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

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