Phalanges of the foot: hallux versus lesser toes
The hallux (big toe) has two phalanges (the small long bones of the toes, singular phalanx), while each lesser toe, the second to fifth, usually has three.
Remember
The hallux has no middle phalanx, so it has one interphalangeal joint (a joint between two phalanges), whereas the lesser toes usually have a middle phalanx and two such joints.
Memory aid
The hallux is the two-bone toe: it has a near bone and a far bone, but no middle one
Picture the hallux as the two-bone toe, with a bone near the foot, a bone far from it and nothing in the middle.
The big toe is the exception among the toes. The hallux has two phalanges, a proximal one at its base and a distal one that carries the nail, and it has no middle phalanx. The four lesser toes, the second to fifth, usually have three phalanges, with a middle phalanx lying between the proximal and distal bones. A fifth toe with only two phalanges is a normal variant.
The metatarsals are the five long bones lying behind the toes. A toe joint is named for the bones it joins. An interphalangeal joint lies between phalanges, whereas a metatarsophalangeal joint joins a metatarsal to a proximal phalanx. Only the proximal phalanx meets a metatarsal, at the ball of the foot.
Each pair of neighbouring bones in a toe has a joint between them, so a toe has one interphalangeal joint fewer than it has phalanges. The hallux has one, and a lesser toe with three phalanges has two.
A phalanx never meets a tarsal bone directly, because the metatarsals sit between the tarsal bones and the toes.
Key facts
- Hallux
- a proximal and a distal phalanx, two bones, and no middle phalanx.
- Lesser toes
- the second to fifth toes usually have a proximal, a middle and a distal phalanx.
- Interphalangeal joints
- always one fewer than the number of phalanges in the toe: one in the hallux, two in a lesser toe with three phalanges.
- Metatarsophalangeal joint
- the joint where a metatarsal meets a proximal phalanx; only the proximal phalanx meets a metatarsal.
- Tarsal bones
- a phalanx never meets a tarsal bone directly, because the metatarsals sit between the tarsal bones and the toes.
- Order of the bones
- from the foot outwards the order is proximal, middle, then distal, and the hallux skips the middle one.
Exam traps
- A claim that every toe has three phalanges is wrong, because the big toe has only a proximal and a distal phalanx.
- Phalanges within a toe meet at interphalangeal joints, so a metatarsophalangeal joint is not where phalanges meet each other; it lies between a metatarsal and a phalanx.
- A big toe described as having a proximal and a middle phalanx gets the number of bones right but the names wrong: the hallux has proximal and distal phalanges, and a middle phalanx is the extra bone that the lesser toes usually have.
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