CorpusHuman Anatomy
SkeletalBone

Scaphoid

Os scaphoideum

Also known as: navicular of the hand, scaphoid bone

The boat-shaped, largest bone of the proximal carpal row on the thumb side, which bridges both carpal rows. It is the most commonly fractured carpal bone and is notorious for non-union and avascular necrosis.

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Overview

The scaphoid lies in the floor of the anatomical snuffbox. It has a proximal pole, a narrow waist and a distal pole bearing the palpable scaphoid tubercle on the palmar side (attachment of the flexor retinaculum and abductor pollicis brevis). It articulates proximally with the radius, medially with the lunate and capitate, and distally with the trapezium and trapezoid. Because it spans the proximal and distal rows, it acts as a mechanical link stabilising the midcarpal joint — and receives large forces when the wrist is extended.

Its blood supply is retrograde: branches of the radial artery enter the dorsal ridge and the tubercle at the distal pole and flow proximally. About 80% of the bone, including the entire proximal pole, depends on these dorsal vessels, so a fracture through the waist can deprive the proximal fragment of blood.

Location

Lateral (radial) side of the proximal carpal row; floor of the anatomical snuffbox.

Parts & subdivisions

  1. Proximal pole
    Articulates with the radius; vulnerable to avascular necrosis.
  2. Waist
    Commonest fracture site (≈65–80%).
  3. Distal pole and tubercle
    Palpable at the base of the thenar eminence; flexor retinaculum attachment.

Anatomy

Arterial supply

Branches of the radial artery entering dorsally and distally — retrograde flow to the proximal pole.

Articulations

Radius, lunate, capitate, trapezium and trapezoid.

Relations

Floor of the anatomical snuffbox (with the trapezium), bounded by the tendons of extensor pollicis longus (medially) and abductor pollicis longus/extensor pollicis brevis (laterally); the radial artery crosses the snuffbox floor.

Ossification

Single centre at ≈5–6 years.

Function

  • Links the proximal and distal carpal rows
  • Transmits load from the thumb side of the hand to the radius

Clinical significance

Scaphoid fracture

Commonest carpal fracture (≈60–70% of carpal fractures), typically a young adult falling on an outstretched, dorsiflexed hand. Signs: anatomical snuffbox tenderness, scaphoid tubercle tenderness and pain on axial thumb compression. Initial X-rays (including scaphoid views) are often normal — treat clinically suspected fractures with immobilisation and arrange MRI/CT or repeat imaging. Complications: non-union and avascular necrosis of the proximal pole (retrograde blood supply), leading to scaphoid non-union advanced collapse (SNAC) and wrist arthritis.

Compiled from standard anatomy and physiology references — see the Skeletal System sources. For education only; not medical advice.