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Equine Nervous System - Horse Anatomy (view source)
Revision as of 15:27, 21 November 2012
, 15:27, 21 November 2012→Oculomotor nerve (III)
====Oculomotor nerve (III)====
====Oculomotor nerve (III)====
The oculomotor nerve is part of the group of cranial nerves responsible for innervating the [[Skull and Facial Muscles - Anatomy & Physiology#Facial_Muscles|muscles of the head]]. The nerve originates from the ventral [[Midbrain - Anatomy & Physiology|midbrain]] and is a motor nerve. It is composed of '''general somatic efferent fibres''' and '''general visceral efferent fibres'''. The general somatic efferent fibres of the oculomotor nerve are responsible for the motor function of four of the six [[Eye - Anatomy & Physiology#Around_the_Eye|external muscles of the eyeball]]; the 'dorsal rectus', 'medial rectus', 'ventral rectus', 'ventral oblique' and 'levator palpebri superioris' (levator of the upper eyelid). The general visceral efferent fibres of the oculomotor nerve are responsible for the control of pupil diameter and therefore control the 'spincter pupillae' muscle and the 'ciliaris' muscle. These fibres control pupillary constriction via the parasympathetic component of the nerve.
The oculomotor nerve has a pre-ganglionic nucleus in the midbrain and the nerve passes through the [[Skull_and_Facial_Muscles_-_Anatomy_%26_Physiology#Major_Foramen_and_Canals|'''orbital fissure''']], along with the trochlear, abducens and opthalmic branch (V1) of the trigeminal nerve. It synapses in the ciliary ganglion of the eye.
During a clinical examination, horizontal eye movements (strabismus) or an absent [[Neurological_Eye_Examination_-_Horse#The_pupillary_light_reflex_(PLR)|pupillary light reflex (PLR)]] may indicate a problem.
====Trochlear nerve (IV====
====Trochlear nerve (IV====
====Trigeminal nerve (V)====
====Trigeminal nerve (V)====