Cranial nerves Flashcards
Type(s) of information (modality) from the olfactory nerve?
SVA (special visceral afferent)
Visceral because the sense of smell is from epithelia where things are dissolved in solution)
Where are the olfactory receptors located?
Around the superior nasal conchae
What path does the olfactory nerve follow from the receptors?
- Receptors at superior nasal conchae
- Olfactory bulb (through cribriform plate of the ethmoid bone)
- Mostly through the lateral olfactory stria
- To the primary olfactory area and the uncus
Why is there a strong emotional response to many olfactory stimuli?
Due to the connections of the olfactory pathways strong association with the limbic system, more specifically the amygdala (emotion) and the hippocampus (memory)
What type(s) of information (modality) is carried by the optic nerve?
SSA - Special Somatic afferent
Fibres from which field of eye remain uncrossed and which cross at the optic chiasm?
Fibres from the Nasal field cross
Fibres rom the Temporal field do not and join with Nasal field fibres to form the optic tract.
What is the path that the optic nerve follows from the receptors in the retina?
Ganglionic layer of cells in retina
The optic nerve
The optic chiasm (nasal fibres cross)
The optic tract
The Lateral Geniculate Nucleus of the Thalamus
Genicular-calcarine tract
Only 80% of fibres from the optic tract terminate at the LGN in the thalamus, where do the other 20% go, what are they involved in?
The other 20% travel to the edinger westphal nucleus at the level of the superior colliculus, where they are involved in visual reflexes like the accommodation reflex, and pupillary light reflex.
What type(s) of information (modality) is carried by the occulomotor nerve?
GSE and GVE
General Somatic Efferent as it carries motor innervation to some of the extra-oscular muscles
GVE as it also has parasympathetic fibres that travel to the ciliary ganglion in the orbit
Where is the oculomotor nerve nucleus?
The periaqueductal grey matter of the midbrain (surrounding the central aqueduct at the level of the superior colliculus
What nerve innervates the muscle that lifts the eyelid and what muscle is this?
The oculomotor nerve and it is called levator palpabrae superioris.
What extrinsic muscles of the eye does the occulomotor nerve innervate?
Superior rectus
Medial Rectus
Inferior Rectus
Inferior oblique
What divisions are there of the occulomotor nerve?
Superior branch
Inferior branch
Ciliary ganglion?
What is the type of information (modality that travels in the trochlear nerve?
GSE - General somatic efferent
Innervates one extra-occular muscle
Where is the trochlear nerve nucleus located and what direction do the nerve fibres leave?
In the midbrain at the level of the inferior colliculus, the fibres pass out the dorsum of the brainstem (the only nerve to do this)
What extra-occular muscle does the trochlear nerve innervate?
Superior oblique
What is the course the trochlear nerve takes from the brainstem to the orbit?
emerges from dorsal surface of the midbrain and runs along the tentorium cerebelli, it travels through the cavernous sinus and then out the superior orbital fissure.
Constriction of the superior oblique muscle causes the pupil to move in what way?
Downwardly and laterally
What are the type(s) of information relayed by the trigeminal nerve? Why?
SVE and GSA
GSA due to the general sensory innervation of the face by the three divisions
SVE as the mandibular division innervates the muscles of mastication which are derived from the pharyngeal arches and therefore it is SVE not GSA
What is the principle sensory nucleus of the trigeminal nerve?
The afferents of the trigeminal nerve from the trigeminal ganglion terminate here
What type of fibres from the trigeminal nerve do not synapse in the trigeminal ganglion?
Fibres carrying proprioception.
What are the three branches of the opthalmic nerve?
Lacrimal, Frontal, nasociliary
Where is the anatomical location of the lacrimal and frontal branches of V1?
Lacrimal runs along lateral rectus
Frontal runs along Levator Palpabrae Superioris
What is the course of the nasociliary branch of V1?
Enters between lateral rectus and the occulomotor nerve, it then courses along the medial wall of the orbit and enters the ethmoidal foramen
What are the two divisions of the maxillary nerve?
The middle meningeal nerve and the infraorbital nerve.
What is the course the maxillary nerve follows once it leaves the brainstem (pons)?
Leaves the cranium via foramen rotundum,
It then passes through the cavernous sinus
and through the pterygopalatine fossa to enter the orbit via the infraorbital fissure
here it becomes known as the infraorbital nerve and enters the infraorbital canal
Where does the mandibular nerve exit the cranium and what are the two main divisions?
Exits via foramen ovale and divides into the inferior alveolar nerve and the lingual nerve.
What route does the lingual nerve take once it branches from the mandibular nerve (V3)?
Descends across the lateral pterygoid muscle and is joined by the chorda tympani (CNVII)
Passes over the superior pharyngeal constrictor and styloglossus muscle
Then lies between the Styloglossus and Submandibular gland
Travels to the tip of the tongue
What route does the inferior alveolar nerve take once it branches from the mandibular nerve (V3)?
Descends along with but lateral to the lingual nerve,
Enters the mandibular foramen
Enters the face via the mental foramen to serve the skin of the lower face/lip and mandibular teeth.
What is the sensory function of the opthalmic nerve?
Sensory innervation to:
The bulb of eye Conjunctiva of eye Lacrimal gland Nasal cavity Skin of forehead and nose Mucous membranes of paranasal air sinuses
What is the parasympathetic function of the lacrimal nerve, where does it receive these Psymp fibres?
The parasympathetic fibres from the pterygopalatine ganglion transmitted to the lacrimal gland via a branch of V2 give secretomotor function to the lacrimal gland.
What is the significance of long and short ciliary nerves?
Long Ciliary nerves extend from the nasociliary nerve and contain sensory and motor function, sympathetic fibres cause pupillary dilatation, short ciliary nerves come from the ciliary ganglia and are entirely sensory and carry parasympathetic fibres from the superior cervical ganglion.
Areas of the face covered by the maxillary nerve? (some is okay)
Skin on the side of the nose Cheek Skin of lower eyelid and conjunctiva Upper lip Naso-pharynx maxillary sinus dura in middle cranial fossa skin over anterior temple
What division of the trigeminal nerve carries both motor and sensory fibres?
Mandibular
What is the sensory innervation of the mandibular nerve?
Cheek Lower lip ear External acoustic meatus (ear canal) Anterior two thirds of tongue Mandibular teeth
What are the muscles of mastication and what nerve are they innervated by specifically?
Temporalis
Masseter
Lateral and medial pterygoid.
Innervated by the mandibular nerve.