NeuroAnatomy - Lecture Eight Objectives - Brainstem Flashcards
which cranial nerves do not emerge from the brainstem?
CN I & CN II
which cranial nerves emerge from the midbrain of the brainstem?
CN III & CN IV
which cranial nerves emerge from the pons of the brainstem?
CN V - CN VIII
which cranial nerves emerge from the medulla of the brainstem?
CN IX - CN XII
which cranial nerves can be viewed in the anterior view?
all of them
which cranial nerves can be viewed in the posterior view?
CN IV is the only CN to emerge from posterior brainstem
what structures are found within the external midbrain?
CN III & CN IV , cerebral peduncles, superior/inferior colliculus
what structures are found within the internal midbrain?
cerebral aqueduct, periaqueductal gray area, CN III/CN IV nuclei, red nucleus, substantia nigra, descending motor tracts in peduncles
what structures are found within the pons?
CN V - CN VIII , motor tracts that descend into anterior pons, 4th ventricle
what structures are found within the medulla?
CN IX - CN XII , pyramids, pyramidal decussation
what are the three vertical columns of the brainstem listed from anterior - posterior?
basis, tegmentum, tectum
what structures are found within the tectum?
superior colliculus and inferior colliculus
what is the function of the superior colliculus?
visual reflexes; pupillary light, looking away/towards stimuli
what is the function of the inferior colliculus?
auditory reflexes
what structures are found within the tegmentum?
reticular formations & ascending/descending somatosensory tracts
what is the function of the ascending somatosensory tracts in the tegmentum?
proprioception, light touch, pain and temperature from the body and head
what are the four descending motor tracts originating from BRAINSTEM NUCLEI?
rubrospinal tract, tectospinal tract, reticulospinal tract, and vestibulospinal tract
where does the rubrospinal tract originate from?
red nucelus in midbrain
where does the tectospinal tract originate from?
tectum in midbrain
where does the reticulospinal tract originate from?
reticular nuclei in lower 2/3 of brainstem
where does the vestibulospinal tract originate from?
vestibular nuclei in lower brainsteam
what structures are found within the basis?
descending motor tracts that originate from cortex
what are the three descending motor tracts originating from CORTEX?
corticospinal tract, corticobulbar tract, and corticopontine tract
where does the corticospinal tract originate/descend to and does what function?
originates in the primary motor cortex, descends in basis of brainstem and continues down the spinal cord to supply muscles of the body
where does the corticobulbar tract originate/descend to and does what function?
originates in the primary motor cortex, descends in basis of brainstem and connect to cranial nerves that supply muscles of the head
where does the corticopontine tract originate/descend to and does what function?
descend from motor cortices, descends in basis of upper brainstem, terminates in pontine nuclei and connects to cerebellum
what is reticular formation and where is it located?
a cluster of nuclei located in tegmentum throughout brainstem
where is the rostral reticular formation?
upper pons/midbrain
where is the caudal rectiular formation?
lower pons/medulla
what does the reticular formation do?
regulates/modulates most CNS areas
what is the function of CAUDAL reticular formation?
- modulate respiratory/cardiovascular nuclei of brainstem 2. modulate motor functions & complex physiological motor reflexes 3. modulate nociception pathways (inhibits)
what is the function of ROSTRAL reticular formation?
modulate consciousness // alertness, attention, awareness. Damage to upper brainstem results in potential coma or impaired consciousness
what are the characteristics of a coma?
unconscious, no meaningful response to stimuli, low GS scores, CNS cells alive but significantly reduces metabolism, generally not permanent and will progress/digress after 2-4 weeks
what areas are affected relating to comas?
severely depressed function of cortex and sub-cortical regions as well as rostral reticular formation
what reflexes are still intact during comas?
spinal cord and brainstem reflexes
what are the characteristics of a vegetative state?
similar to coma, GS score SLIGHTLY higher than coma, displays some sub-cortical function (i.e. sleep-wake cycle and some arousal reflexes)
what areas are affected relating to vegetative states?
severely depressed function of cortex and sub-cortical regions
what reflexes are still intact during vegetative states?
spinal cord and brainstem reflexes as well as some arousal reflexes (open eyes / turn towards stimuli, random sounds or movements, etc)
what are the characteristics of brain death?
no evidence of cortex, diencephalon, and brainstem function including absent brainstem reflexes
what areas are affected relating to brain death?
absent function of cortex, sub-cortical arousal system and brainstem
what reflexes are still intact during brain death?
spinal cord
what artery supplies the medulla?
small branches of vertebral artery supplies most of medulla and PICA supplies lateral medulla
what artery supplies the pons?
small branches of pontine arteries supply most of pons and AICA/branches from VA supplies small lateral region of lower pons
what artery supplies the midbrain?
PCA
what artery is involved in Weber’s Syndrome?
right or left PCA in midbrain
what are the clinical findings of Weber’s Syndrome?
contralateral hemiplegia/paresis, ipsilateral CNIII palsy, Parkinsonian if substantia nigra is affected
what artery is involved in Pure Motor Hemiparesis?
right or left pontine arteries of basilar artery along left or right anterior pons
what are the clinical findings of Pure Motor Hemiparesis?
contralateral hemiplegia/paresis
what artery is involved in Locked-In Syndrome?
basilar artery // “bilateral stroke of anterior pons”
what are the clinical findings of Locked-In Syndrome?
quadriplegia with intact sensation/cognition, all motor function is impaired EXCEPT for CNIII and possibly CNIV
how does a coma vs. locked-in syndrome compare?
locked-in syndrome mimics a coma but the patient is conscious and may be able to communicate via eye blinking and is aware of their environment
what artery is involved in Wallenberg Syndrome?
vertebral artery, PICA, or small branches of PICA // unilateral stroke of lateral medulla
what are the clinical findings of Wallenberg Syndrome?
loss of pain/temp to ipsilateral face (CNV) , contralateral body // vertigo/nausea/vomit/nystagmus (CNVIII) , hoarseness/dysphagia (CNIX/CNX), ataxia
