Short muscle that abducts the thumb(m.abductor pollicis brevis), flat, located superficially. It begins with muscle bundles on the lateral part of the flexor retinaculum, tubercle of the navicular bone and on the trapezoid bone. Attaches 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 (C V -Th I).

Blood supply: superficial palmar branch of the radial artery.

Muscle that opposes the thumb(m.opponens pollicis), partially covered by the previous muscle, fused with the short flexor of the thumb, located medially from it. It starts on the flexor retinaculum and on the trapezoid bone. It is attached to the radial edge and the anterior surface of the I metacarpal bone.

Function: contrasts the thumb with the little finger and all other fingers of the hand.

innervation: median nerve (C V -Th I).

Blood supply:

Flexor thumb short(m.fleixor pollicis brevis) is partially covered by a short muscle that abducts the thumb of the hand. Surface head(caput superficiale) starts on the flexor retinaculum, deep head(caput profundum) - on the trapezoid bone and trapezoid bone, on the II 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 bringing this finger.

Innervation: median nerve (C V -Th I), ulnar nerve (C VIII - Th I).

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

Adductor thumb muscle(m.abductor pollicis), located under the tendons of the long flexors of the fingers (superficial and deep) and under the worm-like muscles. It has two heads - oblique and transverse. The oblique head (caput breve) begins on the capitate and the base of the II and III metacarpal bones.

cross head(caput transversum) begins on the palmar surface of the III metacarpal bone. The muscle is attached by a common tendon, in which there is a sesamoid bone, to the proximal phalanx of the thumb.

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

Innervation:

Blood supply:

Muscles of the little finger elevation

short palmar muscle(m.palmaris brevis) - a rudimentary skin muscle, represented by weakly expressed muscle bundles in the subcutaneous base of the little finger elevation. The bundles of this muscle begin on the flexor retinaculum, attach to the skin of the medial edge of the hand.

Function: on the skin of the elevation of the little finger, weakly expressed folds are formed.

Innervation: ulnar nerve (C VIII -Th I).

Blood supply: ulnar artery.

Muscle that abducts the little finger(m.abductor digiti minimi), located superficially. It originates on the pisiform bone and flexor carpi ulnaris tendon. Attaches to the medial side of the proximal phalanx of the little finger.

Function: withdraws the little finger.

Innervation: ulnar nerve (C VIII -Th I).

Blood supply: deep branch of the ulnar artery.

Muscle that opposes the little finger(m.opponens digiti minimi), begins with tendon bundles on the flexor retinaculum and hook of the hamate. It is located under the muscle that removes the little finger. It is attached to the medial edge and anterior surface of the V metacarpal bone.

Function: contrasts the little finger with the thumb of the hand.

Innervation: ulnar nerve (C VIII -Th I).

Blood supply:

Short little finger flexor(m.flexor digiti minimi brevis) begins with tendon bundles on the flexor retinaculum and hook of the hamate. Attached to the proximal phalanx of the little finger.

Function: bends the little finger.

Innervation: ulnar nerve (C VIII -Th I).

Blood supply: deep palmar branch of the ulnar artery.

Middle group of muscles of the hand

vermiform muscles(mm.lumbricales) thin, cylindrical, in the amount of 4 lie directly under the palmar aponeurosis. They begin on the tendons of the deep flexor of the fingers. The first and second worm-like muscles begin at the radial edge of the tendons going to the index and middle fingers. The third muscle begins on the edges of the tendon facing each other, going to the III and IV fingers, the fourth - on the edges of the tendons facing each other, going to the IV finger and little finger. Distally, each vermiform muscle is directed to the radial side of the II-V fingers, respectively, and passes to the rear of the proximal phalanx. The lumbrical muscles attach to the base of the proximal phalanges along with the extensor tendon sprains of the fingers.

Function: bend the proximal phalanges and unbend the middle and distal phalanges of the II-IV fingers.

Innervation: the first and second worm-like muscles - the median nerve; the third and fourth are the ulnar nerve (C V -Th I).

Blood supply: superficial and deep palmar arches.

Interosseous muscles(mm.interassei) are located between the metacarpal bones, are divided into two groups - palmar and dorsal (Fig. 169).

Palmar interosseous muscles(mm.interassei palmares) in the amount of three are located in the second, third and fourth interosseous spaces. They begin on the lateral surfaces of the I, IV and V metacarpal bones. They are attached by thin tendons to the back of the proximal phalanges of the II, IV and V fingers.

First palmar interosseous muscle begins on the ulnar side of the II metacarpal bone; attached to the base of the proximal phalanx of the second finger. Second and third palmar interosseous muscles begin on the radial side of the IV-V metacarpal bone; attached to the back surface of the proximal phalanges of the IV and V fingers.

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

Innervation: ulnar nerve (C VII -Th I).

Blood supply: deep palmar arch.

Dorsal interosseous muscles(mm. interossei dorsales) is much 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 facing each other surfaces I-V metacarpal bone. 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 fourth finger.

Function: abduct I, II and IV fingers from the middle finger (III).

Innervation: ulnar nerve (C VII -Th I).

Blood supply: deep palmar arch, dorsal metacarpal arteries.

47. Age and gender characteristics of the development of muscles, the impact of work and physical education and sports on the development of muscles.

48. Formations of the auxiliary muscle apparatus (fascia, fascial ligaments, fibrous and bone-fibrous channels, synovial sheaths, mucous bags, sesamoid bones, blocks) and their functions.

49. Abdominal muscles: topography, origin, attachment and functions.

50. Inspiratory muscles. Exhalation muscles.

52. Muscles of the neck: topography, origin, insertion and functions.

53. Muscles that bend the spine.

54. Muscles that extend the spine.

55. Muscles of the anterior surface of the forearm: origin, insertion and functions.

56. Muscles of the posterior surface of the forearm: origin, insertion and functions.

57. Muscles that produce movements of the belt of the upper limb forward and backward.

58. Muscles that produce movements of the belt of the upper limb up and down.

59. Muscles that flex and extend the shoulder.

60. Muscles that abduct and adduct the shoulder.

61. Muscles supinating and penetrating the shoulder.

62. Muscles that flex (basic) and extensor the forearm.

63. Muscles supinating and penetrating the forearm.

64. Muscles that flex and extend the hand and fingers.

65. Muscles that abduct and adduct the hand.

66. Thigh muscles: topography and functions.

67. Muscles that flex and extend the thigh.

68. Muscles that abduct and adduct the thigh.

69. Muscles supinating and penetrating the thigh.

70. Leg muscles: topography and functions.

71. Muscles that flex and extend the lower leg.

72. Muscles supinating and penetrating the lower leg.

73. Muscles that flex and extend the foot.

74. Muscles that abduct and adduct the foot.

75. Muscles supinating and penetrating the foot.

76. Muscles that hold the arches of the foot.

77. General center of gravity of the body: age, sex and individual characteristics of its location.

78. Types of balance: the angle of stability, the conditions for maintaining the balance of the body.

79. Anatomical characteristics of the anthropometric, calm and tense position of the body.

80. Hanging on straightened arms: anatomical characteristics, features of the mechanism of external respiration.

81. General characteristics of walking.

82. Anatomical characteristics of 1,2 and 3 phases of a double step.

83. Anatomical characteristics of 4, 5 and 6 phases of a double step.

84. Standing long jump: phases, muscle work.

85. Anatomical characteristics of back flips.

65. Muscles that abduct and adduct the hand.

Retract the brush: flexor carpi radialis, extensor carpi radialis long and short, abductor thumb longus, extensor pollicis longus, extensor pollicis brevis. In addition, the muscles that go from the forearm to the index finger take a small part in the abduction of the hand.

flexor carpi radialis starts from the medial epicondyle of the shoulder and the intermuscular septum, the muscle passes to the hand under the ligament-retainer of the flexors and is attached to the base of the 2nd metacarpal bone. Being a multi-joint muscle, it participates not only in the movements of the hand, but also in the flexion of the forearm at the elbow joint.

extensor carpi radialis longus starts from the lateral edge of the humerus, intermuscular septum and lateral epicondyle, passes under the ligament-retainer of the extensor and the tendon of the long extensor of the thumb and is attached to the base of the 2nd metacarpal bone. Due to the fact that the resultant of this muscle passes very close to the transverse axis of the elbow joint, its participation in the flexion of the forearm is not significant. Being a strong extensor of the hand, it also produces some abduction during isolated contraction.

extensor carpi radialis brevis starts from the lateral epicondyle of the humerus, the fascia of the forearm and is attached to the base of the 3rd metacarpal bone. Being an extensor of the hand, the muscle simultaneously abducts it.

Long muscle that abducts the thumb, starts from the dorsal surface of the radius and ulna and the interosseous membrane and is attached to the base of the 1st metacarpal bone. This muscle abducts the thumb if it is not fixed by antagonist muscles. If it is fixed, she retracts the hand. When the thumb is abducted to failure, further work of the muscle is also manifested in the abduction of the hand.

Long extensor thumb starts from rear surface ulna and radius, interosseous membrane of the forearm and is attached to the distal phalanx of the thumb. The tendon of this muscle passes under the extensor retinaculum in a separate canal, crossing the tendons of the radial extensor carpi. Unbending the distal phalanx, the muscle at the same time somewhat pulls back the thumb. If it is fixed, then the muscle is involved in the abduction of the entire hand.

Short extensor thumb starts from the posterior surface of the ulna and radius, attaches to the proximal phalanx of the thumb, which it unbends, retracting the entire finger at the same time. If the finger is fixed, then the muscle is involved in the abduction of the entire hand.

Lead brush: ulnar flexor of the wrist, ulnar extensor of the wrist.

Flexor carpi ulnaris starts from the medial epicondyle of the humerus, from the ulna and fascia of the forearm. With its distal end, it reaches the pisiform bone, to which it is attached. Ligaments run from the pisiform bone to the hooked and to the 5th metacarpal bones, which are a continuation of the traction of this muscle.

Elbow extensor of the wrist originates from the lateral epicondyle of the humerus, the collateral radial ligament, and the fascia of the forearm. Descending to the hand, the muscle goes between the head and the styloid process of the ulna and is attached to the base of the 5th metacarpal bone. Being an extensor of the hand, the ulnar extensor of the wrist also leads it.

The muscles of the hand, according to their position, are divided into two groups: the muscles of the palmar and the muscles of the dorsal surfaces. At the same time, among the muscles of the palmar surface, there are the thenar region, the muscles of the little finger elevation - the hypothenar region and the muscles of the middle group.

Muscles of the eminence of the thumb

1. The short muscle that abducts the thumb of the hand, m. abductor pollicis brevis.
2. Short flexor of the thumb, m. flexor pollicis brevis.
3. The muscle that opposes the thumb of the hand, m. opponens pollicis.
4. Muscle adductor of the thumb, m. adductor pollicis.

Muscles of the little finger elevation

1. Short palmar muscle, m.palmaris brevis.
2. The muscle that removes the little finger, m. abductor digiti minimi.
3. Short little finger flexor, m. flexor digiti minimi brevis.
4. The muscle that opposes the little finger, m. opponens digiti minimi.

Muscles of the middle group

1. Vermiform muscles, mm. lumbricales.
2. Palmar interosseous muscles, mm. interossei palmares.

Muscles of the palmar surface

Muscles of the eminence of the thumb

1. The short muscle that abducts the thumb of the hand, m. abductor pollicis brevis, lies on the side of the eminence of the thumb, directly under the skin. It originates from the tendon m. abductor pollicis longus, fascia antebrachii, from tuberositas ossis scaphoidei and retinaculum flexorum, is attached to the lateral surface of the base of the proximal phalanx of the thumb. Its tendon usually contains a sesamoid bone. Action: abducts the thumb of the hand, slightly opposing it, and takes part in the flexion of the proximal phalanx. Innervation: n. medianus (C6-C7). Blood supply: n. palmaris superficialis a. radialis.
2. The short flexor of the thumb, m.flexor pollicis brevis, lies medially from the previous muscle and also directly under the skin. It starts from retinaculum flexorum, from ossa multangulum, trapezoideum, capitatum and the base of the first metacarpal bone. Heading distally, the muscle bundles are also attached radially: superficial (caput superficiale) - to the outer sesamoid bone, and deep (caput profundum) - to both sesamoid bones of the metacarpophalangeal joint of the thumb. Action: flexes the proximal phalanx of the thumb. Innervation: superficial bundles - n. medianus (С6-С7), deep - n. ulnaris (C8-Th1). Blood supply: r. palmaris superficialis a. radialis, arcus palmaris profundus.
3. The muscle that opposes the thumb of the hand, m. opponens pollicis, has the shape of a thin triangular plate and lies under m. abductor pollicis brevis. The muscle starts from tuberositas ossis multanguli and retinaculum flexorum, is attached along the outer edge of the first metacarpal bone. Action: opposes the thumb to the little finger. Innervation: n. medianus (C6-C7). Blood supply: r. palmaris superficialis a. radialis, arcus palmaris profundus.
4. Muscle adductor of the thumb, m. adductor pollicis, the deepest of the muscles of the eminence of the thumb. It originates in two heads, the muscle bundles of which are directed at an angle to one another: a) oblique head, caput obliquum, from lig. carpi radiatum, os capitatum and the palmar surface of II and III metacarpal bones; b) transverse head, caput transversum. from the palmar surface of the II metacarpal bone and the heads of the II and III metacarpal bones. Converging at an angle, the muscle bundles are attached to the base of the proximal phalanx of the thumb, the ulnar sesamoid bone and the capsule of the metacarpophalangeal joint. Action: adducts the thumb and takes part in the flexion of its proximal phalanx. Innervation: n. ulnaris (C,). Blood supply: arcus palmares superficialis et profundus.

Muscles of the little finger elevation

1. The short palmar muscle, m.palmaris brevis, is a thin plate with parallel muscle bundles. The muscle originates from the inner edge of the palmar aponeurosis and retinaculum flexorum and is woven into the skin of the little finger eminence. Action: stretches the palmar aponeurosis, forming a series of folds on the skin of the little finger elevation. Innervation: n. ulnaris [(C7), C8, Th1. Blood supply: a. ulnaris.
2. The muscle that removes the little finger, m. abductor digiti minimi, occupies the most medial position of all the muscles of this group, located directly under the skin and partially under m. palmaris brevis. The muscle originates from os pisiforme, tendon m. flexor carpi ulnaris and retinaculum flexorum, attaching to the ulnar edge of the base of the proximal phalanx of the little finger. Action: abducts the little finger and takes part in the flexion of its proximal phalanx. Innervation: n. ulnaris [(C7), C8 Th1. Blood supply: d. palmaris profundus a. ulnaris.
3. Short little finger flexor, m. flexor digiti minimi brevis, looks like a small flattened muscle lying lateral to the previous one and covered from above by m. palmaris brevis and skin. It originates from hamulus ossis hamati, retinaculum flexorum and, heading distally, is attached to the palmar surface of the base of the proximal phalanx of the little finger. Action: flexes the proximal phalanx of the little finger and takes part in its adduction. Innervation: n. ulnaris (C7-C8). Blood supply: d. palmaris profundus a. ulnaris.
4. The muscle that opposes the little finger, m. opponens digiti minimi, lies medially from the previous one and is somewhat covered by it along the outer edge. The muscle originates from hamulus ossis hamati and retinaculum flexorum and is attached to the ulnar edge of the fifth metacarpal bone. Action: opposes the little finger to the thumb. Innervation: n. ulnaris (C7-C8). Blood supply: d. palmaris profundus a. ulnaris.

middle group

1. Vermiform muscles, mm. lumbricales, four in number, look like small spindle-shaped muscles. Each of them starts from the radial edge of the corresponding tendon m. flexor digitorum profundus and is attached to the back surface of the base of the proximal phalanges from the index finger to the little finger. Here they are woven into the dorsal aponeurosis of the index, middle, ring fingers and little finger from the side of their radial edge. Action: bend the proximal phalanges of four fingers and straighten the middle and distal phalanges of the same fingers. Innervation: first and second - n. medianus, third and fourth - n. ulnaris (C8 Th1). Blood supply: arcus palmaris superficialis.
2. Palmar interosseous muscles, mm. interossei palmares, are three spindle-shaped muscle bundles located in the interosseous spaces between the metacarpal bones. The first interosseous muscle lies on the radial half of the palm and, starting on the ulnar side of the II metacarpal bone, is attached to the ulnar side of the metacarpophalangeal joint of the index finger and is woven into its dorsal aponeurosis. The second and third interosseous muscles are located on the ulnar half of the palm and, starting on the radial side of the IV and V metacarpal bones, are attached to the radial side of the bags of the metacarpophalangeal joints of the ring finger and little finger. Action: bend the proximal phalanges and straighten the middle and distal phalanges of the index and ring fingers and little finger, bring these fingers to the middle finger. Innervation: n. ulnaris (C8 Th1). Blood supply: arcus palmaris profundus.

Dorsal muscles

The muscles of the hand are located mainly on the palmar surface of the hand and are divided into the lateral group (muscles of the thumb), the medial group (muscles of the little finger) and middle group. On the dorsum of the hand are the dorsal (dorsal) interosseous muscles.

Lateral group

The short muscle that abducts the thumb (m. abductor pollicis brevis) (Fig. 120, 121) abducts the thumb, slightly opposing it, and takes part in the flexion of the proximal phalanx. It is located directly under the skin on the side of the eminence of the thumb. It originates on the navicular bone and ligament of the palmar surface of the wrist, and is attached to the lateral surface of the base of the proximal phalanx of the thumb.

	Rice. 120. Muscles of the hand (palmar surface): 1 - square pronator; 2 - long flexor of the thumb: a) abdomen, b) tendon; 3 - a muscle that opposes the thumb of the hand; 4 - flexor retainer; 5 - short flexor of the thumb; 6 - a short muscle that removes the thumb of the hand; 7 — the muscle leading a little finger; 8 - palmar interosseous muscles; 9 - adductor muscle of the hand: a) oblique head, b) transverse head; 10 - worm-like muscle; 11 - dorsal interosseous muscle; 12 - tendon of the superficial flexor of the fingers; 13 - the tendon sheath of the fingers; 14 - tendon of the deep flexor of the fingers
	Rice. 121. Muscles of the hand (palmar surface): 1 - square pronator; 2 - tendon brachioradialis muscle; 3 - tendon of the ulnar flexor of the hand; 4 - tendon of the radial flexor of the hand; 5 - the muscle that opposes the thumb of the hand; 6 - short flexor of the thumb; 7 - palmar interosseous muscles; 8 - a short muscle that removes the thumb of the hand; 9 - dorsal interosseous muscles
	Rice. 122. Muscles of the hand (back surface): 2 - extensor of the little finger; 3 - tendon of the ulnar extensor of the wrist; 4 - extensor of the fingers; 5 - tendon of the long radial extensor of the wrist; 7 - tendon of the long extensor of the thumb; 8 - extensor tendon of the little finger; 9 — the muscle which is taking away a little finger; 10 - extensor tendons of the fingers; 11 - extensor tendon of the index finger; 12 - dorsal interosseous muscles; 13 - tendon long flexor thumb brush
	Rice. 123. Muscles of the hand (back surface): 1 - short extensor of the thumb; 2 - a long muscle that removes the thumb of the hand; 3 - ulnar extensor of the wrist; 4 - tendon of the long radial extensor of the wrist; 5 - extensor tendons of the fingers; 6 - tendon of the short radial extensor of the wrist; 7 - extensor tendon of the little finger; 8 - tendon of the long extensor of the thumb; 9 - extensor tendon of the index finger; 10 - dorsal interosseous muscles; 11 - muscle that removes the little finger; 12 - adductor muscle of the hand; 13 - extensor tendon of the little finger; 14 - tendon of the long muscle that removes the thumb of the hand; 15 - extensor tendons of the fingers; 16 - worm-like muscles

The short flexor of the thumb (m. flexor pollicis brevis) (Fig. 120, 121) flexes the proximal phalanx of the thumb. This muscle is also located just under the skin, has two heads. The point of origin of the superficial head is on the ligamentous apparatus of the palmar surface of the wrist, and the deep head is on the trapezius bone and the radiant ligament of the wrist. Both heads are attached to the sesamoid bones of the metacarpophalangeal joint of the thumb.

The muscle that opposes the thumb of the hand (m. opponens pollicis) (Fig. 120, 121), opposes the thumb to the little finger. It is located under the short muscle that removes the thumb of the hand, and is a thin triangular plate. The muscle starts from the ligamentous apparatus of the palmar surface of the wrist and the tubercle of the trapezium, and is attached to the lateral edge of the first metacarpal bone.

The adductor thumb muscle (m. adductor pollicis) (Fig. 120, 123) leads the thumb and takes part in the flexion of its proximal phalanx. It lies the deepest of all the muscles of the eminence of the thumb and has two heads. The point of origin of the transverse head (caput transversum) is located on the palmar surface of the IV metacarpal bone, the oblique head (caput obliquum) is located on the capitate bone and the radiant ligament of the wrist. The place of attachment of both heads is located on the basis of the proximal phalanx of the thumb and the medial sesamoid bone of the metacarpophalangeal joint.

medial group

The short palmar muscle (m. palmaris brevis) stretches the palmar aponeurosis, while forming folds and dimples on the skin in the area of ​​\u200b\u200bthe elevation of the little finger. This muscle, which is a thin plate with parallel fibers, is one of the few skin muscles that a person has. It has a point of origin on the inner edge of the palmar aponeurosis and the ligamentous apparatus of the wrist. The place of its attachment is located directly in the skin of the medial edge of the hand at the elevation of the little finger.

The muscle that abducts the little finger (m. abductor digiti minimi) (Fig. 122, 123) abducts the little finger and takes part in the flexion of its proximal phalanx. It is located under the skin and is partially covered by a short palmar muscle. The muscle starts from the pisiform bone of the wrist and is attached to the ulnar edge of the base of the proximal phalanx of the little finger.

The short flexor of the little finger (m. flexor digiri minimi) flexes the proximal phalanx of the little finger and takes part in its adduction. This is a small flattened muscle, covered by skin and partly by a short palmar muscle. Its point of origin is located on the hamate bone and the ligamentous apparatus of the wrist, and the place of attachment is on the palmar surface of the base of the proximal phalanx of the little finger.

The adductor muscle (m. opponens digiti minimi) (Fig. 120) opposes the little finger to the thumb. The outer edge of the muscle is covered by a short flexor of the little finger. It begins on the hamate and ligamentous apparatus of the wrist, and is attached to the ulnar edge of the fifth metacarpal bone.

middle group

Vermicular muscles (mm. lumbricales) (Fig. 120, 123) bend the proximal phalanges of the II-V fingers and straighten their middle and distal phalanges. There are four muscles in total, all of them are spindle-shaped and go to the II-IV fingers. All four muscles start from the radial edge of the corresponding tendon of the deep flexor of the fingers, and are attached to the dorsal surface of the base of the proximal phalanges of the II–IV fingers.

Palmar interosseous muscles (mm. interossei palmares) (Fig. 120, 121) flex the proximal phalanges, unbend the middle and distal phalanges of the little finger, index and ring fingers, simultaneously bringing them to the middle finger.

They are located in the interosseous spaces between the II-V metacarpal bones and represent three muscle bundles. The first interosseous muscle is located on the radial half of the palm, its point of origin is the medial side of the II metacarpal bone, the second and third interosseous muscles are located on the ulnar half of the palm, their point of origin is the lateral side of the IV and V metacarpal bones. The place of attachment of the muscles are the bases of the proximal phalanges of the II–V fingers and the articular bags of the metacarpophalangeal joints of the same fingers.

Dorsal interosseous muscles (mm. interossei dorsales) (Fig. 120, 121, 122, 123) flex the proximal phalanges, unbend the distal and middle phalanges, and also remove the little finger, index and ring fingers from the middle finger. They are the muscles of the dorsum of the hand. This group consists of four fusiform bipennate muscles, which are located in the interosseous spaces of the dorsum of the hand. Each muscle has two heads, which start from the lateral surfaces of two adjacent metacarpal bones facing each other. The place of their attachment is the base of the proximal phalanges of the II–IV fingers. The first and second muscles are attached to the radial edge of the index and middle fingers, and the third and fourth - to the ulnar edge of the middle and ring fingers.