What are the important reflexes of the orbit? Flashcards
Sympathetic functions and the pupil
Eye gets wider
Focuses on far objects
Parasympathetic function and the pupil
Less light into the eye
Focuses on near objects
Reflux lacrimation
Long ciliary nerve
First part of the afferent limb of the blink (corneal reflex)
Oculocardiac reflex
the oculocardiac reflex
- reflex bradycardia in response to tension on the extraocular muscles or pressure on the eye
- CNS connections between CN V1 & CN X
Vestibulo-ocular reflex
III, IV, VI, VIII
3, 4, 6, 8 who do we appreciateee
How do post synaptic fibres reach the levator palpebrae superioris?
superioris via:
the superior cervical sympathetic ganglion
the internal carotid nerve the internal carotid plexus
axons carried on the ophthalmic artery…
and on its branches to the orbital structures
Dilator pupillae fibres insertion?
Insert around internal/external circumference
“fixed-dilated” (“blown” pupil)
Often a serious pathological sign
e.g. CNIII pathology
(inhibiting the pupillary constricting action of parasympathetic axons in the ciliary nerves)
Location of the cel bodies of the parasympathetic axons of CNIII?
Edinger Westphal nucleus
These neurones are located entirely within the midbrain
2nd neurones
1st neurones
The retinal ganglion cells (synapse in the pretectal nucleus)
Where do the third neurones synapse?
Third neurones pass via CN III (inferior division)
Synapse in the ciliary ganglion
Which nerves do the 4th neurones course through? and WHERE DO THEY GO TO?
The ciliary nerves
to the SPHINCTER PUPILLAE MUSCLES
Ciliary muscles relax or flatten in “far vision”
Relax in far vision (no parasympathetic)
Ciliary muscle contracts in near vision and the lens become spherical to focus on near objects
Name the 3 components assessed in the accomodation reflex
bilateral pupillary constriction (CNs III)
bilateral convergence - medial rotation of both eyes (CNs III)
bilateral relaxation of the lens
the lens becomes spherical due to contraction of the ciliary muscles (CNs III)
