Lecture 13 Brainstem

brainstem is ___% of the brain's total weight

2.6

brainstem regulates ___ and ___

heart

respiration

brainstem provides ___ and ___ nerve supply to the ___ and ___ via ___ ___

sensory; motor

face; neck

cranial nerves

brainstem is the main output of the

corticobulbar tract

brainstem conveys sensory and motor from ___ to ___ , ___ to ___ via what three tracts

brain; body

body; brain

corticospinal, DCML, spinothalamic

brainstem connects the ___ to the ___ and ___

cerebrum

spinal cord

cerebellum

brainstem is continuous with the ___ of the ___

thalamus

diencephalon

midbrain (___) consists of

(mesencephalon)

tectum, tegmentum, cerebral peduncles, cerebral aqueduct

tectum consists of

superior and inferior colliculus

tegmentum consists of

- reticular formation

- periaqueductal gray

- substantia nigra

- ventral tegmental area (VTA)

- red nucleus

- cerebellar peduncles

cerebral aqueduct contains

Edinger-Westphal nucleus

diencephalon consists of

thalamus, hypothalamus, pineal gland

tectum is latin for

roof

tegmentum is latin for

covering

what serves the midbrain

basilar artery

midbrain is site of ___ nuclei

CN IV (trochlear)

cerebral peduncle anatomy

superior colliculus

integrates visual, auditory, and somatosensory spatial info to initiate orienting movements of the eyes and head toward salient objects in space

superior colliculus receives info from ___ and then uses that info to initiate a ___ appropriate to the current ___

environment

behavioral response

environmental context

superficial layers of superior colliculus receives

visual info from retina and visual cortex

deep layers of superior colliculus receives

info from auditory, visual, and somatosensory system

in many vertebrates (fish, birds), the ___ is one of the largest brain regions

superior colliculus

inferior colliculus

- largest nucleus of the auditory system in humans

- the point in the brainstem where all auditory pathways traveling through the brainstem converge

the point from which auditory pathways branch out to carry auditory info on to other areas of the brain like the (___) is the ___

superior colliculus

inferior colliculus

inferior colliculus neurons are specialized to respond to cues that allow for ___ or ___. this info is transmitted to the ___, which is involved in ___

localization of sound

determination of where in space sound in coming from

movement in response to visual and auditory cues in the environment

red nucleus is involved in

motor coordination

red nucleus is considered to be a subcortical center of ___ along with ___

extrapyramidal motor system

substantia nigra

the cerebral peduncles are

two stalks that attach the cerebrum to the brainstem

cerebral peduncles are at the ___ of the midbrain, which arise from the ___ and contain the ___ nerve tracts that run to and from the ___ from the ___

front

ventral pons

large ascending (sensory) and descending (motor)

cerebrum

pons

important fiber tracts that run through the cerebral peduncles

corticospinal

corticopontine

corticobulbar

how many cerebral peduncles vs cerebellar peduncles are there?

2 cerebral

3 cerebellar

cerebellar peduncles

a paired structure of white matter that connects the cerebellum to the midbrain

where are the cerebellar peduncles located?

superior peduncle: midbrain

middle peduncle: pons

inferior peduncle: medulla

(each part of the brainstem has one cerebellar peduncle)

cerebellar peduncle consists of mainly

efferent fiber

pons makes up the

metencephalon

pons is latin for

bridge

pons evolved from the ___ about ___ years ago

medulla

525 million

pons has two distinct regions:

pontine tegmentum (dorsal part of the pons)

basilar pons (ventral part of the pons)

what artery serves the pons?

basilar artery

what ventricle runs through the pons?

4th ventricle

what peduncle serves the pons?

middle cerebellar peduncle

pons has the base nuclei for what cranial nerves?

V (trigeminal)

VI (abducens)

VII (facial)

VIII (vestibulocochlear)

the pons work with the ___ to serve an esp critical role in generating the ___

medulla oblongata

respiratory rhythm of breathing

pons cranial nerve functions include

- swallowing

- bladder control

- hearing

- equilibrium

- taste

- eye movement

- facial expressions

- facial sensation

- psoture

active functioning of the pons may also be fundamental to

rapid eye movement (REM) sleep

pons contains nuclei that relay signals from ___ to ___

forebrain

cerebellum

middle cerebellar peduncle: paired structures that connect the ___ to the ___ and are composed of ___ fibers

cerebellum

pons

incoming

locus coeruleus is latin for ___ and it gets its name because of

"blue spot"

melanin granules in cells (remember "black substance")

locus coeruleus (LC) is a nucleus in the

posterior area of the rostral pons

LC is principal site for production of

norepinephrine (noradrenaline)

LC projects ___ to...

norepinephrine

- spinal cord

- brainstem

- cerebellum

- hypothalamus

- thalamic relay nuclei

- amygdala

- telencephalon

- cortex

LC plays a role in

•Arousal/stress

•Attention

•Creativity

•Decision making

•Emotions

•Posture and balance

what is known as "black substance"

substantia nigra

norepinephrine (NE) is a

catecholamine

NE does what?

mobilize the brain and body for action

•"Fight or flight"

•Arousal

•Alertness

•Vigilance

•Formation and retrieval of memory

•Focuses attention

•Restlessness and anxiety

•Heart rate and BP

•Reduces blood flow to the GI

LC is activated by ___ and will ___

stress

increase NE secretion

increased NE production alters

cognitive function (PFC)

increase motivation (NAC)

activates HPA

hypothalamic-pituitary-adrenal (HPA) axis is the body's ___. it is a what kind of system?

central stress response

neuroendocrine

HPA axis regulates

•Stress

•Digestion

•Immune system

•Mood

•Emotions

•Sexuality

•Energy storage

•Expenditure

HPA axis

1. ___ of the ___ secretes ___ and ___

paraventricular nucleus

hypothalamus

CRH/CRF

vasopressin

HPA axis

2. CRF and vasopressin release stimualtes the ___ from the ___

adrenocorticotropic hormone (ACTH)

anterior lobe of the pituitary

HPA axis

3. ACTH release stimulates ___ from the ___

cortisol release

adrenal cortex

HPA axis

4. cortisol forms a ___ feedback loop with the ___ and ___

negative

hypothalamus

anterior pituitary

cortisol is a ___ produced by the ___

steroid hormone

adrenal glands (glucocorticoid)

cortisol is released during ___ and ___

stress

low blood sugar

cortisol does what?

- increase blood sugar

- suppress the immune system

- metabolizes fat, protein, carbs

symptoms of adrenal fatigue

•Poor mood

•Brain fog

•"wired" in the evenings

•Cravings for sweet and salty food

what leads to adrenal fatigue?

chronic stress (constant release of cortisol)

medulla oblongata comes from

myelencephalon

medulla oblongata consists of

•Nucleus cuneatus

•Nucleus gracilis

•Internal arcuate fibers

•Pyramids

•Inferior cerebellar peduncle

what artery serves medulla oblongata?

basilar artery

what cranial nerve base nuclei is in medulla?

IX (glossopharyngeal)

X (vagus)

XI (accessory)

XII (hypoglossal)

medulla plays an essential role in

passing messages b/t your spinal cord and brain

medulla is responsible for regulating several basic functions of the ___ nervous system including

autonomic

- respiration

- cardiac function

- vasodilation

- reflexes (e.g. vomiting, coughing, sneezing, swallowing)

nucelus cuneatus represents the rostral termination of the ___, the posterior column spinal pathway that carries info regarding ___ from the ___ extremities

fasciculus cuneatus

proprioception, fine tactile discrimination, and vibratory sensations

upper

nucleus gracilis represents the rostral termination of the ___, the posterior column spinal pathway that carries info regarding ___ from the ___ extremities

fasciculus gracilis

proprioception, fine tactile discrimination, and vibratory sensations

lower

internal arcuate fibers (tract)

axons of the second order sensory neurons that compose the gracile and cuneate of the medulla

medullary pyramids are paired ___ matter structures containing ___ fibers or the ___ and ___ tracts... hence the pyramidal tracts

white

motor

corticospinal

corticobulbar

pyramids are located on the ___ side of the medulla

ventral

pyramids are bordered medially by the

anterior median fissure

at the pyramids most caudal end, the ___ axons decussate the ___ and continue down the spinal cord on the ___ side. these fibers make up the ___ ___ tract. the fibers that don't decussate here make up the ___ ___ tract

corticospinal

midline

contralateral

lateral corticospinal

anterior corticospinal

inferior cerebellar peduncles contain mostly ___ fibers to the ___

afferent

cerebellum

brainstem damage is rare/common? and results from

rare

swelling in other areas of the brain or some stroke

most common consequences of brainstem damage

•Death

•Coma

•Locked in syndrome

•Swallowing problems

•Respiratory problems

•Motor difficulties

locked in syndrome

Individual is aware and capable of thinking but is paralyzed and cannot communicate

separate note!

there are a lot of anatomy images at the end of this lecture; make sure to look at them!