Clinical Mnemonics · Anatomy & Musculoskeletal
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Lists the eight carpal (wrist) bones from lateral (thumb side) to medial (pinky side), proximal row first.
The college version
Lists the eight carpal (wrist) bones from lateral (thumb side) to medial (pinky side), proximal row first.
S — Scaphoid
Proximal row, radial (thumb) side; floor of the anatomical snuffbox
Most commonly fractured carpal bone (~60-70% of carpal fractures), typically from a fall on an outstretched hand (FOOSH). Blood supply enters distally and flows retrograde, so proximal-pole fractures risk avascular necrosis (AVN) and nonunion. Snuffbox tenderness is the hallmark finding.
Physiology. Articulates with the radius proximally and trapezium/trapezoid distally; forms the radial floor of the wrist joint and the anatomical snuffbox.
Safety. A normal initial X-ray does not exclude a scaphoid fracture; immobilize and re-image in 10-14 days to avoid missed AVN/nonunion.
L — Lunate
Proximal row, medial to scaphoid; articulates with the radius
Lunate dislocation (usually volar) can compress the median nerve in the carpal tunnel, causing acute carpal tunnel syndrome (radial 3.5 finger numbness, thenar weakness). Kienbock disease is idiopathic AVN of the lunate.
Physiology. Articulates with the radius and the TFCC; a key proximal-row bone around which the wrist flexes and extends.
Safety. New median-nerve symptoms after wrist trauma suggest lunate dislocation - a time-sensitive injury needing prompt reduction.
T — Triquetrum
Proximal row, ulnar side, medial to the lunate
Second most commonly fractured carpal bone, usually a dorsal avulsion (chip) fracture from forced hyperextension/ulnar deviation or direct impact. Isolated fractures generally heal well with immobilization.
Physiology. Articulates with the lunate, pisiform, hamate, and the triangular fibrocartilage complex (TFCC).
Safety. Ulnar-sided wrist pain can also come from a TFCC tear, so a thorough exam matters.
P — Pisiform
Sesamoid bone in the flexor carpi ulnaris tendon; most palmar/ulnar carpal bone
A sesamoid bone embedded in the flexor carpi ulnaris (FCU) tendon; palpable at the base of the hypothenar eminence. It articulates only with the triquetrum. Fractures result from a direct blow to the heel of the hand.
Physiology. Anchors the FCU tendon and pisohamate/pisometacarpal ligaments; helps form the medial wall of Guyon's canal.
Safety. Because of its proximity to Guyon's canal, assess ulnar-nerve function in pisiform injuries.
T — Trapezium
Distal row, radial side; forms the thumb's saddle (CMC) joint
Forms the carpometacarpal (CMC) joint of the thumb with the first metacarpal - a saddle joint permitting opposition. The trapeziometacarpal joint is a frequent site of osteoarthritis ('basal joint arthritis').
Physiology. Articulates with the first metacarpal, scaphoid, and trapezoid.
Safety. Base-of-thumb pain with pinch/grip in older adults should raise suspicion for thumb CMC osteoarthritis.
T — Trapezoid
Distal row, medial to trapezium; base of the index finger
The smallest distal-row carpal bone and the least commonly fractured carpal bone; rarely injured in isolation. Articulates with the second metacarpal and scaphoid.
Physiology. Wedged between the trapezium and capitate, protected from direct force.
Safety. Isolated trapezoid fractures are rare; consider hand-specialty referral when suspected.
C — Capitate
Distal row, central; the largest carpal bone
The largest carpal bone and the keystone of the carpal arch; articulates primarily with the third metacarpal (and second/fourth) and the scaphoid/lunate proximally. Isolated fractures are rare and usually accompany other carpal injuries (e.g., scaphocapitate syndrome).
Physiology. The scaphoid and lunate rotate around the capitate during wrist motion.
Safety. Central wrist pain after high-energy trauma should raise suspicion for a capitate or associated carpal/ligamentous injury.
H — Hamate
Distal row, ulnar side; bears the hook of hamate
The hook of hamate (hamulus) forms the lateral wall of Guyon's canal, which transmits the ulnar nerve and artery. Hook fractures occur with handle impact (golf, baseball, racket sports) and can cause Guyon's canal syndrome: weak grip, weak finger abduction/adduction, and palmar-ulnar sensory loss.
Physiology. Articulates with the fourth and fifth metacarpals, capitate, and triquetrum.
Safety. Palmar-ulnar pain with grip weakness and ulnar-nerve symptoms warrants prompt referral; hook fractures can cause chronic nonunion and persistent nerve symptoms.
Memory aids
- S = Scaphoid
- L = Lunate
- T = Triquetrum
- P = Pisiform
- T = Trapezium
- T = Trapezoid
- C = Capitate
- H = Hamate
Quick review
- S = Scaphoid — Proximal row, radial (thumb) side; floor of the anatomical snuffbox
- L = Lunate — Proximal row, medial to scaphoid; articulates with the radius
- T = Triquetrum — Proximal row, ulnar side, medial to the lunate
- P = Pisiform — Sesamoid bone in the flexor carpi ulnaris tendon; most palmar/ulnar carpal bone
- T = Trapezium — Distal row, radial side; forms the thumb's saddle (CMC) joint
- T = Trapezoid — Distal row, medial to trapezium; base of the index finger
- C = Capitate — Distal row, central; the largest carpal bone
- H = Hamate — Distal row, ulnar side; bears the hook of hamate
Eli explains
The same idea, in plain words
Explain it like I’m 10
A silly sentence whose first letters name the eight little bones in your wrist, in order from thumb side to pinky side, so you can point to each one.
S — Scaphoid. A little canoe-shaped bone at the base of your thumb. It's the first bone to take the hit when you fall on your hand, and its blood flows backward like a one-way street, so a crack can starve part of it.
L — Lunate. A crescent-moon-shaped bone in the middle of the wrist. If it pops forward out of place, it rolls into the narrow tunnel that carries the main nerve to the thumb and fingers and squishes it.
T — Triquetrum. A three-cornered pyramid bone on the pinky side of the wrist. Its corner chips off when the wrist is snapped backward, making it the second most common wrist bone to break.
P — Pisiform. A pea-shaped bone buried inside a tendon like a pebble in a rope, at the base of the palm on the pinky side. It moves with that tendon and doesn't join the wrist joint like the other bones.
T — Trapezium. The little table that the base of your thumb sits on. Its saddle-shaped joint lets the thumb swing across the palm, and because it does the most work, it's a common place to get worn-out arthritis.
T — Trapezoid. The smaller table tucked right next to the trapezium under your index finger. It's tiny and sandwiched between sturdier bones, so it almost never breaks on its own.
C — Capitate. The big central hub bone of the wrist, like the king's head in the middle of everything. All the other wrist bones are arranged around it, and the wrist moves around this central keystone.
H — Hamate. A pinky-side wrist bone with a little coat hook sticking out into the palm. That hook is one wall of the tunnel carrying the nerve to the pinky; when golfers slam a club handle into the palm, the hook can snap and pinch that nerve.
Study tools & related lessonsKey vocabulary · Related
Key vocabulary
- S
- Scaphoid
- L
- Lunate
- T
- Triquetrum
- P
- Pisiform
- T
- Trapezium
- T
- Trapezoid
- C
- Capitate
- H
- Hamate
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