Joints of right index finger

Capsule and ligaments of metacarpophalangeal joint, medial view

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Image #111-2

Joints of right index finger

Capsule and ligaments of metacarpophalangeal joint, medial view

The finger has been removed from the hand by transecting the shaft of the metacarpal bone (2). The first volar interosseous muscle (3) has been reflected dorsally with the extensor expansion of the medial side of the finger. Transverse fibers of the extensor expansion have been divided (4).

1. Extensor indicis muscle (right pointer indicates insertion on base of proximal phalanx. Tendon of extensor digitorum contributes to this insertion)
2. Metacarpal II
3. Anterior interosseous muscle I (reflected dorsally)
4. Transverse fibers of extensor expansion (divided)
5. Extensor expansion (reflected)
6. Extensor indicis muscle and common extensor digitorum muscle (tendons of insertion fused)
7. Phalanx I
8. Ligament of digital sheath II (pointer on cruciate ligament)
9. Ligament of digital sheath II (pointer on annular ligament)
10. Metacarpophalangeal joint capsule
11. Collateral ligament
12. Anterior accessory ligament
13. Tendon of digital sheath
14. Flexor digitorum superficialis and profundus muscles (tendons cut off)
15. Lumbrical muscle I
16. Dorsal interosseous muscle I