A&P Ch 9: The Nervous System: The Brain & Cranial Nerves

meninges

3 layers of connective tissue that surround both the brain & spinal cord to form a complete enclosure

corpus callosum

a band of white matter at the bottom of the longitudinal fissure; is a bridge between the R & L hemispheres, allowing impulses to cross from one side of the brain to the other

cerebrospinal fluid (CSF)

a clear liquid that circulated in & around the brain & spinal cord; it's function is to support nervous tissue & to cushion shocks, also carries nutrients to the cells & transports waste away

longitudinal fissure

a deep groove dividing the cerebrum into R & L hemispheres

choroid plexus

a network of ependymal cells & blood vessels, which makes CSF within all four ventricles

cerebral aqueduct

a small canal in the midbrain

cerebral cortex

a thin layer of gray matter covering each cerebral hemisphere

hypoglossal (XII)

carries impulses controlling tongue muscles (motor)

vagus (X)

carries motor impulses to most organs in the thoracic & abdominal cavities, also contains motor fibers to the larynx (motor); is the longest cranial nerve, name means "the wanderer"

vestibulocochlear (VIII)

carries sensory impulses for hearing & equilibrium from the inner ear (sensory)

glossopharyngeal (IX)

carries sensory impulses from the tongue & pharynx; controls swallowing muscles & stimulates the parotid salivary gland (mixed)

pons

connects cerebellum with other portions of the brain; helps regulate respiration

midbrain

connects cerebrum with lower portions of the brain; has reflex centers concerned with vision & hearing;

facial (VII)

controls the muscles of facial expressions, also includes sensory fibers for taste and secretory fibers to the smaller salivary glands & the lacrimal gland (mixed)

lateral sulcus

curves along the side of each hemisphere & separates the temporal lobe from the frontal & parietal lobes

gyri

elevated portions of the brain (singular is gyrus)

ventricles

four fluid-filled spaces in the brain

accessory (XI)

has 2 branches, one controls the trapezius & SCM, the other controls the larynx (motor)

trigeminal (V)

has 3 branches; all 3 branches carry general sensory impulses from the eye, upper jaw & lower jaw, 3rd branch also has motor fibers to the muscles of mastication (mixed)

premotor cortex

helps plan complex movements

pia mater

innermost layer of the meninges, attached to the nervous tissue of the brain & spinal cord, follows all contours of these structures; (pia mater means "soft mother")

prefrontal cortex

involved in memory, problem solving & conscious thought

frontal lobe

lies anterior to the central sulcus; gyrus just anterior to central sulcus contains a primary motor area

central sulcus

lies between the frontal & parietal lobes of each hemisphere at right angles to the longitudinal fissure

medulla oblongata

links the brain with the spinal cord; has centers for control of vital functions, such as respiration & heartbeat

hypothalamus

maintains homeostasis, controls autonomic nervous system & pituitary gland

oculomotor (III)

moves eyeball & eyelid, adjusts the pupil & lens of the eye (motor)

trochlear (IV)

moves eyeball (motor)

parietal lobe

occupies the superior part of each hemisphere & lies posterior to the central sulcus

dura mater

outermost layer of the meninges; thickest & toughest layer (dura mater means "hard mother"); is in 2 layers around the brain, outer layer is fused to the crainal bones; is in single layer around the spinal cord

Broca area

plans the sequences of muscle contractions in the tongue, larynx & soft palate required to form meaningful sentences (usually found in the L hemisphere)

cerebellum

posterior to the brain stem & is connected with the cerebrum, brain stem & spinal cord by means of the pons; coordinates voluntary muscles, maintains balance & muscle tone; (cerebellum means "little brain", also divided into 2 hemispheres)

primary motor area

provides conscious control of skeletal muscles

abducens (VI)

sends motor impulses to an eyeball muscle (motor)

sulci

shallow grooves in the brain (singular is sulcus)

optic (II)

sight (sensory)

diencephalon

sits in the center of the brain between the two hemispheres and superior to the brain stem; includes the thalamus & the hypothalamus

interventricular foramina

small openings from the lateral ventricles into the 3rd ventricle

olfactory (I)

smell (sensory)

thalamus

sorts & redirects sensory input

brain stem

spans the region between the diencephalon & spinal cord; superior portion is the midbrain, inferior to that is the pons, followed by the medulla oblongata

arachnoid

the middle layer of the meninges; is loosely attached to the pia mater by weblike fibers, forming a space (subarachnoid space) where CSF circulates

cerebrum

the most superior & largest part of the brain; consists of L & R hemispheres which are each divided into lobes

dural sinuses

where the 2 layers of the dura mater separate to provide venous channels for the drainage of blood coming from brain capillaries