Transverse tarsal joint
The transverse tarsal joint, also referred to as the midtarsal or Chopart’s joint, crosses the foot horizontally in an S-shaped direction, connecting the hindfoot and midfoot. It is a compound joint composed of two smaller, synovial joints: talonavicular and calcaneocuboid articulations. The talonavicular joint, which is the more mobile out of the two, is formed between the talus (talo-) and the navicular bone (-navicular). The calcaneocuboid joint connects the calcaneus (calcaneo-) and the cuboid bone.
The distinctive movement pattern of the transverse tarsal joint facilitates a variety of functions, depending on the position of the foot. During weight bearing, the navicular and cuboid bones become fixed and immobile, permitting the talus and calcaneus to move in relation to them. Through these movements, the transverse tarsal joint facilitates foot inversion and eversion, which requires the synchronous involvement of the subtalar joint. During these movements, but not only, the transverse tarsal joint is reinforced by several soft tissue structures; joint capsules, ligaments, tendons and surrounding muscles.
Talonavicular joint: synovial saddle joint, multiaxial
Calcaneocuboid joint: synovial saddle joint, multiaxial
Talonavicular joint: navicular articular surface of head of talus, proximal/posterior articular surface ofnavicular bone
Calcaneocuboid joint: articular surface for cuboid on calcaneus, proximal/posterior articular surface of the cuboid
Talonavicular joint: plantar calcaneonavicular, calcaneonavicular, talonavicular, medial collateral ligaments
Calcaneocuboid joint: plantar calcaneocuboid, long plantar, calcaneocuboid, dorsal calcaneocuboid ligaments
Talonavicular joint: deep fibular nerve, medial plantar nerve
Calcaneocuboid joint: deep fibular nerve, sural nerve, lateral plantar nerve
|Blood supply||Lateral tarsal artery|
|Movements||Supination - pronation|
This article will discuss the anatomy and functions of the transverse tarsal joint
- Articular surfaces
- Joint capsule
- Blood supply
- Muscles acting on the transverse tarsal joint
The talonavicular joint is an articulation between the head of talus and the proximal/posterior aspect of the navicular bone.
The navicular articular surface of the head of talus points distally or anteriorly. It is orientated inferiorly in the vertical plane and medially in the horizontal plane, having an overall inferomedial orientation. The navicular articular surface is ovoid and convex in the horizontal and vertical planes. The corresponding proximal articular surface of the navicular bone is oppositely shaped and has a concave and oval shape in the horizontal plane, pointing distally to meet the navicular articular surface.
The calcaneocuboid joint connects the anterior (distal) aspect of the calcaneus with the posterior (proximal) aspect of the cuboid.
The articular surface for cuboid located on the calcaneus has a quadrilateral shape and a concavo-convex, undulating surface. It is divided into superior and inferior parts, which have opposite orientations. The superior part is concave in the horizontal and vertical planes, while the inferior part is convex in the same planes. The articular surface of the cuboid has similar, but reciprocal structural characteristics; it is also quadrilateral and undulating, with a convex superior part and a concave inferior part. This matching and mirroring relationship creates a saddle type joint and a congruent fit between the articular surfaces, thus making this joint much less mobile compared to the talonavicular joint.
The transverse tarsal joint is not considered a true anatomical joint due to the fact that it is not contained within one joint capsule. Instead, it is classified as a functional joint that consists of the aforementioned talonavicular and calcaneocuboid anatomical articulations. The talonavicular joint shares a joint capsule with the articulations formed by the anterior and middle calcaneal facets of the talus with their talar counterparts on the calcaneus; hence these three articulations are anatomically referred to as the talocalcaneonavicular joint. The joint capsule of the talocalcaneonavicular joint is weak on all sides, except the posteroinferior border which is shared with the anterior part of the capsule of the talocalcaneal/subtalar joint.
The calcanecuboid joint is exclusively confined to its joint capsule, which encloses the joint on all sides. Its superior and inferior borders are thickened by ligaments which will be discussed below.
Both joint capsules are lined internally with synovial membrane, which secretes viscous synovial fluid that acts as a lubricant. The membrane extends until the margins of the respective articular surfaces, while the latter are lined by hyaline cartilage.
Learn more about the general features of the synovial joints by exploring articles, diagrams, videos and quizzes.
Despite a weak joint capsule, the talonavicular joint is reinforced by three main ligaments;
Inferiorly by the plantar calcaneonavicular ligament,
Laterally by the calcaneonavicular part of the bifurcate ligament (calcaneonavicular ligament),
Superiorly by the (dorsal) talonavicular ligament
Taken as a whole, these structures form a large supporting socket around the navicular bone which can accommodate the ball represented by the head of talus. By doing this, the transverse tarsal joint is also reinforced.
Plantar calcaneonavicular ligament
The triangular shaped, thick but elastic plantar calcaneonavicular ligament extends almost transversely across the foot. It runs from the anteromedial aspect of the sustentaculum tali of calcaneus to the inferomedial aspect of the navicular bone. The ligament is supported medially by the medial collateral ligament and laterally by the calcaneonavicular ligament. The plantar calcaneonavicular ligament supports the head of talus at the talonavicular joint by allowing it to rest onto a dorsal fibrocartilaginous facet. It also stabilizes the medial longitudinal arch of the foot.
The bifurcate ligament consists of two parts: the calcaneonavicular and calcaneocuboid ligaments. The calcaneonavicular ligament (a.k.a. calcaneonavicular part of bifurcate ligament) helps to support the talonavicular joint laterally. It extends from the superoanterior aspect of the calcaneus to the lateral aspect of the navicular bone. The calcaneocuboid ligament (a.k.a. calcaneocuboid part of bifurcate ligament) reinforces the dorsomedial aspect of the calcaneocuboid joint. It runs from the superoanterior aspect of the calcaneus until the dorsomedial angle of the cuboid bone. It connects the adjacent proximal and intermediate rows of tarsal bones.
The broad and thin talonavicular ligament is located between the plantar calcaneonavicular and calcaneonavicular ligaments. It extends between the superior, or dorsal surface of the neck of talus and the dorsal surface of the talus. The talonavicular ligament reinforces the talonavicular joint dorsally.
The previously described ligaments directly surround and strengthen the talonavicular joint. However, several additional ligaments provide more distant, indirect but equally important support to this joint. These include the medial and lateral collateral ligaments of the ankle joint, the inferior extensor retinaculum of ankle and the talocalcaneal ligaments of the subtalar joint.
Similar to its neighbour, the calcaneocuboid joint is also directly reinforced by four major ligaments:
- Laterally by the calcaneocuboid part of the bifurcate ligament (mentioned above)
- Long plantar ligament
- Inferiorly by the plantar calcaneocuboid and the long plantar ligaments
- Dorsally by the dorsal calcaneocuboid ligament
Long plantar ligament
The long plantar ligament lies superficial to the plantar calcaneocuboid ligament and the tendon of fibularis longus muscle on the plantar aspect of the foot. It runs from the anterior calcaneal tubercle to the ridge and tuberosity of cuboid bone, attaching to both of them. It also sends some superficial fibers towards the lateral four metacarpal bases. Therefore, the long plantar ligament spans almost the entire length of the lateral plantar aspect of the foot, reinforcing the plantar aspects of all the respective lateral foot joints, including the calcaneocuboid joint. It also prevents excessive depression of the lateral longitudinal arch of the foot during weight bearing.
Plantar calcaneocuboid ligament
The strong, wide and short plantar calcaneocuboid ligament is situated deep to the long plantar ligament. It extends from the anterior calcaneal tubercle until a point immediately adjacent to the groove for tendon of fibularis longus muscle of cuboid bone, situated on the plantar aspect. The function of the plantar calcaneocuboid ligament is to strengthen the inferior border of the joint capsule of the calcaneocuboid joint. It also supports the lateral longitudinal arch of the foot during weight loading.
Dorsal calcaneocuboid ligament
The thin and broad dorsal calcaneocuboid ligament reinforces the calcaneocuboid joint dorsally. The calcaneocuboid ligament strengthens the dorsomedial aspect of the calcaneocuboid joint. Its details have been discussed previously.
The previously described ligaments reinforce the transverse tarsal joint indirectly by strengthening the respective talonavicular and calcaneocuboid joints. However, the transverse tarsal joint is further supported by the dorsal, plantar and interosseous cuboideonavicular ligaments. These mainly connect the plantar and dorsal aspects of the cuboid and navicular bones.
The talonavicular joint receives innervation from two sources:
- Deep fibular nerve, which stems directly from the sciatic nerve
- Medial plantar nerve, which originates from the tibial nerve
In turn, the calcaneocuboid joint receives innervation from three sources:
- Deep fibular nerve
- Sural nerve, which is formed by the union of cutaneous branches from the tibial and common fibular nerves
- Lateral plantar nerve, which stems from the tibial nerve
In terms of movements, the surrounding ligamentous reinforcements of the transverse tarsal joint create two functional entities which operate concomitantly. One entity, formed by the talus and calcaneus, moves as a functional unit relative to the fixed navicular and cuboid bones. Movement of the transverse tarsal joint is always mechanically linked with that of the functional (talocalcaneal) subtalar joint. This is evident during weight loading of the subtalar joint, which is accompanied by a small degree of movement of the transverse tarsal joint.
The movement of the transverse tarsal joint is biaxial (around two axes) and triplanar (i.e. occurs in all three cardinal planes). The two axes around which the transverse tarsal joint moves are longitudinal and oblique. The longitudinal axis points superiorly, 15° to the transverse plane, and 9° medial to the sagittal plane. The oblique axis also points superiorly, 52° to the transverse plane and 57° medial to the sagittal plane.
The biaxial movements of the transverse tarsal joint have one degree of freedom, which involves supination and pronation. Both are triplanar, occurring in all three cardinal planes.
Supination is a complex movement involving three motions; inversion, adduction and plantarflexion. During supination, the naviculocuboid unit rotates relative to the bifurcate ligament. This involves a superior movement of the navicular bone at the talonavicular joint and an inferior movement of the cuboid at the calcaneocuboid joint. Pronation is an equally complex, but opposite movement. It involves a combination of three motions; eversion, abduction and dorsiflexion. During pronation, the reverse occurs; rotation of the naviculocuboid unit involves an inferior movement of the navicular bone at the talonavicular joint and a superior movement of the cuboid at the calcaneocuboid joint.
Although these cardinal movements (inversion/eversion, adduction/abduction and plantar/dorsiflexion) will be described individually below, it’s important to emphasize that they always occur synchronously with each other, and never in isolation due to the axes of rotation about which movement occurs. It should be also noted that the terms supination/pronation and inversion/eversion are regularly used interchangeably in the literature, despite the aforementioned kinesiologic difference in their definitions.
Inversion and eversion, if considered in isolation, take place around the orthogonal longitudinal axis of the foot. They are the dominant movements when rotation occurs around the longitudinal axis of the joint, due to the fact that this axis is more longitudinal than vertical. The range of motion (RoM) of inversion is approximately 8° to 10°, while the RoM of eversion ranges between 2° and 3°. These values represent between one half and one third of the RoM magnitude of the subtalar joint. During inversion, the sole of the foot rotates towards the midline, pointing the lateral border of the foot inferiorly. Eversion is the opposite. The sole of the foot is orientated laterally and the medial border is directed inferiorly.
Abduction (external rotation) and adduction (internal rotation) take place around a vertical axis in the transverse plane. They also take place at the transverse tarsal joint, but with a lesser RoM compared to inversion and eversion. During abduction, the naviculocuboid unit moves medially, temporarily increasing in the joint cavity of the talonavicular joint. However, the strength of the surrounding ligaments maintains the integrity of the joint, preventing excessing cavity enlargement and moving the forefoot anterolaterally. Adduction involves the opposite movements; here naviculocuboid unit moves laterally, temporarily decreasing the joint cavity of the talonavicular joint. The surrounding ligaments subsequently protect the joints and force the forefoot to move anteromedially.
Dorsiflexion and plantarflexion at the transverse tarsal joint is minor compared to the previous pairs of movements. They mostly occur around the oblique axis of the transverse tarsal joint, due to the fact that this axis is more mediolaterally oriented than longitudinal. Some studies have shown that up to 12% of the first 30 degrees of total foot plantarflexion can occur at the transverse tarsal joint.
By facilitating supination and pronation, the transverse tarsal joint has important functional implications. During weight bearing on uneven surfaces or when turning, the leg and hindfoot supinate and pronate on the forefoot. In turn, this results in a series of continuously adjusting movements that maintain balance.
The close packed position of the transverse tarsal joint is full supination, while open packed (resting) position is midway between the extremes of the total range of motion. The joint’s capsular pattern is dorsiflexion, followed by plantar flexion, adduction and medial rotation. Accessory movements of the transverse tarsal joint is possible at the calcaneocuboid joint. These include superoinferior sliding of the calcaneus relative to the cuboid.
Muscles acting on the transverse tarsal joint
No muscles have immediate actions on the transverse tarsal joint. Instead, movement of this joint relies primarily on the motion of the nearby subtalar (talocalcaneal) and (ankle) talocrural joints.
|Supination||Tibialis anterior, tibialis posterior, flexor digitorum longus, flexor hallucis longus|
|Pronation||Fibularis longus, fibularis brevis, fibularis tertius, extensor digitorum longus|
The prime muscles causing supination at the transverse tarsal joint are tibialis anterior and posterior. They occupy the anterior and posterior compartments of the leg, respectively, and extend medially, inserting onto the medial aspect of the foot. In addition, the two digit flexor muscles (flexor digitorum longus, flexor hallucis longus) contribute to this movement.
The antagonists of the foot inverters are muscles extending laterally, inserting into the lateral aspect of the foot. They are responsible for pronation. The prime pronatorsare fibularis longus and brevis, which occupy the lateral compartment of the leg. The remaining two contributors, fibularis tertius and extensor digitorum longus, are situated within the anterior compartment of the leg.