A5 - Cranial nerves Flashcards
What are the names of the afferent modalities?
General somatic sensory
General visceral sensory
Special somatic sensory
Special visceral sensory
What sensations do general vs special afferent modalities transmit?
General = touch, pressure, pain, vibration
Special = vision, hearing, taste, smell
What information does SSS modality carry?
SSS: Special somatic sensory; special senses derived from the ectoderm, i.e. retina, cochlear and vestibular = sight, sound and balance
What information does SVS modality carry?
SVS: Special visceral sensory; special senses derived from the endoderm, i.e. smell and taste
What information does GSS and GVS carry?
GSS: General somatic sensory; general sensation from the skin, muscles and joints
GVS: General visceral sensory; general sensation from organs
What are the names of efferent modalities?
General somatic motor
General visceral motor
Special visceral motor
What’s the difference between general and special efferent modalities?
General = any muscle not derived from pharyngeal arches
Special = any muscle derived from pharyngeal arches, i.e. muscles of the larynx, pharynx, facial expression
What information does GSM transmit?
GSM: General somatic motor; voluntary control of skeletal muscles (including extra-ocular muscles)
What information does GVM transmit?
General visceral motor; involuntary control of smooth muscle and glands
What information does SVM transmit?
Innervates muscles derived from pharyngeal arches
For cranial nerve I:
- Name
- Exit from the skull
- Nuclei
Olfactory nerve
Exits via cribiform plate
Nuclei: olfactory bulb
What is the modality and function of cranial nerve I?
Modality = sensory (SVS)
Function = smell
For cranial nerve II:
- Name
- Exit from the skull
- Nuclei
Optic nerve
Exits via optic canal
Nuclei: lateral geniculate nucleus
What is the modality and function of cranial nerve II?
Modality = sensory (SVS)
Function = vision (innervates retina)
For cranial nerve III:
- Name
- Exit from the skull
- Nuclei
Oculomotor nerve
Exits via superior orbital fissure
Nuclei: occulomotor nuclei and Edwinger-Westphal nuclei
What is the modality and function of cranial nerve III?
Modalities = motor (GSM and SVM)
GSM function: 4 extra-ocular muscles and levator palpebrae superioris muscle
SVM function: sphincter pupillae and ciliary muscle of eye
For cranial nerve IV:
- Name
- Exit from the skull
- Nuclei
Trochlear nerve
Exits via superior orbital fissure
Trochlear nucleus
What is the modality and function of cranial nerve IV?
Modality = motor (GSE)
Function: innervates superior oblique muscle
For cranial nerve V, list its 3 main branches and their:
- Name
- Exit from the skull
- Nuclei
Trigeminal nerve, branches into ophthalmic (V1), maxillary (V2) and mandibular (V3)
V1= superior orbital fissure
V2= foramen rotundum
V3= foramen ovale
Nuclei for all: trigeminal motor and sensory nuclei
What is the modality and function of cranial nerve V1?
Ophthalmic branch of trigeminal:
Modality = GSS
Function = sensation to scalp, forehead and nose, dura mater
What is the modality and function of cranial nerve V2?
Maxillary branch of trigeminal:
Modality = GSS
Function = sensation to cheeks, lower eyelid, nasal mucosa, upper lip, upper teeth, palate
What is the modality and function of cranial nerve V3?
Mandibular branch of trigeminal:
Modality = GSS and SVM
GSS function = sensation to anterior 2/3 of tongue, skin over mandible and lower teeth
SVM function = muscles of mastication (chewing) and tensor tympani
For cranial nerve VI:
- Name
- Exit from the skull
- Nuclei
Abducens nerve
Exit via superior orbital fissure
Nuclei: abducens nucleus
What is the modality and function of cranial nerve VI?
Modality = GSM
Function = innervates lateral rectus muscle
For cranial nerve VII:
- Name
- Exit from the skull
- Nuclei
Facial nerve
Exits via internal auditory meatus then stylomastoid foramen
Nuclei: facial nucleus, nucleus solitarius and superior salivatory nucleus
What is the modality and function of cranial nerve VII?
GSS: sensation to external ear
SVS: taste from anterior 2/3 of tongue, hard and soft palate
GVM: innervation to lacrimal, submandibular, sublingual and mucous glands
SVM: facial expression muscles, stapedius
For cranial nerve VIII:
- Name
- Exit from the skull
- Nuclei
Vestibulocochlear nerve
Exits via internal auditory meatus
Nuclei: vestibular and cochlear nuclei
What is the modality and function of cranial nerve VIII?
Modality: SSS
Function: hearing and balance
For cranial nerve IX:
- Name
- Exit from the skull
- Nuclei
Glossopharyngeal nerve
Exits via jugular foramen
Nuclei: trigeminal sensory nucleus, nucleus solitarius, nucleus ambiguus, inferior salivatory nucleus
What is the modality and function of cranial nerve IX?
GSS: posterior 1/3 of tongue, external ear, middle ear cavity, eustachian tube
GVS: carotid body and sinus
SVS: taste from posterior 1/3 of tongue
GVM: parotid gland
SVM: innervates stylopharyngeus muscle and internal pharyngeal muscles
For cranial nerve X:
- Name
- Exit from the skull
- Nuclei
Vagus nerve
Exits via jugular foramen
Nuclei: trigeminal sensory nucleus, dorsal motor nucleus of vagus, nucleus solitarius and nucleus ambiguus
What is the modality and function of cranial nerve X?
GSS: external ear, larynx, pharynx
GVS: larynx, pharynx, thoracic and abdominal viscera, aortic bodies
SVS: taste from epiglottis region of tongue
GVM: smooth muscles of larynx, pharynx and most of GI tract
SVM: innervates most muscles of larynx and pharynx
For cranial nerve XI:
- Name
- Exit from the skull
- Nuclei
Accessory (spinal)
Exits via jugular foramen
Nuclei: spinal cord
What is the modality and function of cranial nerve XI?
Modality: motor (GSM)
GSM= trapezius and sternocleidomastoid
For cranial nerve XII:
- Name
- Exit from the skull
- Nuclei
Hypoglossal nerve
Exits via hypoglossal canal
Nuclei: hypoglossal nucleus
What is the modality and function of cranial nerve XII?
Modality: motor (GSM)
GSM = innervates intrinsic and extrinsic tongue muscles, except palatoglossus
What modality represents parasympathetic innervation and which cranial nerves possess this?
GSM - general somatic motor
Think 1973 - nerves 10, 9, 7, 3 = vagus, glossopharyngeal, facial, oculomotor
Describe the path of the facial nerve
1- Enters skull via internal acoustic meatus (with CN VIII) into middle ear
2- Gives off 3 branches
3- Exits via stylomastoid foramen (found on bottom of skull between styloid process and mastoid process)
4- outside the skull it wraps around to go through the parotid gland where it gives off 5 branches
What are the 3 subnuclei of the trigeminal nerve?
Chief sensory - touch and pressure
Spinal nucleus - pain and temperature
Mesencephalic - proprioceptive afferents from muscle of mastication and TMJ
What branches does the ophthalmic (V1) nerve give off?
Frontal
Lacrimal
Nasociliary
What branches does the maxillary (V2) nerve give off and where?
Gives off branches in pterygopalatine fossa:
Zygomatic
Infraorbital
Anterior, middle and posterior superior alveolar
Greater and lesser palatine
Nasopalatine
What branches does the mandibular (V3) nerve give off and where?
Gives off branches in the infratemporal fossa:
Buccal *
Deep temporal
Muscular branches
Auriculotemporal *
Lingual
Inferior alveolar
Mental *
Incisive
*= most important
What ganglion does the facial nerve form in the facial canal?
Geniculate ganglion
What are the first 3 branches of the facial nerve? Give their roles
Greater petrosal - for taste and parasympathetic
Nerve to stapedius - motor innervation
Chorda tympani - taste for anterior 2/3 of tongue and parsympathetic to sublingual and submaxillary glands
What are the 5 branches the facial nerve gives off in the parotid gland?
Temporal (frontal)
Zygomatic
Buccal
Marginal mandibular
Cervical
What is a good way to roughly see where each of the 5 facial nerve branches extends?
Hold heel of hand against ear, thumb directing up to forehead and pinky down to neck
Each finger act as a branch, i.e. thumb = temporal (forehead), index = zygomatic (just under eye), middle finger = buccal (cheek) etc.
From what part of the brainstem do cranial nerves III- XII arise?
III: midbrain- pontine junction
IV: midbrain
V: pons
VI- VIII: pons-medullary junction
IX - XI: medulla, posterior to the olive
XII: medulla, anterior to the olive
Where are the 2 roots of the spinal accessory nerve found?
Cranial root = lateral aspect of medulla, inferior part of nucleus ambiguus
Spinal root = ventral horn of grey matter between C1-C5
What muscles does the hypoglossal nerve pass between?
Between mylohyoid and hypoglossus (tongue) muscles, lies lateral to genioglossus muscle
What is papilloedema and how can it be caused?
Oedema/ swelling of the optic nerve
Caused by increased intracranial pressure, because the optic nerve is enveloped in meninges and CSF so raising the pressure pushes CSF out into the eye
Which cranial nerve is the only one to arise from the posterior aspect of the brainstem?
Trochlear
What does the trigeminal ganglion contain?
Nerve cell bodies of first order sensory neurones
What are the 2 terminal branches of the frontal branch of V1?
Supratrochlear
Supraorbital
What is the terminal branch of V2?
Infraorbital nerve
Where are nerve cell bodies of UMN that supply the lower limb located?
Precentral gyrus within longitudinal fissure
Give the location and roles of the 3 parts of the trigeminal nuclei
Mesencephalic: midbrain - proprioception
Chief: pons - touch and pressure
Spinal: medulla - pain and temperature
What does the mesencephalic nucleus contain?
Nerve cell bodies of primary neurones (not secondary like other proprioceptive pathways)
Which side would the tongue deviate to if a patient had:
- UMN lesion on R side
or
- LMN lesion on R side
UMN lesion on R side = tongue deviate to left
LMN on R side = tongue deviate to right
Which tract might transmit dull, aching pain?
Spinoreticulothalamic
