The cutaneus antebrachii medialis nerve is a nerve from the brachial plexus. Its function is to transmit sensations from specific skin regions of the arm to the brain. Damage to the cutaneus antebrachii medialis nerve can occur, for example, when blood is drawn.
What is the cutaneus antebrachii medial nerve?
The cutaneus antebrachii medialis nerve is a nerve composed entirely of sensory fibers. It innervates some areas of the skin on the forearm and upper arm and feeds the sensations to further information processing in the central nervous system. Unlike many other peripheral nerves in the human body, the cutaneus antebrachii medialis nerve does not form a side branch of a larger nerve pathway. Instead, it originates directly at the brachial plexus, which medical science refers to as the brachial plexus. In this plexus, the tracts from the spinal nerves of some cervical vertebrae (C5 to C8) and from the first thoracic vertebra (Th1) meet. The spinal nerves previously split into trunks (trunci), bundles (fasciculi) and nerves. From one of the trunks, the inferior truncus, the medial bundle (fasciculus medialis) emerges. From this arises the cutaneus antebrachii medialis nerve, which shares this origin with the cutaneus brachii medialis nerve.
Anatomy and structure
The cutaneus antebrachii medialis nerve innervates parts of the skin on the arm. It has two ends, each belonging to a branch of the nerve. At the wrist, the anterior branch (ramus volaris) ends and runs in the subcutaneous tissue. This layer of skin knows many names: Among others, it is called the hypodermis because it is located below the dermis. The epidermis in turn lies on top of the dermis. The posterior branch (ramus ulnaris) of the cutaneus antebrachii medialis nerve also ends at the wrist, but runs down the back of the forearm. In contrast, the nerve signals from the anterior branch travel along the inside of the forearm. Below the fascia, they run largely separately: the bifurcation of the cutaneus antebrachii medialis nerve is usually just below the point where the nerve enters the subcutaneous tissue. Above the elbow, the cutaneus antebrachii medialis nerve innervates the skin region overlying the arm flexor (biceps brachii muscle). From there, the nerve continues to transmit sensitive information toward the axilla, all the way to the brachial plexus.
Function and tasks
There are numerous receptors in a person’s skin. These can shine not only by a high number of pieces, but also their mode of operation is very diverse. Sensitive cells include, for example, receptors that respond only to cold stimuli, special warm receptors, as well as pain receptors (nociceptors). The cutaneus antebrachii medialis nerve also transmits these three different stimulus qualities via its sensitive nerve fibers. Cold and warm receptors work phasically-tonically: if the temperature changes, they initially respond strongly – but if the temperature subsequently remains unchanged, the response strength of the receptor cells in the skin decreases. Pain receptors, on the other hand, are tonic, meaning that they continue to form action potentials as long as the pain stimulus is present. Fibers from the anterior branch of the cutaneus antebrachii medialis nerve connect at the wrist with fibers from the ulnar nerve. This nerve, also known as the ulnar nerve, controls various arm and finger movements. At the wrist, the ulnar nerve extends a branch, the ramus cutaneus palmaris, to the cutaneus antebrachii medialis nerve. The posterior branch also has a natural connection to the ulnar nerve, but to the dorsal ramus rather than the cutaneus palmaris. In addition, it exchanges information with the medial cutaneal brachial nerve, which, like the medial cutaneal antebrachial nerve, originates in the brachial plexus. However, its circumference is comparatively smaller. The cutaneus brachii medial nerve provides sensation from the skin of the elbow. It also contributes to the sensitivity of the forearm. Finally, the cutaneus antebrachii medialis nerve has a third connection to another nerve, the radial nerve. The ramus cutaneus antebrachii dorsalis establishes the communication.
Diseases
Because the cutaneus antebrachii medialis nerve transmits sensory perceptions from the arm to the central nervous system, damage to this nerve can result in sensory disturbances in the innervated area. Injection of agents can affect the cutaneus antebrachii medialis nerve-assuming the substance has a toxic or otherwise damaging effect and reaches the nerve. Direct injury to the nerve is possible during blood sampling if the vein in the crook of the arm is targeted for this purpose. In the clinic, the cutaneus antebrachii medialis nerve is also of interest for transplantation. Such a transplantation is possible if, for example, there is an injury to the hand. In such a case, a nerve transplantation can help to maintain or restore the functionality of the hand – to a certain degree. However, the chances of success vary greatly and must be assessed on a case-by-case basis. However, a failure of the cutaneus antebrachii medialis nerve is not necessarily due to the nerve itself. The cause of the problem may also lie in the higher-level information processing. For example, the cutaneus antebrachii medialis nerve is also potentially affected by lesions to the brachial plexus. Accidents and violence can be considered as causes, as can tumors, inflammation, infection, and damage from radiation (for example, as a result of cancer treatment).
