Innervation It is a concept that is used in the field of anatomy to name the action developed by the nervous system on the functions of organs . The verb innervate, in this framework, is used with respect to what a nerve does when it reaches a body structure .
When motor fibers send impulses to the glands or to the muscles and when the sensory fibers receive the sensitivity of the receptors, innervation occurs. The nerve fibers of the sympathetic trunks and the vagus nerves, to name a case, allow innervation of the heart .
The innervation of the eye On the other hand, it is produced by the cranial nerves. Miscellaneous nerves They are responsible for collecting the sensitivity of the orbital cavity and the functions of the outer muscles of the eye.
Each cutaneous nerve, meanwhile, makes it possible to innervate a specific area of the skin . The region innervated by a single spinal nerve with its spinal ganglion is called dermatome .
In general, it can be said that innervation is associated with Electric impulses . An electric discharge wave crosses the cell membrane and modifies its potential (the distribution of electrical charge). The innervation implies the transmission of a impulse , for example from a nerve cell to a muscle.
It is important not to confuse innervation with irrigation . While the former is linked to the transmission of nerve impulses, irrigation refers to the introduction of a fluid (such as blood ). An organ, in this way, is innervated by certain nerves and irrigated by certain blood vessels.
There is a known disorder with the name of anastomosis which is often mentioned as anomalous innervation; However, given its frequent occurrence in humans, it is not considered as an anomaly as much as a variation. One of the most common types of anastomosis takes place in the forearm and covers the zone that goes from the median and ulnar nerve.
The anomalous innervation that occurs between these nerves is of great importance for the clinical setting, since it usually leads to variations in motor innervation, which is why it also causes alterations in the intrinsic hand muscles. Various studies of nerve and anatomical conduction have shown that this phenomenon creates confusion when an accurate diagnosis is necessary.
Of the various descriptions that scientists have made about the branches that communicate the ulnar and median nerves, the first dating from the year 1741 and was in charge of Berettini , who accompanied her with a series of illustrations. Later, other scholars added their views to the subject, and among them are Martin, Gruber, Brooks, Spourgitis, Richie, Gehwolf, Hirasawa, Rowntree, Meals and Sunderland, who published their findings between 1763 and 1978.
In 1966, Mannerfield pioneered the use of electrophysiological studies to achieve the detection of anastomosis between two nerves. Descriptions of abnormal innervations in the forearm have been made taking into account various points of their paths at or below the elbow, from the distal or proximal part of the forearm and also in the palm of the hand. The communicating branches that are located in the proximal part of the forearm called Martin-Gruber anastomosis they are those that originate in the median nerve and reach the ulnar.
Moreover, the name Marinacci anastomosis or by Martin-Gruber Reverse (Gruber-Martin anastomosis) receives the abnormal innervation that goes from the ulnar nerve to the median. In the palm hand in hand, the Richie-Cannieu anastomosis, which communicates the deep branch of the ulnar and the recurring medium.