Eye autonomics Flashcards
What tends to happen to the zygomatic bone when it is fractured?
rotate medially towards floor of orbit
Why might a zygomatic fracture cause the eye to be lowered to the floor?
the suspensory liagment of the eye attaches to the zygoma laterally so gets pulled down with the zygoma (rotates into floor of orbit when fractured)
What may be damaged in a zygomatic fracture?
the infraobital NVB
What would daamge of infraorbital NVB cause?
a general sensory deficit of facial skin
Where does the ophthalmic nerve supply sensory to the face?
upper eyelid; cornea; conjuctiva; root, bridge and tip of the nose
Where does the maxillary nerve supply sensory to the face?
skin of lower eyelid; skin over maxilla; skin of ala of nose; skin/mucosa of upper lip
Where does the mandibular nerve supply sensory to the face?
skin over mandible and TMJ (apart from angle of mandible)
What supplies the skin over the angle of the mandible?
C2, C3
What is the afferent limb of the blink reflex?
centrally via C1 (long ciliary nerve) to trigeminal gangion then in CNV to pons
What is the efferent limb of the corneal reflex?
conducted in CNVII to palpebrae part of orbicularis oculi
How do sympathetic axons reach the eye from the brain?
exit via T1 spinal nerve and synapse in superior cervical ganglion then internal carotid nerve to plexus on ICA then follow ophthalmic artery
What is the stellate ganglion?
if the inferior cervical and 1st thoracic ganglia fuse
Where is the sympathetic chain?
posteior wall of mediastinum
What is the largest cervical ganglion?
superior
Aside from cranial nerves, what other nerves carry parasympathetics?
sacral spinal nerves
What do the parasympatheticsin the sacral spinal nerves supply?
hindgut; pelvis and perinuem
Where are the parasympathetic ganglions?
in the organ or isolated
Where does CNIII connect with CNS?
near midline at the junction between the midbrain and pons
What is the most superiorly positioned nerve entering the superior oribtal fissure?
CNIII
What are the actions of CNIII?
motor to SR; MR; IR and IO and LPS; presynaptic parasymp axons to the ciliary ganglion
What is the oculocardiac refleX?
reflex bradycardia in response to tension on the extraocular muscles or pressure on the eye
What are the nerves involved in the the oculocardiac reflex?
V1 and X
What are the sympathetic functions in the eye?
open eyes wider (muller muscle)
get more light into eyes( dilator pupillae)
and focus on far objects (ciliary muscles)
emotional lacrimation (goes with CNVII from pterygoid ganglion)
What is a non-physiologically enlarged pupil?
mydriatic
What is a non-physiologically constricted pupil?
miotic
What is the afferent limb of the pupil reflex?
ipsilateral CNII
Where is the CNS connection for the pupil reflec?
thalamus
What is the motor limb of the reflex?
oculomotor
What is hte reflex in the stimulated eye called?
direct
what is the reflexin the non-stimulated eye?
consensual
Where do the axons in the pupillary reflex synapse?
pretectal nucleus in midbrain
Where is the location of hte cell bodies of the parasympathetic axons of CNIII?
edinger westphal nucleus
What nerve carries the CNII parasympathetics to the sphincter pupillae msucle?
short ciliary nerve
What is the shape of the lens in distant vision?
flattened
what is the shape of the lens in close vision?
spherical
When the ciliary muscles contract, how does this affect the lens?
makes the lens fatter and more spherical
Waht happens when the ciliary muscles relax?
ligament tightens and lens flattens
What are the 3 components of the accomodation reflec?
bilateral pupillary constriction; bilateral convergence; bilateral bilateral relaxtion of the lens
Why do the pupils constrict in accomodation?
prevent divergin rays fro mhitting hte periphery of the retina and resulting in a blurred image
What is the accomodation reflex?
response to near
What is the afferent limb in reflex tearS?
CN V1
What is the efferent limb in the reflex tears?
CNVII (orbicularis oculi
