Metacarpal
The metacarpal (Latin metacarpus ) is the part of the hand between the wrist and the fingers . The term pastern is also used in animal anatomy . The skin on the palm side of the metacarpal (palm, palm) has furrows typical of primates and is firmly fused with the palmar aponeurosis . On the back of the hand, on the other hand, the skin is easy to move. But since the subcutaneous fatty tissue is only slightly developed here, the veins stand out clearly.
bone
The metacarpal bones form the bony basis of the metacarpal. In mammals , this is a maximum of five long bones , these are also fully developed in humans. In many mammals, the number is reduced according to the number of toes. The metacarpal bones ensure the mechanical stability of the metacarpal, serve as the origin and insertion of tendons and are involved in the formation of the carpometacarpal joint , the thumb saddle joint and the metacarpophalangeal joints . The ends of the metacarpal bones are connected to one another by the intermetacarpal joints ( articulationes intermetacarpales ).
Muscles
The metacarpal bones are covered by the tendons of the long extensor and flexor muscles of the fingers, the muscle bellies of which lie on the forearm (→ forearm muscles ). On the palm side, the lumbrical muscles and the three palmar interossei muscles are also adjacent. On the back of the hand are the four dorsal interossei muscles . The abductor pollicis brevis , flexor pollicis brevis , opponens pollicis and adductor pollicis muscles are located in the area of the thumb base , which produce a distinct muscle bulge known as the ball of the thumb ( thenar ). On the little finger side, the abductor digiti minimi , flexor digiti minimi brevis and opponens digiti minimi muscles form the ball of the little finger ( hypothenary ). Based on these muscle bulges, the metacarpus is also divided into three boxes - the ball of the thumb, the middle and the little finger ball.
Nerves and blood vessels
The metacarpus is supplied by the radial , median, and ulnar nerves . The median nerve divides in the central compartment into three nervi digitales palmares communes . These innervate the muscles of the ball of the thumb with the exception of the adductor pollicis muscle, the two lumbricales muscles on the spoke side and the deep head of the flexor pollicis brevis muscle. The ulnar nerve also runs in the central compartment, close to the pea bone and together with the ulnar artery . Its superficial branch ( ramus superficialis ) also sends nervi digitales palmares communes , its deep branch ( ramus profundus ) supplies the remaining muscles of the palm. The superficial branch of the radial nerve supplies the skin of the back of the hand together with the dorsal branch of the ulnar nerve.
The blood vessels of the hand form two arched anastomoses in the area of the palm . The superficial metacarpal arteries ( Arteriae digitales palmares communes ) arise from the superficial palm arch ( Arcus palmaris superficialis ) , from the deep palm arch ( Arcus palmaris profundus ) the deep metacarpal arteries ( Arteriae metacarpales palmares ). The accompanying veins are relatively poorly developed. Four arteriae metacarpales dorsales , which arise from the rete carpi dorsale, run on the back of the hand . The veins form the rete venosum dorsale manus , which is connected to the intercapital veins with the palm veins .
literature
- Bernhard Hirt, Harun Seyhan, Michael Wagner, Rainer Zumhasch: Anatomy and biomechanics of the hand . Georg Thieme, Stuttgart, 3rd edition 2014, ISBN 978-3-131-66523-2 , p. 74 ff.
- Gert-Horst Schumacher, Gerhard Aumüller: Topographical anatomy of humans . Elsevier, Urban and Fischer, 2004, ISBN 978-3-437-41367-4 .