Cranial Nerves Flashcards
What do the cranial nerves supply?
Somatic and visceral motor and sensory information to the head.
Which cranial nerves supply visceral sensory and motor innervation to the neck, chest and abdomen?
CNIX and CNX
Which cranial nerves are purely sensory?
CNI, II and VIII
Which cranial nerves are purely motor?
CNIII, IV, VI, XI and XII
Which cranial nerves are mixed sensory and motor?
CNV, VII, IX and X
Why do the mixed cranial nerves have multiple functions?
Because each cranial nerve contains many functional groups of fibres.
What are cranial nerves connected to centrally?
Cranial nerve nuclei
How are the cranial nerve nuclei organised?
Rostral to caudal roughly in order of the target tissues they are associated with, in columns of similar function.
Where are the motor nerve nuclei located in the brainstem?
In 3 columns close to the midline.
How are the 3 motor nerve nuclei columns arranged from medial to lateral?
Somatic, Branchial (gill) and visceral (autonomic)
Which structures are innervated by somatic motor nerves?
Extra-occular muscles and muscles of the tongue.
Which cranial nerves innervate the extra-occular muscles?
CNIII Occulomotor
CNIV Trochlear
CNVI Abducens
Which cranial nerve innervates the muscles of the tongue?
CNXII Hypoglossal
Which structures are innervated by branchial arch nerves?
Muscles of mastication
Muscles of facial expression
Muscles of pharynx and larynx
Which cranial nerve supplies the muscles of mastication?
Mandibular division of CNV (Trigeminal)
Which cranial nerve supplies the muscles of facial expression?
CN VII (Facial nerve)
Which cranial nerves supply the muscles of the pharynx and larynx?
CNIX (Glossopharyngeal nerve) and CNX (Vagus)
What is nucleus ambiguus?
Mostly a motor nucleus that lies behind the inferior olive.
It is the nucleus for CNIX (stylopharyngeus muscle) and CNX (levator palati muscle) that controls the pharynx and larynx.
What do the visceral efferents innervate?
Smooth muscles (autonomic)
Which nuclei comprise the visceral efferents?
CNIII - Edinger-Westfal nucleus
CNVII - Superior salivatory nucleus
CNIX - Inferior salivatory nucleus
CNX - Dorsal motor nucleus of the Vagus
Where are sensory nuclei located in the brainstem?
In 3 columns lateral to the medial 3 motor columns.
How are the 3 sensory nerve nuclei columns arranged from medial to lateral?
Visceral sensory
Somatic sensory
Special sensory
Which structures are innervated by the visceral afferent nerves?
Taste
Autonomic
Which cranial nerves are responsible for taste visceral afferents?
CNVII (Facial)
CNIX (Glossopharyngeal)
CNX (Vagus)
Which cranial nerves are responsible for autonomic visceral afferents?
CNX (Vagus)
CNIX (Glossopharyngeal)
How many nuclei are there in the visceral sensory column?
One (does both taste and autonomic from CNVII, IX and X)
Which nucleus is responsible for general visceral sensation in the visceral sensory column?
Nucleus solitarius
Where does the nucleus solitarius extend between?
From the pons to the level of nucleus gracilis
What are the two divisions of nucleus solitarius
Rostral: gustatory nucleus Caudal: visceral sensory division
What does the rostral aspect of nucleus solitarius contain?
Gustatory nucleus: Primary afferents receiving input from taste buds and the palate (i.e.CNVII, IX and X)
What does the caudal aspect of nucleus solitarius contain?
Visceral sensory division: CNX: afferents from heart; abdominal viscera
CNIX: baroreceptors & chemoreceptors from carotid body and sinus
What does the somatic sensory column receive sensory information on?
Sensation to face, forehead, mucosa of nose & mouth, most of cranial dura: CNV (Trigeminal)
Skin behind ear and lining of external auditory meatus: CNVII (Facial), CNIX (Glossopharyngeal) and CNX (Vagus)
Which cranial nerves does the somatic sensory column receive information from?
CNV (Trigeminal)
CNVII (Facial)
CNIX (Glossopharyngeal)
CNX (Vagus)
Which sensory information does the special sensory column receive?
Smell: CNI (Olfactory)
Vision: CNII (Optic)
Hearing & Equilibrium: CNVIII (Vestibulocochlear)
Which cranial nerve nuclei arise originate from the midbrain?
CNIII and IV
Which cranial nerve nuclei arise originate from the pons?
CNV, VI, VII and CNVIII
Which cranial nerve nuclei arise originate from the medulla?
CNVIII, CNIX, CNX and XII
Which cranial nerves does nucleus solitarious receive?
Visceral afferents: CNVII, IX and X
Which cranial nerves does nucleus ambiguus receive?
Motor: CNIX and X
What is CNI’s name?
Olfactory
What is CNII’s name?
Optic
What is CNIII’s name?
Oculomotor
What is CNIV’s name?
Trochlear
What is CNV’s name?
Trigeminal
What is CNVI’s name?
Abducens
What is CNVII’s name?
Facial
What is CNVIII’s name?
Vestibulocochlear
What is CNIX’s name?
Glossopharyngeal
What is CNX’s name?
Vagus
What is CNXI’s name?
Accessory
What is CNXII’s name?
Hypoglossal
What causes the most common disruption to CNI?
Common cold
Which nerve is the olfactory nerve?
CNI
What does the olfactory nerve do?
Sense of smell (special sensory column)
Where does the olfactory nerve exit the skull?
Cribiform plate
Where does the olfactory nerve project to in the brain?
Gustatory cortex in the insular cortex
Which nerve is the optic nerve?
CNII
What type of nerve is the optic nerve?
Special sensory
What does the optic nerve do?
Vision
Where does the optic nerve project to in the cortex?
V1 in the occipital lobe
What cells in the retina are responsible for light transduction?
Ganglion cells
What happens to some axons of the optic nerve within the optic chiasm?
They cross
Where do optic nerve axons travel to after the optic chiasm?
To the lateral geniculate nucleus within the thalamus
Where do axons project to after the lateral geniculate nucleus?
Visual cortex (V1)
What are the 6 extra-ocular mucles?
Superior rectus; inferior rectus Medial rectus; lateral rectus Superior oblique; inferior oblique
What are the 3 cranial nerves of ocular motion?
CNIII - Oculomotor
CNIV - Trochlear
CNVI - Abducens
What do the nerves to extra-ocular muscles do?
Act in a coordinated fashion
Where do the nerves to extra-ocular muscles exit the skull?
Superior orbital fissue
Where does the optic nerve exit the skull?
Optic canal
Which extra-ocular muscles does the trochlear nerve innervate?
Superior oblique
Which extra-ocular muscles does the abducens nerve innervate?
Lateral rectus
Which nerve is the oculomotor nerve?
CNIII
What type of nerve is the oculomotor nerve?
Somatic motor and visceral motor (PS)
What does the oculomotor nerve do?
Motor: extra-ocular eye muscles MR, SR, IR and IO Elevates eye-lid via levator palpebrae superioris
PS to eye: - Iris (pupils) - Ciliary muscle (focussing)
In which brainstem column do the oculomotor nerves involves in PS to the eye sit?
Visceral efferent column
Where do all 3 extraocular motor nerves travel?
Go through the cavernous sinus and superior orbital fissure.
III and VI go through the common tendinous ring.
Which nerves enter the orbit via the superior orbital fissure?
CNIII, IV, VI and V1
Where is the superior orbital fissure located?
Between the greater and lesser wings of sphenoid.
What do cranial nerves often exit in?
Groups
Which cranial nerves exit the skull via the auditory canal?
CNVII and VIII
Which cranial nerves exit the skull via the jugular foramen?
CNIX, X and XI
Which cranial nerve exits the skull via the hypoglossal foramen?
CNXII
Which nerves are involved in the pupillary light reflex?
Sensory inputs to brain from the retina via CNII.
Motor outputs to Sphincter Pupillae muscle in iris.
PS fibres from Edinger Westfal nucleus.
Which nerve is the trigeminal nerve?
CNV
What type of nerve is the trigeminal nerve?
Somatic sensory and branchial motor
What does the trigeminal nerve do?
Sensory: input from the face and inside of mouth Motor: muscles of mastication. Tensor tympani (inner ear)
Where do the trigeminal nuclei run?
From midbrain to upper spinal cord
What are the 4 nuclei within the trigeminal nucleus?
Mesencephalic
Chief sensory
Spinal trigeminal nucleus (STN)
Motor nucleus
What do the chief sensory and STN nuclei of the trigeminal nucleus provide?
Sensory system to the face and head.
What are the chief sensory and STN nuclei of the trigeminal nucleus analogous with?
Dorsal column and anterolateral system.
What does the motor nucleus of the trigeminal nucleus provide?
Motor (branchial) efferents (located closer to midline)
What are the roots that the trigeminal nerve exits the brainstem as?
Motor and sensory
Where do the sensory roots of the trigeminal nerve travel to?
Trigeminal ganglion
What does the trigeminal ganglion give off?
3 Branches:
V1 - ophthalmic division
V2 - maxillary divison
V3 - mandibular division
With which division does the motor branch of the trigeminal nerve travel?
Mandibular division
What does the motor division of the trigeminal nerve innervate?
Muscles of mastication and tensor tympani (inner ear)
Where do the branches of the trigeminal nerve exit the skull?
V1: Superior orbital fissure
V2: Foramen rotundum
V3: Foramen ovale
What is involved in the corneal blink reflex?
Sensory inputs to brainstem via CNV1.
Motor outputs to eyelid (obicularis oculi) via CNVII.
Used as a test of pontine function.
Which nerve is the facial nerve?
CNVII
What type of nerve is the facial nerve?
Branchial motor
Visceral efferent
Visceral sensory (taste)
Somatic sensory
What are the two functional divisions to the facial nerve?
Motor (facial nerve proper) nervus intermedius: parasympathetic, taste and sensation.
What does the motor component of the facial nerve do?
Branchial motor: innervates the muscles of facial expression, stapedius muscle (ear) and part of digastric muscle.
What does the nervus intermedius component of the facial nerve do?
Provides information on:
Parasympathetic: lacrimal, sublingual and submandibular glands
Taste: from anterior 2/3rds of tongue and soft palate
Sensation: from a small region near the external auditory meatus.
What are the terminal branches of the facial nerve that innervate muscle?
Posterior auricular
Temporal
Zygomatic
Buccal
Mandibular
Cervical
What role does the facial nerve play in the corneal reflex?
It closes the eye via the temporal branch.
What do the terminal branches of the facial nerve all pass through?
The parotid
True or false: the facial nerve innervates the parotid.
False.
Which cranial nerve is the vestibulocochlear nerve?
CNVIII
What does the vestibulocochlear nerve do?
Hearing and balance
What type of nerve is the vestibulocochlear nerve?
Special sensory
Which nuclei give rise to the vestibulocochlear nerve?
Dorsal and ventral cochlear nuclei and 4 vestibular nuclei.
Where does the vestibulocochlear nerve exit the skull?
Internal acoustic meatus
What is the most common cause of gradual hearing loss?
Acoustic neuroma
Which cranial nerve is the glossopharyngeal nerve?
CNIX
What does the glossopharyngeal nerve do?
Sensory from tongue (post. 1/3), pharynx, middle ear and carotid body.
Taste: post. 1/3 of tongue
Visceral motor: PS to parotid
Motor: stylopharyngeus
Where does the glossopharyngeal nerve exit the skull?
Jugular foramen
Where does the glossopharyngeal nerve exit the skull in relation to CNX and CNXI?
In the jugular foramen, lateral and anterior to CNX and CNXI.
What is the pathway of the glossopharyngeal nerve?
Exits the skull via jugular foramen and follows stylopharyngeus muscle to reach the oropharynx and the tongue.
What are the nuclei giving rise to the glossopharyngeal nerve?
Superior and inferior ganglia (containing afferent components of the nerve).
Which cranial nerve is Vagus?
CNX
What type of nerve is Vagus?
Branchial motor
Visceral motor (PS)
Somatic sensory
Visceral sensory (special) taste
Visceral sensory (general)
What does vagus do?
Motor: to many striated muscles - soft palate, pharynx, larynx, upper oesophagus and 1 tongue muscle.
PS to many organs: from pharynx to upper abdomen
Sensory: from pharynx, larynx and oesophagus
Visceral: input from baro- and chemoreceptors of the aortic arch.
What is the majority of Vagus’ function?
Autonomic
Which pathways are involved in the gag reflex?
Sensory inputs: CNIX - sensory to pharynx
Motor outputs: CNX - motor to pharynx
What is the gag reflex used to test?
Medulla function
Which cranial nerve is the spinal accessory nerve?
CNXI
Where is the spinal accessory nucleus?
In the upper 5-6 of cervical spinal cord.
What is the course of the spinal accessory nerve?
Enters cranium via foramen magnum and then travels with CNX roots and exits at the jugular foramen.
What does the spinal accessory nerve do?
Provides motor input to sternocleidomastoid and upper part of trapezius.
Which cranial nerve is the hypoglossal nerve?
CNXII
What type of nerve is the hypoglossal nerve?
Somatic motor
What does the hypoglossal nerve do?
Motor innervation to intrinsic and extrinsic muscles of the tongue (except palatoglossus - CNX). It is the main somatic nerve to the tongue.
Where does the hypoglossal nerve exit the skull?
Hypoglossal foramen
