Lecture 7, Cranial Nerves Flashcards
Cervicomedullary junction
foramen magnum and pyramidal decussation
caudal limit of brainstem
Midbrain-diencephalic junction
brainstem meets the thalamus and hypothalamus at the level of the tentorium cerebelli
Hypoglossal trigone/vagal trigone
formed by the hypoglossal nucleus and dorsal motor nucleus of vagus
Facial colliculi
formed by the abducens nuclei and fibers of the facial nerve
The pons is attached to the cerebellum by
large white matter tracts called superior, middle, and inferior cerebellar peduncles
Motor cranial nerve nuclei are located
more ventrally
Sensory cranial nerve nuclei are located
more dorsally
Somatic motor nuclei
CN 3, 4, 6, 12
derived from occipital somites
extraocular muscles, intrinsic tongue muscles
Visceral motor nuclei
made up of branchial motor nuclei and parasympathetic nuclei
Branchial motor nuclei
CN 5, CN 7, 9, 10, 11
innervate striated muscles
muscles of mastication, facial expression, middle ear, pharynx, larynx, SCM, traps
Parasympathetic motor nuclei
CN 3, 7, 9, 10
do not innervate striated muscle, but innervate glands, smooth muscle, cardiac muscle
Visceral sensory column
made of 2 parts
rostral nucleus solitarius
caudal nucleus solitarius
Rostral nucleus solitarius
receives taste inputs primarily from CN 7, 9, 10
Caudal nucleus solitarius
receives inpt to regulate cardiac, respiratory, and GI function from 9 and 10
General somatosensory nuclei/trigeminal
mediate touch, pain, temp, poisition and vibration sense for the face, sinuses, and meninges. Mostly CN 5 (7, 9, 10)
Special somatic sensory
olfaction, vision, hearing, vestibular sensation
CN 8
Special senses
olfaction, vision, hearing, vestibular sense, taste
olfaction and vision do not have their primary sensory nuclei in brainstem
Olfactory Nerve
specialized chemoreceptors on bipolar primary sensory neurons
axons travel via olfactory nerves, synapse in olfactory bulbs, and travel through tracts. ends in temporal lobe
Optic Nerve
carries visual info from retina to LGN nucleus of the thalamus
visual info travels in optic nerve from orbit to intracranial cavity via optic canal
Edinger-Westphal
nucleus in the midbrain
these synapse on ciliary ganglion located in the orbit
postganglionic neurons then go to pupillary constrictor and ciliary muscles
Mesencephalic nucleus
carry proprioceptive input from the muscles of mastication, tongue, and extraocular muscles
Main/chief trigeminal sensory nucleus
provude sensory for the face and head that are analogous to posterior columns (DCML)
Spinal trigeminal
provide sensory for the face and head that are analogous to the ALS
Trigeminal Lemniscus pathway
Trigeminal ganglion–> main trigeminal sensory nucleus–> 2nd order decussates and ascends in trigeminal lemniscus –> syanpses on VPM in thalamus –> 3rd order leaves VPM –> internal capsule __> corona radiata –> S1
Trigeminothalamic Pathway
Trigeminal ganglion–> spinal trigeminal tract__> spinal trigeminal nucleus–> trigeminothalamic tract –> VPM –> internal capsule –> corona radiata –> S1
Mesencephalic Trigeminal Tract
Mesencephalic nucleus –> mesencephalic trigeminal tract –> main trigeminal sensory nucleus –> trigeminal lemniscus –> VPM –> internal capsule –> corona radiata –> S1
Facial Nerve categories
Brancial motor
parasympathetic
visceral sensory, special
somatic sensory
Branchial Motor CN VII
muscles of facial expresion
Parasympathetic CN VII
lacrimal glands, sublingual, submandibular, salivary glands besides parotid
Visceral sensory CN VII
taste from 2/3 tongue
General Somatic Sensory
sensation from samll region near ear
Preganglionic Parasympathethic Fibers of CN VII
originate in superior salivatory nucleus
CN VIII
special somatic sensory for hearing
Summary of sound
sound enter the external auditory meatus, transmitted mechanically by middle ear to cochlea, transduced by hair cells to neural signals carried by cochlear nerve
Dorsal Cochlear Nuclei
Spiral ganglion–> DCN–> crosses–> trap body–> inf colliculus–> MGN –> A1
Ventral Cochlear Nuclei
Spiral ganglion–> VCN–> splits into 2 separate paths at pons
- superior olivary–> inf colliculus–> MGN–> A1
- Trapezoid body–> inf colliculus –>MGN–> A1