FOOT . TARSALS, METATARSALS & PHALANGES. The human foot is a complex structure containing 26 bones, 33 joints and more than 100 tendons, muscles, and ligaments. Tarsus = ankle. Proximal region of the foot 7 tarsal bones Talus: ankle bone Calcaneus: heel bone Navicular: ‘like a little boat’
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TARSALS, METATARSALS & PHALANGES
The human foot is a complex structure containing 26 bones, 33 joints and more than 100 tendons, muscles, and ligaments.
Sesamoid bones are always present at the metatarsophalangeal joint of the great toe. Function: protect the tendon that flexes the toe, [flexor hallicus longus/brevis] by protecting it from the body's weight.
At the upper and forepart of the medial surface of the calcaneusis a horizontal eminence, the sustentaculum tali, which gives attachment to a slip of the tendon of the Tibialis posterior.
The longitudinal arch of the foot is higher on the medial side, where it forms the instep as can be seen on a foot-print. It is made up of the 1st three digits and their metatarsals, the cuneiforms, the navicular bone and the talus.The lateral longitudinal arch is made up of digits 4 and 5 and their metatarsals, the cuboid and the calcaneum. It is much shallower than the medial arch.
The transverse arch of the foot is primarily formed by the 5 metatarsal bones.
Every ligament that connects the bones of the foot plays a part in the maintenance of the arches, but some which pass across two or more joints are especially important. Among these are the long plantar ligament, the plantar calcaneocuboid ligament and the plantar calcaneonavicular ligament, on which the head of the talus rests.While the normal tone of the small intrinsic muscles of the foot also plays an essential part in keeping the arches intact, the long muscles which are inserted by tendons into the bones of the foot have an even more important role. These are the tendon of the tibialis anterior muscle, the tendon of the tibialis posterior muscle, the tendon of the peroneus longus and the tendons of the flexor hallucis longus and flexor digitorum longus muscles.Finally, more superficially, the plantar aponeurosis also plays an important part in maintaining the medial longitudinal arch.
Once the skin of the sole of the foot has been removed, there is a very dense organized layer of deep fascia that runs down the middle of the sole; this is the plantar aponeurosis. There is also deep fascia covering the medial and lateral muscle groups but it has been removed in this image.The plantar aponeurosis is thought to help maintain the medial longitudinal arch of the foot.
the superior and inferior peroneal retinaculaem keep the tendons of the peroneus longus and brevis close to the lateral malleolus.
After the plantar aponeurosis has been removed you can see the muscles that make up the first layer of the sole of the foot and the arteries and nerves entering the foot. The muscles of the first layer are:
flexor digitorum brevis
abductor digiti minimi
When the flexor digitorum brevis is removed, the muscles of the second layer can be seen:
accessory flexor (quadratus plantae)
tendons of the flexor digitorum longus from which the lumbricals arise
The fourth layer of muscles are the:
dorsal interossei (dab) meaning dorsal abduct
plantar interossei (pad) meaning plantar adduct
At this level, you can also see the tendon of the peroneus longus crossing the sole of the foot.