The muscles of the hand

The muscles of the hand are divided into 3 groups:

1. muscles of the thumb (lateral group), which form a well-defined elevation of the thumb (thenar) in the lateral region of the palm;
2. muscles of the little finger (medial group), which form the eminence of the little finger (hypothenar) in the medial region of the palm;
3. the middle group of muscles of the hand, located between the two specified muscle groups, as well as on the back of the hand.

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Muscles of the eminence of the thumb

The short muscle that abducts the thumb (m.abductor pollicis brevis) is flat and located superficially. It begins with muscle bundles on the lateral part of the flexor retinaculum, the tubercle of the scaphoid bone and on the trapezium bone. It is attached to the radial side of the proximal phalanx of the thumb and to the lateral edge of the tendon of the long extensor of the thumb.

Function: abducts the thumb.

Innervation: median nerve (CV-ThI).

Blood supply: superficial palmar branch of the radial artery.

The opposing muscle of the thumb (m.opponens pollicis) is partially covered by the previous muscle, fused with the short flexor of the thumb, located medially from it. It begins on the flexor retinaculum and on the trapezium bone. It is attached to the radial edge and the anterior surface of the first metacarpal bone.

Function: opposes the thumb to the little finger and all other fingers of the hand.

Innervation: median nerve (CV-ThI).

Blood supply: superficial palmar branch of the radial artery, deep palmar arch.

The short flexor of the thumb (m flexor pollicis bnivis) is partially covered by the short muscle that abducts the thumb. The superficial head (caput superficiale) begins on the flexor retinaculum, the deep head (caput profundum) - on the trapezium and trapezoid bones, on the 11th metacarpal bone. It is attached to the proximal phalanx of the thumb (there is a sesamoid bone in the thickness of the tendon).

Function: flexes the proximal phalanx of the thumb and the finger as a whole; participates in the adduction of this finger.

Innervation: median nerve (CV-ThI), ulnar nerve (CVIII-ThI).

Blood supply: superficial palmar branch of the radial artery, deep palmar arch.

The muscle that adducts the thumb of the hand (m.adductor pollicis) is located under the tendons of the long flexors of the fingers (superficial and deep) and under the lumbrical muscles. It has two heads - oblique and transverse. The oblique head (caput breve) begins on the capitate bone and the base of the second and third metacarpal bones.

The transverse head (caput transversum) originates on the palmar surface of the third metacarpal bone. The muscle is attached by a common tendon, which contains a sesamoid bone, to the proximal phalanx of the thumb.

Function: brings the thumb to the index finger, participates in flexion of the thumb.

Innervation: ulnar nerve (CVIII-ThI).

Blood supply: superficial and deep palmar arches.

Muscles of the eminence of the little finger

The palmaris brevis muscle is a rudimentary cutaneous muscle, represented by weakly expressed muscle bundles in the subcutaneous base of the eminence of the little finger. The bundles of this muscle begin on the flexor retinaculum and are attached to the skin of the medial edge of the hand.

Function: weakly defined folds are formed on the skin of the eminence of the little finger.

Innervation: ulnar nerve (CVIII-ThI).

Blood supply: ulnar artery.

The muscle that abducts the little finger (m.abductor digiti minimi) is located superficially. It originates on the pisiform bone and the tendon of the ulnar flexor carpi. It is attached to the medial side of the proximal phalanx of the little finger.

Function: abducts the little finger.

Innervation: ulnar nerve (CVIII-ThI).

Blood supply: deep branch of the ulnar artery.

The opposing muscle of the little finger (m.opponens digiti minimi) originates from tendinous bundles on the flexor retinaculum and hook of the hamate bone. It is located under the muscle that abducts the little finger. It is attached to the medial edge and anterior surface of the fifth metacarpal bone.

Function: opposes the little finger to the thumb.

Innervation: ulnar nerve (CVIII-ThI).

Blood supply: deep palmar branch of the ulnar artery.

The short flexor of the little finger (m.flexor digiti minimi brevis) originates with tendon bundles on the flexor retinaculum and the hook of the hamate bone. It is attached to the proximal phalanx of the little finger.

Function: bends the little finger.

Innervation: ulnar nerve (CVIII-ThI).

Blood supply: deep palmar branch of the ulnar artery.

Middle group of muscles of the hand

The lumbrical muscles (mm.lumbricales) are thin, cylindrical in shape, and there are 4 of them located directly under the palmar aponeurosis. They originate on the tendons of the deep flexor of the fingers. The first and second lumbrical muscles originate on the radial edge of the tendons going to the index and middle fingers. The third muscle originates on the edges of the tendon facing each other going to the third and fourth fingers, the fourth - on the edges of the tendons facing each other going to the fourth finger and little finger. Distally, each lumbrical muscle is directed to the radial side of the second through fifth fingers, respectively, and passes to the back of the proximal phalanx. The lumbrical muscles are attached to the base of the proximal phalanges together with the tendon extensors of the fingers.

Function: flex the proximal phalanges and extend the middle and distal phalanges of the II-IV fingers.

Innervation: the first and second lumbrical muscles - the median nerve; the third and fourth - the ulnar nerve (CV-ThI).

Blood supply: superficial and deep palmar arches.

The interosseous muscles (mm.interossei) are located between the metacarpal bones and are divided into two groups - palmar and dorsal.

The palmar interosseous muscles (mm.interossei palmares) are three in number and are located in the second, third and fourth interosseous spaces. They originate on the lateral surfaces of the second, fourth and fifth metacarpal bones. They are attached by thin tendons to the back of the proximal phalanges of the second, fourth and fifth fingers.

The first palmar interosseous muscle originates on the ulnar side of the second metacarpal bone; it is attached to the base of the proximal phalanx of the second finger. The second and third palmar interosseous muscles originate on the radial side of the fourth-fifth metacarpal bone; they are attached to the dorsal surface of the proximal phalanges of the fourth and fifth fingers.

Function: adduct the II, IV and V fingers to the middle (III) finger.

Innervation: ulnar nerve (CVIII-ThI).

Blood supply: deep palmar arch.

The dorsal interosseous muscles (mm. interossei dorsales) are significantly thicker than the palmar ones, there are 4 of them. All 4 muscles occupy the spaces between the metacarpal bones. Each muscle begins with two heads on the surfaces of the IV metacarpal bone facing each other. The muscles are attached to the base of the proximal phalanges of the II-V fingers.

The tendon of the first dorsal interosseous muscle is attached to the radial side of the proximal phalanx of the index finger, the second muscle - to the radial side of the proximal phalanx of the middle (III) finger. The third muscle is attached to the ulnar side of the proximal phalanx of this finger; the tendon of the fourth dorsal interosseous muscle is attached to the ulnar side of the proximal phalanx of the IV finger.

Function: abducts the I, II and IV fingers from the middle finger (Ш).

Innervation: ulnar nerve (CVIII-ThI).

Blood supply: deep palmar arch, dorsal metacarpal arteries.

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