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48 terms

Chapter 10 medulla

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What 2 extra pyramidal pathways originate in the medulla?
Vestibulospinal and medullary reticulospinal
Where is the vestibular nucleus
rostral medulla
Where is the reticular formation in the brainstem?
runs length of medulla centrally
What do vestibular and medullary reticulospinal origins/pathways have in common
both originate in medulla and lateral vestibulospinal and medullary reticulospinal pathways maintain posture (muscle tone)
Which column of sensory and motor nuclei are continuous in the brain stem?
GSA (from sacral spinal chord to metencephalon
Cranial nerves associated with the medulla
7. VI - XII
Hypoglossal motor nucleus
caudal medulla ventral to 4th ventricle. GSE
Hypoglossal nerve course
from nucleus in caudal medulla straight down to lateral side of pyramids
Lesion to hypoglossal nucleus
LMN lesion. tongue when atrophied points to side of lesion (ipsilateral)
Corticobulbar tract function and pathway
lap water. Motor cortex - internal capsul - cerebral peduncles - longitudinal fibers of pons - pyramid - decussates onto facial nucleus and hypoglossal nucleus
Nucleus ambiguous
accessory, vagus and glossopharyngeal
Lesion of accessory n or nucleus ambiguous
denervation ipsilaterally of neck muscles (LMN lesion)
Vagus nuclei
4 nerve fiber types; 3 nuclei. GSE in nucleus ambiguous; GVE dorsal motor nucleus of vagus; GVA and SVA solitary nucleus
Glossopharyngeal fiber types
GSE, GVE, GVA, SVA (same as vagus)
Glossopharyngeal nuclei
GSE to pharyngeal m NUCLEUS AMBIGUOUS; GVE to parotid and zygomatic salivary glands CAUDAL SALIVATORY NUCLEUS; GVA (tonsils, oropharynx, auditory tube, carotid body etc) SOLITARY NUC. SVA taste buds from caudal 1/3 of tongue SOLITARY NUC
Nucleus ambiguous
motor from XI, X, IX
Lesion of nucleus ambiguous LMN lesion
dysphagia and dyspnea (pharyngeal and laryngeal m)
Gutteral pouch infections involved nerves
vagus and glosspharyngeal. May involved cranial cervical ganglion -> Horners syndrome
Solitary nucleus
SVA IX, X, VII and GVA IX and VII. Sensory for taste and visceral sensation
How is taste perceived?
SVA from facial, glossopharyngeal and vagus to solitary nucleus, then decussates to medial lemniscus, thru thalamus to primary sensory cortex
How is sensations from GVA fibers (vagus, glossopharyngeal and facial) perceived
same as taste
How is taste linked to behavior such as salivation
solitary nucleus connects to motor nuclei in brain stem
Medial lemniscus pathway carries
conscious proprioception, pressure and touch from forelimbs and hindlimbs, and pain and temp AND taste + visceral sensation
Corticobulbar input to LMNs of IX, X and XI
bilateral so unilateral lesion of motor cortex = few deficits. (note corticobulbar input to facial and hypoglossal nucleus on contralateral side)
Gag reflex can rule out?
caudal medulla
Gag reflec mechanism
sensory (IX) to solitary nucleus then motor out via nucleus ambiguous
Only cranial nerve that doesn't leave the skull
vestibulocochlear nerve
Vestibulochochlear nerve fiber types
SSA
Hearing pathway
hair cells -> primary sensory afferents (bipolar) -> CB in spiral ganglion -> chochlear nucleus in rostral medulla -> dorsal nucleus of trapezoid body (superior olive) (sound mixed from both ears) -> caudal colliculi of midbrain (lateral lemniscus) -> medial geniculate nucleus of thalamus -> internal capsule -> auditory cortex
Big wig nerves with tons of fiber types
facial, vagal and glossopharyngeal
Where does the facial nerve arise
rostral medulla near vestibulochoclear in facial motor nucleus
Facial motor axon pathway
travel dorsomedially then rostrally and circle around the abducens motor nucleus
Facial decussating pathway?
yep UMN synapse in contralateral facial motor nucleus. LMN extend ipsilaterally
Which nerves have their own nuclei?
hypoglossal, cochlear, facial motor, abducens,
Facial GVE
rostral salivatory nucleus for salivary and lacrimal glands
Facial GVA
send axons to solitary nucleus
Facial SVA
taste buds on rostral 2/3rds - solitary nucleus
Facial reflexes
menace/blink response, corneal reflex, nictitating reflex, palpebral reflex
Menace sensory input
optic nerve
Corneal reflex sensory input
ophthalmic branch of trigeminal
Nictitating reflex
sensory input ophthalmic branch of trigeminal
Palpebral reflex
sensory input ophthalmic or max branches of trigem
Lesion of CN II, cerebellum, facial motor nucleus and facial nerve all abolish what response
menace response
4 parasympathetic nuclei
parasympathetic nucleus of CN III, rostral and caudal salivatory nucli and dorsal motor nucleus of the vagus
Where are the parasympathetic nuclei located?
rostral in rostral medulla, caudal in middle medulla and dorsal in caudal medulla
Medial strabismus
medial deviation of eye due to abducens lesion
Inferior olivary nucleus
involved in coordination of movement
How is the reticular formation involved in breathing
phrenic