Medical: Median nerve
English: median nerve
The median nerve is an important arm nerve. It gets its name from the fact that, in relation to the other two large arm nerves, the ulnar nerve and the radial nerve, it runs largely in the middle of the arm on the way from the armpit to the wrist.
It consists of fibers that transport sensitive information from the skin and joints to the spinal cord and brain (sensitive afferents) and from motor fibers that send impulses from the brain to the arm muscles (motor efferents).
Of the Median nerve is one of many nerves from the arm nerve plexus, the Brachial plexus, together.
The spinal nerves from the cervical cord of the Backmarks (C5-C8) assemble directly after exiting the spinal cord to form this bundle of nerves, which is called the arm nerve plexus (Brachial plexus) referred to as.
From this bundle of nerves arise all the nerves that the poor supply.
The nerves of the nerve cord bundle (Brachial plexus) be called :
- Short branches:
Subscapular nerve, thoracodorsal nerve, medial and lateral pectoral nerve, medial antebrachial nerve, intercostobrachial nerve;
- Long branches:
Musculocutaneous nerve, axillary nerve, radial nerve, median nerve, Ulnar nerve
Overview and classification
A nerve contains fibers that carry sensitive impulses from the skin and the Joints transport back to the brain (Afferents) and at the same time fibers, via the impulses from the brain to the Muscles be sent (efferents).
On its way from the armpit to the fingers, the Median nerve protected by muscles.
Anatomy and course
Of the Median nerve runs from the armpit to the palm, where it divides into individual branches for the fingers. The nerve root on the arm plexus in the armpit is called "Median fork" designated. On the upper arm, the nerve pulls above the Humerus artery (Brachial artery) in the pit of the humeral flexor muscle (Sulcus bicipitalis medialis) to the middle of the elbow.
From there he pulls one protected between the two heads Forearm muscle (M. pronator teres ) to the forearm. There, again protected by muscle groups, it pulls between the superficial and deep flexor muscles of the forearm towards the wrist.
To reach the palm of the hand, the nerve pulls the tendons through the fingers Carpal tunnel (Retinaculum musculorum flexorum). Once in the palm of the hand, it divides into fibers that supply the muscles and into sensitive branches.
Physiology (motor skills)
Of the Median nerve is responsible for controlling the muscles of the forearm and fingers. Especially for that Bow in the Elbow joint and wrist. Also for bending the fingers and turning inwards (Pronation) of the forearm.
The most important muscles supplied are:
- Inward Twist Muscle (M. pronator teres): Flexion in the elbow joint, inward rotation of the forearm;
- Superficial finger flexors (Flexor digitorum superficialis muscle): Flexion of the wrist and the metacarpal and middle joints, flexion in the elbow joint;
- Deep finger flexors (Flexor digitorum profundus muscle): Flexion of the wrist and the metacarpal, middle and end joints of the 2nd and 3rd fingers (4th and 5th fingers are controlled by the ulnar nerve);
- Long thumb flexor (Flexor pollicis longus muscle): Flexion in the metacarpophalangeal joint and the wrist.
Other muscles supplied by the median nerve:
- Wrist sideways tilt (Flexor carpi radialis muscle),
- Long palm muscle (Palmaris longus muscle)
- Square inward rotators (Pronator quadratus muscle).
The feeling of Palm of the thumb, index finger, middle finger and half ring finger are placed over the Median nerve conveyed. In addition, the feeling of the back of the fingers in the area of the end links of the index finger, middle finger and half of the ring finger end link.
The median nerve can be damaged at various points in its course. The best known is the "carpal tunnel syndrome". The nerve is thereby attached to the wrist as it passes through the carpal tunnel (Retinaculum musculorum flexorum) narrowed. It comes to tingling sensations and pain in the sensitive supply area in the palm of the hand.
The "Pronator Teres Syndrome" occurs when the nerve between the two heads of the inward-turning muscle is damaged (M. pronator teres). A “sworn hand”, which is typical for the median nerve, occurs: when trying to clench a fist, the thumb, index finger and middle finger cannot be bent, while the ring and little fingers cannot be bent. Another characteristic of such damage is a positive "bottle sign": it is impossible to hold a bottle neck tightly with your hand. If other nerves are damaged in addition to the median nerve, complete brachial plexus paralysis can also occur.