Basic Foot and Ankle Anatomy - Muscles and Fascia
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Description[edit | edit source]
Muscles are responsible for the movement and the primary source of the ankle and foot injury is a movement performed excessively, repetitively, and for a long duration that exceeds tissue capabilities.[1]Weight bearing is a primary function of the foot and ankle and together, these two structures often have different responsibilities in order for this task to be completed. What is expected from them is a quick transformation from being flexible to adapt to the ground to becoming very rigid to propel the body forward. Other functions include maintaining balance, upright posture and recognising body position in space.[1]
Lower Leg Muscle[edit | edit source]
The lower leg muscles are divided into four compartments: the superficial posterior compartment, the deep posterior compartment, the lateral compartment, and the anterior compartment.
Posterior Compartments[edit | edit source]
The primary plantar flexors of the ankle are located in this compartment. Because of its insertion medial to the midline of the foot, they also function as supinators.
Primary responsibilities include:
- transforming the foot into a rigid lever
- assisting with push-off during the gait cycle
- controlling tibia progression over the foot during initial contact through push-off gait cycle
- controlling foot pronation during initial contact through push-off gait cycle
Superficial Posterior Compartment[edit | edit source]
Soleus Origin: Soleal line, medial border of tibia, head of fibula, posterior border of fibula. Insertion: Posterior surface of calcaneus (via calcaneal tendon). Nerve supply: Tibial nerve (S1, S2). Vascular supply: Posterior tibial artery and vein.
Gastrocnemius Origin: Two heads, lateral: Posterolateral aspect of lateral condyle of the femur, medial: Posterior surface of medial femoral condyle, popliteal surface of femoral shaft. Insertion: Posterior surface of the calcaneus via the calcaneal tendon. Nerve supply:Tibial nerve (S1, S2). Vascular supply: Medial sural artery, a branch of the popliteal artery.
Plantaris
Deep Posterior Compartment[edit | edit source]
Flexor digitorum longus
Tibialis posterior
Flexor hallucis longus
Popliteus
Lateral Compartment[edit | edit source]
Peroneus (Fibularis) Longus Origin:Head and superior 2/3 of lateral surface of the fibula. Insertion: base of the 1st metatarsal and medial cuneiform. Nerve supply: superficial fibular nerve (L5 - S1). Vascular supply: Fibular artery.
Function:
- Ankle inversion and week plantaflexion
- Muscular control of the forefoot position
Peroneus (Fibularis) Brevis Origin: Inferior 2/3 of lateral surface of the fibula. Insertion: base of the 5th metatarsal. Nerve supply: superficial fibular nerve (L5 - S1). Vascular supply: Anterior tibial artery.
Function:
- Ankle inversion and week plantaflexion
- Stabilises the lateral column of the foot
Anterior Compartment[edit | edit source]
Ankle dorsiflexion is performed by all the muscles within anterior compartment. In addition
- tibialis anterior and extensor hallucis longus invert the foot during dorsiflexion
- extensor digitorum longus everts the foot during dorsiflexion
- eccentric control of foot lowering during heel strike
- concentric control of toes clearance during swing phase
Tibialis Anterior
Extensor Digitorum Longus
Extensor Hallucis Longus
Peroneus Tertius
Foot Muscle[edit | edit source]
Fascia[edit | edit source]
Arches[edit | edit source]
Clinical relevance[edit | edit source]
- Area posterior to the medial malleolus tends to get injured frequently causing tendon injury of the posterior tibialis, flexor hallucis longus or flexor digitorum and tibial nerve compression.[1]
