easyhumanatomy: how to identify lesion of nerves supply extraocular muscles of eye in an easiest way ?

Wednesday, May 1, 2024

The trochlear nerve innervation, functions of muscles and lesion

	Innervation	Function	Lesion
Extraocular muscle	Superior oblique	Intorsion (medial rotation), depression and abduction, respectively.	Trochlear nerve palsy results in upward deviation of the eye (hypertropia).

The abducent nerve innervation, functions of muscles and lesion

	Innervation	Function	Lesion
Extraocular muscle	Lateral rectus	Abducts the eyeball.	Trochlear nerve palsy results in upward deviation of the eye (hypertropia).

Lesion of oculomotor nerve

The oculomotor nerve innervation, functions of muscles and lesion :

Lesion of this nerve make eye down and out

	Innervation	Function	Lesion
Muscle of eyelid	Levator palpebrae superioris	raises the upper eyelid	Ptosis: Drooping of the eyelid due to weakness or paralysis of the muscle responsible for elevating the upper eyelid (levator palpebrae superioris).
Extra-ocular muscle	Superior rectus muscle	eye rotates upward	Lateral strabismus/squint: due to paralysis of medial rectus and unopposed action of lateral rectus muscle which is supply by abducens nerve Diplopia on looking medially and superiorly.
	Medial rectus muscle	adducts the eye toward the nose
	Inferior rectus muscle	rotates the eyeball down"
	Inferior oblique	Extortion(lateral rotation) , elevation, and abduction.
Muscle of pupil	Sphincter papillae	Constriction of pupil (miosis)	Dilated pupil (mydriasis): Loss of pupillary constriction due to paralysis of the sphincter pupillae muscle, which is innervated by the oculomotor nerve.
Muscle alter curvature of lens	Ciliary muscle	Contraction of this muscle relax suspensory ligament, so diameter of lens increase during near vision (accommodation)	Loss of accommodation: due to paralysis of medial rectus, sphincter papillae and ciliaris muscles.

Lesion of nerves supply extraocular muscle