Functional Anatomy of the Ankle
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Top Contributors - Ewa Jaraczewska, Jess Bell and Kim Jackson
Introduction[edit | edit source]
Understanding the anatomy of the ankle is essential for correct diagnosis and treatment of common ankle injuries. Chronic ankle pain, acute and chronic sprains, fractures, tears and inflammation may be a result of routine daily activities or professional and recreational sports. This article will address the complexity of the ankle joint and its osseous, soft tissue, neural and vascular components and how they relates to function.
Anatomy Basic Vocabulary[edit | edit source]
Axes: lines around which an object rotates. The rotation axis is a line that passes through the centre of mass. There are three axes of rotation: saggital passing from posterior to anterior, frontal passing from left to right, and vertical passing from inferior to superior. The rotation axes of foot joints are perpendicular to the cardinal planes; therefore, motions at these joints result in rotations within three planes. Example: supination involves inversion, internal rotation, and plantar flexion.
Bursae: reduces friction between the moving parts of the body joints. It is a fluid-filled sac. There are four types of bursae: adventitious, subcutaneous, synovial, and sub-muscular.
Capsule: one of the characteristics of the synovial joints. It is a fibrous connective tissue which forms a band that seals the joint space, provides passive and active stability and may even form articular surfaces for the joint.
Closed pack position: most of the area of joint contact between the two sides of the joint. In this position, joint stability increases. The closed pack position for interphalangeal joints is at full extension.
Degrees of freedom: the direction of joint movement or rotation, with six being a maximum, including three translations and three rotations.
Ligament: fibrous connective tissue that holds the bones together.
Open (loose) pack position: least amount of joint contact area where joint stability is reduced.
Planes of movement: describe how the body moves. Up and down movements (flexion/extension) occur in a saggital plane.Sideway movements (abduction/adduction) are done in the frontal plane. Movements in the transverse plane are rotational (internal and external rotation).
Ankle Structure[edit | edit source]
The ankle joint includes three bones: the talus, tibia and fibula. There are three borders forming the ankle joint: the lateral, medial and superior. The mortise joint of the ankle is a hinge connecting the ends of the tibia and fibula to the talus.
- Lateral border of the joint: the articular facet of the lateral malleolus
- Medial border of the joint: the articular facet of the medial malleolus
- Superior border of the joint: the inferior articular surface of the tibia and the superior margin of the talus.
Bones and Articulations of the Ankle[edit | edit source]
The lower leg and foot constitute the ankle. The following bony elements of the ankle joint are part of this structure:
| Bones | Articulation | Characteristic | Key Palpation |
|---|---|---|---|
| Talus
Tibia Fibula |
Talocrural joint ("ankle joint" or TC joint) | It is framed laterally and medially by the lateral and the medial malleolus and from the top by the tibia and the talus | |
| Talus
Calcaneus |
Subtalar joint (ST joint) | Three facets of the talus and the calcaneus are part of the ST joint. | To find calcaneus, palpate distally to the lateral malleolus. It is located directly under the talus.
To locate the head of the talus, find medial and lateral malleoli. Place the thumb on the medial and your index finger on the lateral malleolus and move your fingers anteriorly. You feel a dip located behind the tendon. To verify that you are on the head of the talus, evert the patient's ankle while plantar flexed. You should feel the medial aspect of the head of the talus projecting into your contact. |
| Tibia
Fibula |
Inferior tibiofibular joint (ITF joint) | Provides stabilisation to the ankle mortise. |
Ankle Kinematics[edit | edit source]
| Joint | Type of Joint | Plane of Movement | Motion | Kinematics | Closed pack position | Open pack position |
|---|---|---|---|---|---|---|
| TC joint | Hinge | Mainly saggital
Concomitant transverse and frontal plane |
Plantarflexion &Dorsiflexion
During plantarflexion, the foot adducts and inverts. During dorsiflexion, it abducts and everts.[1] |
Normal range of motion :
12 and 20 degrees of dorsiflexion 50 and 56 degrees of plantarflexion |
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| ST joint | Condyloid | Mainly transverse | Inversion &Eversion | The average ROM:
30 degrees inversion / 18 degrees eversion[2] |
Full inversion | Inversion/plantarflexion |
| ITF joint |
Ankle Bursae[edit | edit source]
There are three bursae located in the ankle region:
- The Achilles Bursa
- Retrocalcaneal Bursa
- The medial malleolus bursa
Ankle Joint Capsule[edit | edit source]
The articular capsule surrounds the joints, and is attached, above, to the borders of the articular surfaces of the tibia and malleoli, and below, to the talus around its upper articular surface. The joint capsule anteriorly is a broad, thin, fibrous layer. Posteriorly, the fibres are thin and run mainly transversely, blending with the transverse ligament. Laterally the capsule is thickened and attaches to the hollow on the medial surface of the lateral malleolus.
The ankle joint capsule communicates with the following structures:
- Flexor hallucis longus tendon sheath
- May communicate with subtalar joint (15%)
The capsule, together with collateral ligaments, they support the talocrural joint, and provide a proprioceptive feedback from the mechanoreceptors, free nerve endings and Ruffini endings located in the ligaments.
Ligaments of the Ankle[edit | edit source]
Medial collateral ligament ( deltoid ligament ) consists of four ligaments: tibionavicular (anterior fibers), tibiospring, tibiocalcaneal (middle fibers) and tibiotalar ligament (posterior fibers).
Lateral collateral ligaments are made of anterior and posterior talofibular, and calcaneofibular ligaments.
| Key Ligaments | Origin | Insertion | Action/Role | Key palpation |
|---|---|---|---|---|
| Deltoid Ligament:
Tibionavicular Anterior Tibiotalar Tibiocalcaneal Posterior Tibiotalar |
Provides medial stability to the ankle
Limits the extreme motion of eversion across the talocrural, subtalar and talonavicular joints Resists valgus stresses coming from the lateral to the medial side of the ankle joints Prevents lateral tilt of the talus |
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| Tibionavicular (TN) | Medial malleolus | |||
| Tibiotalar (anterior)(ATT) | Medial malleolus | |||
| Tibiocalcaneal (TC)(middle) | Medial malleolus | |||
| Tibiotalar (posterior) (PTT) | Medial malleolus | |||
| Lateral Collateral Ligaments:
Anterior Talofibular Posterior Talofibular Calcaneofibular
|
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| Anterior Talofibular (ATF) | ||||
| Posterior Talofibular (PTF) | ||||
| Calcaneofibular (CF) |
Muscles of the Ankle[edit | edit source]
Innervation of the Ankle[edit | edit source]
Vascular Supply of the Ankle[edit | edit source]
Clinical Relevance[edit | edit source]
Resources[edit | edit source]
- Aparisi Gómez MP, Aparisi F, Bartoloni A, Ferrando Fons MA, Battista G, Guglielmi G, Bazzocchi A. Anatomical variation in the ankle and foot: from incidental finding to inductor of pathology. Part II: midfooot and forefoot. Insights Imaging. 2019 Jul 31;10(1):69.
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References[edit | edit source]
- ↑ Pollard E. Foot Orthoses. Chui KK, Jorge MM, Yen S-C, Lusardi MM. (editors). Orthotics and Prosthetics in Rehabilitation (Fourth Edition), Elsevier, 2020; pp:184-219.
- ↑ Ball P, Johnson GR. Technique for measuring hindfoot inversion and eversion and its use to study a normal population. Clin Biomech (Bristol, Avon). 1996 Apr;11(3):165-169.
