lecture 27 brain

brainstem, diencephalon, cerebellum, cerebrum

what regions does a structural examination of the brain reveal?

brainstem

which part of the brain is partially hidden from a lateral view?

diencephalon

which part of the brain is completely hidden from a lateral view?

midbrain, pons, medulla

what can the brainstem be subdivided into?

forebrain (prosencephalon), midbrain (mesencephalon), and hindbrain (rhombencephalon)

what are the regions of the brain when subdivided based on embryological origins?

Prosencephalon

what is the name for the forebrain?

mesencephalon

what is the name for the midbrain?

rhombencephalon

what is the name of the hindbrain?

five

commonly, the brain is divided into how many parts based on embryological development?

telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon

what are the common divisions of the brain based on embryological development?

cerebrum (t)

what is the telencephalon?

thalamus structures (dorsal thalamus, hypothalamus, epithalamus, subthalamus)

what is the diencephalon?

pons and cerebellum

what is the metencephalon?

medulla oblongata (m)

what is the myelencephalon?

medulla oblongata

what is the oldest, most primitive part of the brain?

telencephalon and diencephalon

the prosencephalon (forebrain) consists of what divisions of the brain?

metencephalon and myelencephalon

the rhombencephalon (hindbrain) consists of what divisions of the brain?

cerebral cortex, basal nuclei, hippocampus, olfactory bulb, basal forebrain

what are the adult brain derivatives of the telencephalon?

foramen magnum

what does the medulla oblongata lie partially below the level of?

lowest part of the brainstem that serves as relay station between the spinal cord and pons

what is the medulla oblongata?

pyramids and olives

what can be seen on medulla oblongata anteriorly?

descending motor tracts (upper motor neurons)

what do the pyramids of the medulla oblongata contain?

motor learning

what are the olives of the medulla oblongata involved in?

7

how many cranial nerves emanate from the medulla and its borders?

vital body functions like respiratory rate, heart rate, vasomotor tone, coughing reflex

what is the medulla responsible for maintaining?

no, it modulates it

does the medulla oblongata set the heart rate?

floor of the 4th ventricle

the medulla oblongata contains the inferior part of the...

middle portion of brainstem between the midbrain and medulla oblongata

what is the pons?

vertically oriented motor fibers (upper motor fibers) coursing from midbrain towards spinal cord and transverse nerve fibers carrying information to and from the cerebellum

what does the basilar pons contain?

assists in regulating REM sleep and coordinates respiratory rate and depth with the medulla

what is the function of the posterior portion of the pons?

superior part of the floor of the 4th ventricle

what is formed by the pons?

most superior portion of the brainstem that surrounds the cerebral aqueduct

what is the midbrain?

tegmentum (midbrain)

what is located anterior to the cerebral aqueduct?

nuclei for cranial nerves III and IV and reticular system which regulates consciousness

what does the tegmentum of midbrain contain?

substantia nigra

what is the tegmentum of the midbrain bounded anteriorly by?

dopamine

what do the substantia nigra neurons of the midbrain produce?

large tracts of descending motor fibers from cerebral cortex

what are the cerebral peduncles (midbrain)?

corpora quadrigemina of midbrain

what is located posterior to cerebral aqueduct?

superior colliculi and inferior colliculi

what does the corpora quadrigemina of the midbrain consist of?

visual system reflexes

what does the superior colliculi of corpora quadrigemina integrate?

auditory system function

what does the inferior colliculi of corpora quadrigemina integrate?

Parkinson's disease

in what condition is reduced substantia nigra visible in?

posterior to pons and medulla oblongata

where is the cerebellum located?

cerebellar peduncles

what does the cerebellum receive fibers from all three portions of the brainstem via?

vermis

the cerebellum consists of two lobes or hemispheres that are united by what?

folia

each lobe of cerebellum is covered by fine ridges called what?

arbor vitae

when the cerebellum is cut in a sagittal section, the patterning of the white matter resembles a cedar leaf and is called the...

midbrain and cerebellum

what does the superior cerebellar peduncle connect?

pons and cerebellum

what does the middle cerebellar peduncle connect?

medulla oblongata and cerebellum

what does the inferior cerebellar peduncle connect?

refining motor control and coordination, balance and posture

historically, what was the cerebellum only believed to be associated with?

visual and auditory inputs with proprioceptive information

what does the cerebellum integrate?

language, cognitive tasks, and addiction

what does current research indicate that the cerebellum plays a role in...

cerebellar ataxia, dysmetria, nystagmus, and dysdiadochokinesia

what symptoms may result from cerebellar lesions?

cerebellar ataxia

what is widened gait with poor central posture?

inability to perform rapid, alternating motions

what is dysdiadochokinesia?

dorsal thalamus

what is the thalamus aka?

large ovoid mass of gray matter situated deep within forebrain

what is the thalamus?

third ventricle

what are the two thalami separated by?

band of CT called interthalamic adhesion or massa intermedia

what joins the two thalami?

thalamus

what is the largest part of diencephalon and is a collection of nuclei with distinct functions?

relays all sensory information except for olfaction up to the cortex

what is the function of the thalamus?

up to 90%

what percentage of all sensory information does the thalamus filter out so that we are not overwhelmed/distracted by irrelevant sensory input?

anterior and inferior to the thalamus

where is the hypothalamus located?

floor and lateral walls of the third ventricle

what does the hypothalamus form?

pituitary gland via infundibulum

what is the hypothalamus connected to?

-acting as control center for ANS

-thermoregulation

-regulating circadian rhythm

-controlling the secretion of pituitary hormones

-regulating osmolality, thirst, and hunger

-assisting in formation of new memories

list functions of hypothalamus

ADH and oxytocin

what hormones are produced in the hypothalamus?

maintain homeostasis using autonomic reflexes, endocrine stimulation, and somatic nervous system

what is the primary function of the hypothalamus?

limbic system

the hypothalamus is a component of what system?

emotional responses and memory formation

the hypothalamus is a component of the limbic system and is involved in...

pleasure and pain, sexual satisfaction, emotional situations, anger and aggression

what kind of emotional responses can the hypothalamus be involved with?

stria medullaris, habenula, habenular commissure, pineal gland

what does the epithalamus include?

link components of limbic system in forebrain to those in midbrain

what does the epithalamus and its components do?

antioxidant, influences regulation of circadian rhythm

describe characteristics of melatonin

ventral thalamus or prethalamus

what is the subthalamus aka?

collection of nuclei located anterior to thalamus and lateral to hypothalamus

what is the subthalamus?

substantia nigra and basal nucleus

what are some of the nuclei of the subthalamus connected to?

regulating skeletal muscle contractions

some of the nuclei of the subthalamus assist in...

cognitive abilities

what is the cerebrum responsible for?

cerebrum

what is the most recent evolutionary addition to the nervous system?

longitudinal fissure

the two cerebral hemispheres of the cerebrum are separated by a deep groove called the...

corpus callosum and 3 smaller commissures

what are the two cerebral hemispheres connected to one another by?

four

each cerebral hemisphere consists of how many visible lobes?

five (one is hidden)

each cerebral hemisphere consists of how many total lobes?

frontal, parietal, temporal, occipital, insula

what are the five lobes of the cerebrum?

transverse fissure

what separates the cerebrum from the cerebellum?

gyri (sing. gyrus)

the surface of the cerebrum has ridges or folds called ___ that increase the surface area

sulci (sing. sulcus)

between the gyri of the cerebrum are grooves called...

separation between frontal and parietal lobes

what does the central sulcus of the cerebrum denote?

temporal lobe from frontal and parietal lobes

what does the lateral sulcus of the cerebrum denote the separation between?

parietal from occipital lobes

what does the parieto-occipital sulcus denote the separation between?

parieto-occipital sulcus

what sulcus is only seen in the midsagittal groove?

gray matter and white matter

what is the entire cerebrum composed of?

unmyelinated structures such as cell somas, synapses, and dendrites

what is gray matter composed of?

gray matter

what forms a thin layer covering the surface of the cerebrum called the cortex?

large nuclei

gray matter is found in some ___ within the substance of the cerebrum

6 layers thick

the cortex is usually how many layers thick?

1.5-4.5 mm

the cortex is approximately ___ thick

cognition, memory

what is the cortex responsible for?