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Surgical anatomy of layers & arches of the sole of the foot, https…
Surgical anatomy of layers & arches of the sole of the foot
Arches
Medial arch
The medial arch is the higher of the two longitudinal arches.
It is made up of the calcaneus, the talus, the navicular, the three cuneiforms, and the first, second, and third metatarsals.
Its summit is at the superior articular surface of the talus, and its two extremities or piers, on which it rests in standing, are the tuberosity on the plantar surface of the calcaneus posteriorly and the heads of the first, second, and third metatarsal bones anteriorly.
The chief characteristic of this arch is its elasticity, due to its height and to the number of small joints between its component parts.
Its weakest part, i. e., the part most liable to yield from overpressure, is the joint between the talus and navicular, but this portion is braced by the plantar calcaneonavicular ligament, which is elastic and is thus able to quickly restore the arch to its pristine condition when the disturbing force is removed.
The ligament is strengthened medially by blending with the deltoid ligament of the ankle joint and is supported inferiorly by the tendon of the Tibialis posterior, which is spread out in a fan-shaped insertion and prevents undue tension of the ligament or such an amount of stretching as would permanently elongate it.
The arch is further supported by the plantar aponeurosis, by the small muscles in the sole of the foot, by the tendons of the Tibialis anterior and posterior and Peronæus longus, and by the ligaments of all the articulations involved.
The foot has three arches: two longitudinal (medial and lateral) arches and one anterior transverse arch. These arches are formed by the tarsal and metatarsal bones and are supported by the ligaments and tendons in the foot.
Lateral arch
The lateral arch is the flatter of the two longitudinal arches and lies on the ground in the standing position.
It is composed of the calcaneus, the cuboid, and the fourth and fifth metatarsals.
Its summit is at the talocalcaneal articulation, and its chief joint is the calcaneocuboid, which possesses a special mechanism for locking, and allows only a limited movement.
The most marked features of this arch are its solidity and its slight elevation; two strong ligaments, the long plantar and the plantar calcaneocuboid, together with the Extensor tendons and the short muscles of the little toe, preserve its integrity.
Transverse Arch
The transverse arch is located in the coronal plane of the foot.
At the posterior part of the metatarsus and the anterior part of the tarsus the arches are complete, but in the middle of the tarsus they present more the characters of half-domes the concavities of which are directed downward and medial, so that when the medial borders of the feet are placed in apposition a complete tarsal dome is formed.
The transverse arches are strengthened by the interosseous, plantar, and dorsal ligaments, by the short muscles of the first and fifth toes (especially the transverse head of the Adductor hallucis), and by the Peroneous longus, whose tendon stretches across between the piers of the arches.
Layers
The plantar muscles of the foot are traditionally studied in either layers or groups. If studying by layers, we can organise these muscles into four primary layers:
1st layer: abductor hallucis, flexor digitorum brevis, abductor digiti minimi
2nd layer: quadratus plantae, lumbricals
3rd layer: flexor hallucis brevis, adductor hallucis, flexor digiti minimi brevis
4th layer: plantar and dorsal interossei
Nerve supply
Branches of the Tibial nerve
Medial calcaneal nerve innervates plantar medial heel
Medial plantar nerve innervates Abductor Hallucis, FHB, FDB and lumbircals to 2nd and 3rd toes. Cutaneous distribution to the medial sole and medial three and a half toes including the nail beds on the dorsum
Lateral plantar nerve innervates adductor hallucis, quadratus plantae, all interossei muscles, lateral two lumbricals, abductor digiti minimus (via Baxter's nerve - the first branch of LPN). Cutaneous innervations to the lateral sole and lateral one and a half toes.
Sural Nerve
It consists of the collateral branches of the tibial nerve and common peroneal nerve. Provides sensations to the lateral aspect of the foot and in 4th web space (70-80% of time)
Deep peroneal Nerve
Innervates muscles of the anterior compartment of the leg including tibialis anterior,extensor digitorum longus, peronius tertius and extensor hallucis longus and in the foot it supplies extensor digitorum brevis and extensor hallucis brevis
The medial branch provides sensation to the first dorsal webspace
Superficial Peroneal Nerve
Innervates peroneus longus and peroneus brevis muscles and the skin over the antrolateral aspect of the leg and the dorsum of the foot with the exceotion of the 1st web space
Saphenous Nerve
Largest cutaneous branch of the femoral nerve
Supplies sensation to medial aspect of foot
Blood supply
The 3 primary sources of blood supply to the foot and ankle are posterior tibial, anterior tibial and peroneal arteries.
Posterior Tibial Artery is the larger of the two branches of polpliteal atrery and is the main blood supply to the superficial and deep compartments of the leg.
In the ankle it gives rise to posteromedial malleolar artery, artery of the tarsal canal and a communicating branch. In the foot it divides into lateral and medial plantar arteries.
Anterior tibial artery is the smaller of the two branches of poploiteal artery and supplies the muscles of the anterior compartment of the leg.
In the ankle it gives rise to antero-medial and antero-lateral malleolar arteries. In the foot it continues as dorsalis pedis artery and terminates into deep plantar arch as first dorsal metatarsal artery.
Peroneal Artery is a branch of posterior tibial artery. It divides at the ankle to give rise to posterolateral malleolar artery and a communicating branch. Its terminal branch in the foot is lateral calcaneal artery that is an imporatnt source of blood supply to the fasciocutaneous flap raised during the extensile approach to the calcaneus.
Blood supply to the plantar aspect of the foot and the toes comes from the plantar arch that is formed by the anastmosis of lateral plantar artery and the dorsalis pedis artery. It gives off plantar metatarsal arteries and plantar digital arteries
The dorsal venus arch drains into the great saphenous and short saphensous veins.
Ligaments
The anterior tibiofibular ligament connects the tibia to the fibula.
The lateral ligaments attach the fibula to the calcaneus.
There are 3 main lateral ligaments; the anterior and the posterior talofibular ligaments (ATFL & PTFL) and the calcaneofibular ligament (CFL).
The anterior talofibular ligament is a flat band that extends from the anterior malleolus forward to the talus and is relatively weak.
The posterior talofibular ligament is thicker and stronger than the former ligament and runs horizontally from the back of the malleolus to the posterior surface of the talus.
The calcaneofibular ligament, the longest of the three, is a round cord that goes from the tip of the lateral malleolus down to the lateral surface of the calcaneus.
On the medial side, the deltoid ligaments (superficial & deep) connect the tibia to the talus and calcaneus and are stronger than the lateral ligaments.
Other important ligaments include spring ligament (from sustantaculum tali to the navicular), short planter ligament (between the calcaneus and the cuboid) and long planter ligament (between the calcaneus and the 2nd-4th metatarsals).
All these ligaments are further supported by planter aponeurosis, a thickened fibrous band, which contributes significantly toward the stress of weight bearing.
Clinical significance
https://www.physio-pedia.com/Arches_of_the_Foot
https://www.kenhub.com/en/library/anatomy/central-muscles-of-the-sole-of-the-foot
https://www.ankleinfo.net/anatomy
