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Structure

Bones of the upper limb

Not medically reviewed · Content last updated · 2 min read ·

This is the date the draft was written, not a medical review date.

The upper limb skeleton comprises the pectoral girdle (clavicle and scapula) and the free limb: humerus, radius, ulna, carpal bones, metacarpals and phalanges. It is built for mobility and manipulation rather than weight bearing.

Terminologia Anatomica (Latin): Ossa membri superioris · Open in the 3D atlas

Location

The clavicle and scapula link the limb to the axial skeleton only at the sternoclavicular joint. The humerus lies in the arm, the radius and ulna in the forearm, and eight carpal bones, five metacarpals and fourteen phalanges form the hand.

Structure

Humerus: head, anatomical and surgical necks, greater and lesser tubercles, deltoid tuberosity, radial groove, capitulum and trochlea, epicondyles. The radius is lateral (head, radial tuberosity, styloid process); the ulna is medial (olecranon, coronoid process, trochlear notch). Proximal carpal row: scaphoid, lunate, triquetrum, pisiform; distal row: trapezium, trapezoid, capitate, hamate.

Blood supply

Long bones receive a nutrient artery (for the humerus from the brachial or deep brachial artery) plus periosteal and metaphyseal vessels from the arterial anastomoses around the shoulder and elbow. The scaphoid is supplied mainly by retrograde flow from distal branches of the radial artery.

Innervation

Periosteal innervation follows the nearby nerves: axillary and suprascapular around the shoulder, radial along the humeral shaft, median and ulnar in the forearm and hand. Fractures are painful because of the richly innervated periosteum.

Function

The girdle positions the shoulder and transmits forces to the trunk; the long bones act as levers for muscles; the carpus and hand allow fine grip and precision movements, with an opposable thumb.

Clinical correlations

Clavicle fractures usually involve the middle third. Surgical neck fractures of the humerus risk the axillary nerve, midshaft fractures the radial nerve, supracondylar fractures the median (anterior interosseous) nerve and brachial artery, and medial epicondyle fractures the ulnar nerve. Scaphoid fractures may cause avascular necrosis of the proximal pole.

Common exam points

  • Surgical neck of humerus: axillary nerve; radial groove: radial nerve; medial epicondyle: ulnar nerve.
  • Supracondylar fracture in children: brachial artery and median/anterior interosseous nerve.
  • Scaphoid: anatomical snuffbox tenderness; risk of proximal pole avascular necrosis.
  • Carpal rows: scaphoid, lunate, triquetrum, pisiform; trapezium, trapezoid, capitate, hamate.
  • The clavicle is the only bony link between the upper limb and the axial skeleton.

References

  1. Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. Elsevier — Tier 3 (textbook)
  2. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. Wolters Kluwer, 8th edition (2018) — Tier 3 (textbook)
  3. Netter FH. Atlas of Human Anatomy. Elsevier — Tier 3 (textbook)

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