Upper limb

Humerus

Before you say anything

The longest bone of the upper limb and the one you are most likely to be handed first. Three checks settle the side in seconds, and the examiner will almost always follow with a nerve: the axillary at the surgical neck, the radial in the spiral groove, the ulnar behind the medial epicondyle. Learn the bone and those three nerves together.

Which side? Three checks

Hold it like this first: Hold it vertically so that the head at the upper end faces medially, backwards and upwards, and the olecranon fossa at the lower end faces backwards.

Check 1 — Find the head
A smooth rounded articular surface at one end, about a third of a sphere
That is the upper end, and the head points medially
Check 2 — Find the lesser tubercle
Of the two tubercles at the upper end, one lies in front and one laterally
The lesser tubercle faces forwards, which fixes front from back
Check 3 — Find the olecranon fossa
The deepest of the three hollows above the articular surface of the lower end
It is posterior, so with the head medial and this fossa backwards the side is settled

Drill this against the clock →

Work it out, one rung at a time

Answer each question in your head first. Then open it.

1
Identify
What is this?
2
Orient
Which end is up?
3
Side
Which side?
4
Landmarks
What can you point out?
5
Attachments
What is attached?
6
Applied
Which nerves are at risk?

Landmarks to point out

Head
Upper end, directed medially, backwards and upwards
Articulates with the glenoid cavity; its size relative to the socket explains the mobility of the shoulder.
Anatomical neck
The slight constriction around the margin of the head
Marks the attachment of the capsule; fractures here are uncommon.
Surgical neck
The narrowing just below the tubercles
A common fracture site, related to the axillary nerve and the posterior circumflex humeral vessels.
Greater tubercle
Lateral part of the upper end, with three facets
Insertion of supraspinatus, infraspinatus and teres minor from above downwards.
Lesser tubercle
Anterior part of the upper end
Insertion of subscapularis, and the front-facing clue for side determination.
Intertubercular groove
Between the two tubercles
Lodges the tendon of the long head of biceps; pectoralis major, latissimus dorsi and teres major attach to its lips and floor.

Say these first

A rounded head with two tubercles and a groove between them
A spiral groove running down and laterally across the back of the shaft
A lower end with a capitulum, trochlea and three fossae

Do not confuse it with

The femur
The femur's head sits on a long oblique neck and carries a fovea, and its shaft has a linea aspera behind; the humeral head has a short anatomical neck, no fovea, and the shaft has a spiral groove instead.

Examiner trap

Using the greater tubercle to call the side. It is lateral, but on a worn or juvenile bone the two tubercles look alike — the olecranon fossa is unmistakable and should be your anchor.

Memory hook

Head medial, lesser tubercle forward, olecranon fossa behind.

Why it matters

A fracture of the surgical neck may injure the axillary nerve, causing loss of the rounded contour of the shoulder and a patch of anaesthesia over the deltoid.
A midshaft fracture involving the radial groove may injure the radial nerve, producing wrist drop.
A supracondylar fracture may injure the brachial artery, and the resulting ischaemia can lead to Volkmann's contracture.

Senior’s 30-second takeaway

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

If you see this: A rounded head with two tubercles · A groove spiralling across the back of the shaft · A capitulum and trochlea with three fossae
If asked to identify it: This is a humerus; the head faces medially, the lesser tubercle forwards and the olecranon fossa backwards, giving the side.
If asked one more: The upper end is the growing end, and the elbow centres appear in the order CRITOE.
If asked why it matters: Surgical neck, radial groove and medial epicondyle each place a different nerve at risk.

Then stop. Let the examiner ask the next question.

Humerus

Before you say anything

Which side? Three checks

Work it out, one rung at a time

Landmarks to point out

Senior’s 30-second takeaway

Attachments

Articulations

Ossification

Viva voce

🩺 Before you say anything

Which side? Three checks

Work it out, one rung at a time

Landmarks to point out

Senior’s 30-second takeaway

Attachments

Articulations

Ossification

🎙️ Viva voce

Before you say anything

Viva voce