Capitate !
The capitate is the largest wrist bone, in the centre of the second row; wrist motion pivots around its rounded head.
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What it is
The largest wrist bone, in the middle of the hand's base.
What it does
One of the eight carpal bones that let the wrist bend and carry load to the forearm.
Key facts
- Joints with
- Scaphoid, lunate, trapezoid, hamate, 2nd–4th metacarpals
- Landmarks
- Head; largest carpal bone, ossifies first
Relations
- Above
- Head in the concavity of the lunate, with the scaphoid alongside
- Below
- Bases of the 2nd, 3rd and 4th metacarpals, mainly the 3rd
- Lateral
- Scaphoid and trapezoid
- Medial
- Hamate, joined by a strong interosseous ligament
- In front
- Floor of the carpal tunnel under the median nerve and flexor tendons; origin of the oblique head of the adductor pollicis
How to find it
On the back of the hand it lies in a slight hollow just proximal to the base of the 3rd metacarpal, in line with the middle finger; with the wrist flexed the head is felt just distal to the lunate.
On imaging
On the lateral view the radius, lunate and capitate form a straight column; a capitate displaced dorsally behind a lunate that stays with the radius means perilunate dislocation. On the PA view the third Gilula arc runs along the proximal capitate and hamate.
Clinical notes
- Isolated fractures are uncommon and usually part of a greater arc perilunate injury
- Avascular necrosis of the head can follow a neck fracture or occur without trauma
- It is one of the four bones joined in a four-corner fusion (with the lunate, hamate and triquetrum), an operation for advanced SLAC or SNAC wrist after the scaphoid is removed
Development
The first carpal bone to ossify, in the first months of life, followed by the hamate; the rest appear roughly one per year: triquetrum, lunate, scaphoid, trapezium, trapezoid, and last the pisiform. Counting carpal centres gives a rough bone age.
Test yourself
Think of the answer, then tap the question to see it.
Which is the first carpal bone to ossify?
The capitate, in the first months of life, followed by the hamate.
Why can a fracture through the neck of the capitate leave its head without blood?
Its blood supply enters distally, as in the scaphoid.
What is scaphocapitate syndrome?
A rare combined fracture of the scaphoid and the capitate neck in which the capitate head turns upside down.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- os capitatum TA2 1258
- Official Spanish (DeCS)
- Hueso grande
- English (TA2)
- Capitate
Related
- Adductor pollicis
- CMC ligaments
- Dorsal intercarpal ligament
- Extensor tendons
- Midcarpal ligaments
- Palmar wrist ligaments
- Scapholunate ligament
- Ulnocarpal ligaments
Sources: Terminologia Anatomica (TA2); Anatomy, Shoulder and Upper Limb, Hand Carpal Bones.
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Representative model, for educational purposes only.
