Human Anatomy Part 1 - K. A. Dyubenko, A. K. Kolomiytsev, Yu. B. Chaykovsky 2002

Special Part
Myology, myologia [the study of muscles] - Muscles and fasciae of the upper limb
Muscles of the upper limb, musculi membri superioris - Muscles of the free upper limb - Muscles of the hand - Middle group

1. Lumbrical Muscles, mm. lumbricales — long, thin muscles located between the tendons of the m. flexor digitorum profundus beneath the palmar aponeurosis, extending to all digits except the thumb. They originate from the radial margin of the corresponding tendon of the m. flexor digitorum profundus and insert onto the dorsal surface of the Base of the proximal Phalanges. Here, they blend into the dorsal aponeurosis of the fingers from the index finger to the little finger along their radial margin.

Function: flex the proximal phalanges of digits II–V and extend the middle and distal phalanges.

Blood supply: superficial and deep palmar arches, arcus palmaris superficialis et profundus.

Innervation: the First and Second muscles are supplied by the median nerve, n. medianus; the third and fourth by the ulnar nerve, n. ulnaris (C VIII–Th I).

2. Palmar interossei, mm. interossei palmares — spindle-shaped Muscle bundles situated in the intermetacarpal spaces of the hand that act as adductors toward the third digit. The first muscle lies on the radial side of the palm, originating from the ulnar aspect of the second metacarpal bone, os metacarpale (II), and inserts into the base of the proximal phalanx of the index finger, blending into the dorsal aponeurosis. The second and third muscles are located on the ulnar side of the palm, originating from the radial aspect of the fourth and fifth Metacarpal bones, os metacarpale (IV and V), and inserting onto the radial margin of the proximal phalanges of the ring and little fingers (digits IV and V).

Function: adduct the index, ring, and little fingers (digits II, IV, and V) toward the middle finger (digit III), and assist in maintaining the phalanges in a flexed position.

Blood supply: deep palmar arch, arcus palmaris profundus.

Innervation: ulnar nerve, n. ulnaris (C VII–Th I).

3. Dorsal interossei, mm. interossei dorsales — located in the four intermetacarpal spaces of the dorsal surface of the hand (Fig. 164). Each muscle originates from the adjacent sides of the bases of two neighboring metacarpal bones. Insertions: the first muscle inserts into the radial margin of the index finger; the second muscle inserts into the radial side of the proximal phalanx of the middle finger (digit III); the third muscle inserts into the ulnar margin of the proximal phalanx of the middle finger (digit III); the fourth muscle inserts into the ulnar side of the proximal phalanx of the ring finger (digit IV).

Function: grouped around the middle finger (digit III) and act as abductors. The two muscles on the radial side pull the proximal phalanges of the index and middle fingers toward the thumb; the two muscles on the ulnar side pull the middle and ring fingers toward the little finger. All these muscles participate in flexing the proximal phalanges and extending the middle and distal phalanges of the index, middle, ring fingers, and little finger.

Blood supply: deep palmar arch, arcus palmaris profundus, dorsal metacarpal Arteries, aa. metacarpales dorsales.

Innervation: ulnar nerve, n. ulnaris (C VII–Th I).

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Fig. 164. Muscles of the hand, dorsal surface — interossei (after V. P. Vorobyov)