Page 199 - Edited - Webster HEAD AND NECK - part 1

HN 165

SCHEME OF THE OCULOMOTOR NERVE
(CRANIAL NERVE III)

INTRACARNIUM ORBIT

SKELETOMOTOR COMPONENT
TO FOLLOWING MUSCLES
RECTUS MEDIUS
RECTUS SUPERIOR
RECTUS INFERIOR
INFERIOR OBLIQUE
MID- LEVATOR PALPEBRAE SUPERIORIS
BRAIN (CHOLINERGIC NICOTINIC
RECEPTORS, CURARE
SENSITIVE).

K.E.W.
PARASYMPATHETIC MOTOR
COMPONENT TO SMOOTH
MUSCLE OF
CILIARY BODY (HN 163; 164 Figs. A.&B.)
PRESYNAPTIC
PARASYMPATHETIC CONSTRICTOR PUPILLAE (IN IRIS) (HN164
CELL BODIES - Fig. C.) (CHOLINERGIC MUSCARINIC
EDINGER-WESTPHAL RECEPTORS, BLOCKED BY ATROPINE)
NUCLEUS (OPIATE
RECEPTORS, DRIVEN BY
MORPHINE, HEROIN etc.)
CILIARY GANGLION
ON BRANCH OF OF OCULOMOTOR
NERVE IN ORBIT: SYNAPTIC,
PARASYMPATHETIC GANGLION
(CHOLINERGIC RECEPTORS OF
AUTONOMIC SUB-TYPE).

Stimulating the parasympethetic component (e.g. morphine) will therefore lead to
CONSTRICTED, FIXED PUPILS’ SEE HN 174 et seq.
SHORTSIGHTEDNESS

Blocking or eliminating the parasympathetic component (e.g. atropine) will therefore lead to
DILATED, FIXED PUPIL(S)
LONGSIGHTEDNESS SEE HN 174 et seq.

Eliminating the skeletomotor component will leave the eye(s) to be moved by only the lateral
rectus (CrNVI-abducent nerve) and the superior oblique (CrNIV-trochlear nerve) - SEE HN 176.

NB In order to reach their targets in the anterior chamber the postsynaptic parasympathetic
fibres take advantage of the fact that the sensory innervation of the sclera and cornea is the ophthalmic
trigeminal (V1) nerve, specifically the naso-ciliary nerve. The postsynaptic parasympathetic axons from
the ciliary ganglion “hitch a lift” with this nerve (en route) for the nose, which is why it is called the
“naso-ciliary” nerve (ΗΝ 196-7). For significance of this SEE HN 198.

K.E.W.