Musculocutaneous nerve
The musculocutaneous nerve (" muscle-skin-nerve ") arises from the brachial plexus . In humans he gets fibers from the 5th – 7th centuries. Neck segment (C5 – C7) of the spinal cord , in domestic animals from C6 – C8. In ungulates , it connects to the median nerve on the upper arm (so-called ansa axillaris ).
course
After leaving the lateral fasciculus ( brachial plexus ), the nerve pulls distally at the lateral edge of the pectoralis minor muscle and pierces the coracobrachialis muscle . It then moves between the brachialis and biceps brachii muscles in a distal direction towards the crook of the elbow, from where it innervates the outside of the forearm as a sensitive skin branch (lateral antebrachial nerve).
Muscle branches
The musculocutaneous nerve innervates the muscles on the ventral (front) side of the upper arm that are flexors of the elbow joint and / or cause an anteversion in the shoulder joint:
Branch
After releasing the muscle branches, the nerve between the biceps brachii and brachialis muscles comes to the surface.
In humans , this branch of the skin is called the lateral antebrachial cutaneous nerve . It sensitively innervates the radial part of the forearm on the spoke side.
In domestic mammals, the skin branch is known as the medial cutaneous nerve . It innervates the skin medially on the forearm; in ungulates its innervation area extends to the fetlock joint , i.e. it also includes the dorsomedial part of the pastern.
Clinical Aspects
Damage to the nerve leads to a loss of flexion of the elbow joint . Depending on how far up (proximal) the damage is located, the coracobrachialis muscle may fail and thus a slight disruption of the pulling forward ( anteversion ) of the upper arm and the fixation of the head of the humerus in the shoulder joint . In addition, the outward rotation ( supination ) of the arm can be impaired in humans . In animals, nerve damage manifests itself as a slight gait disorder.
In addition, the damage to the nerve leads to loss of sensitivity in the skin area that it is sensitively innervating.
Neurectomy of the nerve can be used if the arm has no function and the elbow joint is contracted .
literature
- Franz-Viktor Salomon: nervous system, systema nervosum. In: Franz-Viktor Salomon, Hans Geyer, Uwe Gille (Ed.): Anatomy for veterinary medicine. Enke, Stuttgart 2004, ISBN 3-8304-1007-7 , pp. 464-577.
Individual evidence
- ↑ Bernard F. Morrey, Joaquin Sanchez-Sotelo: The elbow and its disorders . Elsevier Health Sciences, 4th ed. 2009, ISBN 9781416029021 , p. 1007.