Brainstem Flashcards
Abducens nuclei
- caudal pons
- CN VI
- motor
Abducens nucleus
•pons, 4th floor of ventricle –> lateral rectus
Basal pons
•longitudinally oriented nerve fibers, transversely oriented nerve fibers and scattered clumps of grey matter called pontine nuclei •the longitudinal fibers are coming from the cerebral cortex; some of them continue caudal through the CST but most of them are corticpontine fibers that end on the ipsilateral pontine nuclei, then they cross the midline and project through the middle cerebellar peduncle to all areas of the cerebellum
Blink Reflex
•CN V in, CN VII out
Caudal edge of the pyramidal decussation
•the formal boundary between the brainstem and the spinal cord
Caudal medulla
- no 4th ventricle, just a vestigial central canal •posterior columns (FG and FC) end by synapse in posterior column nuclei (NC and NG) •pyramid on each side contains the CST •STT
- midline structures - anterior spinal artery & verterbral arteries
- lateral - PICA
Caudal midbrain
- the 4th ventricle is all gone, replaced by the aqueduct (surrounded by the periaqueductal grey) •inferior colliculus above each side of the aqueduct (major component of the auditory pathway) •basal pons is mostly gone, replaced on each side by a cerebral peduncle •STT •ML •superior cerebellar peduncles decussate on their way to the thalamus
- midline - posterior cerebral artery (some from basilar)
- lateral - superior cerebellar artery (some from posterior communicating)
Caudal pons
- the 4th ventricle continues •basal pons •middle cerebellum peduncle •STT •ML •CST
- midline structures - basilar
- lateral - AICA
Cerebellopontine angle
- triangular area formed by the cerebellum, upper medulla and MCP
- CN VII and VII emerge from the brainstem here
Cerebral peduncle
•big collection of fibers from the cerebral cortex on their way to the pontine nuclei (in the caudal pons —> MCP —-> to the cerebellum), the spinal cord (via the CST) and to some cranial nerve nuclei (via the corticobulbar tract)
Cochlear nucleus
•spiral ganglia–> cochlear nucleus in pons/medulla cerebellopontine angle
Corticopontine fibers
- transversely oriented fibers in the rostral pons that cross the midline and project through the middle cerebellar peduncle to all araeas of the cerebellum
- travel along the cerebral peduncle from the cerebreal cortex to the cerebellum
Corticospinal fibers
- fibers that travel downstream from the cerebral cortex and will continue caudally into the pyramid
- travel along the cerebral peduncle from the cerebreal cortex to the pyramids
- longitudinally oriented in basal pons
Corticospinal tract
•The corticospinal tract is a white matter motor pathway starting at the cerebral cortex that terminates on lower motor neurons and interneurons in the spinal cord, controlling movements of the limbs and trunk. •the LCST and ACST decussate in the pyramids and form the CST and travel up through the brainstem •represents the contralateral side of the body
Dorsal motor nucleus
- DMN X
- rostral medulla
- CN X
- parasympathetic cardiovascular functions, breathing, food, digestion etc…
dorsal motor nucleus of teh vagus
- rostral medulla
- thoracic and abdominal viscera
- CN X
Edinger - Westphal nucleus
- CN III
- parasympathetic to ciliary ganglion –> sphincter pupillae, ciliary muscle
Facial motor nucleus
- brainstem near STT
- LMN facial expression and stapedius
- damage = paralysis ipsilateral face, unnatural sounds in ipsilateral ear
facial nuclei
- pontomedullary junction/caudal pons
- CN VII
- motor
- the axons wrap around the abducens nuclei and form the internal genu of the facial nerve before they leave the brainstem
- damage causes paralysis of the entire ipsilateral face and things can also sound unnaturally loud (stapedius)
Gag Reflex
•CN IX in, CN X out
nu
•rostral medulla
•
hypoglossal nuclei
- several rootlets front of medulla
- all extrinsic and instrinsic muscles of the tongue except palatoglossus (CN X)
Hypoglossal nuclei
- rostral medulla
- CN XII
- motor
Hypoglossal nucleus
- rostral medulla
- CN IX
- exits at groove between olive and pyramids