Nervus oculomotorius

Nervus Oculomotorius (also known as the third cranial nerve or CNIII) is a cranial nerve that controls most of the eye's movements, as well as pupil constriction and accommodation. It originates in the midbrain, a part of the brainstem, and extends to the eye.

Anatomy

The Nervus Oculomotorius is composed of two different types of fibers: somatic and parasympathetic. The somatic fibers originate from the nucleus of oculomotor nerve, located in the midbrain, and innervate the extraocular muscles, which control the majority of the eye's movements. The parasympathetic fibers, on the other hand, originate from the Edinger-Westphal nucleus and control pupil constriction and accommodation.

Function

The primary function of the Nervus Oculomotorius is to provide motor innervation to four of the six extraocular muscles: the superior rectus muscle, inferior rectus muscle, medial rectus muscle, and inferior oblique muscle. These muscles are responsible for moving the eye in all directions except laterally. In addition, the nerve also innervates the levator palpebrae superioris muscle, which lifts the upper eyelid.

The parasympathetic component of the Nervus Oculomotorius controls the constriction of the pupil and the shape of the lens. This is achieved by innervating the sphincter pupillae muscle and the ciliary muscle, respectively.

Clinical significance

Damage to the Nervus Oculomotorius can result in a number of symptoms, including diplopia (double vision), ptosis (drooping of the upper eyelid), and mydriasis (dilation of the pupil). This can be caused by a variety of conditions, such as aneurysm, tumor, diabetes mellitus, or trauma.