Hand Anatomy

Question 1

Bones

Answer 1

8 Carpal bones
5 Metacarpals
14 phalanges

Question 2

Intrinsic Muscles

Answer 2

7 Interossei - Supplied by ulnar nerve
4 palmar-adduct fingers
4 dorsal- abduct fingers

Lumbricals
Flex MCPJ and extend the IPJ.
Origin deep flexor tendon and insertion dorsal extensor hood mechanism.
Innervation: 1st and 2nd- median nerve, 3rd and 4th- deep branch of the ulnar nerve.

Question 3

Thenar eminence

Answer 3

Abductor pollicis brevis
Opponens pollicis
Flexor pollicis brevis

Question 4

Hypothenar eminence

Answer 4

Opponens digiti minimi
Flexor digiti minimi brevis
Abductor digiti minimi

Question 5

Muscles of the thumb

Answer 5

There are 8 muscles:

1. Two flexors (flexor pollicis brevis and flexor pollicis longus)
2. Two extensors (extensor pollicis brevis and longus)
3. Two abductors (abductor pollicis brevis and longus)
4. One adductor (adductor pollicis)
5. One muscle that opposes the thumb by rotating the CMC joint (opponens pollicis)

Question 6

Fascia and compartments of the palm

Answer 6

Fascia of the palm is continuous with the antebrachial fascia and the fascia of the dorsum of the hand.
The palmar fascia is thin over the thenar and hypothenar eminences. However, the central palmar fascia is relatively thick.
The palmar aponeurosis covers the soft tissues and overlies the flexor tendons. The apex of the palmar aponeurosis is continuous with the flexor retinaculum and the palmaris longus tendon. Distally, it forms four longitudinal digital bands that attach to the bases of the proximal phalanges, blending with the fibrous digital sheaths.
A medial fibrous septum extends deeply from the medial border of the palmar aponeurosis to the 5th metacarpal. Medial to this are the hypothenar muscles.
A lateral fibrous septum extends deeply from the lateral border of the palmar aponeurosis to the 3rd metacarpal. The thenar compartment lies lateral to this area.
Lying between the thenar and hypothenar compartments is the central compartment. It contains the flexor tendons and their sheaths, the lumbricals, the superficial palmar arterial arch and the digital vessels and nerves.
The deepest muscular plane is the adductor compartment, which contains adductor pollicis.

Question 7

Short muscles of the hand

Answer 7

These comprise the lumbricals and interossei.
The four slender lumbrical muscles flex the fingers at the metacarpophalangeal joints and extend the interphalangeal joint.
The four dorsal interossei are located between the metacarpals and the three palmar interossei lie on the palmar surface of the metacarpals in the interosseous compartment of the hand.

Question 8

Long flexor tendons and sheaths in the hand

Answer 8

The tendons of FDS and FDP enter the common flexor sheath deep to the flexor retinaculum. The tendons enter the central compartment of the hand and fan out to their respective digital synovial sheaths.
Near the base of the proximal phalanx, the tendon of FDS splits to permit the passage of FDP. The FDP tendons are attached to the margins of the anterior aspect of the base of the distal phalanx.
The fibrous digital sheaths contain the flexor tendons and their synovial sheaths. These extend from the heads of the metacarpals to the base of the distal phalanges.