Osteology
|
| Bone |
Structure |
Description |
Notes |
| tibia |
|
the bone on the medial side of the leg |
the tibia is the weight-bearing bone of the leg (Latin, tibia = a pipe or flute, or the large shin bone. Primitive musical instruments were made from reeds, horns, and other things, including the shin bones of birds and other animals) |
|
soleal line |
a ridge of bone that descends obliquely from lateral to medial on the posterior surface of the tibia |
it is the site of origin of the soleus m. |
| tarsal bones |
|
the bones of the ankle |
there are seven tarsal bones: talus, calcaneus, navicular, medial cuneiform, intermediate cuneiform, lateral cuneiform, cuboid |
| talus |
|
the most proximal of the tarsal bones |
the talus articulates with the medial malleolus of the tibia and the lateral malleolus of the fibula to form the ankle mortise joint (Latin, talus = ankle bone) |
| |
body |
the proximal part of the talus |
its superior (trochlear) part participates in the ankle joint and its inferior part articulates with the calcaneus |
| |
trochlea |
the superior portion of the body of the talus that lies between the two malleoli |
it has a smooth articular surface; it participates in the formation of the ankle joint (Latin, trochlea = pulley) |
|
head |
the portion of the talus that projects anteriorly |
it articulates with the navicular bone |
|
neck |
the constricted part of the talus located proximal to the head |
|
| calcaneus |
|
the tarsal bone which forms the heel |
it is the largest and strongest bone in the foot; a fracture of the calcaneus which separates the tuberosity from the body can be a debilitating injury (Latin, calcis = heel) |
| |
calcaneal tuberosity |
the posterior roughened area of the calcaneus which contacts the ground during weight-bearing |
it is the insertion site of the calcaneal (Achilles') tendon |
|
sustentaculum tali |
the shelf-like medial projection of bone located inferior to the medial malleolus |
it is a shelf of bone that articulates with and supports the talus; it is grooved inferiorly by the tendon of the flexor hallucis longus m. (Latin, sustento = to hold upright) |
| navicular |
|
the tarsal bone located distal to the talus and proximal to the three cuneiform bones |
it articulates with the head of the talus and all three cuneiform bones; it is the attachment site for an important ligament (plantar calcaneonavicular or "spring" ligament) that supports the medial longitudinal arch of the foot (Latin, navicular = small boat shaped structure) |
| cuneiform, medial |
|
the most medial bone in the distal row of tarsal bones |
the cuneiform bones articulate with the navicular bone proximally and the bases of the metatarsal bones distally |
| cuneiform, middle |
|
the intermediate bone of the three cuneiform bones |
the cuneiform bones articulate with the navicular bone proximally and the bases of the metatarsal bones distally |
| cuneiform, lateral |
|
the bone that is located between the middle cuneiform and the cuboid bone |
the cuneiform bones articulate with the navicular bone proximally and the bases of the metatarsal bones distally |
| cuboid |
|
the most lateral bone in the distal row of tarsal bones |
the cuboid bone articulates with the calcaneus proximally and the fourth and fifth metatarsal bones distally |
| metatarsals |
|
the bones located between the tarsal bones and the phalanges |
there are five metatarsal bones in the foot |
|
base |
the proximal end of the metatarsal |
it articulates with the distal row of tarsal bones |
|
body |
the slender shaft of the metatarsal |
it is also known as the diaphysis |
|
head |
the rounded distal end of the metatarsal |
it articulates with the proximal phalanx of the corresponding digit |
| phalanx (phalanges) |
|
the distal two or three bones in the digits of the foot |
there are a total of 14 phalanges in the foot; the great toe has two phalanges (proximal and distal) and each of the other four toes has three phalanges (proximal, middle and distal); (Latin, phalanx = line of soldiers) |
|
base |
the proximal end of the phalanx |
the base of the proximal phalanx articulates with the head of the corresponding metatarsal bone; the base of the middle or distal phalanx articulates with the head of the next most proximal phalanx |
|
body |
the slender shaft of the phalanx |
also known as the diaphysis; the body of the distal phalanx is very short |
|
head |
the distal end of the phalanx |
the proximal, middle and distal phalanges each have a head; the head of a proximal or middle phalanx articulates with the base of the next most distal phalanx |
Muscles
|
| Muscle |
Origin |
Insertion |
Action |
Innervation |
Notes |
| gastrocnemius |
femur; medial head: above medial femoral condyle; lateral head: above lateral femoral condyle |
dorsum of calcaneus via calcaneal (Achilles') tendon |
flexes leg, plantarflexes foot |
tibial nerve |
the calcaneal tendon of gastrocnemius & soleus is the thickest & strongest tendon in the body (Greek, gaster = belly + kneme = leg, the calf of the leg) |
| plantaris |
above lateral femoral condyle (above lateral head of gastrocnemius) |
dorsum of calcaneus medial to calcaneal tendon |
flexes leg, plantarflexes foot |
tibial nerve |
none |
| soleus |
posterior surface of head & upper shaft of fibula, soleal line of tibia |
dorsum of calcaneus via the calcaneal (Achilles') tendon |
plantarflexes foot |
tibial nerve |
soleus and the 2 heads of gastrocnemius are sometimes called the triceps surae muscle (Latin, soleus = sole of the foot) |
| popliteus |
lateral condyle of femur (via a round tendon) |
posterior surface of tibia above soleal line |
flexes and rotates leg medially (with foot planted, rotates thigh laterally) |
tibial nerve |
popliteus unlocks the knee joint to initiate flexion of the leg (Latin, poples = the back of the knee) |
| flexor hallucis longus |
lower two/thirds of posterior surface of fibula |
base of distal phalanx of hallux |
flexes metatarsophalangeal and proximal interphalangeal joints of hallux; plantarflexes foot |
tibial nerve |
(Latin, hallex = great toe) |
| flexor digitorum longus |
middle half of posterior surface of tibia |
bases of distal phalanges of digits 2-5 |
flexes metatarsophalangeal, proximal interphalangeal and distal interphalangeal joints of digits 2-5; plantarflexes foot |
tibial nerve |
none |
| tibialis posterior |
interosseous membrane, posteromedial surface of fibula, posterolateral surface of tibia |
tuberosity of navicular & medial cuneiform, metatarsals 2-4 |
plantarflexes foot and inverts foot |
tibial nerve |
acts as both an antagonist and a synergist of tibialis anterior |
| fibularis (peroneus) longus |
upper two/thirds of lateral surface of fibula |
after crossing plantar surface of foot deep to intrinsic muscles, it inserts on medial cuneiform and base of 1st metatarsal |
extends (plantarflexes) and everts the foot |
superficial fibular (peroneal) nerve |
lies superficial to fibularis brevis m. |
| fibularis (peroneus) brevis |
lower one third of lateral surface of fibula |
tuberosity of base of 5th metatarsal |
extends (plantarflexes) and everts the foot |
superficial fibular (peroneal) nerve |
none |
| tibialis anterior |
lateral tibial condyle and upper lateral surface of tibia |
medial surface of medial cuneiform and 1st metatarsal |
dorsiflexes and inverts foot |
deep fibular (peroneal) nerve |
acts as both an antagonist and a synergist of tibialis posterior |
| peroneus mm. (SEE fibularis mm.) |
|
|
|
|
peroneus is the old terminology used for fibularis mm. |
| extensor hallucis longus |
middle half of anterior surface of fibula & interosseous membrane |
base of distal phalanx of hallux |
extends metatarsophalangeal & interphalangeal joints of hallux |
deep fibular (peroneal) nerve |
(Latin, hallex = great toe) |
| extensor digitorum longus |
lateral condyle of tibia, anterior surface of fibula, lateral portion of interosseous membrane |
dorsum of lateral 4 toes via extensor expansions (central slip inserts on base of middle phalanx, lateral slips on base of distal phalanx) |
extends metatarsophalangeal, proximal interphalangeal and distal interphalangeal joints of lateral 4 toes |
deep fibular (peroneal) nerve |
none |
| fibularis (peroneus) tertius |
distal part of anterior surface of fibula |
dorsum of shaft of 5th metatarsal bone |
everts foot |
deep fibular (peroneal) nerve |
fibularis tertius is in the anterior compartment of the leg, not the lateral compartment (which contains fibularis longus and brevis) |
Nerves
|
| Nerve |
Source |
Branches |
Motor |
Sensory |
Notes |
| fibular, common |
sciatic |
lateral sural cutaneous, superficial and deep fibular nn. |
superficial fibular br.: muscles of lateral compartment of leg (fibularis longus and brevis mm.); deep fibular br.: mm. of anterior compartment of leg (tibialis anterior, extensor hallucis longus, extensor digitorum longus, fibularis tertius); mm. of dorsum of foot (extensor digitorum brevis and extensor hallucis brevis) |
superficial fibular: distal 1/3 of anterior leg; dorsum of foot excluding web between great toe and 2nd toe and distal interphalangeal segments of all toes; deep fibular: skin of the web between great and 2nd toes |
peroneal is old terminology which has been replaced by fibular |
| fibular, superficial |
common fibular |
medial dorsal cutaneous n. to medial side of foot; dorsal digital nn. to lateral 3 digits |
muscles of lateral compartment of leg (fibularis longus and brevis mm.) |
distal 1/3 of anterior leg; dorsum of foot excluding web between great toe and 2nd toe and distal interphalangeal segments of all toes; |
|
| fibular, deep |
common fibular |
one proper digital br. to the 1st and 2nd toes |
mm. of anterior compartment of leg (tibialis anterior, extensor hallucis longus, extensor digitorum longus, fibularis tertius); mm. of dorsum of foot (extensor digitorum brevis and extensor hallucis brevis) |
skin of the web between great and 2nd toes |
|
| peroneal, nn. |
SEE: fibular |
|
|
|
peroneal is old terminology which has been replaced by fibular |
| tibial |
sciatic |
medial sural cutaneous, medial calcaneal brs., medial & lateral plantar nn. |
semimembranosus, semitendinosus, long head of biceps femoris, ischiocondylar portion of adductor magnus; mm. of superficial and deep posterior compartments of leg (gastrocnemius, soleus, plantaris, tibialis posterior, flexor hallucis longus, flexor digitorum longus); muscles of plantar side of the foot |
|
|
Arteries
|
| Artery |
Source |
Branches |
Supply |
Notes |
| popliteal |
femoral |
anterior & posterior tibial; 5 genicular brs. |
knee, leg & foot |
the popliteal a. is the continuation of the femoral a.; the name change occurs at the adductor hiatus (Latin, poples = the back of the knee) |
| tibial, posterior |
popliteal |
fibular (peroneal), circumflex fibular, nutrient a. of tibia, communicating br., posterior medial malleolar brs., medial calcaneal brs., lateral & medial plantar aa. |
posterior & lateral leg, plantar aspect of foot |
posterior tibial bifurcates on the medial side of the foot to give rise to the medial and lateral plantar aa. |
| fibular |
posterior tibial |
nutrient br., lateral malleolar br., communicating br., perforating br. |
lateral leg & ankle |
anastomoses at ankle with anterior & posterior tibial aa. |
| tibial, anterior |
popliteal |
anterior & posterior tibial recurrent; anterior, medial & lateral malleolar; dorsalis pedis |
anterior leg, dorsal & deep foot |
anterior tibial a. becomes continuous with the dorsalis pedis a.; name change occurs at the level of the ankle joint |
| tibial, posterior |
fibular (peroneal), circumflex fibular, nutrient a. of tibia, communicating br., posterior medial malleolar brs., medial calcaneal brs., lateral & medial plantar aa. |
posterior & lateral leg, plantar aspect of foot |
posterior tibial bifurcates on the medial side of the foot to give rise to the medial and lateral plantar aa. |
|
Topographic Anatomy
|
| Structure/Space |
Boundaries/Description |
Significance |
| anterior compartment (extensor), leg |
tibia, fibula, interosseous membrane, anterior intermuscular septum |
contains tibialis anterior, extensor hallucis longus, extensor digitorum longus, fibularis tertius; also anterior tibial artery, deep fibular nerve |
| extensor retinaculum, superior |
strong band of deep fascia passing from the fibula to the tibia, proximal to the malleoli |
binds down the tendons of the muscles in the anterior compartment, preventing bowstringing during dorsiflexion of the ankle (Latin, retinaculum = a band or halter) |
| extensor retinaculum, inferior |
a Y-shaped band of fascia attached laterally to the anterosuperior surface of the calcaneus |
forms a strong loop around the tendons of the fibularis tertius and extensor digitorum longus muscles (Latin, retinaculum = a band or halter) |
| fibular retinaculum, superior |
a band of deep fascia that extends from the tip of the lateral malleolus to the calcaneus |
binds down the tendons of the fibularis longus and brevis (Latin, retinaculum = a band or halter) |
| flexor retinaculum |
|
(Latin, retinaculum = a band or halter) |
| lateral compartment (evertor), leg |
anterior & posterior intermuscular septa, fibula |
contains: fibularis longus & brevis mm.; superficial fibular nerve |
| posterior compartment (flexor), leg |
tibia, fibula, interosseous membrane, posterior intermuscular septum |
contains: superficially - gastrocnemius, soleus, plantaris mm.; deeply - popliteus, tibialis posterior, flexor digitorum longus, flexor hallucis longus mm.; also contains posterior tibial vessels & tibial n. |
| fascia, crural |
deep fascia forming tubular investment of leg |
continuous with fascia lata at knee; connected to fibula by anterior & posterior intermuscular septa; thickened near ankle as extensor & flexor retinacula (Latin, crural = the legs) |
