Human Anatomy Vol 1

Extensor

pollicis longus

Extensor

pollicis brdvis

1 st carpo-

metacarpal

joint

1 st carpo-

metacarpal

joint

(a) (b)

Figs 10.32a and b: Extensors of the joints of thumb

ME RPOPHALANGEAT JOINTS

Type

Metacarpophalangeal joints are synovial joints of the

ellipsoid variety.

[igomenls

Each joint has the following ligaments.

'1, Capsular ligament: This is thick in front and thin

behind.

2 Palmar ligament: This is a strong fibrocartilaginous

plate which replaces the anterior part of the capsule.

It is more firmly attached to the phalanx than to the

metacarpal. The various palmar ligaments of the

metacarpophalangeal joints are joined to one another

by the deep transverse metacarpal ligament.

3 Medial andlateral collateralligaments: These are oblique

bands placed at the sides of the joint. Each runs

downwards and forwards from the head of the

metacarpal bone to the base of the phalanx. These

are taut in flexion and relaxed in extension.

Movemenls ol First Joini ond Muscles Producing lhem

'/.. Flexion: Flexor pollicis longus and flexor pollicis brevis.

2 Extension: Extensor pollicis longus and extensor
pollicis brevis (Figs 10.32a and b).
3 Abduction; Abductor pollicis brevis (seeFig.9.20).
4 Adductiorz: Adductor pollicis (see Frg. 9.22).

JOINTS OF UPPER LIMB

Movemenls of Second to Fiflh

Joinls ond Muscles Producing them

I Flexion: Interossei and lumbricals (see Figs 9.21 and

e.23).

2 Extension; Extensors of the fingers (Fig.10.27).

3 Abduction; Dorsal interossei (see Fig. 9.23).

4 Adduction: Palrnar interossei (see Fig.9.23).

5 Circumduction: Above muscles in sequence.

|I{TERPHATANGEAT JOTNTS (PROXTMAL AND DTSTAL)

Type

Hinge variety of synovial joints (Fig. 10.33).

Iigoments

Similar to the metacarpophalangeal joints, that is one

palmar fibrocartilaginous ligament and two collateral

bands running downwards and forwards.

Movements ot Inlerpholongeol Joint of lhumb

Flexion: Flexor pollicis longus.

Extension: Extensor pollicis longus.

Movemenls ot Second to Fitlh Digits

1 Flexion: Flexor digitorum superficialis at the proximal

interphalangeal joint, and the flexor digitorum

profundus at the distal joint (Fig. 10.3a).

2 Extensiou Interossei and lumbricals (see Figs9.21,

and9.23).

Palmar

ligaments

Distal interphalangeal joint

Collateral

ligaments

Proximal interphalangeal joint

Extensor expansion

Metacarpophalangeal joint

Metacarpal

Extensor tendon

.g

E

o

CL

4

f

.9

()

ct)o

Fig.10.33: Joints of the fingers