Spencer's Cranial Nerves Deck Flashcards
Which two cranial nerves are not technically “cranial nerves”?
CN I & II
The Olfactory nerve is really an extension of what part of the brain?
the Telencephalon
The Optic nerve is really an extension of what part of the brain?
the Diencephalon
Where does CN I principally exit the skull?
cribiform foramina
Where does CN I synapse?
the olfactory bulb and tract
Where does sensory input for CN I first arise?
receptors in the nasal cavity
What clinical presentations would follow loss of function of CN I?
anosmia
Where does CN II first receive sensory input?
the retina
What specific type of sensory information is relayed by CN I & II
special sensory
What pathway of the optic nerve lies between the optic canal and optic tract?
the optic chiasm
What clinical findings would follow a loss of function of CN II?
blindness, loss of pupillary light reflex, and visual field problems
Where does CN III originate?
the midbrain
Where does CN II principally exit the skull?
the optic canal
Where does CN III principally exit the skull?
the superior orbital fissure (SOF)
CN III has somatic motor innervation of which extraoccular muscles?
inferior oblique, inferior rectus, medial rectus, superior rectus and the levator palpebrae superioris
CN III has visceral motor innervation of which eye structures?
sphincter pupillae (constrictor) and ciliary muscle (accomodation)
What are the clinical findings following a loss of function in CN III?
Ptosis, mydriasis, loss of pupillary light reflex,and eyes move down and out
Where do the visceral motor neurons in CN III synapse?
the ciliary ganlgion
Where does CN IV orginate in the brain?
the midbrain
Through which cranial fossa does CN IV exit through?
the Superior orbital fissure (SOF)
Which muscle is innervated by the CN IV somatic motor division?
the superior oblique
What clinical findings would follow a loss of function to CN IV?
Inability to look inferiorly and medially
What is the origin of CN VI in the brain?
the pons
Through which cranial fossa does CN VI exit?
the superior orbital fissure (SOF)
Which muscle is innervated by the CN VI somatic motor division?
the lateral rectus
What clinical findings would follow a loss of function of CN VI?
inability to look laterally
Where does CN V originate?
the pons
What are the names of the three branches of CN V?
Ophthalmic branch (V-1), Maxillary branch (V-2), Mandibular branch (V-3)
Through which cranial fossa does CN V-1 exit the skull?
the Superior orbital fissure
CN V-1 provides sensory innervation of what areas?
the scalp, forehead, upper eyelid, cornea, and bridge of the nose
Through what cranial fossa does CN V-2 exit the skull?
the foramen rotundum
What areas does CN V-2 provide sensory innervation of?
the sides of then nose, lower eyelid, upper lip, maxillary teeth, gums, palate, nasal cavity and paranasal sinuses
Through which structure does CN V-2 pass to innervate the skin of the face?
the infraorbital foramen
Through which cranial fossa does CN V-3 exit the skull?
foramen ovale
To which structures does CN V-3 provide sensory innervation?
lower lip, mandibular teeth, gums, palate, anterior tongue
Through which structure does CN V-3 pass to innervate the skin of the chin?
mental foramen
To which major muscles does CN V-3 provide somatic motor innervation?
the temporalis and masseter (elevate mandible) and the medial and lateral pterygoid muscles (side to side motion of mandible)
To which additional muscles does CN-V3 provide somatic motor innervation?
tensor tympani, tensor veli palatini, mylohyoid, and anterior digastric muscles
What constitutes a consensual reflex?
a reflex in which triggering one side of the body will also trigger the reflex on the other side
Before reaching its branch point, CN VII passes through what foramen of the skull?
internal acoustic meatus
Where does CN VII originate in the brain?
the pons
What is the path of the facial nerve proper after the branch point?
stylomastoid foramen -> parotid gland -> 5 branches to muscles of facial expression
the facial nerve proper provides what type of innervation?
branchial motor innervation to the muscles of facial expression
What clinical findings would accompany a disruption in or loss of function of the facial nerve proper?
facial palsy
What are the three main branches of CN VII?
facial nerve proper, chorda tympani nerve, and greater petrosal nerve
What is the pathway of the chorda tympani nerve after the branch point?
tympanic membrane -> petrotympanic fissure -> paired pathway with lingual branch of CN V-3
What type of innervation is provided by the chorda tympani nerve?
VM- submandibular & sublingual salivary glands SS- taste for anterior 2/3 tongue
What clinical findings would accompany a disruption in or loss of function of the chorda tympani nerve?
loss of taste and reduced salivation
What is the pathway of the greater petrosal nerve after the branch point?
palatine branches
What type of innervation is provided by the greater petrosal nerve?
VM- lacrimal, nasal, palatine glands SS- taste from palate
What clinical findings would accompany a disruption in or loss of function of the greater petrosal nerve?
loss of lacrimation, dry nasal cavity
What is the pathway that sensory information relayed by CN VIII travels to reach the brain?
cochlea & SC canals -> internal acoustic meatus -> pons
What type of information is relayed to the brain by CN VIII?
SS- hearing and balance
Which nuclei of CN VIII relay information about sound? To which part of the brain?
cochlear nuclei; pons
Which nuclei of CN VIII relay information about balance? To which part of the brain?
vestibular nuclei; pons & medulla oblongata
What clinical findings would accompany a disruption in or loss of function of CN VIII?
loss of hearing and balance (equillibrium)
Where do CN IX & X originate in the brain? Where do they exit the skull?
medulla; jugular foramen
What functions are innervated by CN IX?
BM- stylopharyngeus VM- parotid gland SS- taste for posterior 1/3 tongue GS- posterior 1/3 tongue, oral pharnyx VS- carotid sinus & body
What functions are innervated by CN X?
BM- muscles of palate, pharynx, larynx VM- thoracic & abdominal viscera GS- laryngopharnyx, larynx VS- thoracic & abdominal viscera
Where does CN XI orginate in the brain and through what pathways does it exit the skull?
upper cervical spinal cord & medulla; foramen magnum & jugular foramen
What type of innervation is provided by CN XI?
BM- sternocleidomastoid & trapezius
What clinical findings would accompany injury or loss of function of CN XI?
difficulty shrugging shoulders or rotating head to look over opposite shoulder
Where does CN XII orginate in the brain, and how does it exit the skull?
medulla; hypoglossal canal
What innervation is provided by CN XII?
SM- control of tongue movements (genioglossus muscle)
What clinical findings would accompany an injury or loss of function to CN XII?
loss of motor function to tongue; tongue deviates to one side when outside of mouth
The phrase “lick your wound” applies to the scenario of an injured/impinged CN XII how?
The tongue deviation, when outside of mouth, will be to the side that is injured. I.e. right injury -> right deviation
What are the five branches of the facial nerve proper?
temporal, zygomatic, buccal, marginal mandibular and cervical
The greater petrosal nerve joins what other nerve as it courses superiorly to the lacrimal gland?
the maxillary branch of the trigeminal nerve (CN V-2)
The chorda tympani nerve joins what other nerve as it courses to the tongue?
the mandibular branch of the trigeminal nerve (CN V-3)
Which two nerves are involved in the corneal reflex?
CN V-1 (sensory) and the chorda tympani (CN VII) (motor)
Where do all sympathetic nerves in the head orginate?
T1 spinal cord
Which cranial nerves have parasympathetic activity?
CN III, VII, IX, and X
