Abducens nerve

Nerves around the eyes

The paired abducens nerve , also known as the sixth cranial nerve , N. VI , consists mainly of motor fibers . It innervates the rectus lateralis muscle ("lateral straight muscle") on the eye , which moves the eye axis to the side (in technical terms " abducted ", hence the name of the nerve). In birds , it also innervates the nictitating membrane muscles ( quadratus membranae nicitantis and pyramidalis membranae nicitantis muscles ).

course

The core area ( nucleus nervi abducentis ) lies in the tegmentum pontis (bridge hood). It runs over the clivus of the occiput and reaches the cavernous sinus which it runs through and then through the superior orbital fissure (in cloven-hoofed animals : foramen orbitorotundum , other animals: fissura orbitalis ) into the orbita and the annulus tendineus communis . In addition to the rectus lateralis muscle, it also supplies the lateral portion of the retractor bulbi muscle (only in animals).

Lesion

A paralysis of Abducens is a sixth nerve palsy refers. As a result of the undisturbed tone of the musculus rectus medialis , the antagonist of the musculus rectus lateralis, an inward squint occurs . The abducens nerve has the longest extradural course of the eye nerves and can therefore be easily injured if the base of the skull breaks. It is also damaged when bleeding occurs in the subarachnoid space . As a result of a lumbar puncture , the pressure of the cerebrospinal fluid inside the skull drops , which can lead to tensile stress on the abducens nerve.

literature

• Martin Trepel: Neuroanatomy. Structure and function. 3rd, revised edition. Urban & Fischer, Munich et al. 2004, ISBN 3-437-41297-3 .
• Franz-Viktor Salomon: nervous system, systema nervosum . In: Franz-Viktor Salomon, Hans Geyer, Uwe Gille (Ed.): Anatomy for veterinary medicine. Enke, Stuttgart 2005, ISBN 3-8304-1007-7 , pp. 464-577.