Foot and Ankle Anatomy and Imaging



Foot and Ankle Anatomy and Imaging


Michael Harbus

Amitabh Gulati



INTRODUCTION

The foot and ankle work together to allow for multiplanar motion and stabilization during the gait cycle. This ability to facilitate both stabilization during weight bearing and ambulation is made possible by the interactions of a network of bony, muscular, tendinous, and ligamentous structures in the foot and ankle.1 This chapter will serve as a review of the clinically relevant structures that make up the foot and ankle.


MUSCLE


Muscles of the Front of the Leg


Tibialis Anterior

The tibialis anterior originates from the upper two-thirds of the lateral surface of the tibia and attaches to the medial cuneiform and the base of the first metatarsal (Figures 4.1 and 4.2). It is responsible for dorsiflexion and inversion of the foot and is innervated by the deep fibular nerve, which is fed by the L4-L5 nerve roots. Clinically, the tibialis anterior is used to test L4 motor function.2,3


Extensor Hallucis Longus

The extensor hallucis longus originates from the middle third of the medial aspect of the fibula and attaches to the base of the distal phalanx of the great toe (Figure 4.3). It is innervated by the deep fibular nerve (L4, L5), and it is responsible for dorsiflexion of the foot and extension of the great toe. The extensor hallucis longus is used to test for L5 motor function.2,3


Extensor Digitorum Longus

The extensor digitorum longus originates from the upper two-thirds of the medial aspect of the fibula and divides into 4 segments to attach to the dorsal digital expansions of the phalanges of the 4 lateral toes (Figures 4.4 and 4.5). It is innervated by the deep fibular nerve (L5, S1) and is responsible for dorsiflexion and extension of the second through fifth toes.2


Fibularis Tertius

The fibularis tertius originates from the lower third of the medial aspect of the fibula and inserts into the shaft of the fifth metatarsal (Figure 4.6). It is innervated by the deep fibular nerve (L5, S1) and is responsible for dorsiflexion and eversion of the foot.2


Muscles of the Lateral Lower Leg


Fibularis Longus

The fibularis longus originates from the upper two-thirds of the lateral surface of the fibula and attaches to the lateral sides of the medial cuneiform and the base of the first metatarsal (Figure 4.7). It is innervated by the superficial peroneal nerve, which is fed by nerve roots L5,
S1, and S2, and is responsible for plantar flexion and eversion of the foot.2












Fibularis Brevis

The fibularis brevis originates from the lower two-thirds of the lateral surface of the fibula and attaches to the base of the fifth metatarsal (Figure 4.7). Due to its attachment site at the base of the fifth metatarsal, trauma to the fibularis brevis can result in an avulsion fracture of the fifth metatarsal. It is innervated by the superficial peroneal nerve (L5-S2) is responsible for plantar flexion and eversion of the foot.2,3












Muscles of the Posterior Lower Leg


Tibialis Posterior

The tibialis posterior originates from the posterior surfaces of the tibia and fibula as well as the interosseous membrane, and it attaches to the
navicular, the plantar aspect middle 3 metatarsals, the cuneiforms, and the cuboid (Figures 4.8 and 4.9). It is innervated by the tibial nerve—predominantly through its contributions from the L4 and L5 nerve roots—and it is responsible for plantar flexion and inversion of the foot during the “heel off” phase of the gait cycle.
Injury to the tibialis posterior tendon can lead to acquired flat foot.2,3



























Flexor Hallucis Longus

The flexor hallucis longus originates from the lower two-thirds of the posterior aspect of the fibula and attached to the plantar surface of distal phalanx of the great toe (Figure 4.10). It is innervated by the tibial nerve—predominantly through its contributions from the S2 and S3 nerve roots—and it is responsible for plantar flexion of the great toe and foot.2


Flexor Digitorum Longus

The flexor digitorum longus originates from the posterior surface of the tibia below the soleal line and attaches to the plantar aspects of the distal phalanges of the 4 lateral toes (Figure 4.11). It is innervated by the tibial nerve (S2, S3), and it is responsible for plantar flexion of the lateral 4 toes and foot. At the level of the ankle, the tendon of the flexor digitorum longus is located anteriorly to the tibial artery.2,3


Extensor Digitorum Brevis

The extensor digitorum brevis originates from the upper surface of the calcaneus and attaches
to the base of the proximal phalanx of the great toe and the dorsal digital expansions of the second through fourth toes (Figure 4.12). It is innervated by the deep peroneal nerve (L5, S1) and is responsible for extension of the first through fourth toes.2

















First Layer


Abductor Hallucis

The abductor hallucis originates from the medial process of the calcaneus tuberosity and the plantar aponeurosis, and it attaches to the medial side of the proximal phalanx of the great toe (Figure 4.13). It is innervated by the medial plantar nerve (S2, S3), and it is responsible for abduction and plantar flexion of the great toe. The fascia of the abductor hallucis can entrap the nerve to the abductor digiti minimi.2,3

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Sep 8, 2022 | Posted by in ORTHOPEDIC | Comments Off on Foot and Ankle Anatomy and Imaging
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