Chapter 12 Antatomy

forebrain

made up of the telencephalon and diencephalon

hindbrain

area of the brain that coordinates information coming into and out of the spinal cord, constricts to the metencephalon and myelencephalon

ventricles of the brain

canals in the brain that contain cerebrospinal fluid. Ventricles are also found in the heart. They are the two lower chambers of the heart

gray matter

brain and spinal cord tissue that appears gray with the naked eye; consists mainly of neuronal cell bodies (nuclei) and lacks myelinated axons, superficial

white matter

whitish nervous tissue of the CNS consisting of neurons and their myelin sheaths, deep

insula

regions of cortex located at the junction of the frontal and temporal lobes

cerebral cortex

enables us to be aware of ourselves and our sensations, to communicate, understand, and initiate voluntary movements; composed of gray matter, neuron cell bodies, dendrites, glia, and blood vessels; contains motor, sensory, and association areas

motor areas of the brain

primary motor cortex; premotor cortex; Broca's area; frontal eye field; control voluntary movements

primary motor cortex

the region of the posterior frontal lobe that contains neurons that control movements of skeletal muscle, located in the precentral gyrus of the frontal lobe of each hemisphere; pyramidal cells- large neurons that allow is to consciously control skilled voluntary movements

premotor cortex

a region of nonprimary motor cortex just anterior to the primary motor cortex; helps plan movements into more complex tasks

broca's area

controls language expression - an area, usually in the left frontal lobe, that directs the muscle movements involved in speech.

frontal eye field

controls voluntary movement of the eyes

primary somatosensory cortex

the region of the anterior parietal lobe whose primary input is from the somatosensory system; receives input from somatic sensory receptors in the skin and from proprioceptors, position in space

somatosensory association cortex

integrates sensory information and produces an understanding of the stimulus being felt

primary visual cortex

the region of the posterior occipital lobe whose primary input is from the visual system

visual association area

interprets information acquired through the primary visual cortex

primary auditory cortex

the region of the superior temporal lobe whose primary input is from the auditory system

auditory association area

located posterior to primary auditory cortex; stores memories of sounds and permits perception of sound stimulus

primary olfactory cortex

located within temporal lobe; provides conscious awareness of smells

rhinencephalon

the part of the forebrain involved in receiving and integrating olfactory impulses

gustatory cortex

area of the brain that receives and interprets tastes from the tongue

visceral sensory area

conscious perception of visceral sensations, such as upset stomach or full bladder

multimodal association areas

receive input from multiple senses and integrate this into an overall perception of our surroundings

anterior association area

in frontal lobe, also called prefrontal cortex; the most complicated cortical region of all; involved with intellect, complex learning abilities, recall, and personality; contains working memory needed for judgment, reasoning, persistence, and conscience; development depends on feedback from social environment

posterior association area

Large region in temporal, parietal, and occipital lobes

Plays role in recognizing patterns and faces and localizing us in space; Involved in understanding written and spoken language (Wernicke's area)

limbic association area

provides emotional impact that makes a scene important to us and helps establish memories

lateralization of cortical functioning

- There is a division of labor between the two cerebral hemispheres

- LATERALIZATION: each hemisphere has abilities NOT completely shared by its partner

- CEREBRAL DOMINANCE: Designates the hemisphere that is DOMINANT FOR LANGUAGE

- In 90% of people the LEFT hemisphere has greater control over language abilities, math + logic

- The other hemisphere (usually the right) is more free-spirited, involved in visual-spatial skills, intuition, emotion + artistic + musical skills.

- Most individuals with left cerebral dominance are RIGHT HANDED

- The remaining 10% of people, the roles of the hemispheres are reversed or the hemispheres share their functions

- Typically, right-cerebral-dominant people are left handed + male

basal nuclei

Controls muscle activity and posture; largely inhibits unintentional movement when at rest; receives input from the entire cerebral cortex, influences muscle movements directed by the primary motor cortex

thalamus

the brain's sensory switchboard, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla; relay station

hypothalamus

a neural structure lying below the thalamus; directs eating, drinking, body temperature; helps govern the endocrine system via the pituitary gland, and is linked to emotion

epithalamus

Contains pineal body. Involved in olfactory senses and sleep/wake cycle

midbrain

Region between the hindbrain and the forebrain; it is important for hearing and sight

pons

A brain structure that relays information from the cerebellum to the rest of the brain; composed of conduction areas

medulla oblongata

inferior part of the brain stem, helps control vital processes like your heartbeat, breathing and blood pressure

cerebellum

the "little brain" at the rear of the brainstem; functions include processing sensory input and coordinating movement output and balance

cerebellar peduncles

large bundles of tracts of white matter passing into the cerebellum

cerebellar processing

follows a functional scheme in which the frontal cortex communicates the intent to initiate voluntary movement to the cerebellum

limbic system

neural system (including the hippocampus, amygdala, and hypothalamus) located below the cerebral hemispheres; associated with emotions and drives

amygdaloid body

recognizes angry or fearful facial expressions, assesses danger, and elicits fear response

reticular formation

a nerve network in the brainstem that plays an important role in controlling arousal; composed of loosely clustered neurons

brain waves

patterns of electrical activity generated by the brain

consciousness

encompasses perception of sensations and control of movement

sleep-wake cycle

a daily, naturally occurring 24-hour circadian rhythm of sleep and wake states regulated by a biological clock

Non-Rapid Eye Movement (NREM) Sleep

Stages 1 through 4 of sleep; contains ever-slowing brain waves as one gets deeper into sleep.

rapid eye movement (REM) sleep

stage of sleep in which the eyes move rapidly under the eyelids and the person is typically experiencing a dream

steps in sleep-wake cycle

- awake

- REM (skeletal muscles are inhibited, dreaming)

- NREM stage 1 (relaxation begins, alpha waves)

- NREM stage 2 (irregular EEG)

- NREM stage 3 (sleep deepens, theta and delta waves appear)

- NREM stage 4 (EEG is dominated by delta waves, arousal is difficult)

meninges

three layers of connective tissue in which the brain and spinal cord are wrapped

dura mater

thick, outermost layer of the meninges surrounding and protecting the brain and spinal cord; enclose Dural venous sinuses that collect venous blood from the brain

arachnoid mater

weblike middle layer of the three meninges; separated from the dura mater by the subdural space; beneath is the subarachnoid space, filled with CSF

pia mater

the delicate innermost membrane enveloping the brain and spinal cord

cerebrospinal fluid

fluid in the space between the meninges that acts as a shock absorber that protects the central nervous system

Circulation of CSF in the brain

-lateral ventricle

-interventricular foramen

-3rd ventricle

-cerebral aqueduct

-4th ventricle

-median and lateral apertures

-cistern magna and pontine cistern

-tentorial notch

-up over the cerebral hemispheres

-arachnoid villi

-superior sagittal sinus

blood brain barrier

Blood vessels (capillaries) that selectively let certain substances enter the brain tissue and keep other substances out

epidural space

Cushion of fat and network of veins in space between vertebrae and spinal dura mater

cauda equina

collection of spinal nerves below the end of the spinal cord

ventral roots

bundle of motor neuron axons that exit the spinal cord

dorsal horns

interneurons that receive somatic and visceral sensory input

lateral horns

(only in thoracic and superior lumbar regions) - sympathetic neurons

ventral horns

gray matter in the spinal cord that contains motor neurons

ascending pathways to the brain

-First order neurons: conduct impulses from the cutaneous receptors of the skin and from the brain stem where they then synapse with the cell bodies of the second order neurons.

-Second order neurons: in dorsal horn of the spinal cord or in medullary nuclei. Transmit impulses to the thalamus or to the cerebellum where the synapse.

-Third order neurons: Relay information to the somatosensory cortex of the cerebellum.

descending pathways

The systems of neurons that bring motor information from the brain down to the appropriate spinal level. Signals travel along two neurons. An example is the corticospinal tract.

upper motor neurons

motor neurons in the central nervous system that control the lower motor neurons in the peripheral nervous system

lower motor neurons

ventral horn motor neurons, innervate skeletal muscles

direct pathways

(pyramidal system) maintenance of muscle tone, controlling speed and precision of skilled movements

indirect pathways

complex, multi-synaptic (synapse before reaching spinal cord)