حسام أبو عوض. - Ahmad. 1 P a g e

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In the last lecture, we finished discussing the superficial part of the posterior compartment and the popliteus muscle of the deep layer[reminder: The entire posterior compartment (superficial and

2 In the last lecture, we finished discussing the superficial part of the posterior compartment and the popliteus muscle of the deep layer[reminder: The entire posterior compartment (superficial and deep) is innervated by the tibial nerve]. In the deep layer of the posterior compartment there re three muscles: Tibialis posterior, Flexor digitorum longus and Flexor hallucis longus. The big muscle, flexor digitorum longus (goes to four toes), originates from the big bone (back of the tibia), while the smaller muscle, Flexor digitorum hallucis (goes to one toe), originates from the smaller bone (fibula). Tibialis posterior, being the largest muscle here, originates from both bones, tibia and fibula (and the interosseous membrane). The flexor digitorum inserts into the distal phalanges of the lateral four toes, the flexor hallucis longus inserts into the distal phalanx of the big toe and the tibialis posterior inserts into all of the tarsal bones (initially navicular). Reminder: of course, all these muscles cause plantar flexion of the ankle (all) and flexion of the toes (except tibialis posterior which causes inversion). After the two retinacula previously discussed we now meet a third one, but this time it s a flexor retinaculum. The flexor retinaculum attaches to the calcaneus (just like the extensor retinacula) and on the other side tothe medial malleolus. The flexor retinaculum attaches to the medial malleolus due to the groove for tibialis posterior present there [this means that the tendon of tibialis posterior (and the other muscles) has to pass by the medial malleolus]. Reminder: The peroneal retinaculum (lateral compartment) attaches to the calcaneus and to the lateral malleolus. This flexor retinaculum is very similar to that of the upper limb. The upper limb s flexor retinaculum made the Carpal Tunnel and our flexor 2 P a g e

retinaculum makes the Tarsal Tunnel, therefore structures passing below our flexor retinaculum pass through the tarsal tunnel [The structures are: Tibialis posterior, flexor Digitorum longus,

3 retinaculum makes the Tarsal Tunnel, therefore structures passing below our flexor retinaculum pass through the tarsal tunnel [The structures are: Tibialis posterior, flexor Digitorum longus, posterior tibial artery (Vessels), tibial Nerve and flexor Hallucis longus Tom Does a Very Nice Homework (in that order)]. The Tarsal Tunnel Syndrome occurs when the tibial nerve passing through the tunnel gets compressed causing neurological manifestations (discussed later). Reminder: The tibial nerve originates from the sciatic nerve. The tibial nerve first enters the popliteal fossa via the upper angle and then leaves via the lower angle into the posterior of the leg and when it crosses the flexor retinaculum it divides into two terminal branches (medial and lateral plantar branches). Other branches of the tibial nerve include the sural nerve (cutaneous innervation of the posterior-lateral area of the leg), the medial calcaneal branch (for the heel) and muscular branches for the posterior compartment of the leg and the hamstring muscles (except the short-head of the biceps). The medial plantar branch of the tibial nerve gives the cutaneous innervation for 2/3 of the sole and the 3 and half medial toes while the lateral plantar branch innervates 1/3 of the sole and the remaining 1 and half lateral toes and the medial calcaneal branch innervates the heel. This means that the sole is almost entirely innervated by the tibial nerve (except a small part laterally by the sural nerve and a small part medially by the saphenous nerve). The importance of the tibial nerve is now apparent, therefore any injury to this nerve will have drastic effects; the plantar-flexion will no longer be possible resulting in a dorsi-flexed foot, the inversion of the ankle will be weakened resulting in a slightly everted foot and the toes will claw. These three deformities together are referred to as calcaneovalgus. And, of course, almost the entire sensation from the sole of the foot will be lost and the sensation of the lower part of the back of the leg (medial calcaneal branch). In the upper limb, some small muscles of the hand, called the Lumbricals, were responsible for the writing position and an injury to 3 P a g e

4 their innervation resulted in a Claw Hand. The tibial nerve supplies the lumbricals of the foot and its injury indeed causes Claw Foot (one of the deformities in calcaneovalgus). Reminder: Injury to the common peroneal nerve causes Foot Drop. Now, what if the sciatic nerve, from which the tibial and the common peroneal nerves originated, got injured? Dorsi-flexion and plantar flexion are both lost, but still the foot looks dropped. This is due to the action of gravity on the foot. For the sensory loss, the sensation is lost from the entire leg and the entire foot except for the medial part of the leg and the foot which are supplied by the saphenous nerve. In the Tarsal tunnel syndrome, if the compression on the tibial nerve is limited then simple numbness or a burning sensation are recorded, but if the compression is complete then a complete sensory loss of the sole (except areas supplied by the saphenous and the sural nerves) is noted (some muscles are also affected). The tarsal tunnel syndrome (compression of the tibial nerve) is quite rare, the carpal tunnel syndrome is way more common [the tibial nerve is also known as the posterior tibial nerve). The Foot Looking from the sole-side, the first thing that meets us in the foot is a fascia called Plantar Aponeurosis. This fascia prevents direct pressing on the underlying structures (nerves, vessels and muscles) while walking and thus, protecting them from injury, for this purpose the plantar aponeurosis is thick. Like the retinacula, the plantar aponeurosis is attached to the calcaneus before dividing to 5 digits, a digit for each toe. It is not uncommon for this fascia to get inflamed, especially after walking a long distance, standing for a long time or wearing new shoes. If this inflammation becomes recurrent and its treatment gets neglected 4 P a g e

Muscles of the Sole In the sole of the foot there are 4 muscular layers: layers #2 and #4 have muscles originating from the leg and foot, layers #1 and #3 contain the small muscles of the sole

5 (which is common too) the plantar aponeurosis might get ossified giving you the feeling of walking on a stone consistently. This condition is mainly treated with physiotherapy; many exercises are common: move your leg over a small ball while sitting, dorsi-flex (strongly) your foot with a tightly attached rope, etc. Muscles of the Sole In the sole of the foot there are 4 muscular layers: layers #2 and #4 have muscles originating from the leg and foot, layers #1 and #3 contain the small muscles of the sole (originate from the foot only) (from bottom to top/ superficial to deep). The 1 st layer is the abductors: abductor hallucis (big toe), abductor digiti minimi (small toe) and in between them the flexor digitorum brevis. Dividing the following diagram to medial and lateral (at the end of this lecture, when we discuss the arches of the foot, you ll see that the medial structures support some arches while lateral ones support others) Medially: Abductor hallucis and the medial half of flexor digitorum brevis;laterally: Abductor digit-minimi and the lateral half of flexor digitorum brevis. The 2 nd layer is that of flexors:flexor hallucis longus and flexor digitorum longus,both coming from the leg,between the tendons of the flexor digitorum longus we have the lumbricals and finally a small square shaped muscle called quadratus plantae muscle. Medially: Flexor hallucis longus and the medial half of flexor digitorum longus. Laterally: The lateral half of flexor digitorum longus. 5 P a g e

Overall, the small muscles of the sole are more concerned with the maintenance of the arches of the foot (to come) than doing specific actions.

6 The 3 rd layer is that of the brevis flexors: Flexor hallucis brevis (medial), flexor digit-minimi brevis (lateral)and the adductor hallucis (medial). The 4 th layer: Interossei (similar to the upper limb), the tendon of peroneus longus (from the leg) and the tendon of tibialis posterior (from the leg). Overall, the small muscles of the sole are more concerned with the maintenance of the arches of the foot (to come) than doing specific actions. Muscles coming from the leg and down to the foot: Tibialis posterior, Flexor digitorum longus, Peroneus longus, Flexor hallucis longus, [the muscles of the anterior compartment of the leg were not included as we are discussing the sole (not the entire foot)]. Two arteries are present in the sole of the foot; the medial and lateral plantar arteries originate from the posterior tibial artery which is a branchof the popliteal artery. The medial plantar arterysupplies the hallucis (big toe) while the lateral plantar arterysupplies the 4 lateral fingers (most of the sole s blood supply comes from the lateral plantar artery). An extremely important artery clinically is the dorsalis pedis artery (on the dorsum of the foot), which is a continuation of the anterior tibial artery, when the anterior tibial artery passes between the lateral malleolus and the medial malleolus its name becomes dorsalis pedis. The dorsalis pedis artery continues till between the first and 2 nd toes and gives a branch that assists the lateral plantar artery. Its importance is in its pulsation. The pulsation of the dorsalis pedis artery can be felt between the first and the second toes. If one managed to feel the pulsation of the dorsalis pedis this means that the circulation of the entire lower limb is good, if not / a weak pulsation was felt then there is a problem and we need to try to track its source. As you see, most of the blood supply of the foot is taken care of by the lateral plantar artery and the dorsalis pedis artery; the medial plantar artery only supplies a small region. 6 P a g e

Taking a look at the medial and lateral plantar nerves (branches of the posterior tibial nerve), the medial plantar nerve seems similar to the median nerve (of the upper limb; it innervates that

7 Taking a look at the medial and lateral plantar nerves (branches of the posterior tibial nerve), the medial plantar nerve seems similar to the median nerve (of the upper limb; it innervates that lateral 3 and a half fingers) as it innervatesthe medial 3 and a half fingersand almost 2/3 of the foot.the lateral plantar nervesupplies 1 and a half toes and around 1/3 of the foot. Joints, Ligaments and Arches Before moving on to the joints and arches let s first revise the bones. Medially we have: part of the calcaneus, talus, navicular, cuneiforms, 1 st 2 nd and 3 rd metatarsals (and the associated phalanges). Laterally: cuboid, lateral part of calcaneus, 4 th and 5 th metatarsals (and associated phalanges). We ll discuss three joints in the foot: 1- Subtalar = below talus calcaneus is below the talus, so this joint is between the talus and the calcaneus (talocalcaneal joint). 2- Calcaneocuboid = between the calcaneus and the cuboid. 3- Talocalcaneonavicular joint = the talus, the calcaneus and the navicular. The calcaneocuboid joint and the talocalcaneonavicular joint together are called Mid-tarsal joints. These three joints are responsible for the inversion. These are synovial joints,plane synovial to be more specific (just some sliding, not too much movement is seen). 7 P a g e

The Ligaments I- The Interosseous (talocalcaneal) ligament is between the sulcus tali and the sulcus calcanei (the main bond between the two bones). It supports the subtalar joint.

radius limits the movement). II- III- The calcaneonavicular ligament (medial)is also known as the spring ligament. The short and the long plantar ligaments(lateral) are quite close to each other.

The Arches In your foot, to the medial side and to the lateral side, you can clearly see curves lifting those parts of the foot and making them not directly on the ground.

8 The Ligaments I- The Interosseous (talocalcaneal) ligament is between the sulcus tali and the sulcus calcanei (the main bond between the two bones). It supports the subtalar joint. Note: Inversion has a higher range of movement than eversion because thelateral malleolus is much lower than medial malleolus limiting the eversion (in theupper limb, the styloid process of the radius limits the movement). II- III- The calcaneonavicular ligament (medial)is also known as the spring ligament. The short and the long plantar ligaments(lateral) are quite close to each other. The short ligament being between the calcaneus and the cuboid and the long one being between the calcaneus, the cuboid and the middle 3 metatarsals. The Arches In your foot, to the medial side and to the lateral side, you can clearly see curves lifting those parts of the foot and making them not directly on the ground. The importance of the arches of the foot is that they distribute the body s weight, (if the body weight is 100% then 50% goes to right side and 50% to left side, due to the arches of the foot, the metatarsals will bear around 20% and the heel around 30%, so most of the weight will be on the heel). Also, this curving protects the underlying structures. Even with the plantar aponeurosis, walking a lot would still injure the nerve, vessels,etc. 8 P a g e

present in babies as they have too much fat in their soles preventing the formation of the arches which develop with age). Bones form the structure of each of the three arches.

9 so this curve prevents these structures from being in direct contact with the bones. There are three arches in the foot, one medial, one lateral and one transverse called the medial longitudinal arch, the lateral longitudinal arch and the transverse arch respectively (these are not present in babies as they have too much fat in their soles preventing the formation of the arches which develop with age). Bones form the structure of each of the three arches. The Medial Longitudinal Arch:The medial part of the calcaneus, the talus, the navicular, thecuneiforms and the 1 st, 2 nd and 3 rd metatarsals. The Lateral Longitudinal Arch:The lateral part of thecalcaneus, the cuboid and the 4 th and 5 th metatarsals. The Transverse Arch:Draw two transverse lines, one passing through all of the 5 metatarsals and another one below itpassing by the cuneiforms and cuboid and that s your third arch. The shape of any bridge (which has some arches) reveals that the stones the arches are made of are wedge shaped, the inferior edges of the stones are attached to each other, tie beams connect the ends of each arch preventing its dislocationand the bridge could be suspended from above. These mechanisms are the exact same ones used in our bodies to maintain the shapes of the arches of the foot. Bones also have shapes that help in strengthening the arches, the inferior edge of the bones is supported by ligaments (and muscles) andthe suspension is done by the muscles coming from the leg.so, there is a bony factor, a ligamental factor and a muscular factor for each arch. For the medial arch, it is supported by the head of the talus bone (the keystone of the arch, if a problem occurs here, the arch gets disrupted) and the talus, in turn, is supported by a process from the calcaneus called the sustentaculum tali. The ligaments involved in the medial arch must be on the medial side, so those are the spring ligament and the medial half of 9 P a g e

10 the plantar aponeurosis. The muscular factor of the arch must also be on the medial side leaving us with the flexor hallucis longus and brevis, flexor digitorum longus and brevis (medial half only), tibialis posterior and the abductor hallucis.the tibialis anterior keeps the arch suspended. The Lateral arch s keystones are thecuboid and the calcaneus. The ligaments involved (must be on the lateral side) are the long and the short plantar ligaments and the lateral half of the plantar aponeurosis.themuscles here are (lateral) the digiti-minimi muscles, the lateral half of flexor digitorum longus and brevis and theperoneus longus and brevis (the last two act as suspensions). The Transverse Archrelies on the metatarsals (all of them) and the cuneiforms. Its associatedligaments are the transverse metatarsal ligaments (connect metatarsals) and the deep plantar ligament.muscles responsible for the maintenance of this arch are theperoneus longus (passes above all the metatarsals) and the peroneus brevis (attaches to the 5 th metatarsal). Flat Foot If the arch is not well developed the foot will be dropped (not like the dropped foot due to the injury of the common peroneal nerve, not that it s just that the curvature is less), diverted outward a bit and the weight of the body will not be well distributed leadingto most of the weight being borne bythe metatarsals (not to the heel!) so instead of 20% of the weight the metatarsals bear more the fat layer in the sole gets lost and the plantar fascia also gets disturbed so continuous pain is seen. Also, the talus might not find anything to support it, so it drops to between the calcaneus and the navicular disturbing the entire weight bearing of the body. Opposite to the flat foot is the pes cavus: the arch is more curved than normal (a highly elevated medial longitudinal arch). These problems could happen due to weaknesses in muscles or ligaments, due to osteomyelitis or due to a congenital problem in the bones (most common). 10 P a g e

The University Of Jordan Faculty Of Medicine FOOT. Dr.Ahmed Salman Assistant Prof. of Anatomy. The University Of Jordan

The University Of Jordan Faculty Of Medicine FOOT Dr.Ahmed Salman Assistant Prof. of Anatomy. The University Of Jordan Tarsal Tunnel Syndrome Due to compression of Tibial nerve as it travels through the