What is the anatomy of the tarsal and metatarsal bones?

Anatomy of the Tarsal and Metatarsal Bones

Tarsal Bones

The tarsal bones form the posterior part of the foot and play a crucial role in weight-bearing and locomotion.

• The talus is a pivotal bone that transfers body weight from the shin to the foot, with most of its surface covered by articular cartilage, making its blood supply relatively poor and increasing risk for poor healing after injury 1
• The calcaneus (heel bone) is the largest tarsal bone and forms the posterior part of the foot
• The navicular bone is critical for maintaining the arch of the foot and may be affected by various pathologies including accessory ossicles, coalition, fractures, Kohler's disease, osteonecrosis, and osteochondral lesions 2
• The cuboid bone articulates with the calcaneus proximally and the fourth and fifth metatarsals distally
• Three cuneiform bones (medial, intermediate, and lateral) articulate with the navicular proximally and the first three metatarsals distally 3

Metatarsal Bones

The metatarsal bones connect the tarsal bones to the phalanges and form the anterior part of the foot.

• There are five metatarsal bones numbered from medial to lateral (1-5)
• Each metatarsal has a base (proximal), shaft (diaphysis), and head (distal) 4
• The first metatarsal is the shortest and thickest, bearing significant weight during walking
• The second metatarsal is the longest and has important mechanical functions due to its specific intrinsic morphology 4
• The fifth metatarsal has a prominent tuberosity on its lateral side, which is a common site for fractures 5
• Metatarsal bones demonstrate intrinsic axial torsion with mean values between 3.2° and 57.7° 4

Regions of the Foot

The foot can be divided into three distinct anatomical regions:

• Forefoot — Extends from the tarsometatarsal joint and incorporates the phalanges, metatarsal, and sesamoid bones 3
• Midfoot — Begins at the transverse tarsal joint and extends to the tarsometatarsal joint, incorporating the navicular, cuboid, and cuneiform bones 3
• Hindfoot — Begins at the ankle joint and ends at the transverse tarsal joint, incorporating the calcaneus and talus bones 3

Ligamentous Anatomy

The tarsal and metatarsal bones are connected by various ligaments that provide stability to the foot.

• The interosseous tarsometatarsal ligaments are observed in the first, second, and third cuneometatarsal joint spaces 6
• The Lisfranc ligament (first interosseous tarsometatarsal ligament) consistently connects the medial cuneiform and the second metatarsal 6
• The interosseous tarsometatarsal ligaments of the second and third cuneometatarsal joint spaces comprise seven and five components respectively, classified into different types based on their configurations 6

Clinical Significance

Understanding tarsal and metatarsal anatomy is crucial for diagnosing and treating various foot conditions:

• The Ottawa Ankle Rules include palpation pain at the base of the fifth metatarsal bone and navicular bone as key indicators for potential fractures 3
• Metatarsalgia (pain in the metatarsal region) often requires treatment with metatarsal pads placed behind the metatarsal heads to relieve focal pressure 7
• For patients with diabetes and bony deformities of the foot, extra wide or deep shoes are recommended to prevent complications 7
• Surgical interventions for metatarsal-related conditions should only be considered after conservative measures have failed 7

The anatomy of the tarsal and metatarsal bones is fundamental to understanding foot biomechanics, diagnosing pathological conditions, and planning appropriate interventions for foot disorders. 3