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What 2 extra pyramidal pathways originate in the medulla?
Vestibulospinal and medullary reticulospinal
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
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
4 nerve fiber types; 3 nuclei. GSE in nucleus ambiguous; GVE dorsal motor nucleus of vagus; GVA and SVA solitary nucleus
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
Gutteral pouch infections involved nerves
vagus and glosspharyngeal. May involved cranial cervical ganglion -> Horners syndrome
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 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)
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
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
Lesion of CN II, cerebellum, facial motor nucleus and facial nerve all abolish what 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
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