PCL 5- Muscles of the hand

MUSCLES OF THE HAND

Thenar muscles.

The Abductor Pollicis Brevis

• Proximal attachments are: flexor retinaculum and the tubercles of the scaphoid and trapezium bones.
• Distal attachments are: lateral side of the base of the proximal phalanx of the thumb.
• Innervation: recurrent branch of median nerve (C8 and T1).

• It abducts the thumb

The Flexor Pollicis Brevis

• It is located medial to the abductor pollicis brevis.

• Proximal attachments are: flexor retinaculum and tubercle of the trapezium bone.
• Distal attachments are: lateral side of the base of the proximal phalanx of the thumb.
• Innervation: recurrent branch of the median nerve (C8 and T1).

• It flexes the thumb

The Opponens Pollicis

• Proximal attachments are: flexor retinaculum and the tubercle of the trapezium bone.
• Distal attachments are: lateral side of the 1^st metacarpal bone.
• Innervation: recurrent branch of the median nerve (C8 and T1).

• It opposes the thumb.

The Adductor Pollici

• Proximal attachments are: oblique head-bases of the 2^nd and 3^rd metacarpals, the capitate and adjacent carpal bones, transverse head-anterior surface of the body of the 3^rd metacarpal bone.
• Distal attachments are: medial side of the base of the proximal phalanx of the thumb.
• Innervation: the deep branch of the ulnar nerve (C8 and T1).

• It adducts the thumb and gives power to the grasp.

Hypothenar Muscles

The Abductor Digiti Minimi

• This is a short, wide, fusiform muscle.
• It is the most superficial of the three muscles forming the hypothenar eminence.

• Proximal attachments are: pisiform bone.
• Distal attachments are: medial side of the base of the proximal phalanx of the 5^th digit.
• Innervation: deep branch of the ulnar nerve (C8 and T1).

• It abducts the 5^th digit and helps to flex the proximal phalanx.

The Flexor Digiti Minimi Brevis

• This is a short, wide, fusiform muscle that is variable in size.
• It lies lateral to the abductor digiti minimi muscle.

• Proximal attachments are: hook of the hamate bone and the flexor retinaculum.
• Distal attachments are: medial side of the base of the proximal phalanx of the 5^th digit.
• Innervation: deep branch of the ulnar nerve (C8 and T1).

• It flexes the proximal phalanx of the 5^th digit at the metacarpophalangeal joint.

The Opponens Digiti Minimi

• This is a quadrangular muscle and it lies deep to the abductor and flexor muscles of the 5^th digit.

• Proximal attachments are: hook of the hamate bone and the flexor retinaculum.
• Distal attachments are: medial border of the 5^th metacarpal bone.
• Innervation: deep branch of the ulnar nerve (C8 and T1).

• It draws the 5^th metacarpal bone anterior and rotates it laterally, thereby deepening the hollow of the palm, and bringing the 5^th digit into opposition with the thumb.

The Lumbrical Muscles

Lumbricals 1 and 2

• Proximal attachments are: lateral two tendons of flexor digitorum profundus.
• Distal attachments are: lateral sides of extensor expansions of the 2^nd and 3^rd digits.
• Innervation: median nerve (C8 and T1).

Lumbricals 3 and 4

• Proximal attachments are: medial three tendons of flexor digitorum profundus.
• Distal attachments are: lateral sides of extensor expansions of the 4^th and 5^th digits.
• Innervation: deep branch of the ulnar nerve (C8 and T1).

• The lumbrical muscles flex the digits at the metacarpophalangeal joints and extend the interphalangeal joints.
• They place the digits into the writing position.

The Interosseous Muscles

Dorsal interossei 1 to 4

• Proximal attachments are: adjacent sides of two metacarpal bones.
• Distal attachments are: extensor expansions and the bases of the proximal phalanges of the 2^nd to 4^th digits.
• Innervation: deep branch of the ulnar nerve (C8 and T1).

Palmar interossei 1 to 3

• Proximal attachments are: palmar surfaces of 2^nd, 4^th and 5^th metacarpal bones.
• Distal attachments are: extensor expansions of digits and the bases of the proximal phalanges of the 2^nd, 4^th and 5^th digits.
• Innervation: deep branch of the ulnar nerve (C8 and T1).