chapter 18

which cranial nerves lets your eyes do tricks?

NIII (oculomotor), NIV (trochlear), & NVI (abducens)

cranial nerves pseudonym

Some Say Money Matters But My Brother Says Big Brains Matter More

NVI

abducens nerve; abducts eyeball; innervates lateral rectus; origin= pons; foramen= superior orbital fissure

falx cerebri

anchors brain in crista galli; between right & left hemispheres of cerebrum along the longitudinal fissure

visual cortex

anything you see

periosteal layer of dura mater

attaches to inner surface of skull; felt within anterior fontanel of baby; only in brain stem- not spinal cord

association fibers

connects areas of the cerebral cortex within the same hemisphere; arcuate fibers (short) & longitudinal fasciculi (long)

infundibulum

connects hypothalamus to pituitary gland; contains axons of specialized neurons (neurosecretory cells) that produce hormones like ADH & oxytocin --> transported to the pituitary gland --> released into bloodstream

longitudinal fissure

divides right & left hemispheres of cerebrum

brain ventricles

have CSF because of choroid plexus

where is CSF found?

in central canal, inside ventricles, & surrounding brain & spinal cord

brainstem

mesencephalon/ midbrain, pons, and medulla oblongata

insula

part of temporal lobe; contains gustatory cortex

gustatory cortex

perception of taste

frontal lobe anatomical landmarks

precentral gyrus/ primary motor cortex, premotor cortex, prefrontal cortex

meningitis

problem w/ reabsorption of CSF; no communication between where CSF is made & where CSF is reabsorbed; increases intracranial pressure which is fatal

prefrontal cortex

thinking, trouble-solving, concentration, behavior, personality, morality, judgement

epicranial aponeurosis

tough layer of dense fibrous tissue which covers the upper part of the cranium

lateral ventricles

a set of paired ventricles located in the cerebral hemispheres mostly in parietal lobes & don't communicate w/ each other; anterior, posterior, & inferior horns

NXI

accessory nerve; only nerve w/ cranial & spinal root; origin= spinal cord & medulla oblongata; foramen= jugular foramen; internal branch destination= muscles of palate, pharynx, & larynx; external branch destination= sternocleidomastoid & trapezius

somatosensory association area

allows recognition of texture, size, & shape

tentorium cerebelli

along the transverse cerebral fissure; separates the cerebrum from the cerebellum

temporal lobe anatomical landmarks

auditory association area, auditory cortex, olfactory cortex; associated w/ hearing & smell

why is the hypothalamus affected by emotional state?

because it's wired to the limbic system (center of emotions of the brain); ex. upset state= increased heart rate & blood pressure, relaxed state= decreased heart rate & blood pressure

what is the reason why a patient may survive an injury to the cerebrum?

because of the brain stem

central sulcus

between frontal and parietal lobes

fourth ventricle

between pons and cerebellum

superior sagittal sinus

between right & left cerebral hemispheres; where CSF gets back into the bloodstream from arachnoid granulations; receives blood from cerebral veins

cerebrum

biggest area of brain; conscious thought processes, intellectual functions; memory storage & processing; conscious & subconscious regulation of skeletal muscle contractions

tight junction

blocks passage of material between cells; only lipid-soluble compounds are capable of passing the lipid bilayer

mandibular division

both sensory & motor functions; innervates muscles of mastication; sensation of lower teeth

what does paralysis of NIV do?

causes deviation of eye

what does damage to NVI do?

causes eye to deviate medially

capillary endothelial cells

cells that line the inside of capillaries

hypothalamus

centers controlling emotions, autonomic functions in internal organs, & hormone production (ex. temperature control, thirst, internal balance, salivation, heart rate); main visceral control center of body; connects to pituitary gland to nervous system

which of the following separates the motor information from sensory information? -occipitoparietal sulcus -temporoparietal sulcus -lateral sulcus -central sulcus

central sulcus

which part of the brain is responsible for fine motor movements?

cerebellum

cerebellar peduncles

cerebellum communication w/ other regions of the brain; superior, middle, & inferior

6 major regions of the brain

cerebrum, diencephalon, mesencephalon, pons, medulla oblongata, & cerebellum

where is the blood brain barrier absent & why?

choroid plexus: filtered plasma forms CSF so a weak barrier is needed between the capillaries & the brain; hypothalamus: have receptors that need to sense chemical content of blood & needs easy access to blood content; pituitary & pineal gland: secrete hormones that need to release directly into bloodstream

inferior cerebellar peduncle

communicates cerebellum to the medulla oblongata

superior cerebellar peduncle

communicates cerebellum w/ mesencephalon, diencephalon, & cerebrum

middle cerebellar peduncle

communicates cerebellum with pons

commissural fibers

connect hemispheres; corpus callosum & anterior commissure

cranial meninges

connective tissue layers that separates soft tissue of brain from skull; continuation of spinal meninges; dura, arachnoid, & pia mater

interthalamic adhesion

connects right and left thalamus

postcentral gyrus/ primary somatosensory cortex

consciously feel sensations of skin, muscles & joints

epithalamus

contains the pineal gland

cerebellum

coordinates complex somatic motor patterns & skeletal muscle movements; adjusts output of other somatic motor centers in brain & spinal cord; second largest part of the brain

what protects the brain?

cranium, cranial meninges, CSF, blood brain barrier, & rich blood supply by carotid arteries

optic chiasm

crossing of nerves; located in anterior margin of diencephalon on top of pituitary gland; allows our visual sensory information from each eye to be received on both sides of the brain simultaneously

corpus callostomy

cutting corpus callosum to prevent seizures from both sides of body

what happens if the brain stem is damaged?

death

fissure

deep depression

sulcus/ sulci

depression or groove in the surface of the cerebral cortex; between gyri; gives us different lobes of the brain

periosteum

double-layered connective tissue that covers and nourishes the bone

spinal cord

end has opening where CSF comes out & enters subarachnoid space

pineal gland

endocrine gland that produces melatonin (helps regulate sleep/wake cycle)

diencephalon

epithalamus, thalamus, & hypothalamus

folia of cerebellum

equivalent to cerebrum gyri

dura septa

extensions of dura mater that go deep inside brain; the folds subdivide the cranial cavity, supports the brain, & limits brain movement

arachnoid granulations

extensions of the arachnoid mater that allow excess CSF to be absorbed by the superior sagittal sinus & gets recycles

which of the following is not a cranial nerve that innervates the eye? -facial - CN VII -oculomotor - CN III -abducens - CN VI -trochlear - CN IV

facial - CN VII

NVII

facial nerve; carries information from anterior 2/3 of tongue; controls most muscles of facial expression; sensory origin= taste buds; motor origin= pons; innervates lacrimal, submandibular, & sublingual glands; foramen= internal acoustic meatus; sensory destination= pons

olfactory bulb

form neuronal masses on either side of crista galli

anterior horn of lateral ventricle

frontal lobe

corpus callosum

gives hemispheres ability to communicate; commissural fiber

NIX

glossopharyngeal nerve; sensory= taste information of posterior 1/3 of tongue & special receptors found within major blood vessels (baroreceptors & chemoreceptors); motor= controls parotid salivary glands (visceral) & pharyngeal muscles for swallowing (somatic motor); motor origin= salivary gland; foramen= jugular foramen; sensory destination= medulla oblongata

projection fibers

group of axons link cerebral cortex w/ other regions of the brain stemlike the diencephalon, brainstem, cerebellum, & spinal cord

interventricular foramen

how lateral ventricles communicates w/ the third ventricle

NXII

hypoglossal nerve; controls tongue movement; origin= medulla oblongata; foramen= hypoglossal canal; destination= tongue muscles

hydrocephalus description & treatment

increased amount of CSF from obstruction within ventricular system or problems w/ reabsorption; occurs in newborns because their skull bones are not fused yet which increases pressure & results in an enlarged head; in adults, the pressure is kept within because of the rigidity of the skull & results in potential brain damage because of the compression of brain blood vessels & crushing of soft nervous tissue; treatment= drain CSF by making a hole in a ventricle w/ a tube & placing it in the abdominal cavity

choroid plexus

inside all 4 ventricles; contains blood vessels surrounded by ependymal cells; have capillary endothelial cells but no astrocytes

what happens once CSF comes out of the spinal cord & enters the subarachnoid space?

it reaches arachnoidvilli/ arachnoid granulations --> if CSF is greater than the venous pressure of the superior sagittal sinus, the CSF gets squeezed out of the subarachnoid space flowing into the bloodstream to get reabsorbed (involves meninges) if CSF is less than the venous pressure, the arachnoidvilli/ arachnoid granulations will not let blood pass into the ventricular system

pyramidal cells

large neurons that allow conscious control of skeletal muscle movements

directionality of CSF

lateral ventricle --> 3rd ventricle --> 4th ventricle; due to ciliated movement of ependymal cells

olfactory receptors

located in dendrites of olfactory sensory neurons in roof of nasal cavity

third ventricle

located in the diencephalon between thalami

arachnoid trabeculae

made of collagen fibers; give arachnoid mater weblike appearance; helps anchor cerebral blood vessels in place

pituitary gland

master endocrine gland of body;

visual association area

matching faces

pia mater

most pliable; delicate connective tissue that attaches to brain; contours every gyri of cerebral cortex; helps nourish brain cells due to blood vessels

posterior horn of lateral ventricle

occipital lobe

NIII

oculomotor nerve; helps to move upper eyelid & intrinsic eye muscles; controls all extrinsic eye muscles except superior oblique & lateral rectus; changes diameter of pupils by adjusting the amount of light entering the eye; changes shape of lens to focus images from retina; origin= mesencephalon; foramen= superior orbital fissure; destination= extra-ocular eye muscles

NI

olfactory nerve; only cranial nerve exposed to exterior; shortest cranial nerve; inside nasal epithelium; where the 5% of sensory information from thalamus is missing; axons from olfactory epithelium form bundles that pass through olfactory foramina within cribriform plate --> synapse w/ secondary neuron within olfactory bulb --> axons of secondary order neurons travel within olfactory tract taking information to cerebrum

ophthalmic division

only sensory function

maxillary division

only sensory function; sensation of upper teeth/ jaw

lateral & median apertures

openings that communicate w/ subarachnoid space; how 90% of CSF leaves the ventricular system & bathes entire surface of CNS

NII

optic nerve; only nerve that comes together, crosses, & splits again; origin= retina; foramen= optic canal of sphenoid bone; destination= diencephalon --> occipital lobe

premotor cortex

planning of motor movement of skeletal muscles(ex. thinking of grabbing pen to write); sends information to precentral gyrus/ primary motor cortex

astrocytes

plays a role in providing nourishment for neurons

parietal lobe anatomical landmarks

postcentral gyrus/ primary somatosensory cortex, somatosensory association area

a psychological disorder happens when something goes wrong in which anatomical landmark?

prefrontal cortex

functions of CSF

prevents contact of neural tissue w/ surrounding bones; gives buoyancy to CNS structures (helps brain float in skull); reduces weight of brain; protects brain & spinal cord from trauma; nourishes brain & removes metabolic waste out of CNS

mesencephalon/ midbrain

processing of visual & auditory data, and associative reflex (reacting to loud sound); generation of reflexive somatic motor responses; maintenance of consciousness; moves eyes because almost all extrinsic eye muscles are innervated by cranial nerves that leave mesencephalon

antidiuretic hormone (ADH)

reaches kidneys to retain water when there is low blood pressure

precentral gyrus/ primary motor cortex

region that sends nerve impulses down spinal cord toward muscle for movement; contains pyramidal cells

blood brain barrier

regulates substances between blood & brain tissue; biochemical isolation of brain from main circulation; made of capillary endothelial cells attached to each other through tight junctions surrounded by astrocytes; allows for nutrients (glucose & oxygen) to pass through & nourish brain tissue; allows carbon dioxide and waste to get out

thalamus

relay and processing centers for sensory information that comes up from the spinal cord, eyes, & ears; separated into right & left; screens what's important or not to send to cerebral cortex; where 95% of sensory information comes in; largest mass of cell bodies found within CNS

medulla oblongata

relay station between spinal cord & rest of brain stem & spinal cord w/ thalamus; autonomic centers for regulation of visceral function (cardiovascular, respiratory, and digestive system activities such as heart rate, blood pressure, & breathing pattern)

pons

relays sensory information to cerebellum & thalamus; relay station between cerebellum & cerebrum; subconscious somatic and visceral motor centers; works w/ cerebellum in coordinating skeletal muscle activity; has role in breathing pattern through centers regulating activity of respiratory reflex center in medulla oblongata

gyrus/ gyri

rounded elevation on the surface of the cerebral hemispheres; increases surface area

diaphragm sellae

seals pituitary gland to sella turcica; anchors dura mater to sphenoid bone

vermis

separates cerebellar hemispheres

transverse cerebral fissure

separates cerebrum and cerebellum

septum pellucidum

separates lateral ventricles

parieto-occipital sulcus

separates parietal and occipital lobes

lateral sulcus

separates temporal lobe from all others

primary fissure

separates the lobes of the cerebellum

falx cerebelli

separates the two hemispheres of the cerebellum

duralvenous sinus

separation of meningeal & periosteal layer of dural mater; blood-filled space where majority of blood from the brain drains into --> then jugular veins get the blood supply in the neck

inferior horns of lateral ventricle

temporal lobe

cranium

the bones of the skull that protect the brain to a certain extent due to soft consistency of brain; frontal, parietal, occipital, & temporal

what are the most protected parts of the body?

the brain & spinal cord

dura mater

toughest; has 2 layers (periosteal & meningeal)

NV

trigeminal nerve; branches into ophthalmic, maxillary, & mandibular divisions; sensation of entire face & voluntary control of chewing muscle (masseter)

NIV

trochlear nerve; goes to superior oblique; origin= mesencephalon; foramen= superior orbital fissure

meningeal layer of dura mater

true layer that covers the brain; extends into vertebral canal as spinal dura mater

NX

vagus nerve; goes to thoracic & abdominal cavities of the body & has autonomic control of its organs; sensory + motor functions of internal organs; innervates the respiratory, cardiovascular, & digestive organs; longest cranial nerve;slows down heart rate

NVIII

vestibulocochlear nerve; carries sensory information about equilibrium, balance, & hearing; origin= receptors of inner ear (vestibule and cochlea); foramen= internal acoustic meatus; destination= pons & medulla oblongata

balls palsy

virus affecting facial nerve that causes paralysis of facial expressions; mostly on left branch

occipital lobe anatomical landmarks

visual association area, visual cortex

arachnoid mater

weblike layer that encloses and protects blood vessels that supply brain; contains & circulates CSF

central canal of spinal cord

where remaining 10% of CSF flows through; communicates w/ the fourth ventricle

cerebral aqueduct

where third ventricle communicates w/ the fourth ventricle