Topic Overview

Frequently Asked Questions – Bones of the Upper Limb

Q1. How many bones are present in one upper limb?
→ 32 bones (Clavicle, Scapula, Humerus, Radius, Ulna, 8 Carpals, 5 Metacarpals, 14 Phalanges, Sesamoids).

Q2. Which is the first bone to ossify in the body?
→ Clavicle (5th–6th week intrauterine life).

Q3. Which is the last carpal bone to ossify?
→ Pisiform (10–12 years).

Q4. Why is the clavicle considered a modified long bone?
→ Because it:

• Lies horizontally.

• Has no medullary cavity.

• Ossifies in membrane.

Q5. Which fracture is most common in the upper limb?
→ Clavicle fracture (junction of medial 2/3 and lateral 1/3).

Q6. Which carpal bone is most commonly fractured?
→ Scaphoid (risk of avascular necrosis).

Q7. Which carpal bone is most commonly dislocated?
→ Lunate.

Q8. Which nerve is most commonly injured in supracondylar fracture of humerus in children?
→ Median nerve, along with injury to brachial artery.

Q9. Which nerve is most commonly injured in fracture of surgical neck of humerus?
→ Axillary nerve.

Q10. Which nerve is most commonly injured in midshaft fracture of humerus?
→ Radial nerve (in spiral groove).

Q11. Which nerve is injured in fracture of medial epicondyle of humerus?
→ Ulnar nerve.

Q12. What is the clinical importance of the olecranon and epicondyles of humerus in diagnosis of dislocations?
→ In extension → all three in a straight line.
→ In flexion → form an equilateral triangle.
(Disrupted in dislocation).

Q13. What is Colles’ fracture?
→ Fracture of lower end of radius with dorsal displacement of distal fragment → produces dinner fork deformity.

Q14. What is Smith’s fracture?
→ Reverse of Colles’ fracture; distal radius displaced anteriorly.

Q15. What is Monteggia fracture-dislocation?
→ Fracture of proximal ulna with dislocation of radial head.

Q16. What is Boxer’s fracture?
→ Fracture of neck of 5th metacarpal, usually after punching injury.

Q17. What is Bennett’s fracture?
→ Fracture-dislocation at base of 1st metacarpal involving carpometacarpal joint of thumb.

Q18. Why are distal phalanges ossified earlier than other phalanges?
→ Because they are essential for fingertip development and nail support → ossification begins as early as 8th week IUL.

Q19. Which constant sesamoid bone is present in the hand?
→ Pisiform (sesamoid in tendon of flexor carpi ulnaris).

Q20. Which bone of the upper limb is most important in forensic age estimation?
→ Clavicle → because its secondary center (sternal end) fuses last, around 21–22 years.