Topic Overview

General Features

• The skeleton of the upper limb consists of 32 bones.

• Arranged into 4 main groups:

  1. Shoulder Girdle → clavicle, scapula.

  2. Arm (Brachium) → humerus.

  3. Forearm (Antebrachium) → radius, ulna.

  4. Hand (Manus) → 27 bones (carpals, metacarpals, phalanges).

Classification of Bones of Upper Limb

1. Clavicle

   • Long bone but placed horizontally.

   • Only long bone ossifying in membrane.

   • Connects axial skeleton (sternum) to appendicular skeleton (scapula).

2. Scapula

   • Flat bone, triangular in shape.

   • Forms the posterior part of the shoulder girdle.

3. Humerus

   • Long bone of the arm.

   • Articulates proximally with scapula, distally with radius & ulna.

4. Radius and Ulna

   • Long bones of the forearm.

   • Radius: lateral, participates in wrist joint.

   • Ulna: medial, mainly stabilizing bone of forearm.

5. Carpal Bones

   • 8 short bones arranged in 2 rows (proximal & distal).

   • Provide flexibility and mobility to wrist.

6. Metacarpals

   • 5 miniature long bones, numbered I to V (thumb to little finger).

7. Phalanges

   • 14 in number (2 in thumb, 3 in each of the other fingers).

Clinical Importance

• Clavicle fracture → most common bone fracture in upper limb.

• Scaphoid fracture → risk of avascular necrosis.

• Surgical neck of humerus fracture → axillary nerve injury.

• Supracondylar fracture of humerus (children) → brachial artery injury.

• Colles’ fracture (radius) → common wrist fracture in elderly.

Key Exam Points

• Number of bones in upper limb: 32.

• Type of bones: long bones (clavicle, humerus, radius, ulna, metacarpals, phalanges), flat bone (scapula), short bones (carpals).

• Hand bones = 27 (8 carpals + 5 metacarpals + 14 phalanges).

• Uniqueness: Clavicle ossifies in membrane; others ossify in cartilage