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The human arm - also known as the (free) upper extremity in medical jargon - is the transformation / further development of the animal's forelegs into a gripping tool , but with its pendulum movements it also serves to balance the upright gait .
anatomy
The arm ( membrum superius ) is divided into:
- Shoulder girdle ( Cingulum pectorale; Cingulum membri superioris )
- Upper arm ( brachium )
- Forearm ( antebrachium )
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Hand ( manus )
- Carpal ( carpus )
- Metacarpal ( metacarpal )
- Finger ( digiti manus )
function
The upper extremity of the human being has the greatest possible freedom of movement of all parts of the body, which determine their functionality through the mobility of the shoulder joint, the elbow joint, the forearm bones to one another, the wrist and subsequently the carpal and finger joints .
Movements in the shoulder joint
- The movement about a sagittal axis makes it possible to pull the arm from the side of the body and is known as adduction , those laterally away from the body as abduction referred to, wherein the limit latter movement reaches at 90 ° and then further raising the arm to its elevation is . The corresponding muscle groups are called adductors , abductors and elevators.
- As anteversion is the lifting of the arm about a frontal axis forward as retroversion the opposite movement referred to the rear.
- Internal and external rotation (turning inwards or outwards) in the shoulder joint serve to support supination and pronation in the forearm area.
Movements in the elbow joint and forearm
The diffraction ( flexion ) and stretching ( extension ) in the elbow joint are made possible by the flexors and extensors of the respective muscle groups. But the turning movements (pronation and supination) of the forearm are only made possible by the rotational movement of the radial head in the elbow joint.
Movements in the wrist
As movements in the wrist are dorsal and palmar flexion and ulnar and radial abduction to call.
Movements of the finger joints
Flexion, extension, adduction and abduction of all fingers and opposition and apposition of only the thumb.
Idioms
A “long arm” is a powerful influence of an institution, a person or other influencing factors, which occasionally acts in the background and which is exerted over greater distances of time and space, e.g. B.
- "The long arm of the law";
- "The long arm of history";
- “The Long Arm of Chance”, a film from the TV series Tatort ;
- “The long arm of the mullahs. Notes from my Exile ”( 1995 ), a book by the poet Said
