The ankle, or the talocrural region,
is the region where the foot
and the leg
meet. The ankle includes three joint
s: the ankle joint proper or talocrural joint, the subtalar joint
, and the inferior tibiofibular joint
The movements produced at this joint are dorsiflexion and plantarflexion
of the foot. In common usage, the term ankle refers exclusively to the ankle region. In medical terminology, "ankle" (without qualifiers) can refer broadly to the region or specifically to the talocrural joint.
The main bones of the ankle region are the talus
(in the foot), and the tibia
(in the leg). The talocrural joint is a synovial hinge joint
that connects the distal ends of the tibia and fibula in the lower limb with the proximal end of the talus. The articulation between the tibia and the talus bears more weight than that between the smaller fibula and the talus.
As a region, the ankle is found at the junction of the leg
and the foot
. It extends downwards (distally
) from the narrowest point of the lower leg and includes the parts of the foot closer to the body (proximal) to the heel
and upper surface (dorsum
) of the foot.
The talocrural joint is the only mortise and tenon joint in the human body,
the term likening the skeletal structure to the woodworking joint
of the same name. The bony architecture of the ankle consists of three bones: the tibia
, the fibula
, and the talus
. The articular surface of the tibia may be referred to as the ''plafond'' (French
The medial malleolus
is a bony process extending distally off the medial tibia. The distal-most aspect of the fibula is called the lateral malleolus
. Together, the malleoli, along with their supporting ligaments, stabilize the talus underneath the tibia.
Because the motion of the subtalar joint provides a significant contribution to positioning the foot, some authors will describe it as the lower ankle joint, and call the talocrural joint the upper ankle joint.
Dorsiflexion and Plantarflexion are the movements
that take place in the ankle joint. When the foot is plantar flexed, the ankle joint also allows some movements of side to side gliding, rotation, adduction, and abduction.
The bony arch formed by the tibial plafond and the two malleoli is referred to as the ankle "mortise
" (or talar mortise). The mortise is a rectangular socket.
The ankle is composed of three joints: the talocrural joint (also called talotibial joint, tibiotalar joint, talar mortise, talar joint), the subtalar joint
(also called talocalcaneal), and the Inferior tibiofibular joint
The joint surface of all bones in the ankle are covered with articular cartilage
The distances between the bones in the ankle are as follows:
*Talus - medial malleolus : 1.70 ± 0.13 mm
*Talus - tibial plafond: 2.04 ± 0.29 mm
*Talus - lateral malleolus: 2.13 ± 0.20 mm
Decreased distances indicate osteoarthritis
The ankle joint is bound by the strong deltoid ligament
and three lateral ligaments: the anterior talofibular ligament
, the posterior talofibular ligament
, and the calcaneofibular ligament
* The ''deltoid ligament'' supports the medial side of the joint, and is attached at the medial malleolus
of the tibia and connect in four places to the talar shelf
of the calcaneus
, calcaneonavicular ligament
, the navicular tuberosity
, and to the medial surface of the talus.
* The ''anterior'' and ''posterior talofibular ligaments'' support the lateral side of the joint from the lateral malleolus
of the fibula to the dorsal and ventral ends of the talus.
* The ''calcaneofibular ligament'' is attached at the lateral malleolus and to the lateral surface of the calcaneus.
Though it does not span the ankle joint itself, the syndesmotic ligament makes an important contribution to the stability of the ankle. This ligament spans the syndesmosis
, i.e. the articulation between the medial aspect of the distal fibula and the lateral aspect of the distal tibia. An isolated injury to this ligament is often called a high ankle sprain
The bony architecture of the ankle joint is most stable in dorsiflexion
. Thus, a sprained ankle
is more likely to occur when the ankle is plantar-flexed, as ligamentous support is more important in this position. The classic ankle sprain involves the anterior talofibular ligament
(ATFL), which is also the most commonly injured ligament during inversion
sprains. Another ligament that can be injured in a severe ankle sprain is the calcaneofibular ligament
Retinacula, tendons and their synovial sheaths, vessels, and nerves
A number of tendons pass through the ankle region. Bands of connective tissue called ''retinacula'' (singular: ''retinaculum'') allow the tendons to exert force across the angle between the leg and foot without lifting away from the angle, a process called bowstringing.
The superior extensor retinaculum of foot
extends between the anterior (forward) surfaces of the tibia and fibula near their lower (distal) ends. It contains the anterior tibial artery
and the tendons of the tibialis anterior muscle
within its tendon sheath and the unsheathed tendons of extensor hallucis longus
and extensor digitorum longus
muscles. The deep peroneal nerve
passes under the retinaculum while the superficial peroneal nerve
is outside of it. The inferior extensor retinaculum of foot
is a Y-shaped structure. Its lateral attachment is on the calcaneus, and the band travels towards the anterior tibia where it is attached and blends with the superior extensor retinaculum. Along with that course, the band divides and another segment attaches to the plantar aponeurosis
. The tendons which pass through the superior extensor retinaculum are all sheathed along their paths through the inferior extensor retinaculum and the tendon of the fibularis tertius muscle
is also contained within the retinaculum.
The flexor retinaculum of foot
extends from the medial malleolus to the medical process of the calcaneus, and the following structures in order from medial to lateral: the tendon of the tibialis posterior muscle
, the tendon of the flexor digitorum longus muscle
, the posterior tibial artery
, the tibial nerve
, and the tendon of the flexor hallucis longus muscle
The fibular retinacula
hold the tendons of the fibularis longus
and fibularis brevis
along the lateral aspect of the ankle region. The superior fibular retinaculum extends from the deep transverse fascia of the leg and lateral malleolus to calcaneus. The inferior fibular retinaculum is a continuous extension from the inferior extensor retinaculum to the calcaneus.
Mechanoreceptors of the ankle send proprioceptive sensory input to the central nervous system (CNS). Muscle spindles are thought to be the main type of mechanoreceptor responsible for proprioceptive attributes from the ankle. The muscle spindle gives feedback to the CNS system on the current length of the muscle it innervates and to any change in length that occurs.
It was hypothesized that muscle spindle feedback from the ankle dorsiflexors played the most substantial role in proprioception
relative to other muscular receptors that cross at the ankle joint. However, due to the multi-planar range of motion at the ankle joint there is not one group of muscles that is responsible for this. This helps to explain the relationship between the ankle and balance.
In 2011, a relationship between proprioception of the ankle and balance performance was seen in the CNS. This was done by using a fMRI machine in order to see the changes in brain activity when the receptors of the ankle are stimulated. This implicates the ankle directly with the ability to balance. Further research is needed in order to see to what extent does the ankle affect balance.
Historically, the role of the ankle in locomotion has been discussed by Aristotle
and Leonardo da Vinci
. There is no question that ankle push-off is a significant force in human gait
, but how much energy is used in leg swing as opposed to advancing the whole-body center of mass
is not clear.
Of all major joints, the ankle is the most commonly injured. If the outside surface of the foot is twisted under the leg during weight bearing, the lateral ligament
, especially the anterior talofibular portion
, is subject to tearing (a sprain
) as it is weaker than the medial ligament and it resists inward rotation
of the talocrural joint.
Symptoms of an ankle fracture
can be similar to those of ankle sprain
), though typically they are often more severe by comparison. It is exceedingly rare for the ankle joint to dislocate in the presence of ligamentous injury alone.
The talus is most commonly fractured by two methods. The first is hyperdorsiflexion, where the neck of the talus is forced against the tibia and fractures. The second is jumping from a height - the body is fractured as the talus transmits the force from the foot to the lower limb bones.
In the setting of an ankle fracture the talus can become unstable and subluxate
. People may complain of ecchymosis
(bruising), or there may be an abnormal position, abnormal motion, or lack of motion. Diagnosis is typically by X-ray
. Treatment is either via surgery or casting depending on the fracture types.
The initial evaluation of suspected ankle pathology is usually by projectional radiography
Varus or valgus deformity, if suspected, can be measured with the frontal tibiotalar surface angle (TTS), formed by the mid-longitudinal tibial axis (such as through a line bisecting the tibia at 8 and 13 cm above the tibial plafond) and the talar surface.
An angle of less than 84 degrees is regarded as ''talipes varus'', and an angle of more than 94 degrees is regarded as ''talipes valgus''.
For ligamentous injury, there are 3 main landmarks on X-rays: The first is the ''tibiofibular clear space'', the horizontal distance from the lateral border of the posterior tibial malleolus to the medial border of the fibula, with greater than 5 mm being abnormal. The second is ''tibiofibular overlap'', the horizontal distance between the medial border of the fibula and the lateral border of the anterior tibial prominence, with less than 10 mm being abnormal. The final measurement is the ''medial clear space'', the distance between the lateral aspect of the medial malleolus and the medial border of the talus at the level of the talar dome, with a measurement greater than 4 mm being abnormal. Loss of any of these normal anatomic spaces can indirectly reflect ligamentous injury or occult fracture, and can be followed by MRI or CT.
or talipes equinovarus, which occurs in one to two of every 1,000 live births, involves multiple abnormalities of the foot.
Equinus refers to the downard deflection of the ankle, and is named for the walking on the toes in the manner of a horse.
This does not occur because it is accompanied by an inward rotation of the foot (varus deformity
), which untreated, results in walking on the sides of the feet. Treatment may involve manipulation and casting or surgery.
Occasionally a human ankle has a ball-and-socket ankle joint and fusion of the talo-navicular joint.
The word ankle or ancle is common, in various forms, to Germanic languages
, probably connected in origin with the Latin
, or Greek
, meaning bent.
It has been suggested that dexterous control of toes has been lost in favour of a more precise voluntary control of the ankle joint.
File:Slide3Bubu.JPG|Dorsum of Foot. Ankle joint. Deep dissection
File:Slide2bubu.JPG|Dorsum of Foot. Ankle joint. Deep dissection
File:Slide2tat.JPG|Ankle joint. Deep dissection. Anterior view.
File:Slide2coco.JPG|Dorsum of Foot. Ankle joint. Deep dissection
Category:Lower limb anatomy