Upper limb · Arm
Humerus
The humerus is the bone of the arm, running from the shoulder to the elbow. Its rounded head sits in the glenoid cavity of the scapula, and its distal end articulates with both the radius and the ulna.
- Latin (TA)
- Humerus
- Type
- Typical long bone: a shaft with two expanded ends, the longest and largest bone of the upper limb
- Side
- Paired — right and left
- Model size
- 31.8 cm longest
Showing a right bone. Rotate it to inspect every surface; switch sides to practise siding.
3D model: Z-Anatomy (CC BY-SA 4.0), derived from BodyParts3D © DBCLS (CC BY-SA 2.1 JP). Adapted by PharmaWallah. Credits & licence
Landmarks
28 of 28 marked on the modelTap a landmark to find it on the bone and read what it is.
A smooth, rounded articular surface, roughly one-third of a sphere.
Where: Upper end, facing medially, upwards and backwards.
Why it matters: Articulates with the glenoid cavity of the scapula at the shoulder joint.
Related: Glenohumeral joint
Marked on the model at the point Z-Anatomy places this label.
A faint groove encircling the margin of the head.
Where: Immediately around the head, separating it from the tubercles.
Why it matters: Attachment of the capsule of the shoulder joint (except medially, where the capsule extends further down the shaft).
Related: Shoulder joint capsule
Marked on the model at the point Z-Anatomy places this label.
The narrowed region just below the head and tubercles, where the upper end joins the shaft.
Where: Upper end of the shaft, below the tubercles.
Why it matters: A common fracture site; the axillary nerve and posterior circumflex humeral vessels wind around it.
Viva: Which nerve is at risk in a fracture of the surgical neck?
Marked on the model at the point Z-Anatomy places this label.
A large projection on the lateral side of the upper end.
Where: Lateral part of the upper end, the most lateral bony point of the shoulder region.
Why it matters: Insertion of supraspinatus, infraspinatus and teres minor on three facets (superior, middle and inferior).
Related: Rotator cuff
Marked on the model at the point Z-Anatomy places this label.
A smaller, prominent projection on the front of the upper end.
Where: Anterior aspect of the upper end, medial to the intertubercular sulcus.
Why it matters: Insertion of subscapularis; its anterior position helps side the bone.
Related: Subscapularis (insertion)
Marked on the model at the point Z-Anatomy places this label.
A vertical groove between the greater and lesser tubercles.
Where: Front of the upper end and upper shaft.
Why it matters: Carries the tendon of the long head of biceps; latissimus dorsi inserts into its floor.
Viva: What lies in the intertubercular sulcus?
Marked on the model at the point Z-Anatomy places this label.
The ridge running down from the greater tubercle, forming the lateral lip of the sulcus.
Where: Lateral margin of the intertubercular sulcus.
Why it matters: Insertion of pectoralis major.
Related: Pectoralis major (insertion)
Marked on the model at the point Z-Anatomy places this label.
The ridge running down from the lesser tubercle, forming the medial lip of the sulcus.
Where: Medial margin of the intertubercular sulcus.
Why it matters: Insertion of teres major.
Related: Teres major (insertion)
Marked on the model at the point Z-Anatomy places this label.
The shaft, cylindrical above and more triangular and flattened below.
Where: Between the surgical neck and the supracondylar ridges.
Why it matters: Fractures of the middle of the shaft can injure the radial nerve.
Marked on the model at the point Z-Anatomy places this label.
A V-shaped roughened area on the lateral side of the shaft.
Where: Lateral surface, about the middle of the shaft.
Why it matters: Insertion of deltoid.
Related: Deltoid (insertion)
Marked on the model at the point Z-Anatomy places this label.
A shallow groove running obliquely downwards and laterally across the back of the shaft.
Where: Posterior surface of the middle of the shaft, behind and below the deltoid tuberosity.
Why it matters: Lodges the radial nerve and the profunda brachii vessels; it separates the origins of the lateral and medial heads of triceps.
Viva: Which nerve lies in the radial groove, and what happens if it is injured there?
Marked on the model at the point Z-Anatomy places this label.
A sharp ridge running up from the lateral epicondyle.
Where: Lower lateral margin of the shaft.
Why it matters: Origin of brachioradialis (upper part) and extensor carpi radialis longus (lower part).
Marked on the model at the point Z-Anatomy places this label.
A rounded, knob-like articular surface on the lateral part of the lower end.
Where: Lower end, lateral, mainly on the anterior and inferior aspects.
Why it matters: Articulates with the head of the radius.
Related: Elbow joint (humeroradial part)
Viva: What articulates with the capitulum?
Marked on the model at the point Z-Anatomy places this label.
A pulley-shaped articular surface on the medial part of the lower end.
Where: Lower end, medial to the capitulum, wrapping round from front to back.
Why it matters: Articulates with the trochlear notch of the ulna.
Related: Elbow joint (humero-ulnar part)
Marked on the model at the point Z-Anatomy places this label.
A prominent bony projection on the medial side of the lower end.
Where: Medial side of the distal end; more prominent than the lateral epicondyle.
Why it matters: Common flexor origin of the forearm flexors; attachment of the ulnar collateral ligament of the elbow.
Related: Common flexor origin
Marked on the model at the point Z-Anatomy places this label.
A shallow groove on the back of the medial epicondyle.
Where: Posterior surface of the medial epicondyle.
Why it matters: The ulnar nerve lies here, just under the skin (the "funny bone"), and can be injured or compressed here.
Viva: Which nerve lies behind the medial epicondyle?
Marked on the model at the point Z-Anatomy places this label.
A smaller projection on the lateral side of the lower end.
Where: Lateral side of the distal end, above the capitulum.
Why it matters: Common extensor origin of the forearm extensors; attachment of the radial collateral ligament of the elbow.
Related: Common extensor origin
Marked on the model at the point Z-Anatomy places this label.
A deep hollow on the back of the lower end, above the trochlea.
Where: Posterior surface of the distal end.
Why it matters: Receives the olecranon of the ulna in full extension of the elbow; marks the posterior surface when siding.
Marked on the model at the point Z-Anatomy places this label.
A small hollow on the front of the lower end, above the trochlea.
Where: Anterior surface of the distal end, medially.
Why it matters: Receives the coronoid process of the ulna in full flexion.
Marked on the model at the point Z-Anatomy places this label.
Classification & region
Typical long bone: a shaft with two expanded ends, the longest and largest bone of the upper limb.
- Upper (proximal) end
- Head, anatomical neck, greater and lesser tubercles, intertubercular sulcus and surgical neck.
- Shaft (body)
- Cylindrical above and triangular-to-flattened below; carries the deltoid tuberosity and the radial groove.
- Lower (distal) end
- The condyle (capitulum and trochlea), the medial and lateral epicondyles, and the coronoid, radial and olecranon fossae.
Hold it in the anatomical position
- Hold the bone vertically with the rounded head at the top.
- Turn it so the head faces medially (and slightly backwards) and the intertubercular sulcus faces forwards.
- At the lower end the deep olecranon fossa is posterior, and the more prominent epicondyle (the medial one) is on the inner side.
Right or left? Side determination
- Upper end: the rounded head is proximal; the lower end is flattened and wide.
- Medial: the head faces medially (and upwards and backwards).
- Anterior: the intertubercular sulcus (bicipital groove) and the lesser tubercle face forwards; the greater tubercle is lateral.
- Check at the lower end: the deep olecranon fossa is posterior; the medial epicondyle is the more prominent one.
- Hold the bone in this position against your own arm: it belongs to the side on which the head points towards your midline and the sulcus faces forwards.
Check yourself: switch the 3D model to “Left bone” and apply the same steps.
Articulations
- With the glenoid cavity of scapula at the Glenohumeral (shoulder) joint — Head of humerus..
- With the trochlear notch of ulna at the Elbow joint (humero-ulnar part) — Trochlea..
- With the head of radius at the Elbow joint (humeroradial part) — Capitulum..
Muscle and ligament attachments
| Structure | Type | Where on the bone |
|---|---|---|
| Supraspinatus | insertion | Superior facet of the greater tubercle. |
| Infraspinatus | insertion | Middle facet of the greater tubercle. |
| Teres minor | insertion | Inferior facet of the greater tubercle. |
| Subscapularis | insertion | Lesser tubercle. |
| Pectoralis major | insertion | Lateral lip of the intertubercular sulcus (crest of the greater tubercle). |
| Latissimus dorsi | insertion | Floor of the intertubercular sulcus. |
| Teres major | insertion | Medial lip of the intertubercular sulcus (crest of the lesser tubercle). |
| Deltoid | insertion | Deltoid tuberosity. |
| Coracobrachialis | insertion | Middle of the medial side of the shaft. |
| Brachialis | origin | Lower half of the anterior surface of the shaft. |
| Triceps brachii, lateral head | origin | Posterior surface above the radial groove. |
| Triceps brachii, medial head | origin | Posterior surface below the radial groove. |
| Brachioradialis | origin | Upper part of the lateral supracondylar ridge. |
| Extensor carpi radialis longus | origin | Lower part of the lateral supracondylar ridge. |
| Common extensor origin (extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris) | origin | Front of the lateral epicondyle. |
| Anconeus | origin | Back of the lateral epicondyle. |
| Common flexor origin (pronator teres humeral head, flexor carpi radialis, palmaris longus, flexor digitorum superficialis humeral head, flexor carpi ulnaris humeral head) | origin | Front of the medial epicondyle. |
| Shoulder joint capsule | ligament | Anatomical neck (extending down the shaft medially). |
| Ulnar (medial) and radial (lateral) collateral ligaments of the elbow | ligament | Medial and lateral epicondyles. |
Functions
- Forms the bony lever of the arm between the shoulder and the elbow.
- Provides the ball of the shoulder joint and the upper surfaces of the elbow joint.
- Gives attachment to the rotator cuff, the major muscles of the shoulder, the muscles of the arm, and the forearm flexors and extensors.
Clinical & practical relevance
- Fracture of the surgical neck (common in older adults after a fall) can injure the axillary nerve, weakening deltoid and leaving a patch of numb skin over the lower deltoid (the "regimental badge" area).
- Fracture of the shaft in the region of the radial groove can injure the radial nerve, causing wrist drop.
- Supracondylar fracture, typically in children after a fall on the outstretched hand, can injure the brachial artery and median nerve; impaired blood supply to the forearm flexors can lead to Volkmann's ischaemic contracture.
- Fracture or injury of the medial epicondyle can damage the ulnar nerve, which lies behind it.
- Lateral epicondylitis ("tennis elbow") and medial epicondylitis ("golfer's elbow") are painful overuse conditions at the common extensor and common flexor origins.
Identification tips
- Three nerves touch the humerus from top to bottom: axillary (surgical neck), radial (radial groove), ulnar (behind medial epicondyle).
- "A lady between two majors": latissimus dorsi in the floor of the sulcus, between pectoralis major (lateral lip) and teres major (medial lip).
- The medial epicondyle is larger and more prominent than the lateral one.
- The deep olecranon fossa is always at the back; the two smaller fossae (coronoid and radial) are in front.
Common student mistakes
- Confusing the anatomical neck with the surgical neck.
- Putting the radial groove on the front of the shaft: it runs across the back.
- Naming the capitulum and trochlea the wrong way round: capitulum is lateral (radius), trochlea is medial (ulna).
- Placing the ulnar nerve in front of the medial epicondyle: it lies behind it.
Common exam questions
How do you side a humerus?Show answer
Head upwards and medially, intertubercular sulcus forwards; olecranon fossa is posterior at the lower end.
Name the nerves in direct contact with the humerus and where.Show answer
Axillary nerve at the surgical neck, radial nerve in the radial groove, ulnar nerve behind the medial epicondyle.
What attaches to the lips and floor of the intertubercular sulcus?Show answer
Pectoralis major to the lateral lip, teres major to the medial lip, latissimus dorsi to the floor.
Which muscles insert into the greater tubercle?Show answer
Supraspinatus, infraspinatus and teres minor.
Differentiate the anatomical and surgical necks.Show answer
The anatomical neck is the groove around the head (capsule attachment); the surgical neck is the narrow part below the tubercles where fractures commonly occur.
What articulates with the capitulum and the trochlea?Show answer
The head of the radius with the capitulum; the trochlear notch of the ulna with the trochlea.
What is a supracondylar fracture and what structures are at risk?Show answer
A fracture just above the condyles, usually in children; the brachial artery and median nerve are at risk.
Revision summary
- Typical long bone: head, necks, tubercles, shaft, condyle.
- Head medial, sulcus anterior, olecranon fossa posterior.
- Greater tubercle: supraspinatus, infraspinatus, teres minor. Lesser tubercle: subscapularis.
- Sulcus: pec major (lateral lip), lat dorsi (floor), teres major (medial lip).
- Nerves: axillary (surgical neck), radial (radial groove), ulnar (medial epicondyle).
- Capitulum with radius; trochlea with ulna.
- Supracondylar fracture: brachial artery and median nerve at risk.
Test yourself on the humerus
Spotting questions on bones, sides and landmarks — untimed, with explanations.
Joints of the humerus
References
- Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. 5th ed. Philadelphia: Elsevier; 2023.
- Moore KL, Dalley AF, Agur AMR. Moore's Clinically Oriented Anatomy. 9th ed. Philadelphia: Wolters Kluwer; 2023.
- Federative International Programme for Anatomical Terminology (FIPAT). Terminologia Anatomica. 2nd ed. FIPAT.library.dal.ca; 2019. fipat.library.dal.ca/TA2
- Kervyn G, Zielinski M, Vinent L, et al. Z-Anatomy: the libre 3D atlas of anatomy. Models derived from BodyParts3D, The Database Center for Life Science (CC BY-SA 2.1 JP). CC BY-SA 4.0. www.z-anatomy.com/
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