Basic Foot and Ankle Anatomy - Bones and Ligaments

Original Editor - Ewa Jaraczewska

Top Contributors - Ewa Jaraczewska, Wanda van Niekerk, Jess Bell, Niha Mulla, Tarina van der Stockt, Kim Jackson and Olajumoke Ogunleye

Description

Ankle and foot injuries are fairly common not only within professional athletes or as a result of sporting activities, but they occur during routine daily activities. The typical injuries include sprains, fractures, tears, and inflammation. Good knowledge of the foot and ankle anatomy is necessary for proper diagnosis and treatment.

Structure

The ankle is formed by three bones: talus, tibia and fibula. The anatomic structure of the foot consists of hindfoot, midfoot and forefoot, each composed of several bones.

Ankle bones

Ankle Bones

The lower leg and the foot constitute the ankle. The following bony elements of the ankle joint are part of this structure:

• Distal tibia
• Distal fibula
• Talus.

Foot bones

Talus and calcaneus and two tarsal bones form the posterior aspect of the foot called the hindfoot. The midfoot located between the hindfoot and forefoot is made up of five tarsal bones: navicular, cuboid, and medial, intermediate, and lateral cuneiforms.  The most anterior aspect of the foot including metatarsals, phalanges, and sesamoid bones is called a forefoot. Each digit, except for the great toe, consists of a metatarsal and three phalanges. The great toe has two phalanges only.

Function

The foot and ankle provide various important functions which include bodyweight support, balance maintenance, shock absorption, response to ground reaction forces, or substitution for hand function in individuals with upper extremity amputation.It has a crucial role in gait and posture and its malalignment can cause problems eg., back pain or mobility limitations.

Ankle and Foot Articulations

Basic Ankle and Foot Motion

Talocrural joint (TC or sometimes called a tibiotalar joint) is referred to as the ankle joint. The joint is framed laterally and medially by the lateral and the medial malleolus and from the top by the tibia and the talus. Saggital plane dorsiflexion and plantarflexion are the primary movements in this joint.

The hindfoot has a talus and calcaneus articulation called a subtalar joint (ST, also known as the talocalcaneal joint). Three facets of the talus and of the calcaneus are part of this joint. The main motions are inversion and eversion of the ankle and hindfoot.

The talonavicular and calcaneocuboid joints are known as a Chopart joint (MT, midtarsal or transverse tarsal joint) is located between the hindfoot and midfoot. This joint allows forefoot rotation. The navicular and all three cuneiform bones compose articulation distally. In addition to the navicular and cuneiforms bones, the cuboid bone has a distal articulation with the base of the fourth and fifth metatarsal bones.

The tarsometatarsal joint (TMT or Lisfranc joint)connecting the midfoot with the forefoot originates from the lateral, intermediate and medial cuneiforms articulating with the bases of the three metatarsal bone (1st, 2nd, and 3rd). The small movement that occurs in the joint is described as dorsal and plantarflexion. The bases of the remaining metatarsal bones(4th and 5th) connect with the cuboid bone.

The five rays, metatarsal and corresponding phalanges create forefoot medial and lateral columns where rays 1,2, and 3 belong to the middle column, rays 4 and 5 to the lateral column. Metatarsophalangeal joints (MTP joints) are the main components of the forefoot. Each toe, except for the great toe, has proximal and distal IP joints. The latter has only one IP joint.

Below is the summary of the ankle and foot articulation.

Joint	Type of Joint	Plane of Movement	Motion
TC joint	Hinge	Sagittal	Dorsiflexion & Plantarflexion
ST joint	Condyloid	Mainly transverse Some sagittal	Inversion & Eversion Dorsiflexion & Plantarflexion
MT joint	TN joint - Ball and socket CC joint - Modified saddle	Largely in transverse     Some sagittal	Inversion & Eversion Flexion & Extension Forefoot rotation
TMT joint	Planar
MTP joint	Condyloid	Sagittal Some Transverse	Flexion & Extension Abduction & Adduction
IP joint	Hinge	Sagittal	Flexion & Extension

Ligaments

Acute and chronic ankle pains are often associated with either ligament injury or ligament laxity.The ligaments of the ankle consist of the medial side ligaments (the deltoid ligament), the lateral ligaments, and the ligaments connecting the distal epiphyses of the tibia and fibula called the tibiofibular syndesmosis.

There are 4 main ligaments of the foot including plantar fascia ligament, plantar calcaneonavicular ligament (known as a spring ligament), calcaneocuboid ligament, and Lisfranc ligaments.

Galano P. et al. Anatomy of the ankle ligaments: a pictorial essay. Medial Collateral Ligament. 1. Tibionavicular ligament; 2. tibiospring ligament; 3. tibiocalcaneal ligament; 4. deep posterior tibiotalar ligament; 5. spring ligament complex (plantar and superomedial calcaneonavicular ligaments);

Medial Collateral Ligament (Deltoid Ligament)

There are various descriptions of the medial collateral ligament(MCL), but the definition provided by Milner and Soames (1998) is the most commonly accepted. The authors divide the MCL into two layers: superficial and deep layers with bands either always present or which presence will vary (bands that are always present are in italic):

• Superficial: tibiospring ligament, tibionavicular ligament, superficial posterior tibiotalar ligament, tibiocalcaneal ligament
• Deep: deep posterior tibiotalar ligament, deep anterior tibiotalar ligament.

It is important to mention that the dissection revealed the continuous nature of these ligaments and individual bands were impossible to distinguish.

The characteristic of the MCL:

• multifascicular
• originates from the medial malleolus and inserts in the talus
• tendon sheath of the posterior tibial muscle covers the posterior and middle part of the deltoid ligament
• tendons cover most of the MCL as it inserts at the foot.

Lateral ankle ligament

Lateral Collateral Ligament

Lateral collateral ligament (LCL) form three ligaments: anterior talofibular, calcaneofibular , and posterior talofibular ligaments.

Anterior talofibular ligament (ATFL):

• is made up of two bands
• originates at the anterior margin of the lateral malleolus and inserts on the talus
• lays horizontally to the ankle
• limits anterior displacement of the talus and ankle plantarflexion
• the weakest part of the LCL.

Calcaneofibular ligament (CL):

• originates from the anterior part of the lateral malleolus and attaches to the posterior region of the lateral calcaneal surface
• located below the lower band of the anterior talofibular ligament
• runs obliquely downwards and backwards
• bridges the talocrural joint and subtalar joint
• allows talocrural joint flexion and extension and subtalar movement.

Posterior Talofibular Ligament (PTFL):

• originates from the malleolar fossa and inserts in the posterolateral talus
• some fibres become involved in forming the tunnel for the flexor hallucis longus tendon
• runs almost horizontally
• at the neutral ankle and during plantarflexion, the ligament is relaxed, in dorsiflexion taut.

There are interconnections between the ATFL, CFL, and PTFL that lead to the formation of an anatomical and functional lateral fibulotalocalcaneal ligament complex.

Tibiofibular Syndesmosis

Tibiofibular syndesmosis articulation allows medial rotation of the fibula during maximum ankle dorsiflexion and inversion of the fibula during ankle plantarflexion. In addition, it provides stability between the tibia and the fibula at their distal ends. It includes:

• Anteroinferior tibiofibular ligament
  • originates in the anterior tubercle of the tibia and inserts in the anterior margin of the lateral malleolus
  • made up of several fascicles
  • when damaged can cause ankle instability.
• Posteroinferior tibiofibular ligament
  • has two independent parts: superficial and deep
  • superficial component (a true posteroinferior tibiofibular ligament) originates at the posterior edge of the lateral malleolus and is inserted in the posterior tibial tubercle
  • deep component (transverse ligament) originates in the proximal malleolar fossa and inserts in the posterior edge of the tibia.
  • provides talocrural joint stability and prevents posterior talar translation.
• Interosseous tibiofibular ligament
  • short fibres running between tibia and fibula
  • distal continuation of the interosseous membrane
  • responsible for maintaining ankle stability.

A fatty synovial fringe located distal to the ligament insertion is also part of this structure. Its upward and downward movement occurs during ankle movement and alters its placement between the tibia and the fibula. This adipose tissue is considered a cause of a syndesmotic impingement following an ankle sprain.

Ligaments of the foot-plantar surface

Ligaments of the foot-dorsal surface

Ligaments of the Foot

The main function of the short and long plantar ligaments and the calcaneonavicular ligament (spring ligament) is to assist in the passive maintenance of the arch.

Plantar fascia ligament

• originates in the medial calcaneal tubercle and ends at the five metatarsal bones
• consider primary passive plantar tissue that supports the medial longitudinal arch
• extremely strong ligament
• absorbs the impact of ground reaction force in running or jumping
• disperse stress throughout the metatarsus
• dysfunction of plantar fascia affects the height and shape of the medial longitudinal arch
• any morphological or mechanical changes in the plantar fascia will produce lesions.

Plantar calcaneonavicular ligament (SL, spring ligament)

• a passive stabilizer of the plantar arch in the talocalcaneal joint
• supports compression forces
• the strongest medial ligament
• assist with avoiding talus medial rotation and plantar flexion
• limits navicular dorsal flexion, eversion, and abduction
• pes planus may be produced by isolated SL injuries.

Calcaneocuboid ligament

• consists of the medial calcaneocuboid ligament(a component of the bifurcate ligament), the dorsolateral calcaneocuboid ligament, the plantar calcaneocuboid ligament (SPL or short plantar ligament), and the long plantar ligament (LPL)
• LPL originates on the inferior surface of the calcaneus and inserts into the bases of the second to fourth metatarsals (MTs) and not the distal cuboid.
• SPL originates at the anterior tubercle of the calcaneus and attaches to the plantar surface of the cuboid
• supports the medial and lateral longitudinal arches
• can be damaged during inversion injury of the foot.

Lisfranc ligament

• originates from the lateral side of the medial cuneiform bone and inserts at the medial side of the base of the second metatarsal bone
• maintains the stability of the medial column and axial column of the foot arch.

You can now watch this short video on how to palpate important anatomic structures of the foot and the ankle.

Clinical relevance

1. Ankle fractures affect mainly two groups: young active males and older females. In the first group, fractures occur as a consequence of sporting activities, whereas in the latter group it is an osteoporotic injury.
2. Injuries to the ankle are painful and cause significant mobility limitations.
3. Patient- reported outcome measures (PROM) are used in clinical trials to measure the effect of treatment after lower limb fracture.
4. 1/3 of all ankle fractures can result in tibiotalar joint dislocations.
5. Chronic ankle ligaments injury is difficult to diagnose and using the ultrasound showed high diagnostic accuracy.
6. Chronic ankle instability may be a result of poorly managed acute ankle ligaments injury.
7. After 1 to 5 years post-acute ligament sprain, the individual can still suffer from pain, functional instability, mechanical instability or recurrent sprain.

Resources

Anatomy of the Ankle Ligaments: A Pictorial Essay - In this pictorial essay, the ligaments around the ankle are grouped, depending on their anatomic orientation, and each of the ankle ligaments is discussed in detail.