Brainstem Flashcards
Function of SA
mediates touch, pain, temp, vibration, proprioception (general sensory)
Function of VA
mediates sensory input, except pain from viscera
Function of VE
innervates viscera including glands, mucosae and all involuntary smooth muscle (parasympathetic)
Function of SE
innervates vol. mm. that develop from somites
Function of special visceral efferents
innervates voluntary mm. that develop from branchial arches (branchial motor)
Function of special SA
carries info from special senses of vision, hearing and balance
Function of special VA
carries olfaction and taste info (special senses using chemoreceptors)
What are the uncrossed large myelinated primary afferents that enter the posterior column CAUDAL T6 and carry tactile and proprioceptive info from ipsilateral LOWER limb? Where do they terminate if they ascend to the medulla?
fasciculus gracilis; nucleus gracilis
What are the uncrossed large myelinated primary afferents that enter the posterior column ROSTAL to T6 and carry tactile and proprioceptive info from ipsilateral UPPER limb? Where do they terminate if they ascend to the medulla?
fasciculus cuneatus; nucleus cuneatus
The descending pathway originating in the cerebral cortex and travels to reach the spinal cord w/ its principal function being to mediate voluntary movement?
corticospinal tract
Ascending pathway from spinal cord to thalamus that mediates pain, temp and tactile sensation
spinothalamic tract
Major ascending pathway arising from nucleus gracilis and nucleus cuneatus that mediates conscious proprioception and tactile sensations from limbs to contralateral ventral posterolateral thalamic nucleus
posterior column medial lemniscus
longitudinal fiber bundle involved in coordinating eye and head movements
medial longitudinal fasciculus
The ascending pathway from spinal cord to cerebellum that carries proprioceptive info from the upper limb
posterior spinocerebellar tract
ascending pathway that runs from lumbosacral spinal cord to cerebellum that carries mechanoreceptive and other leg movement info
anterior spinocerebellar tract
This originates in red nucleus of midbrain and terminates in cervical spinal cord.
rubrospinal tract
What functions to mediate voluntary movement, mostly being flexion in upper limb?
rubrospinal tract
What is the fiber tract that originates in the superior colliculus of midbrain and ends in upper segments of spinal cord functioning to coordinate eye and head movement toward relevant stimuli?
tectobulbospinal tract
The tract that originates in pontine reticular formation and terminates in the spinal cord for locomotion and postural control.
reticulospinal tract
This is part of the vestibular system for upright posture and head stabilization originating in the vestibular nuclei located in the medulla and pons and terminating in the spinal cord.
vestibulospinal tract
What is the spinal trigeminal nucleus?
center for all SA pain and temperature info conveyed on spinal nerves
How are the fibers of anterolateral system and spinal trigeminal tract positioned to each other? What territory?
adjacent to each other throughout the lateral medullar in the territory of PICA
What do the SE fibers from the nucleus ambiguus travel through?
CN IX and X
What part of the caudal medulla receives spinal input and projects into the cerebellum?
lateral reticular nucleus
What consists of principal, medial, accessory and posterior accessory olivary nuclei?
inferior olivary complex
Where does the inferior olivary nuclei project?
cerebellum
What is the principal visceral sensory nucleus of the brainstem? What does it contain/convey?
nucleus of the solitary tract; primary afferents that convey visceral and gustatory info from CN VII, IX, and X into the solitary nucleus
What structure of the midmedullary level contains the posterior spinocerebellar, cuneocerebellar, olivocerebellar, reticulocerebellar and other cerebellar afferenets?
restiform body
Where do axons of the salivatory nucleus distribute?
to otic ganglion via peripheral branches of glossopharyngeal nerve
At the level of the rostral medulla, what does the solitary nucleus receive its input from?
mostly VA (taste) input from CN VII and IX (gustatory nucleus)
In the tegmentum, these are axons that constitute 3rd order auditory neurons from the superior olivary complex and nucleus of the trapezoid body that ascend bilaterally.
lateral lemniscus
In the tegmentum, this is the pathway from spinal cord to thalamus that mediates pain, temp and tactile sensation.
spinothalamic pathway
Located in the tegmentum, this contains somatosensory (pain and temp) info from the head.
trigeminothalamic pathway
In the tegmentum this is the major ascending pathway from the nucleus gracilis and nucleus cuneatus that mediates conscious proprioception and tactile sensations from limbs to contralateral ventral posteriolateral thalamic nucleus
medial lemniscus
Part of brainstem that contains CN nuclei for 3-5
midbrain
Has CN nuclei for 6 and 7 and parts of 5 and 8
pons
Relay station betwn cerebral cortex and cerebellum and descending motor fibers that travel to all spinal lvls
pontine nuclei
What has CN nuclei for 9, 10 and 12 and parts of 5 and 7 that has ascending and desc. tracts to/from spinal cord?
medulla oblongata
What part of the brainstem is essential for respiratory regulation and HR?
medulla oblongata
Where is the tectum?
midbrain
Where are the CN nuclei dispersed?
tegmentum
What is the reticular formation part of?
tegmentum
Where are long pathways?
base of brainstem
What part of the reticular formation controls HR and respiration?
ventrolateral reticular area
What inhibits pain transmission in the posterior horn from the raphe magnus?
raphespinal fibers
The ventrolateral reticular area and raphespinal fibers are nuclei in the?
reticular formation
9-12
What CN roots are attached to the medullar oblongata?
External fts of medullar oblongata (7)
CN roots 9-12, ant. median fissure, pyramids, pyramidal decussation, olive, pre and postolivary sulci at medial and lateral borders of olive
Lateral recesses of rhomboid fossa divide what on the medulla?
pons and medulla
obex
where 4th ventricle narrows to central canal (posterior medulla)
Rhomboid fossa
(posterior medulla) floor of 4th ventricle
How is the fasciculuc gracilis and cuneatus connected to the cerebellum?
ICP (inferior cerebellar peduncle) (posterior medulla)
What overlies the spinal tract of trigeminal nerve on (posterior medulla)?
tuberculum cinereum
Name the ascending pathways (fiber tracts) in the medulla. (3)
posterior column medial lemniscus, anterolateral system (including spinothalamic tract), posterior and anterior spinocerebellar tracts
Name the descending pathways (fiber tracts) in the medulla and their origins. (4)
corticospinal tract- cerebral cortex, rubrospinal and tectobulbospinal- midbrain, reticulospinal and vestibulospinal- pons, medial longitudinal fasciculus- medulla
Where do the majority of pyramids cross?
anterior/central medulla
Where is the nucleus of CN XI?
anterior/central medulla
The anteriolateral system and spinal trigeminal tract and nucleus are where?
Lateral medulla
The posterior medulla has what fasciculi? (2)
gracile and cuneate fasciculi
What surrounds the central canal?
central gray
What part of the medulla has teh internal arcyate fibers, medial leminiscus, corticospinal fibers (pyramid) and inferior olivary complex?
anterior/central
What part of the medulla in the level of sensory decussation has posterior columns (gracile and cuneate fasciculi) (replaced by their nuclei), spinal trigeminal tract and nuc., lat. reticular nuc., and nucleus ambiguus?
lateral medulla
The posterior medulla has what in the sensory decussation compared to motor dec.?
gracile and cuneate nuclei instead of fasciculus
The central gray of the motor crossing in the medulla contains what?
hypoglossal nuclei and dorsal motor vagal nuclei with solitary nucleus and tract
What is at the anterior/central midmedullary level?
principal olivary nucleus, corticospinal fibers (pyramids), medial lemniscus
What is at the lateral midmedullary level?
restiform body, spinal trigeminal tract and nucleus, nucleus ambiguus, lat. reticular nucleus, anteriorlateral system
What is at the rhomboid fossa of the midmedullary level?
hypoglossal nuclei, dorsal motor vagal nuclei, sulcus limitans, vestibular nuclei (med and inf.), solitary tract and nucleus
What is the main bundle of fibers that connects the brainstem and cerebellum?
restiform body
What is at the anterior/central rostral medulla?
same as anterior/central midmedullary level- principal olivary nucleus, corticospinal fibers (pyramids), medial lemniscus
What is at the lateral rostral medulla?
med. & inf. vestibular nuclei, posterior and anterior cochlear nuclei, spinal trigeminal tract, solitary tract and nucleus (gustatory nucleus)
What is at the rhomboid fossa of the rostral medulla?
hypoglossal nucleus and inf. salivatory nucleus
What is the inferior cerebellar peduncle made from?
fibers from the restiform body that enter the cerebellum that join the juxstarestiform body
Syndrome caused by occluding perforating branches of anterior spinal artery
medial medullary syndrome/Dejerine syndrome
Deficits of Dejerine syndrome/medial medullary syndrome. What are each of the structures responsible for these deficits?
contralateral hemiparesis (pyramidal and corticospinal) and loss of proprioception and vibratory sense (medial lemniscus), tongue deviate to ipsilateral side when protruded (hypoglossal root/nucleus)
What syndrome is caused by PICA occlusion?
lateral medullary syndrome/PICA syndrome/Wallenberg syndrome
Deficits of PICA syndrome. What are the associated structures that are damaged to cause these deficits?
contralateral loss of pain and temp sensation from body(ant.lat system), ipsilateral loss of pain and temp sensation from face (spinal trigeminal), vertigo and nystagmus (vestibular), lose of taste from ipsilateral half of tongue (solitary), hoarseness and dysphagia (ambiguus or roots of CN IX and X), horner syndrome (hypothalamospinal fibers)
What CNs come from the pons?
CN 5-8
What is the lateral walls of 4th vent formed by in the pons?
brachium pontis (middle cerebellar peduncles) and brachium conjunctivum (supeior cerebellar peduncles)
What is teh facial colliculus of the caudal pons formed by?
abducens nucleus and int. genu of facial nerve
What is picked up by the facial nerve (intermediate nerve) when it passes to exit the brainstem? What else mades the intermediate nerve?
fibers from the superior salivatory nucleus; VA fibers from anterior 2/3 of tongue and SA fibers from pinna
What are in the lateral tegmentum of the midpontine?
principal/chief sensory trigeminal nucleus, trigeminal motor nucleus, middle cerebellar peduncle
What are in the surrounding 4th ventricle of the midpontine?
mesencephalic tract and nucleus of CN V, nucleus (locus) ceruleus, sup cerebellar peduncle
What is easily seen on the rostral pons?
superior cerebellar peduncle (SCP)
What branches of the basilar artery supply the pons? What areas do they supply?
paramedian (medial), short circumferential (lateral), long circumferential (entire tegmentum and part of middle cerebellar peduncles)
At the caudal level of pons, what additional branches supply the pons?
anterior inf. cerebellar artery
What additional artery helps supply pons at rostral level?
superior cerebellar artery
What is the syndrome associated with occluding the paramedian branches at the caudal pons level?
inferior medial pontine syndrome
What deficits occur from inf. medial pontine syndrome? Lack of blood supply to what structures cause these?
ipsilateral abducens nerve paralysis (abducens nuclei), contralateral hemiparesis (foville syndrome), variable contralateral sensory loss (medial lemniscus)
What syndrome occurs with inferior medial pontine syndrome if the area of damage shifts laterally to include the root of the facial nerve?
Gubler or Millard-Gubler syndrome
Occlusion of paramedian and short circumferential arteries at the midpontine level causes what syndrome?
syndrome of the midpointine base
What deficits occur with syndrome of the midpontine base? What structures cause these?
contralateral hemiparesis (corticospinal fibers), ipsilateral loss of pain and thermal sense and paralysis of masticatory mm. (sensory and motor trigeminal roots), ataxia (middle cerebellar peduncle)
What does the midbrain lie between?
pons and forebrain
What passes through the midbrain?
cerebral aqueduct
Where does the cerebral aquaduct merge with the 4th ventricle?
pons-midbrain junction
What is the midbrain connected to the cerebellum by?
superior cerebellar peduncle
What level of the inferior colliculus represents the relay component of the auditory pathway?
tectum
The tegmentum of the inferior colliculus has acetylcholine containing neurons that participate in what?
sleep-wakefulness regulation and maintenance of consciousness
What does the periaqueductal gray matter play a role in?
autonominc function regulation, emotional precesses like fear and anxiety and modulating pain impulses
What does the trochlear nerve innervate? What is the result of damage?
superior oblique; diploplia when trying to look down such as when walking down stairs
Fibers associated with the head region are located where on the crus cerebri?
medially
Where are the fibers in the crus cerebri that are associated with the upper limb, trunk and lower limb?
lateral
Parkinson’s disease is associated with loss of what? Where does this occur?
loss of dopamine containing cells in the pars compacta of substantia nigra
Where is the pars compacta in the substantia nigra?
medially located
What does the pars compacta release?
dopamine
What do cells in the pars reticulata release?
GABA
Where is the pars reticulata in the substantia nigra?
laterally
What is the visual reflex center at the tectum?
superior colliculus
What area does the superior colliculus produce reflexes for?
head and neck
What does the superior colliculus contribute to?
oculomotor responses and mediates tracking movements of objects and they move through the visual field (horizontal conjugate gaze)
The oculomotor nuclear complex contains what nucleus?
Edinger-Westphal nucleus
What is the Edinger-Westphal nucleus composed of? (2)
Edinger-Westphal preganglionic cells (EWpg) and Edinger-Westphal centrally projecting cells (EWcp)
What does the EWpg do?
involved in pupillary light reflex by parasympathetically innervating the pupillary cnostrictor mm. and innervates the ciliary muscle for lens accommodation
What does the EWcp do?
function in behaviors of stress, eating and drinking
The pretectal region of the midbrain diencephalic junction is involved in what reflex?
pupillary light reflex
The posterior commissure in the midbrain-diencephalic junction does what?
controls extraocular eye movement and coordinates movement of the 2 eyes
The pupillary light reflex involves what CN for the afferent and what CN for the efferent limb?
CN II afferent, CN III efferent
Lesion of the post. cerebral artery and paramedian branches of basilar artery causes what syndrome?
weber syndrome
Lesion of the post. cerebral artery and top of the basilar artery causes what syndrome? (superior alternating hemiplegia)
Claude syndrome (central midbrain lesion)
Lesion of the medial aspect of the crus cerebri causes what syndrome?
benedikt syndrome
A tumor in the pineal (or any tumor that impinges the superior colliculus) causes what syndrome?
parinaud syndrome (dorsal midbrain syndrome)
Deficits of claude syndrome?
ipsilateral eye down and out, contralateral ataxia, tremor, incoordination; NO WEAKNESS ISSUES
Deficits of Weber syndrome?
ipsilaterl eye down and out dilated, unresponsive puil, ptosis, hemiparesis (WEAKNESS) of UE and LE, weakness of facial mm. or lower half of face and tongue deviates when protruded
Deficits of Benedikt syndrome?
paralysis of most eye movement, contralateral extremities weakness, tremor and ataxia
Deficits seen in Parinaud syndrome?
*paralysis of upward gaze, large pupil, abnormal elevation of upper lid (ptosis), paralysis of accommodation, absence of convergence, light near dissociation
Light near dissociation. What syndrome is this seen in?
pupil can’t constrict when exposed to bright light (no pupillary reaction to light); present in Parinaud syndrome
Where are the red nuclei and what are they for?
in the superior colliculi and are for motor coordination
What is the purpose of the reticular formation?
mediates level of consciousness
What can be used to ID the midbrain in all cross sections?
substantia nigra
What degenerates in Parkinson’s disease?
substantia nigra
Cerebral peduncle= (2 other names)
crus cerebri=basis pediculli
What does the spinothalamic tract relay?
temperature, pain and crude touch from contralateral side
What does the dorsal column medial leminiscus (DCML) tract relay?
vibration and proprioception from contralateral side
Where does the corticospinal tract decassate?
pyramids
Purpose of corticospinal tract?
motor information
Spinothalamic tract (ALS)
relays pain and temperature from contralateral side
What are the CNs the pons has?
CN V-3, CN VI (abducens), CN VII (facial), CN VIII (vestibulocochlear)
What is the functional significance of the pons?
reflex control of respiratory system, eye movements and coordinating movement of eyes and head, corneal reflex
What structure of the medulla contains the squiggly dentate nucleus?
olive
What is located at the back of the medulla?
4th ventricle
CN associated with the medulla
9-12
What nerve exits between the olive and pyramid?
CN XI
Functional significance of medulla
reflex control of cardiovascular and respiratory systems
reflex control of swallowing and vomiting
phonation- control of tongue, larynx and pharynx
phonation
contol of tongue, larynx and pharynx
a function of the medulla
