BIO 201: Chapter 4.2 Gross Anatomy of the Nervous System - The Brain

brain

complex mass of nerve, connective, and epithelial tissue that is divided into 4 anatomical and functional regions

cerebrum, diencephalon, cerebellum, and brainstem

4 anatomical and functional regions of the brain

cerebrum

largest region that occupies most of the space in the cranial cavity

• split into 2 cerebral hemispheres and made up of 4 lobes

diencephalon

pair of oval shaped structures deep into the cerebrum

• superior to the brainstem’s midbrain

• contains multiple nuclei

• gateway to the cerebral cortex

cerebellum

second largest region of the brain

• inferior to the cerebrum and posterior to the brainstem

• consists of a left and right cerebellar hemispheres

brainstem

long structure that extends inferiorly from the diencephalon

• 10 of the 12 cranial nerves originate from here

• made up of the midbrain, pons, and medulla oblongata

fissures, sulci, and gyri

external features of the cerebellum described as grooves and folds

fissures

deeper grooves or furrows that usually separate bigger parts of the brain

sulci

shallow grooves found in the cerebrum

gyri

folds found in the cerebrum

true

true or false: it takes two gyri to form a sulcus and two sulci are found on each side of a gyrus

gray matter

located superficial in the cerebrum and cerebellum

• composed of neuron cell bodies, dendrites, and synapses

cerebellar and cerebral cortexes

superficial layer on both the cerebrum and cerebellum

nuclei

deeper masses of gray matter surrounds by white matter

white matter

lies deep to the gray matter

• composed of bundles of axons and tracts

meninges

set of 3 connective tissue membranes that surround the brain and spinal cord

dura mater

most superficial cranial meninge layer that is tough and protects the brain

• made up of 2 layers (periosteal and meningeal layers)

periosteal layer

outer layer of dura mater that surrounds the cranial bones

meningeal layer

inner layer of dura mater that faces the other meninges, surrounds and supports the dural sinuses that drain deoxygenated blood from brain

• formed by 3 structures: falx cerebri, tentorium cerebelli, and falx cerebelli

falx cerebri

separates each cerebral hemisphere and is located in longitudinal fissure

tentorium cerebelli

separates cerebrum from cerebellum and is located in longitudinal fissure

falx cerebelli

separates each cerebellar hemisphere and is located inferior to the cerebellum

subdural space

potential space below the dura mater and above the arachnoid matter

• potential space as it can be opened if needed in case of brain bleed

dural sinuses

spaces formed by the layers of the dura mater that collect deoxygenated blood and CSF circulated through the brain

• ex: superior sagittal sinus

arachnoid mater

second layer of the cranial meninges that resembles a spider web and has small parts called arachnoid granulations

arachnoid granulations

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

subarachnoid space

an actual space below the arachnoid mater where CSF flows and surrounds the brain and spinal cord

pia mater

deepest layer of the cranial meninges, very thin and delicate and closely follows every contour of the brain including the sulci

ventricles

system of fluid filled cavities spaces located in different parts of the brain

choroid plexus

spongy mass of capillaries that line ventricles

lateral ventricles

aka the 1st and 2nd ventricles which form an arc with an anterior, posterior, and inferior horns and is located within the left and right cerebral hemispheres

interventricular foramen

located inferior to the anterior horn and functions to connect the lateral ventricles to the 3rd ventricle

3rd ventricle

ventricle located below the corpus callosum and within the medial part of the thalamus

cerebral aqueduct

located in the midbrain and functions to connects the 3rd ventricle to the 4th ventricle

4th ventricle

ventricle located between the pons and cerebellum

central canal and apertures

located by the medulla oblongata and function to drain CSF into the subarachnoid space

cerebrospinal fluid

clear and colorless fluid that flows in the ventricles and is derived from plasma to protect the brain by allowing it to float in the insulation fluid

500, ependymal

about ____ mL/day of CSF is produced by _____ cells lining the choroid plexus found in each ventricle

functions of CSF

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

• protection: protects the brain from striking the cranium when head is jolted to prevent TBIs or concussions

• chemical stability: rinses metabolic wastes from the nervous tissue and regulates its chemical environment

left and right lateral ventricles → interventricular foramen → third ventricle → cerebral aqueduct → fourth ventricle → out the apertures and central canal → to subarachnoid space → reabsorbed by arachnoid granulations into the dural sinuses

CSF flow in the ventricles

frontal lobe

responsible for emotion, mood, memory, and aggression

broca area

motor language area for speech or sign language located superficial and anterior in the left frontal lobe

parietal lobe

responsible for sensory and integration of taste

temporal lobe

responsible for hearing, smell, learning, visual recognition, and emotional behavior

wernicke area

recognition of spoken and written language located superficial and posterior in the left temporal lobe

occipital lobe

principal visual center of the brain

insula

small mass of cerebral cortex deep to the lateral sulcus that plays role in pain and empathy

central sulcus

shallow groove found between the frontal and parietal lobes

lateral sulcus

shallow groove found between the frontal and temporal lobes

parieto-occipital sulcus

shallow groove found between the parietal and occipital lobes

transverse fissure

deep groove found between the cerebellum and cerebrum

longitudinal fissure

deep groove found between each cerebral hemisphere

precentral gyrus

aka the primary motor cortex, immediate fold anterior to the central sulcus located in the frontal lobe

• signals sent from here result in muscle contractions

postcentral gyrus

aka the primary somatosensory cortex, immediate fold posterior to the central sulcus located in the parietal lobe

• awareness of stimulation occurs here

corpus callosum

thick C-shape structure made up of nerve axons/tracts that connect the cerebral hemispheres to each other

fornix

thin C-shape structure located inferior to the corpus callosum

basal nuclei

striped masses of gray matter buried deep in the white matter lateral to the thalamus and are involved in motor control

• caudate nucleus: superior and medial

• putamen: lateral

• globus pallidus: inferior and medial

cerebellar cortex

central control point for muscle contraction

arbor vitae

translates to “tree of life” and is white matter of the cerebellum

folia

folds found within the cerebellum

vermis

medial structure that connects each cerebellar hemisphere

tentorium cerebelli

separates cerebrum from cerebellum, located in the transverse fissure

falx cerebelli

separates each cerebellar hemisphere, located inferior to cerebellum

thalamus

gateway to the cerebral cortex, filters information and relays a small portion of it to the cerebral cortex, made up of at least 23 nuclei

hypothalamus

anterior and inferior to the thalamus and optic chiasm, connected to the pituitary gland via the infundibulum and rests on the hypophyseal fossa, it is the major control center of the autonomic nervous and endocrine systems

epithalamus

posterior and superior to the thalamus, found in it is the pineal gland which releases the hormone melatonin

mammillary bodies

pair of round structures located posterior to the pituitary gland

midbrain

associated with controlling our awareness of pain and collaborates in fine motor control, located inferior to the thalamus and superior to the pons, contains colliculi

• 2 cranial nerves originate here

colliculi

4 bulges in the midbrain that split into 2 superior colliculi and 2 inferior colliculi

• superior colliculi: involved with control of extrinsic eye muscles

• inferior colliculi: relay signals from the inner ear to the thalamus

pons

responsible for relaying signals, hearing, equilibrium, taste, eye movements, swallowing, bladder control, and posture, located below the midbrain and above the medulla oblongata

• 4 cranial nerves originate here

medulla oblongata

cardiac, respiratory, and vasomotor center, once it passes through the foramen magnum it becomes the spinal cord, located inferior to the pons

• 4 cranial nerves originate here