Central nervous system (CNS) The brain

Which is the cerebrum & what is it?

A

• largest region & occupies most of the space

• split into 2 cerebral hemispheres (left & right) & each is made up of lobes

which is the diencephalon & what is it?

B

• pair of oval-shaped structures deep into cerebrum

• contains multiple nuclei (deep mass of gray matter surrounded by white matter)

• dubbed as the gateway to the cerebral cortex

Which is the cerebellum & what is it?

D

• 2 largest region of the brain

• located inferior to the cerebrum but posterior to the brainstem

• consists of left & right cerebellar hemispheres

Which is the brainstem & what is it?

C

• long structure that extends inferiorly from the diencephalon

• 10 out of the 12 cranial nerves originate from here

• made up of 3 parts (superior midbrain, pons, medulla oblongata)

what are the 2 cranial nerves that only originate from the cerebrum?

• CN I olfactory nerve

• CN II optic nerve

Fissures

deeper groves/furrows usually separating bigger arts of the brain

sulci

shallow grooves found in cerebrum

gyri

fold found in cerebrum (think of a gyro sandwich which is folded)

what are gray matter composed of?

• neuron cell bodies

• dendrites

• synapses

what is white matter mainly composed of?

bundles of axons/tracts

the brain & spinal cord are surrounded by a set of 3 connective tissue membranes knows as what?

meninges

what are the 3 layers from superficial to deep?

1. dura mater

2. arachnoid mater

3. pia mater

dura mater

tough layer protecting the brain; made up of 2 layer

what are the 2 layers that make up the dura mater?

• periosteal layer

• meningeal layer

periosteal layer

outer layer surrounding the cranial bones, equivalent to periosteum

meningeal layer

inner layer facing other meninges; ONLY part of dura that extends to the vertebral canal

What does the meningeal layer do?

surrounds & supports the dural sinuses that drain deoxygenated blood from the brain

What are the 3 structures formed by the meningeal layer that separates parts of the brain

• falx cerebri

• tentorium cerebelli

• falx cerebelli

subdural space

a potential space (meaning it can be opened if needed; for issues like brain bleed)

dural sinuses

spaces formed by the layers of the dura mater that collects deoxygenated blood & CSF circulated throughout the brain

what is an example of the dural sinuses found in the brain?

superior sagittal sinus

Arachnoid mater

2 layer resembling a spider web

what are the small parts called on the arachnoid mater?

arachnoid granulations

arachnoid granulations

tree-like protrusions piercing through the dura mater, which reabsorbs CSF into the dural sinuses

subarachnoid space

an actual space below the arachnoid mater where CSF flows

pia mater

very thin & delicate layer that closely follows every contour of the brain even the sulci

ventricles

the brain contains a system of fluid filled cavities (spaces); located in diff parts of brain

what is the ventricles lined with?

a spongy mass of capillaries called the choroid plexus

how many ventricles are there?

4 ventricles & other pathways that connect each ventricle

lateral ventricles (aka 1st & 2nd)

forms an arc with an anterior, posterior, inferior horns

where is the lateral ventricle located?

with the left & right cerebral hemispheres

Interventricular foramen

located inferior to the anterior horns, connected the lateral ventricles to the 3rd ventricle

3rd ventricle

located below the corpus callous & within the medial part of the thalamus

cerebral aqueduct

located in the midbrain; connects the 3rd ventricle to the 4th ventricle

4th ventricle

located btw the pons & cerebellum

central canal & apertures

located by the medulla oblongata

what does the central canal & apertures drain?

CSF into the subarachnoid space (actual space)

cerebrospinal fluid

clear & colorless fluid flowing in the ventricles

what is the CSF derived from?

plasma

what does the CSF protect?

serves to protect the brain by allowing it to float in the insulating fluid of the CSF

about how many CSF is produced?

500ml/day of CSF

what type of cells produces CSF?

ependymal cells lining the choroid plexus found in each ventricle & pathways

what are the 3 functions of the CSF?

• buoyancy

• protection

• chemical stability

buoyancy

allows the brain to attain considerable size without being impaired by its own weight

protection

it protects the brain from striking the cranium when the head is jolted

what happens if the brain is jolted?

could lead to traumatic brain injuries or concussions

chemical stability

it rinses metabolic waste from the nervous tissue & regulates its chemical environment

what is the steps of the CSF flow in the ventricles?

1. left & right lateral ventricles

2. interventricular foramen

3. 3rd ventricle

4. cerebral aqueduct

5. 4th ventricle

6. out of the apertures & central canal

7. to the subarachnoid space that surrounds the brain & spinal cord

8. reabsorbed by arachnoid granulations into the dural sinuses