Brainstem I Flashcards
Brainstem functions
- conduit for info to/from spinal and supraspinal levels
- origin of descending pathways (motor, pain)
- processes/integrates info
- centers for respiration, HR, BP, consciousness
- cranial n.=spinal n. (equivalent functions), and convey taste, hearing, equilibrium
- preganglionic parasympathetic neurons (thoracic and abd viscera, pupillary sphincter, salivation/ lacrimation)
- synthesis of NTs (CNS)
- critical functions = small region
Characteristics of SPINAL CORD LESIONS involving LONG TRACTS
- effects observed at level of lesion and below
- pain and temp loss side opposite of lesion
- weakness, position sense and vibration sense lost ipsilaterally
Characteristics of BRAINSTEM LESIONS
- lesions of 3 long tracts in brainstem –> contralateral deficits
- cranial nerve signs will reveal the level of the lesion in brainstem
- cranial nerve signs observed on the side of lesion
3 parts of the brainstem
medulla
pons
midbrain
____ a. –> supplies medulla
vertebral a. –> supplies medulla
____ a. –> supplies pons
basilar a. –> supplies pons
the basilar a. ends at the level of the ____, giving rise to the ____ a. –> which supplies the ____
the basilar a. ends at the level of the MIDBRAIN, giving rise to the POSTERIOR CEREBRAL a. –> which supplies the MIDBRAIN
The ventral surface of the brainstem contains
pyramids (corticospinal path decussation)
olives
cranial nerve rootlets of IX, X, XI. XII
midline bulge of medulla
pyramid
where corticospinal tract crosses
between pyramids and olive, CN __ exits
between pyramids and olive, CN XII exits
___ forms roof of fourth ventricle
___ forms floor of fourth ventricle
CEREBELLUM forms roof of fourth ventricle
MEDULLA/PONS forms floor of fourth ventricle
The dorsal surface of the brainstem contains
inferior/superior colliculus
inferior/middle/superior cerebellar peduncle
F. cuneatus/F. gracilis (dorsal column paths)
cuneate tubercle/gracile tubercle (surface elevations formed by second order neurons for dorsal column path which reside underneath)
reticular formation
central core of medulla,
pons and midbrain
controls…
respiration
BP
HR
medial lemniscus is formed by fibers leaving the
nucleus gracilis and nucleus cuneatus
becomes more horizontal and unites with spinothalamic path as you ascend through brainstem
medial medullary lesion
TRACTS LOST: Reticular Formation -respiration, BP, HR Medial Lemniscus -dorsal column pathway -position, vibration loss (contralateral) Corticospinal Tract -fine, distal movement (hemiparesis contralaterally)
CN SIGNS CN XII: Hypoglossal -ipsilateral tongue paralysis -fasiculations -protrusion causes tongue deviation TWD lesion
LMN send axons out to
striated m.
analogous to LMN in spinal cord, also receive input
motor cranial n. nuclei receive cortical input via ______
w/ the exception of…
motor cranial n. nuclei receive cortical input via CORTICOBULBAR PATHWAY
w/ the exception of CN NUCLEI INNERVATING EYE
corticobulbar pathway
UMN synapse on facian nucleus either bilaterally (upper face) or contralaterally (lower face) on motor nuclei of the brain stem
alar plate gives rise to
sensory neurons
basal plate gives rise to
motor neurons