Human Anatomy
Bones of the Upper Limb
Upper limb osteology for MBBS: clavicle, scapula, humerus, radius, ulna and hand bones with nerve relations and ossification, mapped to NMC codes AN8.1 to AN8.6.
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Bones of the Upper Limb
Upper limb osteology for MBBS: clavicle, scapula, humerus, radius, ulna and hand bones with nerve relations and ossification, mapped to NMC codes AN8.1 to AN8.6.
This chapter surveys the individual bones of the upper limb and the surface features that guide dissection and clinical examination. It highlights the ossification of the clavicle, the nerve relations of the humerus, and the carpal bones that most often fracture or dislocate.
High-yield: Bones of the Upper Limb
- The bones of the upper limb are the clavicle, scapula, humerus, radius, ulna, carpals, metacarpals and phalanges.
- The clavicle is the first bone to ossify and the only long bone to ossify in membrane.
- The clavicle has no medullary cavity and its commonest fracture site is the junction of its middle and lateral thirds.
- The scapula presents a spine, acromion, coracoid process and a glenoid cavity for the head of the humerus.
- The surgical neck of the humerus is closely related to the axillary nerve and the posterior circumflex humeral vessels.
- The radial nerve lies in the spiral (radial) groove on the back of the humeral shaft.
- The medial epicondyle of the humerus is related to the ulnar nerve, which can be palpated behind it.
- The head of the radius is proximal, whereas the head of the ulna is distal.
- The scaphoid is the most commonly fractured carpal bone and is prone to avascular necrosis of its proximal pole.
- The lunate is the most commonly dislocated carpal bone and may compress the median nerve.
- The anatomical snuffbox is bounded by the tendons of extensor pollicis longus and the two radial extensors, with the scaphoid in its floor.
- The trapezium articulates with the first metacarpal to form the saddle joint of the thumb.
- The upper end of the humerus ossifies from three centres and the growing epiphysis is at the upper end.
- The hook of the hamate and the pisiform provide attachment for the flexor retinaculum medially.
Nerve relations of the humerus
- **Surgical neck:** Axillary nerve and posterior circumflex humeral vessels; injured in fracture or shoulder dislocation.
- **Spiral groove:** Radial nerve; a midshaft fracture may cause wrist drop.
- **Medial epicondyle:** Ulnar nerve runs behind it; injury gives claw hand and altered sensation.
- **Scaphoid:** Commonest carpal fracture; risk of avascular necrosis of the proximal pole.
NMC competencies in this chapter
- **AN8.1:** Features and attachments of the clavicle and scapula
- **AN8.2:** Features and attachments of the humerus
- **AN8.3:** Features and attachments of the radius and ulna
- **AN8.4:** Bones of the hand: carpals, metacarpals and phalanges
- **AN8.5:** Ossification of the bones of the upper limb
- **AN8.6:** Applied anatomy of upper limb bones
Frequently Asked Questions
Why is the clavicle unusual among long bones?
It is the first bone in the body to begin ossifying, the only long bone to ossify in membrane, and it has no medullary cavity. It commonly fractures at the junction of its middle and lateral thirds.
Which nerve is at risk with a midshaft humeral fracture?
The radial nerve, which lies in the spiral groove on the back of the humeral shaft, may be injured, producing wrist drop and loss of extension at the wrist and fingers.
Why is a scaphoid fracture dangerous?
The scaphoid receives most of its blood supply distally, so a fracture across its waist can cut off the supply to the proximal pole and lead to avascular necrosis and non-union.
What forms the anatomical snuffbox?
It is bounded by the tendon of extensor pollicis longus on one side and extensor pollicis brevis with abductor pollicis longus on the other. The scaphoid lies in its floor, so tenderness here suggests a scaphoid fracture.
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