Comprehensive Anatomy of the Foot and Ankle
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Basic Structure of the Foot and Ankle[edit | edit source]
The anatomic structures below the ankle joint comprise the foot, which includes:
- Hindfoot: The hindfoot is the most posterior aspect of the foot, is composed of the talus and calcaneus, two of the seven tarsal bones. The talus and calcaneus articulation is referred to as the subtalar joint, which has three facets on each of the talus and calcaneus.
- Midfoot: The midfoot is made up of five of the seven tarsal bones: navicular, cuboid, and medial, middle, and lateral cuneiforms. The junction between the hind and midfoot is termed the Chopart's joint, which includes the talonavicular and calcaneocuboid joints.
- Forefoot: The forefoot is the most anterior aspect of the foot. It includes metatarsals, phalanges (toes), and sesamoid bones. There are a metatarsal and three phalanges for each digit apart from the great toe, which only has two phalanges. The articulation of the midfoot and forefoot forms the Lisfranc joint.
Bones[edit | edit source]
The bones of the ankle are named as follows:
The bones of the foot are named as follows:
- Numbered from medial or first (big toe), to lateral or fifth (little toe)
- Toes 2-5 each have 3 phalanges. The first or big toe (hallux) has only two
Joints[edit | edit source]
|Joint||Type of Joint||Plane of Movement||Motion|
|Talocrural joint||Hinge||Sagittal||Dorsiflexion & Plantarflexion||Formed between the distal tibia-fibula and the talus, and is commonly known as the ankle joint. The distal and inferior aspect of the tibia – known as the plafond – is connected to the fibula via tibiofibular ligaments forming a strong mortise which articulates with the talar dome distally.|
|Subtalar joint (Talocalcaneal joint)||Condyloid||Mainly transverse
|Inversion & Eversion
Dorsiflexion & Plantarflexion
|Formed between the talus and calcaneus.
|Midtarsal joint (Transverse tarsal joints or Chopart’s joint)||Talonavicular joint - Ball and socket
Calcaneocuboid joint - Modified saddle
|Largely in transverse
|Inversion & Eversion
Flexion & Extension
|It is an S-shaped joint when viewed from above. It consists of two joints – the Talonavicular Joint and Calcaneocuboid Joint.|
|Talonavicular joint||Ball and socket||Largely in transverse||Inversion & Eversion||Formed between the anterior talar head and the concavity on the navicular. It does not have its own capsule, but rather shares one with the two anterior talocalcaneal articulations.|
|Calcaneocuboid joint||Modified saddle||Sagittal||Flexion & Extension||Formed between the anterior facet of the calcaneus and the posterior cuboid. Both articulating surface, present a convex and concave surface with the joint being convex vertically and concave transversely. Very little movement occurs at this joint.|
|Tarsometatarsal joint (Lisfrank Joint)||Planar||The distal tarsal rows including the three cuneiform bones and cuboid articulate with the base of each metatarsal to form the TMT complex. It is an S-shaped joint and is divided into 3 distinct columns:
|Flexion & Extension
Abduction & Adduction
|Formed between the metatarsal heads and the corresponding bases of the proximal phalanx.|
|Interphalangeal joint||Hinge||Sagittal||Flexion & Extension||Formed between the phalanges of the toes. Each toe has proximal and distal IP joints except for the great toe which only has one IP joint.|
Ligaments[edit | edit source]
Ankle ligament injury is the most frequent cause of acute ankle pain. Hence, it is important to understand the anatomy of ankle ligaments for correct diagnosis and treatment.
The ligaments around the ankle can be divided, depending on their anatomic position, into three groups: the lateral ligaments, the deltoid ligament on the medial side, and the ligaments of the tibiofibular syndesmosis that join the distal epiphyses of the tibia and fibula.
The lateral collateral ligament complex (LCL) consists of:
- Anterior talofibular ligament: it is the most frequently injured ligament of the ankle. This ligament plays an important role in limiting anterior displacement of the talus and plantar flexion of the ankle.
- Posterior talofibular ligament: The posterior talofibular ligament originates from the malleolar fossa, located on the medial surface of the lateral malleolus, coursing almost horizontally to insert in the posterolateral talus. It is the strongest ligament of the lateral ankle. plays only a supplementary role in ankle stability when the lateral ligament complex is intact.
- Calcaneofibular ligament: The calcaneofibular ligament originates from the anterior part of the lateral malleolus. Its primary role is to restrain inversion in a neutral or dorsiflexed position, restrains subtalar inversion, thereby limiting talar tilt within the ankle mortise.
The medial collateral ligament (MCL), also known as Deltoid ligament, is composed of two layers; superficial and deep. The MCL is a multifascicular ligament, originating from the medial malleolus to insert in the talus, calcaneus, and navicular bone. It primary restrains to valgus tilting of the talus. Both the superficial and deep layers individually resist eversion of the hindfoot. It also stabilizes ankle against plantar flexion, external rotation, and pronation.
The ligaments of the tibiofibular syndesmosis consist of anterior or anteroinferior tibiofibular ligament, the posterior or posteroinferior tibiofibular ligament, and the interosseous tibiofibular ligament. The syndesmotic ligament complex ensures the stability between the distal tibia and the fibula and resists the axial, rotational, and translational forces that attempt to separate the tibia and fibula.
|LIGAMENT||DESCRIPTION||PROXIMAL ATTACHMENT||DISTAL ATTACHMENT||FUNCTION|
|Anterior Talofibular Ligament (ATFL)||Flat Weak Band that extends Anteriomedially.
Most commonly damaged ligament of the ankle.
|Lateral Malleolus||Neck of Talus||Restrain anterior displacement of the talus in respect to the fibula and tibia.
Resists Inversion in plantarflexion.
|Posterior Talofibular Ligament
|Thick, a fairly strong band that runs horizontally medially.
This ligament is under greater strain in full dorsiflexion of the ankle.
Rarely injured because bony stability protects ligaments when ankle in dorsiflexion.
|Malleolar Fossa of Fibula||Lateral Tubercle of Talus||Forms the back wall of the recipient socket for the talus' trochlea.
Resists posterior displacement of the talus.
|Calcaneofibular Ligament (CFL)||Round cord that passes posteroinferior||Tip of Lateral Malleolus||Lateral Surface of Calcaneus||Aids Talofibular stability during Dorsiflexion.
Restrain inversion of the calcaneus with respect to the fibula.
Prevent Talar tilt into Inversion.
|LIGAMENTS||DESCRIPTION||PROXIMAL ATTACHMENT||DISTAL ATTACHMENT||FUNCTION|
|Medial Malleolus||Head of Talus||Reinforces Ankle Joint.
Control Plantarflexion & Eversion
|Talus Posteriorly||Control Dorsiflexion|
|Forms most anterior part of the Deltoid Ligament||Dorsomedial Aspect of Navicular||Reinforces Ankle Joint|
|Very thin ligament||Sustentaculum Tali||Reinforces Ankle Joint|
Muscles of the Foot[edit | edit source]
Extrinsic Foot Muscles
These muscles have contractile portions that lie outside the ankle, in the leg, and the tendons of those muscles insert onto the bones of the foot in such a way that ankle motion occurs when the muscles contract
There are four 4 compartments, separated by fascia
- Superficial Posterior compartment (Plantar Flexors)
- Gastrocnemuis (TA)
- Soleus (TA)
- Deep posterior compartment (Plantar Flexors)
- FHL (inversion) (plantar surface of 1 toe)
- FDL (inversion) (plantar surface 2-5 toes)
- Tibialis Posterior (inversion) (navicular, medial cuneiform, 2-4 toes, other cuneiforms, cuboid)
- Lateral compartment (Plantar Flexors)
- PL (eversion, PF first metatarsal) (medial cuneiform and 1 toe)
- PB (eversion) (5 toe)
- Anterior compartment (Dorsiflexors)
- Tibialis anterior (inversion) (1 toe, medial cuneiform
- EHL (inversion)
- PT (eversion)
The dorsum of the foot has only one muscle (maybe 2 depending on classification). This is the extensor digitorum brevis (some authors name the most medial part of this muscle extensor hallucis brevis). Tendons are the main collagenous structures in the dorsum. The tendons connect anterior/dorsiflexor compartment muscles of the leg to the foot bones.
|MUSCLE||ACTION||PROXIMAL ATTACHMENT||DISTAL ATTACHMENT||INNERVATION||BLOOD SUPPLY|
|SUPERFICIAL POSTERIOR COMPARTMENT|
|Gastrocnemius||Plantarflexion when Knee Extended
Raises Heel during Walking
|Lateral Head: Lateral Aspect of Lateral Femoral Condyle
Medial Head: Popliteal Surface of Femur Superior to Medial Femoral Condyle
|Posterior Surface Calcaneus via Calcaneal Tendon (Achilles Tendon)||Tibial Nerve
Steadies Leg on Foot
|Posterior Aspect of Head Fibula
Superior ¼ Posterior Surface Tibia
Soleal Line & Medial Border Tibia
|Plantaris||Weakly Assists Gastrocnemius in Plantarflexion||Inferior end Lateral Supracondylar Line of Femur
Oblique Popliteal Ligament
|DEEP POSTERIOR COMPARTMENT|
Supports Medial Longitudinal Arch
Posterior Surface Tibia inferior to Soleal Line
Posterior Surface Fibula
Bases of Metatarsals 2-4
|Flexor Digitorum Longus||Plantarflexion
Flexion Lateral Four Digits
Supports Longitudinal Arch
|Medial Part Posterior Surface
Tibia inferior to Soleal Line
Broad Tendon to Fibula
|Base Distal Phalanges Digits 2-4||Tibial Nerve
|Flexor Hallucis Longus||Weak Plantarflexion
Flexion Big Toe at all Joints
Supports Medial Longitudinal Arch
|Inferior 2/3 Posterior Surface Fibula
Inferior Part Interosseous Membrane
|Base Distal Phalanx of Big Toe|
|Peroneus Brevis||Weak Plantarflexion
|Inferior 2/3 of Lateral Surface Fibula||Dorsal Surface Tuberosity of Base
|Superficial Peroneal Nerve
(Superficial Fibular Nerve)
L5 - S2
|Peroneus Longus||Weak Plantarflexion
Supports Transverse Arch
|Head & Superior 2/3 of Lateral Surface Fibula||Base 1st Metatarsal
Supports Medial Longitudinal Arch
|Lateral Condyle Tibia
Superior ½ Lateral Surface Tibia
|Medial & Inferior Surfaces
Base of 1st Metatarsal
|Deep Peroneal Nerve
(Deep Fibular Nerve)
Extends Lateral Four Digits
|Lateral Condyle Tibia
Superior ¾ Anterior Surface
|Middle & Distal Phalanges of Lateral Four Digits||Deep Peroneal Nerve
(Deep Fibular Nerve)
Extends Big Toe
|Middle Part Anterior Surface Fibula
|Dorsal Aspect of Base Distal
Phalanx of Big Toe
|Inferior 1/3 Anterior Surface Fibula
|Dorsum Base 5th Metatarsal|
Intrinsic Foot Muscles
The plantar aspect of the foot contains the tough fibrous plantar aponeurosis covering muscles and tendons arranged in 4 layers, numbered from 1 superficial to 4 deep:
- Layer 1
- abductor didgiti minimi,
- Flexor digitorum brevis
- Abductor hallucis
- Layer 2
- Layer 3
- Flexor hallucis brevis,
- Adductor hallucis and
- Flexor digiti minimi brevis
- Layer 4
Arches[edit | edit source]
The arches of the foot provide functions of force absorption, base of support and acts as a rigid lever during gait propulsion.
The medial longitudinal arch, lateral longitudinal arch and transverse arch are the 3 arches that compromise arches of foot.
- Medial Longitudinal Arch (MLA)
- It is the longest and highest of all the arches. Bony components of MLA include the calcaneus, talus, navicular, the three cuneiform bones and the first 3 metatarsals. The arch consists of two pillars: the anterior and posterior pillars. The anterior pillar consists of the head of first 3 metatarsal heads and the posterior pillar consists of the tuberosity of the calcaneus. The plantar aponeurosis forms the supporting beam connecting the two pillars. The apex of the MLA is the superior articular surface of talus. In addition to the plantar aponeurosis the MLA is also supported by the spring ligament and the deltoid ligament. The Tibialis anterior and posterior muscles play an important role in raising the medial border of the arch, whereas Flexor hallucis longus acts as bowstring.
- Lateral Longitudinal Arch (LLA)
- It is the lowest arch and comprises of the calcaneus, cuboid, fourth & fifth metatarsal as its bony component. Like the Medial Longitudinal Arch (MLA) the posterior pillar consists of the tuberosity of the calcaneus. The anterior pillar is formed by the metatarsal heads of 4th and 5th metatarsals. The plantar aponeurosis, long & short plantar ligaments provides support to the LLA. The Peroneus longus tendon plays an important role in maintaining the lateral border of the arch.
- Transverse Arch
- It is concave in non-weight bearing and runs medial to lateral in the midtarsal and tarsometatarsal area. The bony component of the arch consists of the metatarsal heads, cuboids and 3 cuneiform bones. The medial and lateral pillars of the arch is formed by the medial and lateral longitudinal arch respectively. The arch is maintained by the Posterior tibialis tendon and the Peroneus longus tendon which cross the plantar surface from medial to lateral and lateral to medial respectively.