Brain (CNS) Flashcards
What are the parts of the brain?
- cerebral hemispheres
- diencephalon
- cerebellum
- brainstem
What are the 3 parts of the brain stem?
- midbrain
- pons
- medulla oblongata
What does the brain start off as in an embryo?
neural tube that contains neural canal
- anterior side (rostral)
- posterior side (caudal)
What are the 3 primary brain vesicles?
- prosencephalon (forebrain)
- mesencephalon (midbrain)
- rhombencephalon (hindbrain)
What are the 5 secondary brain vesicles?
- telencephalon
- diencephalon
- mesencephalon
- metencephalon
- myelencephalon
Which secondary brain vesicle does the prosencephalon (forebrain) become?
- telencephalon
- diencephalon
Which secondary brain vesicle does the mesencephalon (midbrain) become?
mesencephalon
Which secondary brain vesicle does the rhombencephalon (hindbrain) become?
- metencephalon
- myelencephalon
What adult brain structures does the telencephalon become?
cerebral hemispheres (cortex, white matter, basal nuclei)
cerebrum
What adult brain structures does the diencephalon become?
thalamus, hypothalamus, epithalamus
diencephalon
What adult brain structures does the mesencephalon become?
midbrain (brain stem)
What adult brain structures does the metencephalon become?
- pons (brain stem)
- cerebellum
What adult brain structures does the myelencephalon become?
medulla oblongata (brain stem)
What adult neural canal regions does the telencephalon form?
lateral ventricles
What adult neural canal regions does the diencephalon form?
third ventricle
What adult neural canal regions does the mesencephalon form?
cerebral aqueduct
What adult neural canal regions does the metencephalon form?
fourth ventricle
What adult neural canal regions does the myelencephalon form?
fourth ventricle
What is the cortex?
thin outer shell of gray matter
Brainstem
What is the brainstem composed of?
(inferior)
medulla oblongata
pons
midbrain
(superior)
Brainstem
What are the 3 major functions of the brainstem?
- acts as passageway for all ascending and descending tracts between cerebrum and spinal cord
- contains nuclei of cranial nerves III to XII
- regulates automatic behaviours required for survival (ie. respiration)
Brainstem - Medulla Oblongata
Describe the structure.
pyramidal
separated from pons by the ponto-medullar sulcus (a transverse sulcus) superiorly
continuous with spinal cor inferiorly
Brainstem - Medulla Oblongata
What is the pyramid?
elevation on either side of the median anterior fissure, formed by pyramidal tracts
Brainstem - Medulla Oblongata
What is the olive?
elevation lateral to the pyramid that overlies inferior olivary nucleus
Brainstem - Medulla Oblongata
Which cranial nerves emerge from the medulla oblongata, and where?
cranial nerves IX, X, XI, and XII emerge from the anterolateral surface
Brainstem - Medulla Oblongata
Describe the composition (inferior half and superior half).
inferior half: composed of gray and white matters - same arrangement as spinal cord
superior half: gray matter is embedded within white matter as clusters of nuclei (that are associated with cranial nerve V, VIII, IX, V, XI, and XII)
Brainstem - Medulla Oblongata
What is the inferior olivary nucleus?
relay centre for proprioceptive info to cerebellum
Brainstem - Medulla Oblongata
What are 3 other major nuclei?
inferior olivary nucleus
nucleus gracilis
nucleus cuneatus
Brainstem - Medulla Oblongata
What tract are the nucleus gracilis and nucleus cuneatus both associated with?
medial lemniscus tract
Brainstem - Pons
How is the pons related to the cerebellum, medulla oblongata, and midbrain?
cerebellum: posteriorly
medulla oblongata: inferiorly
midbrain: midbrain
Brainstem - Pons
Describe the shape.
anterior surface is convex, and carries basilar sulcus (a longitudinal sulcus) occupied by the basilar artery
Brainstem - Pons
What cranial nerves emerge from the pons, and where?
cranial nerves VI, VII, and VIII emerge from ponto-medullary sulcus
cranial nerve V appears at anterolateral surface
Brainstem - Pons
What is the white matter of the pons formed by?
the ascending and descending tracts
Brainstem - Pons
How is the gray matter in pons organized?
as nuclei embedded in white matter
- some of these nuclei are related to cranial nerves V, VI, VII, and VIII
Brainstem - Pons
What is the 1 other major nuclei? What does it do?
pontine nuclei
- acts as relay centre for motor pathways between the cerebrum and cerebellum that coordinates the voluntary movements
Midbrain
What does the midbrain connect to?
pons inferiorly
diencephalon superiorly
Midbrain
What are cerebral peduncles?
two columns on anterior aspect of midbrain, between which CN III emerges
Midbrain
What are crus cerebri?
descending tracts in cerebral peduncles, such as corticospinal and corticobulbar tract
Midbrain
What are the superior and inferior colliculi?
4 elevations on posterior aspect of midbrain
Midbrain
What do the nuclei deep to the colliculi do?
act as relay center for visual (superior colliculi) and auditory (inferior) reflexes
Midbrain
Where are the ascending tracts?
occupy white matter of midbrain behind the cerebral peduncles
Midbrain
The nuclei embedded within the white matter is associated with what cranial nerve?
III, IV, V
Midbrain
What are 2 other major nuclei?
red nucleus
substantia nigra
Midbrain
What is the red nucleus associated with?
rubrospinal tract, as part of the extrapyramidal pathways
Midbrain
What is the substantia nigra functionally linked to?
basal ganglia regulating the voluntary movements
Cerebellum
Where is the cerebellum?
contained within posterior cranial fossa, underneath tentorium cerebelli, behind medulla and pons from which is separated by the fourth ventricle
Cerebellum
What does the cerebellum consist of?
2 cerebellar hemispheres
Cerebellum
What are the cerebellar hemispheres connected by?
vermis - a worm-like structure
Cerebellum
How is the cerebellum attached to the brainstem?
by 3 pairs of cerebellar peduncles
- superior cerebellar peduncles
- middle cerebellar peduncles
- inferior cerebellar peduncles
Cerebellum
What do superior cerebellar peduncles do?
carry axons that connect the cerebellum to the red nucleus of the midbrain and thalamus
Cerebellum
What do middle cerebellar peduncles do?
connect pontine nuclei of the pons to the cerebellum