Upper limb

Ulna

Before you say anything

The hook at the top is the whole bone in one glance. Get the concavity of that hook facing forwards and the sharp crest facing the radius, and the side falls out. Remember that the ulna is excluded from the wrist joint — that single fact answers a surprising number of viva questions.

Which side? Three checks

Hold it like this first: Hold it vertically with the hook-like upper end uppermost, the concavity of the trochlear notch facing forwards, and the sharp interosseous border facing laterally.

Check 1 — Find the hook
One end is much larger and forms a hook made of the olecranon and coronoid process
That is the upper end
Check 2 — Read the concavity
The hollow of the hook — the trochlear notch — opens to one side
It faces forwards, which fixes front from back
Check 3 — Feel the crest
One border of the shaft is a sharp crest
That is the interosseous border and it points laterally, towards the radius

Drill this against the clock →

Sign in to open the rest of this bone

The identification ladder, landmarks, attachments, ossification and the viva deck are free with an account. No card, no trial.

Create a free account

Say these first

A hook-shaped upper end with olecranon and coronoid process
A trochlear notch whose concavity faces forwards
A small head with a styloid process at the lower end

Do not confuse it with

The radius
The ulna's large end is proximal and hooked; the radius's large end is distal and flat. The ulnar head is at the bottom, the radial head at the top.

Examiner trap

Saying the ulna forms part of the wrist joint because it reaches the wrist. It reaches the wrist but does not enter the joint; the articular disc intervenes.

Memory hook

Ulna: hook up, hollow forward, crest towards the radius.

Why it matters

A nightstick fracture is an isolated fracture of the ulnar shaft from a direct blow on the raised forearm.
In a Monteggia fracture the upper shaft of the ulna is fractured and the head of the radius dislocated.
Triceps can avulse the olecranon, and the fragment is pulled proximally.
The ulna takes no part in the wrist joint, being separated from the carpus by the articular disc of the distal radio-ulnar joint.

Senior’s 30-second takeaway

Ulna — the whole bench in four lines. Read this on the way in.

If you see this: A hooked upper end · A deep notch whose concavity faces forwards · A small head with a styloid at the far end
If asked to identify it: This is an ulna; the trochlear notch faces forwards and the radial notch and interosseous border face laterally, giving the side.
If asked one more: Its lower end is the growing end, and the olecranon centre appears within the triceps tendon.
If asked why it matters: It is excluded from the wrist joint by the articular disc — a favourite viva point.

Then stop. Let the examiner ask the next question.

🩺 Before you say anything

Which side? Three checks

Sign in to open the rest of this bone

Senior’s 30-second takeaway

Before you say anything