Gross Brain-Wilson Flashcards
What is a tract?
Gray Matter
White Matter
Nerves
Tract
in CNS but synonymous to nerves in PNS
What consists of the CNS?
brain and spinal cord
What consists of the PNS?
cranial and spinal nerves
What are the primary brain vesicles?
- prosencephalon (forebrain)
- mesencephalon
- rhombencephalon (hindbrain)
What does do the primary brain vesicles become?
prosencephalon:
- telencephalon (cerebral cortex)
- dicencephalon (anything with thalamus in its name
mesencephalon:
- midbrain
rhombencephalon
(hindbrain) :
- metencephalon (pons)
- myelencephalon (medulla)
Entire NS develops from a neural tube?
central canal of neural tube is lumen of the spinal cord that will become the ventricular system of the brain filled with CSF
What is the brainstem made up of?
- midbrain
- pons (metencephalon)
- medulla (myelencephalon)
What is gray matter in the spinal cord?
surrounds the lumen
consists of neurons
-in the brain organized into nuclei
-organized into a dorsal horn for sensory function and ventral horn for motor function
What is white matter in the spinal cord?
- axons coming and going to the cell bodies in the gray matter
- appears white because most of the axons are myelinated
What is the organization of the gray matter in the spinal cord?
- dorsal: sensory
- ventral: motor
dorsal/ventral organization extends all the way to the brainstem but becomes a bit blurry in the brain
The adult brain consists of what 4 parts?
- brain stem
- cerebellum
- Diencephalon
- Cortex
What are the 3 parts of the brainstem?
- continuation of the spinal cord which is medulla oblongata
- pons: has a ventral potbelly
- midbrain: part of the brain between the lower brainstem diencephalon and and the cortex
Where is the landmark used to distinguish the transition of the spinal cord to the medulla oblongata?
the decussation of the pyramids
What are the boundaries of the medulla oblongata?
- caudal: decussation of the pyramids which is . the gradual transition from the spinal cord and extends below the foramen magnum
- rostral: pontomedullary junction
What are the function of the medulla oblongata?
- cardiac center that controls the force and rate of heartbeat and rate of breathing
- respiratory center that controls the contraction and relaxation of the diaphragm (controls the rhythm and rate of breathing)
the diaphragm is skeletal muscle so you have complete voluntary control but the rhythm generator of that contraction and relaxation are located in the medulla
What happens when you have a stroke that affects the medulla oblongata?
you will affect the breathing and cardiovascular centers
What are the pyramids and what is contained in them?
two long columns of axon traveling from the cortex to the spinal cord
-contained in them are the corticospinal tract (supresses the extensor Babinski response in the adult )
What is the corticospinal tract?
a tracts of axons that goes from the cortex where the cell bodies are located
and the axons descend through the diencephalon route, brainstem, spinal cord innervating motor neuron in the ventral horn
-allows for voluntary control of movement moving away from reflex type of movement (you can learn new movements)
What is the reason for the swelling of the olives in the medulla oblongata?
inferior olivary complex inside the medulla which has close connections to the cerebellum and that is involved in motor learning
What are the dorsal columns?
- carry sensory fibers for fine touch, vibration, an proprioception
- these fibers ascend from the spinal cord to terminate in the medulla
What are the ascending sensory systems and where are they located in the brain?
they are the dorsal columns which are located in the medulla on the posterior side right underneath the cerebellum
What are the 4 cranial nerves that originate from the medulla?
CN IX, X, XI, XII
-CN XII (hypoglossal nerve): originates in the groove between the pyramids and inferior olives; series of rootlets that very very fine and come together to form CN XII
below CN originate dorsal to the olive
- CN IX: the very first root that comes off of the olive (large)
- CN X: arises as a series of rootlets, not just one
- CN XI (accessory nerve): is divided into two parts: a cranial* part and a spinal part that originate from the cervical spinal cord
What are the 3 CN that originate from the pontomedullary junction?
CN VI, VII, VIII
CN VI (abducens nerve): most medial nerve; innervates lateral rectus muscle)
CN VII (facial nerve): comes off of the pons; control muscles of facial expression
CNVIII: the acoustic and vestibular nerve for hearing and balance
What is the does the pons contain and what CN is associated with it?
middle cerebellar peduncle : massive tract of axons carrying info from cortex through the pons up to the cerebellum
-main root of the CN V (trigeminal nerve): will find a trigeminal ganglion not attached to the brain itsel; it is a sensory ganglion (V1, V2, V3)
What is the function of the pons?
relays signals between the cerebral cortex and cerebellum
The tube of the neural tube forms the ventricular system of the brain. Where is the fourth ventricle found in the brain?
dorsal to the medulla and pons
- it SEPARATES the medulla/pons from the cerebellum
- filled with CSF (remember the lumen of the neural tube becomes the ventricular system of the brain filled with CSF)
What is the function of the middle cerebellar peduncle?
- connects pons with cerebellum; carrying cortical info via the pons to the cerebellum
- cell bodies (neurons) are found in the pons and their axons go to the cerebellum
Because of the presence of the cerebellum, the roof plate is split and the central canal enlarges to become the 4th ventricle over the pons and medulla.
the cerebellum develops from the roof of the medulla and as it enlarges, the medulla flattens out
-the general embryonic origin of sensory and motor nuclei seen in the spinal cord is maintained
What are the parts of the midbrain?
- superior colliculus for visual oculomotor reflexes
- inferior colliculus for auditory relay center
they all together come to form the corpora quadrigemina
relay center so that when ??????
Which nerve exits the brain immediately caudal to the inferior colliculus?
CN IV (trochlear nerve)
- CN IV originates from the dorsum of the midbrain
- this is the only CN that exits the brain DORSALLY; all the other nerves exits ventrally or ventrolaterally)
Cerebral peduncle
a column of axons in the midbrain that includes the corticospinal tract with axons coming from cortex go through pons to reach the pyramids
CST important for voluntary movements
What other nerve is associated with the midbrain?
CN III (occulomotor nerve)
What is the cerebral aqueduct?
the brain has a ventricular system
-the large 4th ventricle becomes very narrow and becomes the cerebral aqueduct: a channel carrying CSF from the 3rd to 4th ventricle
-its not just axons but also contains other neuronal structures
What is the tectum?
the roof over the cerebral aqueduct
-it is found dorsal to the cerebral aqueduct
What is crus cerebri?
the anterior portion of the cerebral peduncle that contains descending motor tracts (e.g. corticospinal, corticobulbar).
-they are axons coming from cortex going to the spinal cord, the pons, or to the brainstem
Where is substantia nigra
(Parkinson’s disease)?
part of the cerbral peduncle
What is the periaqueductal gray responsible for?
- visceral pain response
2. fight flight
What is tegmentum?
the core of nuclei and tract that you find near the midbrain and pons ????
it is DIFFERENT FROM TECTUM