Oculomotor nerve palsy results in
T F
Answer
a. T
b. F
c. F
d. T
e. F
Discussion
Anatomy of occulomotor nerve
The occulomotor nerve( 3rd Cranial nerve ) has two nucleus
1. Main motor nucleus
2. Parasympathetic nucleus
Main motor nucleus
- Situated anterior to the cerebral aqueduct at superior coleculus level of the mid brain
- Receives corticonucalear fibers from both cerebral hemispheres
- Supply levator palpebrae superioris and all the extrinsic muscle except lateral rectus and superior oblique muscle.
Parasympathetic nucleus (Edinger-Westphal nucleus)
- Is situated posterior to the main motor nucleus
- Receives corticonuclear fibers for the accommodation reflex
- Receives fibers form pretectal nucleus for the direct and consensual light reflex
- Preganglionic fibres leave the Edinger-Westphal nucleus and synapse with postganglionic fibers at cilliary ganglion
- Postganglionic fibers supply to the constrictor papillae and the ciliary muscle via short ciliary nerves
Function of occulomotor nerve
Main motor nucleus supply all the extra ocular muscle except lateral rectus and superior oblique muscle
- Levator palpebrae superioris– elevate upper eye lid
- Superior rectus- Elevation, adduction, medial rotation of eyeball
- Medial rectus – Adduction of eyeball
- Inferior rectus- Depression, adduction, lateral rotation of eyeball
- Inferior oblique- Elevation, abduction, lateral rotation of eyeball
Parasympathetic nucleus
- Constricts pupil
- Accommodates eye
Clinical features of complete occulomotor nerve palsy
- .Ptosis – due to paralysis of levetor palpebrae superioris
- Downward and lateral rotation of eye- due to paralysis of all extra ocular muscle except lateral rectus and superior oblique muscle
- Dilatation of pupil (Mydriasis )- due to loss of action of parasympathetic fibers on constrictor papillae
- Loss of accommodation
- Double vision ( diplopia )