18 - Cranial Nerves 2 Flashcards
Role of CNI (olfactory nerve).
Sense of smell (special sensory)
Where does CNI exit the skull?
Cribiform plate
Role of CNII (optic nerve)
Vision (special sensory)
Where does CNII exit the skull?
Optic canal
Where do visual afferents cross over?
Optic chiasm
Number of extraocular muscles
Six
Extraocular muscles
1 - 6
Rectus muscles Superior rectus, inferior rectus Medial rectus, lateral rectus Oblique muscles Superior oblique Inferior oblique
Where do CNIII, IV and VI exit the skull?
Superior orbital fissure (CNV also travels through here)
Role of CNVI (abducent)
Moves eyes laterally (abducts)
Role of CNIII
Constriction of pupil.
Gives parasympathetic innervation to these muscles.
Innervates superior, inferior and medial rectus muscles of eye and inferior oblique muscle of eye.
Levator palpebrae superioris (elevates eyelid)
Type of nerve that CNIII is
Somatic nerve.
Visceral motor.
Role of CNIII
Motor - extraocular muscles, elevates eyelid.
Parasympathetic innervation to eye - Iris (pupillary constriction), ciliary muscle (focussing)
Muscle that elevates eyelid
Levator palpebrae superioris
Do nerve nuclei in the brain stem serve one or more purposes?
One. EG: motor nerves from one nucleus, sensory nerves from one nucleus. These do not emerge from a single nucleus.
CN exiting skull through cribiform plate
CNI
CN exiting skull through optic canal
CNII
CNs exiting skull through superior orbital fissure
CNIII, IV, VI, V(1)
CN exiting skull through auditory canal
CNVII, VIII
CN exiting skull through jugular foramen
CN IX, X, XI
CN exiting skull through hypoglossal formaen
CNXII
Pupillary light reflex
•Sensory inputs to brain from retina via CNII.
•Motor outputs to Sphincter Pupillae muscle in iris:
– Parasympathetic fibres from Edinger Westfal nucleus (CNIII).
Where does VZV sit dormant?
Sensory ganglia (dorsal rot ganglia, trigeminal nerve ganglia)
CNV is what type of nerve?
Somatic sensory and brachial motor
Role of CNV
1
2
3
Sensory input from the face, inside mouth.
Muscles of mastication (motor)
Tensor tympani (middle ear)
Number of branches of trigeminal nerve
Three