🦴 Medical Terminology Lesson

"Some Lovers Try" — the 8 carpal bones

The 8 carpal bones of the wrist, arranged proximal-to-distal and lateral-to-medial — a classic anatomy lab and board exam sequence.

Scaph.

Lunate

Triq.

Pisi.

Trapez.

Trapzd.

Capit.

Hamate

📖 Full Breakdown

The 8 carpal bones, proximal row first, then distal row

"Some Lovers Try Positions That They Can't Handle" runs lateral to medial across the proximal row, then lateral to medial across the distal row.

Scaphoid

Proximal row, most lateral

The most commonly fractured carpal bone. Tenderness in the "anatomical snuffbox" (the hollow at the base of the thumb) is treated as a scaphoid fracture until imaging proves otherwise, because early X-rays can miss it.

Lunate

Proximal row

Moon-shaped (hence the name). The most commonly dislocated carpal bone — often missed on initial X-ray review because the dislocation can look subtle.

Triquetrum

Proximal row

Three-cornered pyramid shape. Sits on the medial (pinky) side of the proximal row.

Pisiform

Proximal row, most medial

Pea-shaped. It is a sesamoid bone (embedded within a tendon) rather than a true load-bearing carpal bone.

Trapezium

Distal row, most lateral

Articulates with the thumb's metacarpal — critical for thumb mobility and opposition.

Trapezoid

Distal row

The smallest of the distal carpal bones, wedged between the trapezium and capitate.

Capitate

Distal row, center

The largest carpal bone, sitting at the structural center of the wrist.

Hamate

Distal row, most medial

Named for its hook-shaped process (hamulus). The ulnar nerve runs directly beside this hook, so hamate fractures can cause ulnar nerve symptoms.

🩺 Clinical / Exam Application

A patient falls onto an outstretched hand and complains of wrist pain localized to the base of the thumb, worse with snuffbox pressure. Even with a normal initial X-ray, this presentation is treated as a presumed scaphoid fracture and immobilized, because scaphoid fractures are notorious for not showing up on early imaging — a delayed diagnosis risks avascular necrosis of the bone due to its limited blood supply.

⚠️ Exam Alert

The scaphoid's unique blood supply (entering distally and flowing proximally) is a favorite board exam detail: a fracture can cut off blood flow to the proximal fragment, causing avascular necrosis — a complication unique to this bone among the carpals.

🚧 Common Trap

Students often reverse the row order, placing pisiform in the distal row because it feels "smaller" like the distal bones. Pisiform is proximal — anchor it by remembering it sits right where the wrist meets the forearm, on the pinky side.

✅ Quick Check

Starting from the thumb side, name the 4 proximal row bones, then the 4 distal row bones, without checking the list above.

📝 Exam Prep

Common Exam Questions

❓ What are the 8 carpal bones in order?

✅ Proximal row (lateral to medial): Scaphoid, Lunate, Triquetrum, Pisiform. Distal row (lateral to medial): Trapezium, Trapezoid, Capitate, Hamate.

❓ Why is the scaphoid considered high-risk among carpal fractures?

✅ Its blood supply enters from the distal end and flows proximally, so a fracture can cut off circulation to the proximal fragment, risking avascular necrosis (bone death) if not properly diagnosed and immobilized.