Central Nervous System (CNS) = made up of the brain and spinal cord, sensory input is sent to CNS and motor output is sent from the CNS

Anatomical Organization and Composition of Brain

gyrus = raised parts of cerebrum, "hills"

sulcus = grooves between gyrus of cerebrum, "valleys"

fissure = a division, deeper than sulcus, divides lobes of brain

Ventricles of brain

2 lateral ventricles located on each side of cerebral cortex

third ventricle in lower brain near diencephalon

fourth ventricle runs along brain stem and continues into central canal of spinal cord

2 lateral apertures, 1 medial apertures

Blood-brain barrier: simple squamous epithelium (blood vessels and capillaries), cells connected together by tight junctions (special connections that serve as a barrier and prevent molecules from passing between)

Major portions of the brain

Cerebrum

Frontal lobe: initiates voluntary movement, prefrontal cortex (gray matter, where processing occurs, planning, decision-making, task management, problem-solving, some memory

Parietal lobe: processes sensory stimuli

Temporal lobe: auditory and olfactory cortex, recognition of objects, written words, faces, emotional response (limbic system), memory

Occipital lobe: visual cortex

Insula: deeper lobe within lateral sulcus, gustatory cortex (taste), general visceral sensations processed (hunger, thirst, etc)

Broca's area = speech production/talking, located on left side of brain

Wernicke's area = recognizes/understands speech, located only on left side of brain, partly on parietal and partly on temporal

Precentral Gyrus

Postcentral Gyrus

initiating voluntary movement (motor, efferent, away from CNS)

controls feet, legs, thigh, hands, head

facial expressions, tongue movement

primary motor cortex = main area of brain invlolved in motor function, located on frontal lobe, directly anterior to central sulcus

recieving signals (sensory, afferent, towards CNS)

primary somatosensory cortex = mian area of brain involved in sensory function located on parietal lobe, directly posterior to central sulcus

signals going TO this area from skin, general senses, genitals

control of all skin receptors, head, arms, hands, genitals, mouth, throat

3 major cerebral regions

Cortex = gray matter, located along superficial surface, has neuron cell bodies that are NOT myelinated, "cities" (where processing occurs

White matter = myelinated and unmyelinated neurons, where signals travel, "highways" (no processing)

Cerebral (basal) nuclei = deep gray matter, anything NOT myelinated, area of processing and integration

Association tracts - connects parts of same hemisphere

Commissural tracts - connects one hemisphere to another, largest of these tracts is corpus callosum

Projection tracts - run vertically, longest, run from cerebrum through thalamus, through brain stem and into spinal cord

signals are both ascending (sensory) and descending (motor) tracts

Diencephalon

Thalamus

Hypothalamus

can amplify or dampen signals

relay station for all conscious sensory signals traveling to cerebral cortex (except olfactory)

control/regulation of autonomic or visceral motor system, body temp, sleep/wake cycles, endocrine system, etc, emotion and memory

Epithalamus

pineal gland - produces hormone melatonin (prepares for sleep)

Brainstem - connector between CNS and PNS, most sensory information goes through brainstem

Midbrain

cerebral peduncles = motor tracts that connect midbrain to cerebral cortex

corpora quadrigemina (4 bumps)

superior colliculi (visual reflexes, subconscious tracking/following)

inferior colliculi ( auditory reflexes, "fight or flight" response

Pons

Pyramidal tracts = motor tracts, run through entire brainstem

Reticular formation nuclei = gray matter in pons, control of autonomic behavior (vital functions), cardiovascular center, vascular center, respiratory center

Medulla oblongata (collection of gray matter)

pyramids = nerves pyramidal in shape

decussation of pyramids = "crossing over" of pyramidal tracts

cranial nerve nuclei = where cranial nerves connect with brainstem

sensory tracts = input from sensory neurons to thalamus to cerebral cortex

cerebellum = smooths and coordinates body movement, maintain posture and equilibrium (receives messages from proprioceptors)

cerebellar peduncles

superior - connects cerebellum to midbrain

middle - connects cerebellum to pons

inferior - primarily carries proprioceptive signals to cerebellum

Anatomical Organization & Components of Spinal Cord

Gross anatomy

Cervical and lumbar enlargements = areas where more axons are present from the upper and lower extremities

Conus medullaris = located on L1 or L2 vertebrae, where spinal cord tapers and gets thinner

Cauda equina = looks "horse's tail", nerves/nerve roots leaving the spinal cord

Filum terminale = connects spinal cord to coccyx, stabilizes/anchors it

Location, Composition, Function of Roots (refer to color-coated image in notes)

Anterior root (ventral root) = made up of multipolar neurons (output)

Posterior root (dorsal root) = unipolar neurons in ganglion (input)

dorsal horn = where visceral sensory and somatic sensory are, input go into the spinal cord through the dorsal root

Posterior root ganglion (dorsal root ganglion) = sensory neurons

Lateral horn = where visceral motor is, output leaves the spinal cord through the anterior root

Ventral horn = where somatic motor is, output leaves the spinal cord through the anterior root

Tracts

Ascending tracts = sensory signal traveling toward the brain

Descending tracts = signals traveling away from the brain, major motor tracts (movement signals)

Meninges & Cerebrospinal Fluid (CSF)

dura mater = "tough mother"

periosteal dura mater = next to bone (superficial)

meningeal dura mater = deep to periosteal layer

subdural space = under menigeal dura mater, very little fluid

arachnoid mater = "spider mother", looks like web, thin/transparent layer deep to subdural space

blood vessels running through it

where CSF is located, besides in ventricles of brain and central canal of spinal cord

pia mater = "gentle mother", thin layer that covers cortex, vascular layer w/ small blood vessels

dura mater continues from brain around spinal cord, but only 1 layer (meningeal) around spinal cord

Dural venous sinuses = formed by periosteal and meningeal dura mater (where they split apart)

dural and coronary sinuses = vessels (oxygen poor blood)

no smooth muscle in sinus walls

where veins empty oxygen poor blood

epidural space = superficial to dura mater, adipose tissue located here

CSF functions: bouyancy for brain and spinal cord, cushions/protects head from jolts/impact, nourishes brain

arachnoid granulations = villus-like locationsin the arachnoid mater of brain where CSF is pushed out into the dural sinus

choroid plexus = where CSF is made, a network of capillaries and ependymal cells (glial cells)

ependymal cells = take in and modify fluid