Digits of foot

Bony framework:

• There are five digits of foot. From medial to lateral, they are the 1st, 2nd, 3rd, 4th, and 5th digits.

1)      The 1st digit is the hallux or great toe, located on the innermost side.

2)      The 2nd digit is the long toe.

3)      The 3rd digit is the middle toe.

4)      The 4th digit is the ring toe.

5)      The 5th digit is the little toe or baby toe, positioned on the outermost side.

• Each digit of foot comprises three phalangeal bones, except for the great toe (1st digit), which has only two phalanges.

• The proximal phalanges articulate with the rounded heads of the metatarsals, forming ellipsoid synovial metatarsophalangeal joints. These joints are reinforced by medial and lateral collateral ligaments and plantar ligaments, enabling flexion, extension, adduction, abduction, rotation, and circumduction movements.

• The phalanges within each digit articulate with each other, forming proximal and distal interphalangeal joints, except for the great toe, which has a single interphalangeal joint.

Fibrous flexor sheaths:

• These sheaths create tunnels on the plantar side of the digits of foot. They attach to the margins of the phalanges and the plantar ligaments associated with the metatarsophalangeal and interphalangeal joints.

• Since the tendons of the flexor digitorum longus, flexor hallucis longus, and flexor digitorum brevis muscles pass through these fibrous tunnels, they are held in place with the phalanges, preventing bow-stringing during flexion movements.

Extensor hoods:

• These are triangular fibrous expansions of the distal tendons of the extensor muscle of the leg and foot, namely the extensor digitorum longus, extensor hallucis longus, and extensor digitorum brevis. They are located on the dorsum of the toes and attach to the apices of the distal phalanges, midway along the middle phalanges, and wrap around the bases of the proximal phalanges, hooking onto the deep transverse metatarsal ligaments.

• Intrinsic muscles of the foot, including the lumbricals and interossei, attach to the bases of the extensor hoods. This attachment allows for flexion at the metacarpophalangeal joints and extension at the interphalangeal joints.

Muscles:

• Various extrinsic and intrinsic muscles of the foot insert into the phalanges of the digits of foot. Extrinsic muscles originate from the leg bones, while the intrinsic muscles are located entirely within the foot region, primarily in the sole. These muscles are innervated by the medial and lateral plantar nerves, except for the extensor digitorum brevis, which is innervated by the deep peroneal nerve.