Musculoskeletal Lower Body

Anterior thigh muscles:

? Iliacus:
- origin: iliac fossa and posterior aspect of sacrum
- insertion: lesser trochanter via the iliopsoas tendon
- action: flexion and medial rotation of hip
- nerve innervation: femoral L2, L3
? Psoas Major:
- origin: lumbar vertebrate
- insertion: lesser trochanter via the iliopsoas tendon
- action: flexion and medial rotation of hip
- nerve innervation: 2nd and 3rd lumbar nerve
 Sartorius: longest muscle in the body and act as a synergist with other thigh muscles.
- origin: anterior superior iliac spine
- insertion: superior aspect of the medial surface of tibia
- action: mainly flexion of knee
- nerve innervation: femoral L2, L3
 Rectus femoris:
- origin: straight head on the anterior inferior iliac spine while reflected head on the posterior-superior margin of the acetabulum
- insertion: tibial tuberosity
- action: flexion of hip and extension of knee
- nerve innervation: femoral L2, L3, L4
 Vastus lateralis:
- origin: greater trochanter, intertrochanteric line, linea aspera, lateral intermuscular septum
- insertion: tibial tuberosity
- action: extension of knee
- nerve innervation: femoral L2, L3, L4
 Vastus medialis:
- origin: intertrochanteric line, spiral line and medial intermuscular septum
- insertion: tibial tuberosity
- action: extends knee
- nerve innervation: femoral L2, L3, L4
 Vastus intermedius:
- origin: 2/3 of upper portion of femur and one half of lower lateral intermuscular septum
- insertion: tibial tuberosity
- action: extends knee
- nerve innervation: femoral L2, L3, L4
 Articularis genu:
- origin and insertion: slips of muscle deep to the vastus intermedius
- action: pulls synovial membrane out of way of articular surfaces during knee extension
- nerve innervation: femoral
 Quadriceps: the tendons of the four parts of quadriceps unite in the distal l portion of the thigh to form a single strong board quadriceps tendon. The patellar ligament is attached to the tibial tuberosity and is a continuation of the quadriceps tendon.

Medial thigh muscle:

 Adductor longus: most anterior adductor muscle
- origin: pubic body immediately inferior to the pubic crest
- insertion: linea aspera
- action: adduction, flexion and rotation of the hip laterally
- nerve innervation: obturator anterior division L2, L3, L4
 Adductor brevis: lies deep to the pectineus and adductor longus. Obturator nerve splits passing anteriorly and posteriorly to this muscle
- origin: inferior ramus and body of pubis
- insertion: upper portion of the linea aspera
- action: adduction, flexion and rotation of the hip laterally
- nerve innervation: obturator anterior division L2, L3, L4
 Adductor magnus:
- origin: inferior ischiopubic ramus (adductor portion) and ischial tuberosity (hamstring portion)
- insertion: extensively into linea aspera, gluteal tuberosity and media supracondylar ridge (adductor portion), and adductor tubercle (hamstring portion)
- action: adduction, flexion and rotation of hips laterally (adductor portion), extension and medial rotation of hip (hamstring portion)
- nerve innervation: obturator posterior division L2, L3, L4 (adductor), sciatic/tibial L4 (hamstring)
 Pectineus: located in the anterior part of the superomedial aspect of the thigh. It’s composed of two layers – deep and superficial
- origin: superior ramus and pubic pecten (pectineal line of the pelvis)
- insertion: posteriorly between the lesser trochanter and the linea aspera (pectineal line of the femur)
- action: adduction and flexion of hip
- nerve innervation: obturator and femoral L2, L3
 Gracilis: most superficial and weakest muscle of the adductor group.
- origin: lower half of the pubic body
- insertion: superior portion of the medial surface of tibia
- action: Adduction, flexion and rotation of the knee medially
- nerve innervation: obturator L2, L3
 Obturator externus: extends from the external surface of the obturator membrane and surrounding bone of the pelvis to the posterior aspect of the greater trochanter, passing directly under the acetabulum and neck of the femur.
- origin: margin of the obturator foramen and obturator membrane
- insertion: posterior aspect of the intertrochanteric fossa of femur
- action: flexion and rotation of hip laterally
- nerve innervation: obturator L3, L4

Posterior thigh muscles:

 Bicep femoris: contains two heads. The long head crosses and provide protection for sciatic nerve and follows the lateral branch (common fibular nerve).
- origin: ischial tuberosity (long head), linea aspera and upper half of supracondylar ridge of femur (short head)
- insertion: common tendon into head of fibula
- action: flexion of knee, lateral rotation of leg and extension of hip
- nerve innervation: tibial (long head), fibular (short head) L5, S1, S2
 Semitendinosus: the muscle has a fusiform belly that is usually interrupted by a tendinous intersection and a long-cord like tendon that begins two thirds of the way down the thigh
- origin: ischial tuberosity
- insertion: superior aspect of the medial surface of tibia
- action: flexion of knee, rotation of leg medially and extension of hip joint
- nerve innervation: tibial L5, S1, S2
 Semimembranosus: broad muscle with a flattened membranous form at its proximal attachment to the ischial tuberosity. The tendon divides distally into three parts – a direct attachment to the posterior aspect of the medial tibial condyle, a part that blends with popliteal fascia and a reflected part called oblique popliteal ligament.
- origin: ischial tuberosity
- insertion: medial condyle of tibia
- action: flexion of knee, extension of hip and medial rotation of leg
- nerve innervation: tibial L5, S1, S2

Gluteal muscles:

 Gluteus maximus: most superficial gluteal muscle and the largest, heaviest and most coarsely fibered muscle of the body. Covers all of other gluteal muscles except for the antero-superior third of the gluteal medius. When the thigh is flexed, maximus moves superiorly exposing the ischial tuberosity and the fatty tissue and skin above it.
- origin: upper portion of the ilium, posterior aspect of sacrum and coccyx and sacrotuberous ligament
- insertion: iliotibial band and gluteal tuberosity
- action: powerful extension and lateral rotation of hip
- nerve innervation: inferior gluteal L5, S1, S2
 Gluteus medius:
- origin: upper ilium between the anterior and posterior gluteal line
- insertion: greater trochanter and oblique ridge of the femur
- action: abduction and medial rotation of the hip
- nerve innervation: superior gluteal L4, L5, S1
 Gluteus minimus:
- origin: ilium between the anterior and inferior gluteal line
- insertion: greater trochanter and the capsule of the hip joint
- action: abduction and medial rotation of the hip
- nerve innervation: superior gluteal L4, L5, S1
 Tensor fascia lata: fusiform muscle enclosed between two layers of fascia lata. It produces flexion in concert with the iliopsoas and rectus femoris. Also tenses the fascia lata and iliotibial tract and support the femur on the tibia when standing.
- origin: iliac crest and anterior border of the ilium
- insertion: iliotibial band
- action: tenses the fascia lata and assist in flexion, abduction and medial rotation of the hip
- nerve innervation: superior gluteal L4, L5, S1
 Piriformis: located partly on the posterior wall of the lesser pelvis and posterior to the hip joint. Leaves the pelvis through the greater sciatic foramen. Superior gluteal vessel and nerve emerge superior to it and inferior vessels and nerve emerge inferior.
- origin: greater sciatic notch, internal aspect of the sacrum and sacrotuberous ligament
- insertion: greater trochanter
- action: lateral rotation of the hip
- nerve innervation: branches of sacral plexus S1, S2
 Gemelli superior and inferior: these muscles act as one with obturator internus
- origin: upper portion of lesser sciatic notch (superior), lower portion of lesser sciatic notch (inferior)
- insertion: greater trochanter or obliquely into the border of the tendon of obturator internus
- action: lateral rotation of hip
- nerve innervation: branches of sacral plexus
 Obturator internus: located partly in the pelvis and leaves through the lesser sciatic foramen, becomes tendinous, and receives the distal attachments of the gemelli before attaching to the medial greater trochanter.
- origin: margin of obturator foramen and obturator membrane
- insertion: greater trochanter
- action: lateral rotation of hip
- nerve innervation: nerve to obturator internus L5, S1, S2
 Quadratus femoris: short flat quadrangular muscles located inferior to the obturator internus and gemelli
- origin: lateral ischial tuberosity
- insertion: quadrate tubercle of the femur
- action: lateral rotation of hip
- nerve innervation: nerve to quadratus femoris L4, L5 and S1

Anterior leg muscles

 Tibialis anterior: the most medial and superficial dorsiflexor that lies against the lateral surface of the tibia. Its tendon beings half way down the leg and passes within its own synovial sheath deep to the superior and inferior extensor retinacula to the medial side of the foot.
- origin: superior half of lateral surface of shaft of tibia and interosseous membrane
- insertion: medial cuneiform and base of first metatarsal bone
- action: dorsiflexes ankle, inverts foot at subtalar and transverse tarsal joints, holds up medial longitudinal arch of foot
- nerve innervation: deep fibular nerve L4, L5
 Extensor digitorium longus: most lateral of the anterior leg muscles. A small part of the proximal attachment is to the lateral tibial condyle, the muscle becomes tendinous superior to the ankle forming four tendons and each tendon forms a membranous extensor expansion over the dorsum of the proximal phalanx of the toe.
- origin: superior 3/4 of anterior surface of shaft of fibula and interosseous membrane
- insertion: extensor expansion of lateral four toes (phalanges)
- action: extends toes; dorsiflexes ankle
- nerve supply: deep fibular nerve L5, S1
 Extensor hallucis longus: thin muscles that lies deeply between TA and EDL at its superior attachment to the middle half of the fibula and interosseous membrane. The EHL rises to the surface in the distal third of the leg, passing deep to the extensor retinacula.
- origin: middle portion of anterior surface of shaft of fibula
- insertion: base of distal phalanx of great toe
- action: extends big toe, dorsiflexes ankle and inverts foot at subtalar and transverse tarsal joint
- nerve innervation: deep fibular nerve L5, S1
 Fibularis tertius: proximally, the attachments and fleshy parts of the DL and PT are continuous however the PT tendon separate and attaches to the 5th metatarsal.
- origin: inferior 1/3 of anterior surface of shaft of fibula
- insertion: base of fifth metatarsal bone
- action: dorsiflexes ankle; everts foot at subtalar and transverse tarsal joints
- nerve innervation: deep fibular nerve L5, S1

Lateral and posterior leg muscles

 Fibularis longus: the longer and more superficial muscle of the fibular muscles. Its tendon can be palpated and observed proximal and posterior to the lateral malleolus. The muscles helps stead the leg when standing on one foot.
- origin: superior 2/3 of lateral surface of shaft of fibula
- insertion: base of first metatarsal and the medial cuneiform
- action: plantarflexes ankle, everts foot at subtalar and transverse tarsal joint, and supports lateral longitudinal and transverse arches of foot
- nerve innervation: superficial fibular nerve L5, S1
 Fibularis brevis: the broad tendon of this muscles grooves the posterior aspect of the lateral malleolus
- origin: lateral surface of shaft of fibula
- insertion: base of fifth metatarsal bone
- action: plantarflexes ankle and everts foot at subtalar and transverse tarsal joint, supports lateral longitudinal arch of foot
- nerve innveration: superficial fibular L5, S1
 Gastrocnemius: most superficial muscle of the posterior compartments. It’s two headed, two joint with the medial head slightly larger and longer distally than the lateral head. Gastrocnemius can’t exert its full power on both joints at the same time; it functions best when knee is extended and foot dorsiflexed and least when knee is fully flexed.
- origin: lateral condyle of femur (lateral head) and popliteal surface and medial condyle of femur (medial head)
- insertion: posterior surface of calcaenus via calcaneal tendon
- action: plantarflexes ankle and flexion of knee
- nerve innervation: tibial S1, S2
 Soleus: Located deep to gastrocnemius, the soleus is a flat muscles with a proximal attachments resembling the shape of an inverted U. It does not act on knee joint and plantarflexes the ankle alone if knee is fully flexed. Soleus is also an antigravity muscle which cooperates to contract posteriorly and keeps body in balance.
- origin: superior surface of fibula and soleal line on tibia
- insertion: posterior surface of calcaenus via calcaneal tendon
- action: plantarflexes ankle
- nerve innervation: tibial S1, S2
 Plantaris: vestigial small muscle that acts with gastrocnemius insignificantly
- origin: popliteal surface of femur above lateral head of gastrocnemius
- insertion: medial side of calcaneal tendon
- action: plantarflexes ankle
- nerve innervation: tibial S1, S2
 Popliteus: thin triangular muscle that forms the inferior part of the floor of the popliteal fossa.
- origin: popliteus groove, lateral condyle of femur
- insertion: tibia above soleal line
- action: lateral rotation of knee joint when fully extended
- nerve innervation: tibial L4, L5, S1
 Flexor digitorium longus: direction of pull is realigned by the quadratus plantae muscles which is attached to the posterolateral aspect of the FDL tendon
- origin: middle one half of tibia below soleal line
- insertion: distal phalanges of the four lateral toes
- action: flexes phalanges of lateral toes and continued plantarflexion and inversion of foot
- nerve innervation: tibial S2, S3
 Flexor hallucis longus: powerful flexor of all the joints of great toe. The tendon of FHL passes posterior to the distal end of the tibia and occupies a shallow groove on the posterior surface of the talus. It then crosses the FDL tendon and to the distal phalanx of great toe
- origin: inferior 2/3 of fibula and intermuscular septa
- insertion: base of distal phalanx of great toe
- action: flexes great toe and continued plantarflexion of ankle and inversion of foot
- nerve innervation: tibial S2, S3
 Tibialis posterior: the deepest muscles in the posterior compartment and lies between FDL and FHL. Its primary role is to support the medial longitudinal arch during weight bearing
- origin: interosseous membrane and adjoining of tibia and fibula
- insertion: into tuberosity of navicular and also cuneiforms, cuboid and bases of 2nd, 3rd and 4th metatarsals
- action: principal inverter of foot and plantarflexes ankle
- nerve innervation: tibial L4, L5

Dorsum of foot

 Extensor digitorium brevis:
- origin: anterolateral upper surface of calcaneus and deep surface of inferior extensor retinaculum
- insertion: middle and distal phalanges of 2-4th toes along with EDL
- action: extends toes without dorsiflexing foot
- nerve innervation: deep fibular L5, S1
 Extensor hallucis brevis:
- origin: same as EDB
- insertion: proximal phalanx of big toe
- action: extends proximal phalanx of big toe
- nerve innervation: deep fibular L5, S1

Sole of foot

First Layer
 Abductor hallucis:
- origin: medial tubercle calcaneum and lower edge flexor retinaculum
- insertion: medial side base proximal phalanx big toe and medial tendon FHB
- action: flexes and abducts big toe
- nerve innervation: medial plantar
 Abductor digiti minimi:
- origin: medial and lateral tubercle calcaneum
- insertion: lateral base proximal phalanx of 5th
- action: flexes and abducts 5th toe
- nerve innervation: lateral plantar
 Flexor digitorium brevis:
- origin: medial tubercle calcaneum
- insertion: lateral 4 toes
- action: flexes four lateral toes
- nerve innervation: medial plantar
Second Layer
 Quadratus plantae:
- origin: two heads medial-lateral sides calcaneum
- insertion: posterolateral margin tendon of FDL
- action: flexes lateral 4 toes (aiding FDL)
- nerve innervation: lateral plantar
 Lumbricals:
- origin: 4 tendons of FDL
- insertion: medial side dorsal expansion tendons of EDL
- action: prevent lateral toes from buckling by extending toes at interphalangeal joints
- nerve innervation: medial plantar (1st lumbricals), lateral plantar (2nd, 3rd, 4th lumbrical)
 Flexor digitorum longus tendon
 Flexor hallucis longus tendon
Third Layer
 Flexor hallucis brevis:
- origin: cuboid and lateral cuneiform and tendinous extension from tibialis posterior
- insertion: medial tendon to medial side proximal phalanx big toe, lateral tendon joins adductor hallucis to lateral side of same bone
- action: flexion of metatarsophalangeal joint
- nerve innervation: medial plantar
 Adductor hallucis:
- origin: oblique head on base of 2nd, 3rd, 4th metatarsal, transverse head on metatarsophalangeal joint of 3rd, 4th and 5th toes
- insertion: both join lateral tendon of FHB into lateral base proximal phalanx big toe
- action: flexion of big toe (oblique), holds metatarsal together (transverse)
- nerve innervation: lateral plantar
 Flexor digiti minimi brevis
- origin: base 5th metatarsal
- insertion: lateral base proximal phalanx little toe
- action: flexion of metatarsophalangeal joint of little toe
- nerve innervation: lateral plantar
Fourth Layer
 Interossei 4 dorsal
- origin: adjacent sides metatarsal bones
- insertion: 1st dorsal inserts medially to 2nd toe and 3 others inserts laterally to 2nd, 3rd and 4th toes
- action: abduct away from 2nd toe, and flex metatarsophalangeal and extend interphalangeal joint
- nerve innervation: lateral plantar
 3 plantar
- origin: inferior surface of 3rd, 4th and 5th metatarsal bones
- insertion: medially at base of proximal phalanges of 3rd 4th and 5th toes and dorsal extensor expansions for both interossei groups
- action: adducts toes towards center toe, flex metatarsophalangeal joint and extended interphalangeal joint
 Fibularis longus tendon
 Tibialis posterior tendon

Fascia of the lower limb:

 Superficial fascia: layer of loose connective tissue containing a variable amount of fat, cutaneous nerves and superficial veins, lymphatic vessels and nodes. At the knee the subcutaneous tissue blends with the deep fascia.
 Fascia lata: deep fascia of the lower limb. Its attached to/continuous with:
- inguinal ligament, superior pubis, scarpa fascia of the inferior abdominal wall
- iliac crest laterally and posteriorly
- sacrum, coccyx, sacrotuberous ligament and ischial tuberosity posteriorly
- exposed parts of the bones around the knee and the deep fascia of the leg
 Crural fascia: deep fascia of the lower leg
 Iliotibial tract: a broadening of the lateral fascia lata which is the conjoint aponeurosis of the tensor fascia lata and gluteus maximus. It begins in the iliac tubercle and ends at the anterolateral tibial tubercle, and the function is stabilization muscles on the lateral side and keep leg extended.
 Upper thigh intermuscular septum: walls of the deep fascia that attaches to the linea aspera and separates the thigh into three apartments. The lateral intermuscular septum is especially strong and it extends deeply from the iliotibial tract to the linea aspera thus providing a internervous plane for surgeons
- medial IS separate medial and anterior compartments
- posterior IS separate medial and posterior
- lateral IS separate anterior and posterior
 Lower thigh intermuscular septum:
- anterior IS attached to the anterior surface fibula separates anterior and lateral compartments
- posterior IS attaches to lateral side of fibula separate lateral and posterior compartments
- interosseous membrane that joins fibula and tibia separates anterior and posterior compartments
- transverse IS separates superficial and deep posterior muscles
 Saphenous opening: a gap in the fascia lata inferior to the medial part of the inguinal ligament, which transmit the great saphenous vein
 Fascia of foot (plantar fascia)
- plantar aponeurosis: the thick central part of the plantar fascia with longitudinally arranged bundles of dense fibrous connective tissue investing the central plantar muscles. It arises posteriorly from the calcaneus and functions like a superficial ligament, dividing into five bands and become continuous with the fibrous digital sheath. Function of the plantar aponeurosis include protection, compartmentalization and support of longitudinal arch of foot

Anatomic Features of the Upper Thigh

 Pes anserinus: the common tendinous insertion of the three muscles, from medial to lateral - sartorius, gracilis and semitendinosus into the upper part of the medial surface of the tibia. It allows the three muscles to add stability to the medial aspect of the extended knee
 Adductor hiatus: an opening or gap between the aponeurotic distal attachment of the adductor magnus adductor part and tendinous distal attachment of the hamstring part. It’s located just lateral and superior to the adductor tubercles of the femur. The hiatus transmit the femoral artery and vein from adductor canal to popliteal vessels in the popliteal fossa.
 Femoral triangle: a subfascial space in the medial thigh bounded superiorly by the inguinal ligament (base of triangle), medially by the adductor longus, and laterally by sartorius (apex is where the sartorius crosses the adductor longus).
- roof: fascia lata and cribriform fascia, subcutaneous tissue and skin
- floor: iliopsoas laterally and pectineus medially.
- content: lateral to medial – femoral nerve, femoral sheath containing femoral artery, vein and deep inguinal lymph nodes and associated lymphatic
 Clinical importance of femoral triangle:
- Location of femoral artery: the initial part of the femoral artery is superficial making it especially accessible and useful for clinical procedures. The femoral artery maybe cannulated just inferior to the midpoint of the inguinal ligament for left cardial angiography.
- Location of femoral vein: femoral vein is not usually palpable but its position can be located inferior to inguinal ligament by feeling the pulsation of the femoral artery, immediately lateral to the vein.
- Saphenous Varix: a localized dilation of the terminal part of the great saphenous vein may cause edema in the femoral triangle.
- Femoral hernia: a protrusion of the abdominal viscera (often a loop of the small intestine) through the femoral ring in to the femoral canal. It’s often a tender mass in the femoral triangle inferolateral to the pubic tubercles. Strangulation of hernia by femoral ring can cause death of tissue.
 Subinguinal space: a passage way created by the gap between the two bony prominences to which the inguinal ligament spans and connects the trunk/abdominopelvic cavity to the lower limb.
 Femoral sheath: funnel shaped fascial tube that passes deep to the inguinal ligament, lining the vascular lacuna of the subinguinal space. It terminates inferiorly by blending with the adventitia of the femoral vessels. The sheath is formed by the transversalis and iliac fascia that is carried down around the femoral vessels.
- function: allows the femoral artery and vein to glide deep to the inguinal ligament during movement of the hip joint.
 Femoral canal: the smallest medial canal of the three compartment of the femoral sheath, containing the lymph vessels, connective tissue and fat.
- the femoral canal extends distally to the level of the saphenous opening
- the base of the canal is formed by a small proximal opening called femoral ring at the abdominal end
- function: allows the femoral vein to expand when venous return from the lower limb is increased or when increased intra-abdominal pressure causes a temporary stasis in the vein
 Femoral ring: opening in the femoral septum that is punctured by the lymph vessels in the femoral canal.
- lateral: the vertical septum between the femoral canal and the femoral vein
- posteriorly: superior ramus of the pubis covered by the pectineus and its fascia
- medially: the lacunar ligament
- anteriorly: medial part of the inguinal ligament
 Adductor canal: narrow passageway in the middle third of the thigh and extends form the apex of the femoral triangle to the adductor hiatus.
- function: provides a intermuscular passage for femoral artery and vein, the saphenous nerve, and the nerve to vastus medialis, delivering the femoral vessels to the popliteal fossa
- boundaries: anteriorly and laterally by vastus medialis, posteriorly by the adductor longus and magnus and medially by the sartorius

Anatomic Features of the Lower Leg:

 Retinaculum: thickenings of the fascia that bind the tendons of the lower leg compartment muscles before and after they cross the ankle joint, preventing them from bowstringing.
- superior extensor retinaculum: strong broad band of fascia passing from fibula to tibia proximal to the malleoli
- inferior extension retinaculum: a y-shaped band of deep fascia that covers all anterior tendons from medial to lateral part of the anterosuperior surface of the calcaneus
- superior fibular retinaculum: fascia that covers the tendinous endings of the lateral compartment muscles and spans from the distal tip of the fibula to the calcaneus
- inferior fibular retinaculum: continuation laterally of the inferior extensor retinaculum to the fibular trochlea to cover and separate the fibularis tendons and ultimately attaches to the lateral side of the calcaneus
- Flexor retinaculum: reinforcing transverse fibers that extends between the tip of the medial malleolus and the calcaneus
- Extensor hood: retinaculum for extensor tendon at the phalanges
 Calcaenus tendon: the common tendon in which the two heads of gastrocnemius and soleus converge into and attaches to the calcaneus. It’s the thickest and strongest tendon in the body and a continuation of the flat aponeurosis formed half way down the leg where the gastrocnemius terminates and fleshy fibers of soleus is received deeper and proximally.
 Triceps surae: the muscular mass collectively made up by the gastrocnemius and soleus that acts through the lever provided by calcaneal tuberosity and generating as much as 93% of plantarflexion force
 Tendinous arch of the soleus: tendon bridge of the soleus muscles between the tibia and fibula where the popliteal artery and tibial nerve exits the popliteal fossa. This is also where the popliteal artery bifurcates into its terminal branches.
 Clinical significance of anterior compartment:
- shin splints: repetitive micro-trauma to TA can cause tear in the periosteum covering the shaft of the tibia or overlying deep fascia, leading to edema and pain in distal two-thirds of the tibia. Muscle in the anterior compartment inflame from sudden overuse and are painful and tender to pressure
- deep fibular nerve entrapment: compression of the fibular nerve through swollenness in the anterior compartment or by tight fitting boots at the extensor retinaculum, e.g. ski boot syndrome. Pain is felt in the dorsum of the foot and radiates to the between space between 1st and 2nd toe.
 Clinical significance of lateral compartment:
- used to support and depress the medial foot during the toe off of the stance phase to resist inadvertent inversion and prevent injury
- injury to common fibular nerve: common fibular is the most injured nerve in the lower limb due to its superficial position of winding around the fibular neck. Severance of the nerve result in flaccid paralysis of all muscles in the anterior and lateral compartments of leg. Loss of dorseflexion produce foot drop and coupled with loss of eversion has the effect of making limb “too long”
- avulsion of the tuberosity of 5th metatarsal: violent inversion of foot can tear the tuberosity of the 5th metatarsal this distal attachment of fibularis brevis and is associated with a severely sprained ankle. Consequential injury to superficial fibular nerve causes inversion of the foot due to paralysis of lateral muscle.
 Clinical significance of posterior compartment:
- compartment syndrome: hemorrhage, edema or inflammation of the muscle due to trauma can leads to an increase in the intracompartmental pressure due to the strength of lower leg fascia. Consequently affected structures may lose function or die due to compression of the blood supply and/or nerve innervation. Lowering of temperature or loss of distal pulse is an obvious sign.
- Ruptured calcaneal tendon: injury experienced by people with a history of calcaneal tendonitis during a forceful plantarflexion. There is loss of plantarflexion and excessive passive dorseflexion. Bruising appears in the malleolar region and limb in the calf.
- Gastrocnemius strain: painful acute injury resulting from partial tearing of the medial belly of the gastrocnemius at or near its musculotendinous junction. Occurs through overstretching of the muscle by concomitant full extension of the knee and dorseflexion of the ankle

Anatomic Features of gluteal region

 Boundary of gluteal region: bounded superiorly by the level of iliac crest and inferiorly the inferiormost boundary of the gluteus maximus muscle (usually at the gluteal fold)
 Clinical significance of gluteal region:
- Injury to the superior gluteal nerve: injury to this nerve results in a characteristic motor loss resulting in a disabling gluteus medius limp. Normally the gluteus minimus and medius contract as soon as the contralateral foot leaves the floor. But this action is absent when the person suffers a superior gluteal nerve lesion and the pelvis on the unsupported side descends. The observation is referred as a positive Trendelenburg test.
- Injury to sciatic nerve: piriformis syndrome causes pain sensations in the buttock as a result from compression of the sciatic nerve. With complete section of sciatic nerve, lower leg action and extension of hip and flexion of leg are all impaired.
- Intragluteal injection: gluteus region is a common site for intramuscular injection as muscles are thick and large and consequently provide a substantial volume for absorption by intramuscular veins. Injection into buttocks is safe only in the superior lateral quadrant (superior border of gluteus maximus)

Popliteal Fossa

 Popliteal fossa: a rough diamond shaped shallow depression at the back of the knee joint
 Boundary of popliteal fossa:
- superolaterally: biceps femoris
- superomedially: semimembranosus
- inferomedially: medial head of the gastrocnemius
- inferolaterally: lateral head of the gastrocnemius
- roof: skin and popliteal fascia
- floor: popliteal surface of the femur, posterior capsule of knee joint and popliteus fascia covering popliteus muscle
 Content of popliteal fossa:
- termination of small saphenous vein
- popliteal arteries and vein and their branches and tributaries
- tibial and common fibular nerve
- posterior cutaneous nerve of thigh
- popliteal lymph nodes and vessels
 Popliteal fascia: a strong sheet of deep fascia continuous superiorly with fascia lata and inferior with the deep fascia of the leg that forms a protective covering for the neurovascular structure passing through the popliteal fossa. When leg is extended, the popliteal fascia becomes taut and semimembranosus moves laterally providing further protection of the content.
 Nerve of the popliteal fossa: the sciatic nerves ends at the superior angle of the popliteal fossa by dividing into tibial and common fibular nerves.
- The tibia nerve is the most superficial component and it bisects the fossa. Medial sural nerve is also derived from the tibial nerve in the fossa and forms communicating branches by the common fibular nerve to form sural nerve
- Common fibular nerve is the lateral smaller branch of sciatic and begs at the superior angle of the popliteal fossa and follows closely he superolateral border. The nerve exits the fossa by passing superficially to the gastrocnemius head and over the posterior aspect of the fibular head.
- The inferior branches of the posterior cutaneous nerve of the thigh supply the skin overlying the popliteal fossa.
 Blood vessels of popliteal fossa:
- Popliteal artery, the continuation of femoral artery, is the deepest component and passes inferior laterally through the fossa and divides into anterior and posterior tibial arteries. The genicular anastomoses maintain blood supply to knee joint when the knee is flexed (popliteal artery kinked), and it includes all genicular arteries and also lateral femoral circumflex artery and anterior tibial recurrent
- Popliteal vein lies superficially to the popliteal artery. Small saphenous vein passes from the posterior aspect of the lateral malleolus to the popliteal fossa and enters the popliteal vein by piercing the popliteal fascia.
 Clinical significance of popliteal fossa:
- popliteal pulse: pulsation of the pulse is performed with person in the prone position with knee flexed to relax the fascia and hamstring and pulsation are best felt in the inferior part of the fossa where the popliteal artery is related to the tibia. Weakened pulse shows femoral artery obstruction
- popliteal tumours: popliteal fascia is strong and limits expansion, pain from tumour in the popliteal fossa is usually severe. Popliteal abscesses tends to spread inferiorly and superiorly
- popliteal aneurysm and hemorrhage: abnormal dilation of the popliteal artery causing edema and pain in the popliteal fossa. This can be distinguished from other masses by palpable pulsation and abnormal arterial sounds. Expansion of artery may stretch the tibial nerve or compress its blood supply and pain is felt in the calf, ankle or foot.

Arterial supply of gluteal and posterior region:

 Course of gluteal arteries:
- Superior gluteal artery: Leaves the pelvis through the greater sciatic foramen, superior to the piriformis and divides immediately into superficial and deep branches
- Inferior gluteal artery: Leaves pelvis through greater sciatic foramen inferior to the piriformis and enters the gluteal region deep to the gluteus maximus and descend medial to the sciatic nerve
- Internal pudendal artery: Lies anterior to the inferior gluteal artery and parallels that of the pudendal nerve

Arterial supply of the lower limb:

Course of lower limb arteries

- Femoral artery: Descends through femoral triangle and courses through adductor canal and terminates at the adductor hiatus
- Profunda femoris: Passes deeply between pectineus and adductor longus, descend posterior to medial side of femur
- Perforating arteries: three to four perforating branches pass through aponeurotic portion of adductor magnus muscles, winding around femur to supply muscles in medial, posterior and lateral part of anterior compartments
- Medial circumflex femoral: Passes medially and posteriorly between pectineus and iliopsoas and enters gluteal region
- Lateral circumflex femoral: Passes laterally deep to sartorius and rectus femoris
- Popliteal artery: Passes through popliteal fossa to leg and ends at lower border by dividing into anterior and posterior tibial arteries
- Anterior tibial: Passes between tibia and fibula into anterior compartment and descend between tibialis anterior and extensor digitorium longus
- Posterior tibial: Passes through posterior compartment of leg and terminates distal to flexor retinaculum and divide into medial and lateral plantar arteries
- Fibular: Descends in posterior compartment down the medial side of fibular between tibialis posterior and FHL
- Obturator: Passes through obturator foramen and enters medial compartment of thigh, divides and passes adductor brevis

Lymph Drainage of lower limb:

 Superficial inguinal lymph nodes: nodes in which the superficial lymphatic vessels from the medial foot, anteromedial leg and thigh drain into (converge toward and accompany the great saphenous vein)
 Popliteal lymph nodes: nodes in which the superficial lymphatic vessels of the lateral foot and posterolateral leg drain into (accompany the lesser saphenous vein)
 Deep inguinal lymph nodes: located near the saphenous opening, these are the nodes in which efferent vessels from popliteal node and other lymphatic that accompany the femoral vessel drain into.
 Lymph from the superficial and deep inguinal lymph nodes traverses the external and common iliac nodes before entering the lateral aortic lymph notes and the lumbar lymphatic trunk

Venous Drainage of lower limb:

 Lower limb has superficial a deep veins. While the superficial veins lie in the subcutaneous tissue, the deep veins are deep to the deep fascia and accompany all major arteries.
 Superficial Venous pathways:

 Course of superior vein:
- Great saphenous: ascends anterior to the medial malleolus, and passes posterior to the medial condyle of the femur and the medial superficial side of the upper thigh where it traverse the Saphenous opening and empties into the femoral vein.
- Small saphenous: ascends posterior to the lateral malleolus and passes along the lateral border of the calcaneal tendon and inclines the midline of the fibular where it penetrates the deep fascia. Then the vein ascends between the heads gastrocnemius and empties into the popliteal vein. (Also forms anastomoses with GSV)

 Deep veins of the lower limb:

Vessel supply of the foot:

 Arteries of dorsum of foot

 Course of arteries of the dorsum of foot
- dorsal artery of foot: direct continuation of anterior tibial and begins midway between malleoli and runs anteromedially deep to the inferior extensor retinaculum between EHL and EDL tendons and divides into 1st dorsal metatarsal and deep plantar artery
- deep plantar: passes deeply between heads of the first dorsal interosseous muscle to enter sole of the foot and joins the plantar arch
- lateral tarsal artery: a branch of the dorsal artery of foot runs laterally in an arched course beneath EDB (supply) and anastomoses with arcuate artery
- arcuate artery: runs laterally across the base of the lateral four metatarsals and deep to the extensor tendon and gives rise to dorsal metatarsal artery (2nd – 4th)
- dorsal metatarsal arteries: run distally in the clefts of the toes and connected to plantar arch by perforating branches. Each artery supplies the dorsal aspect of the sides of adjoining toes, e.g. 2nd supply 2nd and 3rd toe.
- dorsal digital artery: branches of the dorsal metatarsal artery that run along the phalanges
 Arteries of sole of foot

 Course of arteries of the sole of foot
- medial plantar: smaller terminal branch of the posterior tibial artery running medially on the sole of the foot and gives off a deep branch that supplies mainly muscles of he great toe and larger superficial branch that supplies the medial skin and anastomoses with deep plantar arch
- lateral plantar artery: runs laterally anteriorly deep to the adductor hallucis at first then between FDB and quaratus plantae. The lateral plantar arches medially across the foot with its deep branch to form deep plantar arch
- deep plantar arch: crossing middle of the metatarsal of the digits
- plantar metatarsal: divides near the base of the proximal phalanges to form the plantar digital arteries

Cutaneous nerve supply to gluteal region and lower limbs:

 Courses of cutaneous nerves of the lower limb and gluteal region:
- Subcostal: along inferior border of 12th rib and des ends over iliac crest
- Iliohypogastric: parallels iliac crest
- ilioguinal: passes through inguinal canal
- Genitofemoral: descends anterior surface of psoas major
- Lateral femoral cutaneous: passes deep to inguinal ligament
- Anterior femoral cutaneous: arise in femoral triangle and pierce fascia lata along path of sartorius muscle
- Cutaneous branch of obturator: descent between adductors longus and brevis and anterior division pierces fascia lata to reach skin of thigh
- Saphenous: traverses adductor canal but does not pass through adductor hiatus, crossing medial side of knee
- Posterior femoral cutaneous: enters gluteal region via infra-piriformis portion of greater sciatic foramen deep gluteus maximus, then descends deep to fascia lata
- Superficial fibular: courses superficially through lateral compartment of leg
- Deep fibular: after supplying muscles on dorsum of foot, pierces deep fascia superior to heads of 1st and 2nd metatarsals
- Sural: arises from tibial nerve
- Lateral sural: cutaneous branch of fibular nerve merge at varying levels on the posterior leg
- Medial plantar: passes between first and second layer plantar muscle
- Lateral plantar: passes between first and second layers of plantar muscles
- Superior clunial: course laterally and inferior in subcutaneous tissue
- Medial clunial: emerge from dorsal sacral foramina and enter overlying subcutaneous tissue
- Inferior clunial: arise deep to gluteus maximus and merge from beneath inferior border of muscle

Nerve supply to the upper thigh:

 Femoral:
- origin: posterior division of L2 - L4 lumbar plexus
- course: descends posterolaterally though the pelvis to approximately midpoint of the inguinal ligament and passes deep and enters femoral triangles where it divides to many branches
- distribution: all anterior thigh muscles and skin of the anteromedial side
 Obturator:
- origin: anterior division of L2 – L4 lumbar plexus
- course: descends along the walls of the inner pelvic cavity, passes through the obturator foramen and divides into anterior and posterior branches above adductor brevis and down the medial compartment
- distribution: all adductor compartment muscles and skin above it.

Nerve supply to the gluteal region:

 Superior clunial
- origin: lateral cutaneous branches of posterior rami of L1 – L3 spinal nerves
- course: pass inferolateral across iliac crest
- distribution: supply skin of superior buttock as far as tubercle of iliac crest
 Middle clunial
- origin: lateral cutaneous branches of posterior rami of S1 – S3 spinal nerves
- course: exit through posterior sacral foramina and pass laterally to gluteal region
- distribution: supply skin over sacrum and adjacent area of buttock
 Inferior clunial:
- origin: posterior cutaneous nerve of thigh
- course: emerges from inferior border of gluteus maximus and ascends superficial to it
- distribution: supplies skin of inferior half of buttock as far as greater trochanter
 Sciatic: most lateral nerve to pass the GSF
- origin: sacral plexus (anterior and posterior division of anterior rami of L4-S3 nerves)
- course: enters gluteal region via greater sciatic foramen inferior to piriformis and deep to gluteus maximus and descends in posterior thigh deep to biceps femoris and divides into tibial and common fibular nerve at apex of popliteal fossa
- distribution: supplies no muscles in gluteal region but all muscles of posterior compartment of thigh
 Posterior cutaneous: supplies more skin than any other cutaneous nerve. The main part of the nerve lies deep to the deep fascia unlike most cutaneous nerves.
- origin: sacral plexus (anterior and posterior divisions of anterior rami of S1-S3 spinal nerves)
- course: follows sciatic nerve in the gluteal region but emerges from inferior border of gluteus maximus and descends in posterior thigh deep to fascia lata
- distribution: supply skin of inferior half of buttocks, skin over posterior thigh and popliteal fossa and skin of lateral perineum and upper media thigh
 Superior gluteal:
- origin: sacral plexus (posterior division of anterior rami of L4 – S1)
- course: enters gluteal region via greater sciatic foramen superior to piriformis and course laterally between gluteus medial and minimus as far as tensor fascia lata
- distribution: innervates gluteus medius, gluteus minimus and tensor fascia lata muscles
 Inferior gluteal:
- origin: sacral plexus (posterior division of anterior rami of L5-S2]
- course: enters gluteal region via greater sciatic foramen inferior to piriformis and deep to inferior part of gluteus maximus
- distribution: supplies gluteus maximus
 Nerve to quadratus femoris:
- origin: sacral plexus (anterior division of anterior rami of L4-S1 spinal nerves)
- course: enters gluteal region via greater sciatic foramen inferior to piriformis
- distribution: innervates hip joint, inferior gemellus and quadratus femoris
 Pudental: the most medial nerve to exit the GSF
- origin: sacral plexus (anterior division of anterior rami of S2-S4)
- course: exits pelvis via greater sciatic foramen inferior to piriformis and descends
- distribution: supplies no structure in gluteal region or posterior thigh but supplies perineum
 Nerve to obturator internus:
- origin: sacral plexus (posterior divisions of anterior rami of L5-S2)
- course: exits pelvis via greater sciatic foramen inferior to piriformis and descends posterior to sacrospinous ligament and enter perineum through lesser sciatic foramen
- distribution: supplies superior gemellus and obturator internus

Nerve supply to the lower leg:

 Tibial:
- origin: sciatic nerve
- course: forms as sciatic bifurcates at apex of popliteal fossa and descends and lies on popliteus, runs inferiorly on tibialis posterior with posterior tibial vessels between FHL and FDL and terminates beneath flexor retinaculum by dividing into medial and lateral plantar nerves
- distribution: supplies posterior muscles of leg and knee joint
 Common fibular:
- origin: sciatic nerve
- course: branching from sciatic nerve at popliteal fossa and follows medial border of biceps femoris and its tendon down and passes over posterior aspect of head of fibula and then winds around neck of fibula deep to fibularis longus, where it develops into deep and superficial fibular nerves
- distribution: supplies skin on lateral part of posterior of leg via lateral sural cutaneous nerve and also supplies knee joints.
 Superficial fibular:
- origin: common fibular nerve
- course: arise between fibularis longus and neck of fibula and descends in lateral compartment of leg, pierces deep fascia at distal third of leg to become subcutaneous
- distribution: supplies fibularis longus and brevis and skin on distal third of anterior surface of leg and dorsum of foot
 Deep fibular:
- origin: common fibular nerve
- course: arise between fibularis longus and neck of fibula passes through extensor digitorum longus and descends on interosseous membrane, crosses distal end of tibia and enters dorsum of foot

Nerve supply to the foot

 Saphenous:
- origin: femoral nerve
- course: arise in femoral triangle and descends through thigh and leg and accompanies great saphenous vein anterior to medial malleolus and ends on medal side of foot
- distribution: supplies skin on medial side of foot as far anteriorly as head of 1st metatarsal
 Superficial fibular
- origin: common fibular nerve
- course: pierces deep fascia in distal third of leg to become cutaneous then sends branches to foot and digits
- distribution: supplies skin on dorsum of foot and all digits except adjoining side of 1st and 2nd
 Deep fibular:
- origin: common fibular nerve
- course: passes deep to extensor retinaculum to enter dorsum of foot
- distribution: supplies EDB and skin on contiguous side of 1st and 2nd digit
 Medial plantar:
- origin: tibial nerve
- course: passes distally in foot between abductor hallucis and FDB and divides into muscular and cutaneous branches
- distribution: supplies skin of medial side of sole of foot and sides of the first three digits and abductor hallucis, FDB, FHB and first lumbrical
 Lateral plantar:
- origin: smaller terminal branch of tibial nerve
- course: passes laterally in foot between quadratus plantae and FDB muscles
- distribution: every other muscles that medial plantar does not supply on the sole of the foot
 Sural:
- origin: tibial and common fibular nerves
- course: passes inferior to the lateral malleolus to lateral side of foot
- distribution: lateral aspect of hindfoot and midfoot
 Calcaneal branch:
- origin: tibial and sural nerves
- course: pass from distal part of the posterior aspect of leg to skin on heel
- distribution: skin on heel

Hip Joint

 Hip joint: a strong, multi-axial ball and socket joint between the lower limbs and pelvic girdle.
- joint capsule: proximally attached just peripheral to the rim of the acetabulum and distally, anteriorly, the femoral neck at the intertrochanteric line and root of greater trochanter and, posteriorly, proximal to the intertrochanteric crest.
- ligament of joint capsules take a spiral course from the hip to femur. Flexion unwinds the fibers hence have greater mobility
 Acetabulum: the hemispherical hollow on the lateral aspect of the hip bone that articulates with the head of the femur
- lunate surface of the acetabulum: the semilunar area covered with articular cartilage in the joint
- acetabular notch: the depression in the circular rim of the acetabulum
- acetabular labrum: fibrocartilage lip that attaches to the acetabular rim and increases the acetabular articular area by nearly 10%
- acetabular fossa: deep non-articular part in the center of the acetabulum
 Factors increasing stability of hip joint:
- Parallel fibers attached to the femur and acetabulum pulls the joint closer together when rotated (fiber increase obliquity
- Muscles of hip rotators are counterbalanced by intrinsic ligaments whose strength is proportional to the size of the acting muscle, i.e. lateral rotator muscles are stronger hence the ligament that stabilize this (iliofemoral ligament) is stronger too.
- The acetabulum complex engulfs the head of the femur completely while the thick weight bearing bone of the ilium is directly superior to the head of the femur.
 Three intrinsic hip joint ligament:
- iliofemoral ligament: the anterior and superior Y-shaped ligament which attaches to the anterior inferior iliac spine and the acetabular rim proximally and the intertrochanteric line distally. This ligament prevents hyperextension of the hip joint during standing by screwing the femoral head into the acetabulum
- pubofemoral ligament: the anterior and inferior ligament that arises from the obturator crest of the pubic bone and passes laterally and inferiorly to merge with the fibrous layer of the joint capsule. It prevents overabduction and extension of the hip joint
- ischiofemoral ligament: posterior ligament which arises from the ischial part of the acetabular rim and spirals superolaterally to the femoral neck, medial to the base of the greater trochanter.
 Synovial membrane of the hip joints: lines the internal surfaces of the fibrous layer as well as any intracapsular bony surfaced not lined with articular cartilages. Where the fibrous capsule attach to the femoral neck, the membrane reflects proximally to the edge of the femoral head, giving synovial folds or retinacula
 Blood supply to the hip:
- medial and lateral circumflex femoral arteries
- artery to the head of the femur (branch of obturator artery)
 Nerve supply to the hip: Hilton’s law
- femoral nerve innervating flexors passes anteriorly to hip joint
- inferior aspect of joint is innervated by obturator nerve and posterior aspect by the nerve to quadratus femoris
- superior gluteal nerve innervating the abductors supply the superior aspect of the joint
 Clinical significance of hip joint:
- fracture of femoral neck: resulting from high-energy impacts such as car accidents. Fracture of the neck often disrupts blood supply to the head of the femur, i.e. the retinacular supply of the medial circumflex artery. When fracture occurs at the neck, both anterior and posterior blood supplies are cut, producing avascular necrosis. When fracture occurs at intertrochanteric line, posterior supply is preserved and if fracture occurs below intertrochanteric line, all vessels are preserved
- Surgical hip replacement: severe traumatic injury and degenerative disease such as osteoarthritis can destroy the hip joint. A hip replacement is used for treatment where a metal prosthesis anchored to the person’s femur replaces the femoral head and neck and a plastic socket cemented to the hip bone replaces the acetabulum
- Dislocation of hip joint: congenital dislocation of hip joint where the femoral head is not properly located in the acetabulum from birth (more superior than normal), and Trendelenburg sign is observed. Acquired dislocation of the hip joint occurs during physical impacts, e.g. posterior displacement of head due to car accident or anterior displacement due to catching ski tip.

Knee Joint

 Knee joint: contains two articulation of femorotibial (lateral and medial) between lateral and medial femoral tibial condyles and one inferomedial femoropatellar between patella and femur
 Factors affecting strength of knee joint:
- strength and action of surrounding muscles and tendons (quadriceps femoris most important muscle)
- ligaments that connects femur and tibia
 Joint capsule of knee joint:
- external fibrous layer: attaches to the femur superiorly , proximal to the articular margins of condyles and inferiorly to the margin of the superior articular surface of tibia
- internal synovial membrane: covers all surface not covered by articular cartilage including periphery of femoral and tibial condyles, posterior surface of patella and edges of menisci. Posteriorly, the synovial membrane reflect anteriorly into the intercondylar region covering the cruciate ligaments and infrapatellar fat-pad giving the medial infrapatellar synovial fold.
 External ligaments:
- patellar ligament: distal part of the quadriceps tendon and receives medial and lateral patellar retinacula of vastus medialis and lateralis. Patellar ligament plays a role in maintaining alignment of patella in articulation.
- lateral collateral ligaments: a cord like extrinsic ligament that extends inferiorly from lateral epicondyle of the femur to the lateral surface of the fibular head
- medial collateral ligament: strong flat intrinsic band that extends from medial epicondyle of femur to medial condyle and superior medial surface of tibia. Weaker than LCL so easily damaged
- oblique popliteal ligament: recurrent expansion of the tendon of semimembranosus that spans the intracondylar fossa from the medial tibial condyle and lateral femoral condyle
- arcuate popliteal ligament: joins the posterior aspect of fibular head and posterior surface of the knee joint.
 Cruciate ligaments: located in the center of the joint and cross each other obliquely. Helps maintain contact with femoral and tibial articular surfaces
- anterior cruciate ligament: arises from anterior intercondylar area of tibia to the medial side of the lateral femoral condyle of femur. Role is to prevent posterior displacement of femur and hyperextension
- posterior cruciate ligament: stronger than ACL and arise from posterior intercondylar area of the tibia and pass medial to ACL and attach to lateral surface of medial condyle of femur. Role is to prevent anterior displacement of femur on tibia and hyperflexion
 Menisci of knee joint: crescent plates of fibrocartilage on the articular surface of the tibia that act as a shock absorber. The menisci are thicker at their external margins and thinner toward center and attaches firmly to the intercondylar area of tibia. The transverse ligament of the knee joints the menisci together
- medial meniscus: C shaped, broader posteriorly than anteriorly. Its anterior end is attached anterior to ACL and posterior attachment is posterior to PCL. Less mobile than lateral meniscus
- lateral meniscus: circular, smaller and freer than medial meniscus. The posterior meniscofemoral ligament joins the lateral meniscus to the PCL and medial femoral condyle.
 Nerve supply:
- anteriorly by the femoral nerve (branches to the vasti muscles)
- posteriorly by the tibial nerve
- laterally by the common fibular nerve
 Blood supply: knee joint is supplied by 10 vessels that form the genicular anastomoses which are the genicular branches of femoral, popliteal and anterior and posterior recurrent branches of anterior tibial and fibular circumflex arteries. The middle genicular artery penetrates the fibrous layer of joint capsule and supply cruciate ligaments, synovial membrane and margins of the menisci.
 Bursae of the knee joint:
- suprapatellar: located between femur and tendon of quadriceps femoris and continuous with the synovial cavity of knee joint.
- prepatellar: located between skin and anterior surface of patella to allow free movement of skin over patella during movement.
- Superficial infrapatellar: between skin and tibial tuberosity to help knee withstand pressure when kneeling
- Deep infrapatellar: between patellar ligament and anterior surface of tibia
- Semimembranosus: between medial head of gastrocnemius and semimembranosus tendon
 Screw home mechanism: the mechanism by which the knee locks into place during standing phase to relax muscles
- extension causes ACL to become taught
- medial rotation of the lateral femoral condyle is permitted with ACL as the pivot and medial condyle slides posteriorly to produce further extension
- max rotation reached when the MCL and LCL and oblique popliteal ligament is taut. The knee is hyperextended and locked into place
- unscrew mechanism: popliteus muscle produce lateral rotation to unlock the knee
 Q-angle: the angle created at the knee joint between the medially diagonal femur within the thigh and the vertical shaft of the tibia.
 Patella stabilizer: due to the Q angle, the action of the quadriceps tends to pull the patella laterally. Three structure counteract this:
- line of action of the vastus medialis
- medial patella retinacula
- large anterior projection of the lateral femoral condyle
 Clinical significance of knee joint:
- genu varum: deformity of the femur producing an abnormally small Q-angle and will lead to unequal weight bearing. Line of gravity is placed medial to the center of the knee and result in arthrosis and lateral collateral ligament overstressing.
- genu valgum: abnormally large Q angle causing weight bearing line to fall lateral to the center of the knee and consequently the medial collateral ligament is overstretched, and there is excess stress on the lateral meniscus and cartilage of the condyles.
- Patellofemoral syndrome: an abnormal tracking of the patella relative to the patellar surface of the femur as a result from direct blow to patella and from osteoarthritis, causing pain.
- Popliteal cysts: abnormal fluid filled sac of synovial membrane in the region of the popliteal fossa from chronic joint effusion. This could be caused by herniation of gastrocnemius or semimembranosus bursa through joint capsule into popliteal fossa and synovial fluid from joint or bursa forms a synovial lined cyst. Knee joint movement may be interfered.
- Aspiration of knee: fractures of the distal end of the femur may result in infection of the knee joint and increase joint effusion (increased synovial fluid). Suprapatellar bursa is continuous with the synovial cavity thus help indicate build up of fluid. Aspiration of the fluid for examination is approached laterally with anterolateral tibial tubercle, lateral epicondyle of femur and apex of patella as landmarks.
- Bursitis of knee: caused usually by excessive friction or penetrating wound (bacterial infection). Housemaid’s knee is prepatellar bursa swelling while clergyman’s knee is superficial infrapatellar bursitis.
 Ligament sprains:
- Unhappy triad: firm attachment of the medial collateral ligament to the medial meniscus is of considerable significance because tearing of this ligament will result in the tearing of the medial meniscus. Injury is caused by lateral blow or excess lateral twisting. In addition anterior cruciate ligament is taut during extension, can also rupture with MCL.
- ACL rupture: hyperextension or force directed anteriorly may tear the ACL. This causes the tibia to slide anteriorly under fixed femur known as anterior drawer sign.
- PCL rupture: hyperflexion due cases such as impact on tibial tuberosity with knee flexed. This causes the tibia to slide posteriorly with fixed femur known as the posterior drawer sign

Tibiofibular joint

 Superior tibiofibular joint: occurs between the flat facet n the fibular head and a similar articular facet located posterolaterally on lateral tibial condyle
- ligament: strengthened by anterior and posterior tibiofibular ligaments that pass superomedially from fibular head to the lateral tibial condyle
- movement: slight movement during dorseflexion
- blood supply: inferior lateral genicular and anterior tibial recurrent arteries
- nerve supply: common fibular nerve and nerve to popliteus
 Inferior tibiofibular joint (syndesmosis): essential for stability of the ankle because it keeps the lateral malleolus firmly against the lateral surface of the talus.
- ligaments: principally connected by interosseous tibiofibular ligament and strengthened anteriorly and posteriorly by the anterior and posterior tibiofibular ligaments
- movement: slight movement occurs to accommodate the wedging of the wide portion of trochlea (round superior articular surface of the talus) of talus during dorseflexion
- blood supply: arteries are from the perforating branch of the fibular artery and from medial malleolar branches
- nerve: deep fibular, tibial and saphenous nerves

Ankle and foot joints

 Articulation surface: tibia articulates with talus in two places
- inferior surface of tibia to roof of talus to transfer body’s weight to talus
- medial malleolus with medial surface of talus
 Stability of ankle joint: ankle is most stable during dorsiflexion as wider anterior portion of talus fits between the malleoli and stretches the interosseous ligament. During plantarflexion, trochlea is loose within the mortise and most injury occurs such as hyper-inversion of foot
 Sustenaculum tali: a bony horizontal eminence situated at the upper forepart of the calcaneus that provide attachment anteriorly for the spring ligament and medially the talocalcaneal ligament.
 Lateral collateral ligaments:
- anterior talofibular ligament: extends anteromedially from lateral malleolus to neck of talus
- posterior talofibular ligament: runs horizontally medially and posteriorly from malleolar fossa to lateral tubercle of talus.
- calcaneofibular ligament: passes posteroinferiorly from tip of the lateral malleolus to lateral surface of calcaneus
 Medial collateral ligaments: deltoid ligament that attaches proximally to medial malleolus and fans out to neighbouring bones. The ligaments stabilizes the ankle joint eversion and prevents dislocation of joint
- tibionavicular ligament
- tibiocalcaneal
- anterior tibiotalar
- posterior tibiotalar
 Movement of ankle joint: dorseflexion (muscle of anterior compartment) and plantarflexion (muscles of posterior compartment) of foot that occur around a transverse axis through the talus.
 Blood supply of ankle joint: malleolar branches of the fibular and anterior posterior tibial arteries
 Nerve supply of ankle joint: tibial nerve and deep fibular nerve
 Subtalar joint (clinical): the anatomical subtalar joint which is a single synovial joint between the talus to the slightly posterior concave calcaneal surface and the talocalcaneal part of the talocalcaneonavicular joint.
- type: plane synovial joint
- articulating surface: inferior surface of body of talus with superior surface of calcaneus
- joint capsule: fibrous layer of joint capsule is attached to margins of articular surfaces
- ligament: medial lateral and posterior talocalcaneal ligaments support capsule and interosseous talocalcaneal ligaments binds bones together
- movements: inversion and eversion of foot
- blood supply: posterior tibial and fibular arteries
- nerve supply: medial and lateral plantar nerves and deep fibular nerve
 Transverse tarsal joint (talonavicular): talonavicular part of talocalcaneonavicular joint
- type: ball and socket
- articulating surfaces: head of talus articulates with navicular bone
- joint capsule: joint capsule incompletely encloses joint
- ligament: plantar calcaneonavicular ligament (spring) to support head of talus
- movement: gliding and rotatory movements possible
- blood supply: lateral tarsal artery
- nerve supply: medial and lateral plantar nerves and deep fibular nerve
 Transverse tarsal joint (calcaneocuboid): calcaneocuboid joints
- type: plane synovial joint
- articulating surfaces: anterior end of calcaneus articulates with posterior surface of cuboid
- joint capsule: fibrous capsule encloses joint
- ligaments: dorsal, plantar calcaneocuboid ligaments and long plantar ligaments support joint capsule
- movement: inversion and eversion of foot, circumduction
- blood supply: lateral tarsal artery
- nerve supply: medial and lateral plantar nerves and deep fibular nerve
 Major ligament of foot:
- spring ligament: extends from the talar shelf to the inferior margin of the posterior articular surface of navicular. The spring ligaments support the head of talus and transfer weight from talus.
- long plantar ligament: passes from plantar surface of calcaneus to groove on the cuboid
- short plantar ligament: extends from the anterior aspect of inferior calcaneus to inferior surface of cuboid
- All three ligament helps maintain longitudinal arch of the foot
 Clinical significance of ankle joint
- ankle sprain: most common is inversion injury, involving twisting of the weight-bearing plantarflexed foot. The lateral collateral ligament sprains are the result, with the anterior talofibular ligament being the most common one.
- Pott fracture: dislocation of the ankle when the foot is forcibly everted and this action pulls on the extremely strong medial collateral ligament and tearing off the medial malleolus. The talus can then shear off the lateral malleolus or breaking the fibula and the distal end of the tibia to produce a trimalleolar fracture
- Chronic ankle instability: condition where the foot fails to support the body’s weight when walking or standing due to repeated ankle sprain and weakening of the tendon.

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