for
eversion and weak plantarflexion
 Eversion: bringing the lateral malleolus up
 Plantarflexion: pointing the toes to the ground
o 2 muscles
 Fibularis longus and brevis
 Longus is superficial and longer than brevis
o Insertion
 Fibularis longus inserts on the base of the 1st metatarsal and
the medial cuneiform
 Is the primary evertor of the foot
 Fibularis brevis inserts on the base of the 5th metatarsal
o The tendons of fibularis longus and brevis pass through the superior
fibular retinaculum and the inferior fibular retinaculum
o Importance of eversion
 Keeps the medial margin of your foot on the ground during the
toe-off stage of walking
 Prevents excessive inversion of the foot (that would otherwise
lead to ankle sprain)
o Because of the placement of fibularis longus in the human leg, it
allows us greater eversion
 Ultimately allows us to walk on the medial (inner) part of our
foot, as opposed to other primates
o Innervation is via the superficial fibular nerve
o Blood supply
 The lateral compartment leg muscles do NOT have an artery
directly supplying them
 They INDIRECTLY receive blood via perforating arteries derived
from the fibular and anterior tibial arteries
 Common fibular nerve
o Because of its superficial location in the leg, it can become easily
damaged
o It can actually be severed with fibular neck fractures or knee injuries
o Common fibular nerve divides into the superficial and deep fibular
nerves
 Superficial fibular nerve innervates the lateral compartment of
the leg, which allows for eversion of the foot
 Deep fibular nerve innervates the anterior compartment of the
leg, which allows for dorsiflexion of the foot
o Clinical scenario: if you sever the common fibular nerve, you
essentially “kill” the nerves distally derived from it, i.e. the superficial
and deep fibular nerves
 w/o this innervation, the anterior and lateral compartment leg
muscles will be paralyzed and atrophy, and be accompanied by
inability to dorsiflex or evert the foot
 ultimately results in footdrop w/unopposed inversion; the toes
now drag the floor during the swing phase of walking
 the patient resultantly develops a compensatory gait in which
the leg is brought up, swung out and “clops” to the ground
 “clopping” due to the inability to smoothly lower the
foot (b/c of loss of dorsiflexion)
 Posterior leg
o The posterior compartment (the largest) leg muscles are located
posterior to the tibia, fibula and interosseous membrane
o Posterior compartment leg muscles are responsible for plantarflexion
of the foot and toes and inversion
o Propulsion during locomotion (walking) is performed mainly by way
of the plantarflexors of the leg
 Greatest amount of energy expenditure during locomotion is
in the concentric contraction of these muscles
o Posterior compartment leg muscles are divided by the transverse
intermuscular septum into
 Superficial posterior compartment muscles
 Deep posterior compartment muscles
o Superficial posterior compartment leg muscles
 Form the prominence of the calf
 3 muscles
 Gastrocnemius, soleus, plantaris
o Gastrocnemius and soleus form the triceps surae
o Gastrocnemius has a medial and lateral head
o Soleus and plantaris are deep to the
gastrocnemius
o Plantaris is superior to soleus
o Plantaris is absent in a small percentage of the
population
o All three muscles come together inferiorly to form
the calcaneal tendon
o Gastrocnemius
 Consists of a medial and lateral head
 Originates on the distal end of the femur and inserts as the
calcaneal tendon
 b/c it crosses the knee and the ankle, it has action at
both joints
 allows for flexion of the knee and plantarflexion of the
ankle
o note: it cannot exert full power on both @ the
same time
o checks and balances: if the knee is fully extended,
gastrocnemius is not at work on the knee,
therefore all of its power can be diverted to
plantarflexion of the ankle
o however, as the knee approaches full flexion, you
are engaging (at least in part) your gastrocnemius,
and thus less power is able to be diverted to
plantarflexion (b/c the muscle has become too
slack)
o Soleus
 Located deep to gastrocnemius
 Considered the “workhorse” of plantarflexion
 Can perform plantarflexion of the foot regardless of
knee angle
 Consists mainly of slow-twitch (red, aerobic, myoglobin-rich)
fibers
 Allows for strong, sustained plantarflexion
 Originates as an inverted “U” on the tibia and fibula
 Inserts on the calcaneus as the calcaneal tendon
o Deep posterior compartment leg muscles
 4 muscles
 Flexor hallucis longus
 Flexor digitorum longus
 Tibialis posterior
o These first 3 are your plantarflexors
 Popliteus
 These muscles are weak contributors to plantar flexion
 Due to the close proximity of the tendons to the ankle
joint
 They are not able to raise the body in plantarflexion by
themselves (require the superficial posterior leg muscles for
help)
o Absence of plantarflexion
 If plantarflexion is absent, you have a diminished “push-off”
phase during walking
 Compensatory gait: lower limb is externally rotated and the
transversely positioned foot is “rolled-over” during the stance
phase
 Involves extension of the hip via gluteus maximus and
hamstrings and extension of the knee via quadriceps
o Flexor hallucis longus and flexor digitorum longus
 Flexor hallucis longus
 Origin: middle posterior aspect of the fibula
 Inserts: distal phalanx of digit #1 (big toe)
 Important to our sense of foot position and leverage
 Flexor digitorum longus
 Origin: middle posterior aspect of the tibia
 Inserts: distal phalanges of digits #2-5
 Are crucial in the “toe-off” action near the end of walking and
keeping the pads of the toes in contact w/the ground
o Tibialis posterior
 The deepest posterior leg muscle
 Is located between flexor hallucis longus and flexor digitorum
longus
 Originates on the superior aspect of the tibia, fibula and
interosseous membrane
 Insertion: navicular, cuboid, calcaneous, medial and
intermediate cuneiforms, 2nd to 4th metatarsals
 Supports the medial longitudinal arch of the foot; main
invertor muscle of the leg
o ALL muscles of the posterior compartment of the leg (superficial and
deep) are innervated by the tibial nerve
o Blood supply to the posterior compartment leg muscles is via the
posterior tibial artery
 Popliteal artery passes the inferior border of popliteus and
splits to form the anterior and posterior tibial arteries
 Anterior tibial artery supplies the anterior compartment
leg muscles
 Posterior tibial artery supplies the posterior
compartment leg muscles
 The posterior tibial artery branches to form the fibular artery,
which runs deep to flexor hallucis longus
o Leg cutaneous innervation
 Derived from the femoral and sciatic nerves
 Femoral nerve gives rise to the saphenous nerve which
provides cutaneous innervation to the anteromedial side of
the leg
 Sciatic nerve gives rise to the tibial and common fibular nerves
which both contribute to the lateral and medial sural nerves
that provides cutaneous innervation to the posterolateral side
of the leg
 Remember: cutaneous innervation means SENSORY
innervation to the SKIN
Gluteal Region
 Pelvis: comprised of multiple bones
o Os coxae: 2 each of the ilium, ischium, pubis
o Sacrum: consists of 5 fused vertebrae
o Coccyx: consists of roughly 3 fused vertebrae
o Contains many sites for muscle attachment
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 Offers support in regards to locomotion and posture
 Keeps you steady and upright
Structures of the pelvis are bound to one another by way of ligaments
o Anterior and posterior sacroiliac ligaments
 Attach the upper sacrum to the ilium
o Sacrotuberous ligament extends from the sacrum to the ischial
tuberosity
o Sacrospinous ligament extends from the sacrum to the ischial spine
o Ischial spine separates the greater and lesser sciatic notches
o Note: the sacrotuberous ligament, the sacrospinous ligament and the
ischial spine form the greater and lesser sciatic foramina
Greater sciatic foramen
o Serves as a passageway into the pelvis
o Contains:
 Piriformis muscle, sciatic nerve, superior and inferior gluteal
nerves and arteries, obturator internus nerve, quadratus
femoris nerve, pudendal nerve and artery
Lesser sciatic foramen
o Serves as a passageway into the perineum
o Contains:
 Obturator internus muscle, nerve to obturator internus,
pudendal nerve and artery
Note: the pudendal artery and nerve come out via the greater sciatic
foramen, make a loop around the sacrospinous ligament and enters via the
lesser sciatic foramen
Gluteus maximus:
o Innervation: inferior gluteal nerve
o Actions: extends the thigh, lateral rotation, steadies thigh, assists in
rising from a seated position
Gluteus medius:
o Innervation: superior gluteal nerve
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o Actions: abduct and medially rotate the thigh, keeps pelvis level
when ipsilateral limb is weight-bearing, advances leg during swing
phase of walking
Gluteus minimus:
o Innervation: superior gluteal nerve
o Actions: abducts and medially rotates the thigh, keep pelvis level
when ipsilateral limb is weight-bearing, advances leg during swing
phase of walking
Tensor of fascia lata
o Innervation: superior gluteal nerve
o Action: abduct and medially rotate the thigh, keep pelvis level when
ipsilateral limb is weight-bearing, advances leg during swing phase of
walking
Piriformis
o Innervation: branches of VENTRAL RAMI of S1, S2
o Actions: laterally rotate and extend thigh, abduct a flexed thigh,
steadies femoral head in the acetabulum
Obturator internus
o Innervation: nerve to obturator internus
o Actions: laterally rotate and extend the thigh, abduct a flexed thigh,
steadies the femoral head in the acetabulum
Superior and inferior gemelli
o Innervation:
 Superior: nerve to obturator internus
 Inferior: nerve to quadratus femoris
o Action: laterally rotate and extend the thigh, abduct a flexed thigh,
steadies the femoral head in the acetabulum
Quadratus femoris
o Innervation: nerve to quadratus femoris
o Actions: laterally rotate thigh, steadies the femoral head in the
acetabulum
 Note: there are 6 muscles that serve to laterally rotate the thigh and
stabilize the hip joint
o Piriformis, obturator internus, superior and inferior gemelli,
quadratus femoris, obturator externus
 Gluteal Region Muscles: Superficial and Deep Layer
o Superficial: big gross actions, origin is on external surface/margins of
the ala of the ilium
 Gluteus Maximus
 Innervation: inferior gluteal nerve
 Blood supply: superior and inferior gluteal arteries
 Actions: extension and weak lateral rotation of the thigh
o Strongest hip extensor; also used when rising
from a seated position, straightening from a
bending position, walking uphill/upstairs, running
 Injury: results in gluteus maximus lurch
o Patient extends trunk (leans back) during heel
strike on affected side
o Done to compensate for weakness in hip
extension
 Gluteus Medius and Minimus
 Medius is deep to Gluteus Maximus; Minimus is deep to
Gluteus Medius
 Innervation: superior gluteal nerve
 Blood supply: superior gluteal artery
 Actions: abduct/stabilize the thigh and medially rotate
the thigh; also helps keep pelvis level during gait
 Tensor Fasciae latae
 Merges with the IT band which in turn inserts on the
anterolateral tubercle of the tibia
 Innervation: superior gluteal nerve
 Blood supply: superior gluteal artery
 Actions: flexor of the thigh; abducts and medially rotates
the thigh
o Is a synergist muscle (it works in concert w/other
muscles to perform these functions)
o Works alongside iliopsoas and rectus femoris to
perform flexion of the thigh
o Works alongside gluteus medius/minimus to
perform abduction/medial rotation of the thigh
o Deep: smaller more precise actions; they laterally rotate the thigh
(duck walk) and stabilize the hip joint (by working alongside the
strong hip ligaments to steady the femoral head in the acetabulum)
 Piriformis
 Largest of the deep gluteal muscles
 Innervation: ventral rami of S1 and S2 (nerve to
piriformis)
 Blood supply: variable
 Actions: laterally rotates, abducts the thigh; stabilizes
hip joint
 Serves as the landmark for the gluteal region b/c the
blood vessels/nerves in this area are named in reference
to their location to piriformis
 Sciatic nerve: consists of tibial nerve and common fibular
nerve
o Normally runs inferior to piriformis
o However, it is possible for the common fibular
portion of the sciatic nerve to run through or pass
over piriformis
 Piriformis syndrome:
o Peripheral neuritis (inflammation/irritation) of the
sciatic nerve
o Often due to sitting on a wallet
o Treatment includes: stretching, NSAIDs,
analgesics, OMT (counterstrain), etc.
 Triceps Coxae: Obturator internus, superior/inferior gemelli
 Obturator internus is “sandwiched” between the gemelli
 Innervation:
o Obturator internus: nerve to obturator internus
o Superior gemellus: nerve to obturator internus
o Inferior gemellus: nerve to quadratus femoris
 Actions: lateral rotation and abduction of the thigh;
stabilizes the hip
 Quadratus femoris:
 Located inferior to the triceps coxae
 Is rectangular in shape
 Innervation: nerve to quadratus femoris
 Actions: strong lateral rotation of the thigh; stabilizes
the hip
 Roadmap (to get your bearings)
 Superior to inferior orientation of deep gluteal muscles
o Piriformis, superior gemellus, obturator internus,
inferior gemellus, quadratus femoris
o Obturator externus
 Is technically a muscle of the medial compartment of the thigh
 Innervation: obturator nerve
 Action: lateral rotation of the thigh; stabilizes the hip
 Gluteal bursae
o Synovial fluid sacs that function to reduce friction and permit free
movement
o Trochanteric bursa: largest; separates the superior fibers of gluteus
maximus from the greater trochanter of the femur
o Ischial bursa: often absent; separates the inferior part of the gluteus
maximus from the ischial tuberosity
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o Gluteofemoral bursa: separates the IT band from the superior part of
the proximal attachment of vastus lateralis
Clunial nerves:
o Cutaneous nerves that supply the skin of the gluteal region
 Remember: cutaneous = sensory, skin
o Are susceptible to injury during procedures of removing iliac bone for
grafting purposes
o Superior clunial nerves:
 Supply skin of superior buttock as far as the tubercle of the
iliac crest
o Middle clunial nerves:
 Supply skin over the sacrum and adjacent areas of the buttock
o Inferior clunial nerves:
 Supply skin of inferior half of the buttock as far as the greater
trochanter of the femur
Femoral nerve
o Derived from L2-L4 (lumbar plexus)
o Innervates the anterior compartment of the thigh (flexors of the
thigh and extensors of the knee)
Obturator nerve
o Derived from L2-L4 (lumbar plexus)
o Passes through obturator foramen to innervate the medial
compartment of the thigh (adductors of the thigh)
Sciatic nerve
o Largest nerve in the body
o Derived from L4-S3
o Consists of the tibial nerve and common fibular nerve
 Tibial nerve: supplies posterior compartment of the thigh
(extension of the thigh and flexion of the knee) and posterior
compartment of the leg (plantarflexion of foot and flexion of
the toes)
 Common fibular nerve: wraps around the fibular head to
branch into a deep fibular nerve (innervates the anterior
compartment of the leg (dorsiflexion of the foot and extension
of the toes)) and a superficial fibular nerve (innervates lateral
compartment of the leg (eversion of the foot))
o Also gives off articular branches that supply the hip and motor
branches that supply the foot
 Gluteal IM injections
o Provides a large surface area for absorption of IM medications
o Avoid neurovascular damage by injecting in the superolateral
quadrant
 How to find:
 Open hand and place middle finger on the tubercle of
the iliac crest
 Place forefinger on the ASIS
 The area in between is considered safe for injection
 Pudendal nerve
o Main nerve of the perineum and chief nerve of the external genitalia
o Derived from S2-S4
o Innervation:
 Sensory innervation to the genitalia
 Muscular branches to perineal muscles, external urethral
sphincter, external anal sphincter
 Superior gluteal nerve
o Derived from L4-S1
o Innervates gluteus medius and gluteus minimus
o Trendelenburg Test:
 Have your patient stand on one leg
 Normal: the gluteus medius and minimus muscles on the
contralateral side should contract, keeping the pelvis level
 With injury to the superior gluteal nerve, when the patient
stands on one leg, the pelvis will “fall” towards the
unsupported side
 Reason: the superior gluteal nerve is injured, which
means that gluteus medius/minimus are non-functional
(or weak) and can’t contract, resulting in a positive
Trendelenburg test
 Inferior gluteal nerve
o Derived from L5-S2
o Innervates gluteus maximus
 Posterior cutaneous nerve of the thigh
o Supplies more skin than any other cutaneous nerve
o Derived from S1-S3
 Perineal branch (S2-S3) supplies skin of perineum
 Inferior clunial nerves (S1-S2) supplies skin of inferior buttock
 Other fibers supply skin of posterior thigh and proximal leg
 Arteries of the gluteal region
o Roadmap: abdominal aorta becomes common iliac artery which splits
into external and internal iliac arteries
 The internal iliac artery gives rise to:
 Superior gluteal artery, inferior gluteal artery, internal
pudendal artery
o Superior gluteal artery
 Largest branch of the internal iliac artery
 Branches into:
 Superficial division: supplies gluteus maximus and the
skin overlying its origin
 Deep division: supplies gluteus medius/minimus, tensor
fascia latae
 Forms anastomoses with the inferior gluteal and medial
circumflex femoral arteries
o Inferior gluteal artery
 Supplies gluteus maximus, obturator internus, quadratus
femoris and the superior portion of the hamstrings (biceps
femoris, semitendinosus, semimembranosus)
o Internal pudendal artery
 Supplies the skin, external genitalia and muscles in the perineal
region
 Veins of the gluteal and posterior thigh regions
o Roadmap: remember veins take blood UP towards the heart
 Femoral vein becomes the external iliac vein
 External iliac vein joins with the internal iliac vein to become
the common iliac vein
 The common iliac veins on either side join to become the
inferior vena cava
o Gluteal veins (superior and inferior): drain blood form the gluteal
region and are considered tributaries of the internal iliac veins
o Internal pudendal veins: drain blood from the external genitalia or
pudendum and joins up with the internal iliac vein
 Lymphatic drainage of the gluteal and thigh regions
o Deep tissues: lymph travels to the superior and inferior gluteal lymph
nodes and then to the internal/external/common iliac lymph nodes
and then to the lateral lumbar (aortic) lymph nodes
o Superficial tissues: lymph travels to the superficial inguinal lymph
nodes and then to the external iliac lymph nodes
Posterior Thigh and Popliteal Fossa
 Thigh has 3 compartments: anterior, posterior, medial
o Anterior and posterior compartment separated via lateral
intermuscular septum
o Anterior and medial compartments separated via medial
intermuscular septum
o NO TRUE FASCIAL SEPARATION BETWEEN POSTERIOR AND MEDIAL
COMPARTMENTS
 Posterior compartment of thigh:
o Actions: extension of the thigh, flexion of the knee
o Occupied principally by the hamstrings
 Lateral to the hamstrings is vastus lateralis
 Medial to the hamstrings is adductor magnus
 Hamstring Muscles (lateral to medial)
o Biceps Femoris
 2 heads: long and short
o Semitendinosus
 Look for the long tendon that attaches to the medial aspect of
the tibia
o Semimembranosus
 Deep to semitendinosus
 The hamstrings all originate on the ischial tuberosity EXCEPT for the short
head of biceps femoris (originates on the linea aspera of the femur)
 Pes anserinus: the location on the medial aspect of the tibia where the
tendons of sartorius, gracillus, and semitendinosus all insert
 Actions of the hamstrings
o Designed to extend the thigh and flex the knee
o However, they are not able to do both maximally at the same time
(just like gastrocnemius)
 When the knee is flexed, the hamstrings have been shortened
such that full thigh extension is not possible
 When the thigh is extended, the hamstrings have been
shortened such that full knee flexion is not possible
o If the lower limbs are fixed, hamstring contraction will help to extend
the trunk (bend backward)
o When the knees are flexed…
 Semitendinosus and semimembranosus allow medial rotation
of the knee while biceps femoris allows lateral rotation of the
knee
 Note: this rotation about the knee is SUBTLE
 Think skiing motion
 Hamstrings and gait
o Hamstring contraction allows you to remain upright while standing
 Prevents falling forward
o During walking:
 Hamstring contraction during swing phase allows for the slight
knee flexion required to bring your leg up off the ground
 Also allows for deceleration of thigh flexion and knee
extension during the terminal swing phase
 Hamstrings injury
o Hamstrings strains are more common than quadriceps strains
o Often occurs in sports with rapid/violent muscle exertion (sprinting)
o Most often occur when the hamstrings muscle is in a lengthened
position
 During limb deceleration in the terminal swing phase of
walking
 i.e. when the thigh is flexed and the knee is extended
o Reasoning: thigh flexion and knee extension is
facilitated by the QUADRICEPS (these muscles
contract and therefore are shortened), which
means the antagonistic muscle group, the
HAMSTRINGS are lengthened
o If significant, it may also result in an avulsion fracture at the ischial
tuberosity
 Nerves
o All hamstring muscles are innervated by the tibial portion of the
sciatic nerve
 EXCEPTION: the short head of biceps femoris is innervated by
the common fibular division of the sciatic nerve
o Cutaneous innervation to the posterior thigh is mainly via the
posterior femoral cutaneous nerve
 This nerve is actually located deep to the fascia lata, with only
terminal branches extending to the surface
 However, the lateral femoral cutaneous nerve innervates the
skin on the lateral aspect of the posterior thigh
 Blood supply
o The posterior compartment of the thigh has no major artery
DIRECTLY supplying it
o Instead it receives its blood supply via:
 Inferior gluteal artery (derived from internal iliac artery)
 Medial circumflex femoral artery and perforating branches
(both derived from the profunda femoris)
 Profunda femoris = deep artery of the thigh, a branch off
the femoral artery
 Note that the perforating branches run transversely inbetween compartments
 Most lymphatic drainage of the thigh comes by way of superficial inguinal
lymph nodes (which follow the femoral vein)
 Popliteal fossa
o A fat-filled, diamond-shaped intermuscular space on the posterior
aspect of the knee
o Represents a key transition point between the thigh and the leg
o Is where the sciatic nerve branches into the tibial and common
fibular nerves, also where the femoral artery becomes the popliteal
artery
o Is covered by popliteal fascia which serves to protect the contents
within
o Boundaries:
 Medial:
 Upper: semitendinosus and semimembranosus
 Lower: medial head of gastrocnemius
 Lateral:
 Upper: biceps femoris
 Lower: lateral head of gastrocnemius, plantaris
 Roof: skin and popliteal fascia
 Floor: femur, knee join capsule, popliteus muscle
o Contents
 In the popliteal fossa, the sciatic nerve splits into the tibial
nerve and the common fibular nerve
 Note that the common fibular nerve will later split into
the deep and superficial fibular nerves
 Cutaneous nerves:
 The tibial nerve gives rise to the medial sural cutaneous
nerve
 The common fibular nerve gives rise to the lateral sural
cutaneous nerve
o The lateral sural cutaneous nerve in turn gives off
a branch known as the sural communicating
branch
o The sural communicating branch joins the lateral
and medial sural cutaneous nerves to form the
sural nerve
 The sural nerve provides sensory innervation to the skin
of the lateral half of the posterior leg
 The saphenous nerve provides sensory innervation to
the skin of the medial half of the posterior leg
 The small saphenous vein pierces the popliteal fossa to empty
into the popliteal vein
 Note: the posterior tibial vein becomes the popliteal
vein at the inferior border of popliteus
 The popliteal vein in turn becomes the femoral vein at
the adductor hiatus (near the tendinous insertion of
adductor magnus)
 The femoral artery becomes the popliteal artery at the
adductor hiatus
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 At the inferior border of popliteus, the popliteal artery
splits to become the anterior and posterior tibial arteries
 Note that the popliteal artery is the deepest structure in
the popliteal fossa
The popliteal artery gives off multiple muscular and genicular
branches
 The genicular branches supply the capsule and ligaments
of the knee joint
o Five total:
 Superior/inferior medial genicular arteries
 Superior/inferior lateral genicular arteries
 Middle genicular artery
 These branches form anastomoses that provide
extensive circulation to the knee
o Is important b/c when the knee is flexed, the
popliteal artery is clamped down, but blood is still
able to flow to the knee via the other branches
Lymph from popliteal lymph nodes eventually reaches the
deep inguinal lymph nodes
The popliteal fascia superficial to the fossa is strong and
resistant to expansion
In the popliteal fossa, since the popliteal artery and vein are in
close proximity to one another, it is possible for a fistula to
form, compromising blood supply to structures distal to this
point (i.e. the leg and foot)
Ankle and Foot
 Ankle (talocrural joint)
o Made up of the medial malleolus (from the tibia), the lateral
malleolus (from the fibula) and the talus (keystone of the ankle)
 Foot: the portion of the lower limb distal to the ankle
o Includes: tarsal bones, metatarsal bones, phalanges
o Designed to support body weight (bipedal stance) and provide
leverage for locomotion
o Has both a dorsal and plantar surface
o Can be classified anatomically or functionally
 Anatomical classification
 Tarsus (tarsal bones), metatarsus (metatarsal bones),
phalanges
 Functional classification
 Hindfoot: talus and calcaneus
 Midfoot: navicular, cuboid, cuneiforms, metatarsals
 Forefoot: phalanges
o Parts of the foot vary in thickness and texture of the skin,
subcutaneous tissue and deep fascia
 Dependent upon the extent of weight-bearing, distribution,
grip and abrasion
o Dorsum of foot: superior
 Features thinner, less sensitive skin alongside loose
subcutaneous tissue
 As a result, swelling of the foot is more prominent on
this side
o Sole of the foot: plantar surface
 Features thicker, highly vascularized and sensitive skin
alongside strong fibrous connective tissue
 Makes sense since this is what is in contact with the
environment
 Also contains pressure chambers (fat-filled pockets lined with
ligaments) designed to evenly distribute pressure/forces across
the foot during standing and walking
 If these weren’t present, forces and pressures would
accumulate more in certain areas than others, resulting
in pressure necrosis
o The deep fascia of the foot is thicker on the sole rather than the
dorsum of the foot
 The deep fascia on the sole is known as plantar fascia
 The thickest part of the plantar fascia (located in the middle of
the sole of the foot) is known as the plantar aponeurosis
 Role of the plantar aponeurosis: protects underlying
structures, maintains the arch of the foot, offers
attachment for skin/subcutaneous tissue, helps create
muscular compartments in the foot
 Plantar fasciitis: inflammation of the plantar fascia
 Often caused by overuse
 Creates pain in the plantar and medial aspects of the
foot; especially upon extension of big toe and
dorsiflexion of foot
 Repeated tearing of the plantar aponeurosis can
generate a bone spur at its proximal attachment to the
calcaneal tuberosity
o Functions of the foot: support body weight, provide leverage for
locomotion
 The foot has the ability to deform on contact, allowing it to
absorb many of the forces that otherwise would be
transmitted farther up the skeleton
 Much of the flexibility of the foot is provided by the numerous
bones and joints (alongside the associated muscles and
ligaments) contained therein
o Arches of the foot
 Medial/lateral longitudinal arches, transverse arch
 Formed by the arrangement of the tarsal and metatarsal bones
 Function to absorb shock and offer a springboard effect for
locomotion
 In addition, they also offer sufficient strength
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o
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 The arches are supported via: the wedge-shape of the bones,
associated ligaments and tendons
Joints of the foot
 Intertarsal joints: between the tarsal bones
 Tarsometatarsal joints: between the tarsal and metatarsal
bones
 Intermetatarsal joints: between the metatarsal bones
 Metatarsophalangeal joints: between the metatarsals and
phalanges
 Interphalangeal joints: between the phalanges (think DIP and
PIP)
Movements at the FOOT joints
 Inversion/eversion of the foot
 Inversion: bringing medial malleolus up
 Eversion: bringing lateral malleolus up
 Flexion/extension of the toes
 Flexion: pointing toes down (like your gripping
something)
 Extension: pointing toes up towards your chin
 NOTE: dorsiflexion and plantarflexion are permitted at the
ANKLE (talocrural) joint!
When the foot is weight-bearing, the arches of the foot allow
transmission of force through the talus to:
 Calcaneus (heel)
 Heads of 1st to 5th metatarsals
 Note that the head of the 1st metatarsal (big toe) is in
proximity to two sesamoid bones that are designed to
protect the tendon of flexor hallucis longus
Foot inversion/eversion
 These motions are facilitated by the intertarsal and
tarsometatarsal joints
 Subtalar joint: functionally speaking consists of two parts
 Talocalcaneal joint: articulation between the talus and
calcaneus
 Talocalcaneal portion of the talocalcaneonavicular joint
(the articulation amongst the talus, calcaneus and
navicular bones)
 Transverse tarsal joint: also consists of two parts
 Talonavicular portion of the talocalcaneonavicular joint
 Calcaneocuboid joint: articulation between the
calcaneus and the cuboid
 The greatest amount of foot movement occurs at this
joint
o Here you have rotation of the midfoot and
forefoot about the hindfoot
 Often a site of surgical amputation
 Tarsometatarsal joints
 Allows for some foot rotation and flexion/extension
o This is important in allowing the foot to adapt to
uneven surfaces
o Flexion/extension of the toes
 Permitted via the metatarsophalangeal and interphalangeal
joints
 Note: digits 2-5 have BOTH a PIP and DIP joint while digit
1 (big toe) has a single IP joint
 The metatarsophalangeal joints also allow for
abduction/adduction of the toes
 Abduction: spreading toes apart
 Adduction: bringing toes together
 Three main ligaments on the plantar surface of the foot:
 Long plantar ligament
 Short plantar ligament (plantar calcaneocuboid)
 Spring ligament (plantar calcaneonavicular)
o Supports the talus
 All three are involved in supporting the longitudinal arch
of the foot
o Flatfoot = Pes Planus
 Is normal before the age of three
 Different types
 Flexible flatfeet: feet are normal when not bearing
weight
o Due to loose or degenerated ligaments
 Rigid flatfeet: feet are flat in ALL conditions
o Due to bone deformity
 Acquired flatfeet: fallen arches secondary to tibialis
posterior dysfunction
o Spring ligament is unsupported and fails
 With loss of the arch(es), the talus will be displaced inferiorly
and medially
o Muscles of the foot
 Intrinsic muscles of the foot originate and insert in the foot
 Grouped into two categories
 Dorsal extensors and plantar flexors
 Function: support the arches and assist the long muscles in
locomotion
o Plantar foot muscles
 Located under the boney arch between the heel and the toes
 Organized into 4 layers
 Layer one:
o Deep to plantar aponeurosis but superficial to the
neurovasculature
o Abductor hallucis: abducts big toe
o Flexor digitorum brevis
o Abductor digiti minimi: abducts digit 5
 Layer two:
o Deep to flexor digitorum brevis and abductor
hallucis
o Quadratus plantae: inserts on the tendon of flexor
digitorum longus
o Lumbricals: originate on the tendon of flexor
digitorum longus
 Flex proximal phalanges and extend the
middle and distal phalanges of digits 2-5
 Layer three:
o Deep to quadratus plantae and tendon of flexor
digitorum longus
o Flexor hallucis brevis: contains a channel that
allows passage of the tendon of flexor hallucis
longus
o Adductor hallucis: transverse and oblique head
o Flexor digiti minimi brevis
 Layer four:
o NOTE: axis of abduction/adduction of the toes is
digit 2
o Plantar interossei (PAD): adduct digits 3-5
o Dorsal interossei (DAB): abduct digits 2-4
 Remember digits 1 and 5 have their own
separate abductor muscles (abductor
hallucis and abductor digiti minimi)
o Furthermore, these muscles also flex the
metatarsophalangeal and extend the
interphalangeal joints
 Plantar foot muscles are innervated via the medial and lateral
plantar nerves (derived from the tibial nerve)
 Lateral plantar nerve innervates deep and lateral plantar
muscles, including all the interossei
 Medial plantar nerve innervates superficial and medial
plantar muscles
 Plantar foot muscles receive their blood supply from the
medial and lateral plantar arteries (derived from the posterior
tibial artery)
 Note: lateral plantar artery gives rise to plantar arch
 Roadmap:
o Posterior tibial artery gives rise to the medial and
lateral plantar arteries
o Lateral plantar artery gives rise to the plantar arch
o Plantar arch gives rise to the plantar metatarsal
arteries
o Plantar metatarsal arteries give rise to the plantar
digital arteries
o Dorsal foot muscles
 Extensor digitorum brevis
 Assists extensor digitorum longus
 Extensor hallucis brevis
 Assists extensor hallucis longus
 Innervated by the deep fibular nerve
 Note: the deep fibular nerve also innervates the anterior
compartment leg muscles
 Blood supply:
 Dorsalis pedis supplies most of the forefoot
o Is derived from the anterior tibial artery (which
becomes dorsalis pedis at the malleoli)
 Dorsalis pedis in turn branches to form:
o Arcuate and lateral tarsal arteries
 Both these form anastomoses with one
another
 Dorsalis pedis is a common site in which to take a pulse
o Diminished pulse may indicate peripheral artery
disease
o Cutaneous innervation of the foot
 Dorsum: deep and superficial fibular nerves and saphenous
nerve
 Sole: medial and lateral plantar nerves
o Deep fibular nerve entrapment
 Also known as “ski boot syndrome”
 Results in pain in the anterior compartment of the leg,
radiating to the web-space between digits 1 and 2