Joints of Foot

Introduction

The joints of the foot are divided into five groups:

1. Intertarsal joints
2. Tarsometatarsal joints
3. Intermetatarsal joints
4. Metatarsophalangeal joints
5. Interphalangeal joints

Intertarsal Joints

The intertarsal joints are the joints between the tarsal bones of the foot. They include:

1. Subtalar (talocalcaneal) joint
2. Talocalcaneonavicular joint
3. Calcaneocuboid joint
4. Cuneonavicular joint
5. Intercuneiform joints

Subtalar (Talocalcaneal) Joint

• The subtalar joint is formed between the talus and the calcaneus. It has two articular components:
  1. Anterior talocalcaneal articulation: The convex surface of the talus articulates with the concave facet on the superior surface of the calcaneus.
  2. Posterior talocalcaneal articulation: The concave surface of the talus articulates with the convex surface of the calcaneus.

• It is a plane synovial joint.
• The joint is supported by:
  • Fibrous capsule
  • Medial talocalcaneal ligament
  • Lateral talocalcaneal ligament
  • Interosseous talocalcaneal ligament
  • Cervical ligament
• It permits inversion and eversion of the foot.

Talocalcaneonavicular Joint

• The talocalcaneonavicular joint is a ball-and-socket synovial joint. It is a compound joint formed by the talus, calcaneus, and navicular bones. The head of the talus fits into a socket formed by the calcaneus, navicular bone, and the spring (plantar calcaneonavicular) ligament. It allows inversion and eversion of the foot.

Calcaneocuboid Joint

• The calcaneocuboid joint is a saddle-type synovial joint. It is formed between the calcaneus and the cuboid.
• The joint is supported by:
  • Fibrous capsule
  • Calcaneocuboid ligament
  • Bifurcate ligament
  • Long plantar ligament

Transverse Tarsal (Midtarsal or Chopart’s) Joint

• The transverse tarsal joint is a compound synovial joint.
• It is formed by the:
  1. Talonavicular joint
  2. Calcaneocuboid joint

• Although these joints lie in the same plane, they have different axes of movement.
• Together, they permit:
  • Inversion
  • Eversion
  • Adduction
  • Abduction of the foot

Tarsometatarsal Joints

• There are five tarsometatarsal joints. They are plane synovial joints.
• They are supported by:
  • Dorsal tarsometatarsal ligaments
  • Plantar tarsometatarsal ligaments
  • Interosseous tarsometatarsal ligaments
• These joints allow limited gliding movements.

Intermetatarsal Joints

• The intermetatarsal joints are plane synovial joints located between adjacent metatarsal bones. They are strengthened by the:
  • Dorsal intermetatarsal ligaments
  • Plantar intermetatarsal ligaments

Metatarsophalangeal Joints

• There are five metatarsophalangeal joints. They are ellipsoid synovial joints.
• These joints are supported by:
  • Fibrous capsule
  • Collateral ligaments
  • Plantar ligaments
  • Deep transverse metatarsal ligament

They permit the following movements:

• Plantar flexion: 30° to 40°
• Dorsiflexion: 50° to 60°
• Adduction and abduction

Note: The axis for adduction and abduction passes through the second metatarsal.

Interphalangeal Joints

• There are nine interphalangeal joints in the foot. They are hinge synovial joints. These joints permit:
  • Dorsiflexion (extension)
  • Plantar flexion (flexion) of the toes.

Ligaments of Foot

The foot is supported by several strong ligaments that provide stability and help maintain the arches of the foot. The major ligaments are:

1. Dorsal talonavicular ligament: Extends from the neck of the talus to the dorsal surface of the navicular.
2. Spring (plantar calcaneonavicular) ligament: Connects the calcaneus to the navicular bone.
3. Bifurcate ligament: A Y-shaped ligament that extends from the sulcus calcanei to the dorsal surfaces of the navicular and cuboid bones.
4. Dorsal calcaneocuboid ligament: Extends from the lateral surface of the calcaneus to the cuboid.
5. Long plantar ligament: Extends from the plantar surface of the calcaneus to the groove of the cuboid and the bases of the second, third, and fourth metatarsals.
6. Short plantar ligament: Lies deep to the long plantar ligament and extends from the anterior tubercle of the calcaneus to the plantar surface of the cuboid.
7. Plantar cuneonavicular ligament: Extends from the plantar surface of the navicular to the plantar surfaces of the three cuneiform bones.
8. Dorsal cuneonavicular ligament: Connects the dorsal surface of the navicular to the dorsal surfaces of the three cuneiform bones.
9. Plantar cuboideonavicular ligament: Connects the plantar surfaces of the cuboid and navicular bones.
10. Dorsal cuboideonavicular ligament: Connects the dorsal surfaces of the cuboid and navicular bones.
11. Deep transverse metatarsal ligament: Connects the heads of the metatarsal bones.
12. Anterior talocalcaneal ligament: Extends from the front and lateral aspect of the neck of the talus to the sinus tarsi of the calcaneus.
13. Posterior talocalcaneal ligament: Extends from the lateral tubercle of the talus to the upper medial part of the calcaneus.
14. Lateral talocalcaneal ligament: Extends from the lateral surface of the talus to the lateral surface of the calcaneus.
15. Medial talocalcaneal ligament: Extends from the medial tubercle of the talus to the sustentaculum tali.

Spring (plantar calcaneonavicular) ligament

• The spring ligament is a thick and strong ligament. It extends from the anterior margin of the sustentaculum tali to the plantar surface of the navicular bone. The head of the talus rests on the upper surface of this ligament. The articular surface of the ligament is covered by fibrocartilage. It completes the socket of the talocalcaneonavicular joint. It plays an important role in maintaining the medial longitudinal arch of the foot.

Long plantar ligament

• The long plantar ligament is the longest and strongest plantar ligament of the foot. It extends from the plantar surface of the calcaneus to the groove of the cuboid and the bases of the second, third, and fourth metatarsals. It converts the groove on the plantar surface of the cuboid into a fibro-osseous tunnel for the tendon of the peroneus (fibularis) longus. It helps maintain the longitudinal arches of the foot. Morphologically, it is considered a detached part of the tendon of the gastrocnemius.

Short plantar ligament

• The short plantar ligament, also called the plantar calcaneocuboid ligament, is broad and strong. It extends from the anterior tubercle of the calcaneus to the plantar surface of the cuboid, behind its ridge. It lies deep to the long plantar ligament. It also helps maintain the longitudinal arches of the foot.

Bifurcate ligament

• The bifurcate ligament is a Y-shaped ligament. Its stem is attached to the anterolateral part of the sulcus calcanei.
• It divides into two parts:
  • One part is attached to the navicular bone.
  • The other part is attached to the cuboid bone.
• It strengthens the calcaneocuboid joint, which forms part of the midtarsal (transverse tarsal) joint.

Cervical ligament

• The cervical ligament extends from the upper surface of the calcaneus to the inferolateral aspect of the neck of the talus. It strengthens the subtalar joint.
• The ligament becomes tight during inversion of the foot and helps limit excessive inversion, thereby contributing to the stability of the subtalar joint.

Inversion and Eversion of Foot

• Inversion and eversion are rotational movements of the foot.

• Inversion: In inversion, the medial border of the foot is raised, and the sole faces medially.
• Eversion: In eversion, the lateral border of the foot is raised, and the sole faces laterally.

Joints Involved

The following joints take part in inversion and eversion:

Main joints:

• Subtalar (talocalcaneal) joint
• Talocalcaneonavicular joint

Accessory joint:

• Transverse tarsal (midtarsal) joint

Axis of Movement

• Inversion and eversion occur around an oblique axis. This axis runs forward, upward, and medially. It extends from the posterior part of the calcaneus, passes through the sinus tarsi, and reaches the superomedial aspect of the neck of the talus.

Range of Movement

• Inversion has a greater range of movement than eversion.
  • Inversion: 30°
  • Eversion: 20°
• During plantar flexion, the ankle joint becomes less stable. In this position, the narrow posterior part of the trochlea of the talus occupies the ankle mortise, allowing greater side-to-side movement of the talus. As a result, the range of inversion and eversion increases.

Muscles Producing the Movements

Muscles of Inversion

Principal muscles:

• Tibialis anterior
• Tibialis posterior

Accessory muscles:

• Flexor hallucis longus
• Flexor digitorum longus

Muscles of Eversion

Principal muscles:

• Peroneus (fibularis) longus
• Peroneus (fibularis) brevis

Accessory muscle:

• Peroneus (fibularis) tertius

Limiting Factors

The range of these movements is limited by the following structures:

Inversion is limited by:

• Tension in the peroneal (fibularis) muscles
• Cervical ligament

Eversion is limited by:

• Tension in the tibialis anterior
• Tension in the tibialis posterior
• Deltoid ligament

Functional Significance

• Inversion and eversion help the foot adapt to uneven or sloping surfaces during walking. These movements improve balance and make walking more stable on irregular ground.

Pronation and Supination of the Foot

• Pronation and supination are modified movements related to inversion and eversion when the foot is in contact with the ground. In these movements, the forefoot rotates on the talus and calcaneus. In supination, the medial border of the forefoot is elevated. In pronation, the lateral border of the forefoot is elevated. These movements occur mainly at the midtarsal and tarsometatarsal joints.

Table 16.1: Comparison between inversion and eversion

Feature	Inversion	Eversion
Movement	Medial border of the foot is elevated.	Lateral border of the foot is elevated.
Position of the sole	Sole faces medially.	Sole faces laterally.
Associated movements	Plantar flexion and adduction of the foot.	Dorsiflexion and abduction of the foot.
Range of movement	About 30°	About 20°
Principal muscles	Tibialis anterior and Tibialis posterior	Peroneus (fibularis) longus and Peroneus (fibularis) brevis
Main joints involved	Subtalar and talocalcaneonavicular joints	Subtalar and talocalcaneonavicular joints
Associated with	Supination of the foot	Pronation of the foot

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