NRSC 1110 Ch 7

Neuraxis

an imaginary line beginning at the base of the spinal cord and ending at the front of the brain

Unilateral

one side

Bilateral

both sides

Ipsilateral

same side

Contralateral

opposite side

Afferent

carry to a location (usually toward the CNS)

Efferent

carry from a location (usually away from the CNS)

CNS is encased in\_______

bone

CNS consists of \______

cerebrum, cerebellum, brainstem, spinal cord

Spinal cord

attached to the brain stem, conduit of sensory AND motor information (brain <-\> body), gray matter: "butterfly shape," dorsal and ventral "horns"

Dorsal root

somatic and visceral sensory (afferents)

Ventral root

somatic and visceral motor (efferents)

• Spinal nerves - mixed

Dorsal Root Ganglia (DRG)

contains somas of sensory neurons

brain stem

center of heart rate, respiration, cough reflex, vomiting

Can live without a \_________—cannot live without a \_________________

cortex, brain stem!

Peripheral nervous system (PNS)

Nervous system outside the brain and spinal cord

Two parts of the PNS

somatic and autonomic

Somatic

innervates skin, joints, muscles

• Sensory and motor subdivisions

Autonomic

innervates internal organs, blood vessels, glands

* Two subdivisions: Sympathetic and Parasympathetic

Enteric

brain in the gut

Sympathetic

"Fight-or-flight"

• dominates during times of stress, excitement, and exertion; the "fight-or-flight"system.

• Increases heart rate and blood pressure, stimulates secretion of adrenaline, increases blood flow to skeletal muscles

Parasympathetic

"Rest and digest"

• dominates when energy reserves can be conserved and stored for later use.

•Increases salivation, digestion, and storage of glucose and other nutrients, slows heart rate, decreases respiration

Meninges

•"Covering"

•CNS does not come in direct contact with bone

• Inflamed in meningitis

3 parts of meninges

Three membranes that surround the brain and spinal cord:


1. Dura mater ('hard mother")
2. Arachnoid membrane
3. Pia mater ("gentle mother")

• adheres closely to brain surface

subarachnoid space

between arachnoid and pia

•Contains CSF

•Blood vessels

Subdural hematoma

• trauma damages tiny veins within the meninges

• Blood accumulates rapidly, causing pressure to rise within the brain

• Results in loss of consciousness, paralysis or death

Subarachnoid hemorrhage

• Subarachnoid hemorrhage is sudden bleeding into the subarachnoid space (csf mixes with blood)

• Symptoms include sudden, severe headache, usually with loss or impairment of consciousness.

• frequently a sign of a ruptured aneurysm

Ventricles

Cerebrospinal fluid (CSF)-filled caverns and canals inside brain

Cerebrospinal Fluid (CSF)

Brain floats in it

• cushions

• delivers nutrients

• removes waste

\
• produced by choroid plexus

• circulates through ventricles and out into subarachnoid space

• Is absorbed by blood vessels in arachnoid villi

• Normal flow is very important--hydrocephalus

Embyro

begins as a flat disk

3 Germ Layers

ectoderm, mesoderm, endoderm

Ectoderm

nervous system and skin

Endoderm

lining of internal organs

Mesoderm

bones and muscles

Neurulation

process by which neural plate becomes the neural tube

• E17: "valley" of that fold is called the neural groove, edges are called neural folds

E22: As the tissue folds, the ends of the \____________ come together to form \______________

neural groove, neural tube

E23: the neural folds pinch off on either side of the neural \_________ to become the neural \___________

tube, crests.

neural \______ becomes the CNS

tube

neural \________ becomes the PNS

crest

Folic acid deficiency

increases the incidence of neural tube defects

anencephaly

Failure of anterior tube to close

spina bifida

Failure of the posterior tube to close

Neural tube defects

Neurulation is complete by E22

Differentiation

neural tube develops into forebrain, midbrain, hindbrain, and spinal cord

\_________ differentiates to form the 3 primary vesicles that give rise to the entire brain

rostral end of neural tube

Forebrain differentiation

3 primary vesicles \>>> 5 secondary secondary brain vesicles

Telencephalon

cerebral hemispheres, olfactory bulbs, basal telencephalon

Diencephalon

thalamus and hypothalamus

Forebrain differentiation: main divisions

telencephalon, diencephalon

Forebrain differentiation: ventricles

lateral ventricle, third ventricle

Forebrain differentiation: gray matter structures

cerebral cortex, thalamus, hypothalamus, basal telencephalon

Forebrain differentiation: white matter structures

corpus callosum, cortical white matter, internal capsule

Cerebral cortex

Seat of perception, cognition, consciousness, voluntary action; Analyzes sensory input\>>>commands motor output - Telencephalon

Basal Ganglia

Voluntary movement; Procedural memory (skills and action/non declarative memory) - Telencephalon

Limbic System

Emotion (amygdala); Memory (hippocampus) - Telencephalon

Thalamus

"gateway to the cortex,"(in relation to sensory information) a relay for most sensory information from periphery (not olfactory), motor portions as well - Diencephalon

Hypothalamus

Overall goal: maintain homeostasis; Regulates: body temperature, salt-water balance, hunger, thirst, energy metabolism, reproductive behaviors, and emotional responses; Mediates circadian rhythms (SCN); Controls Autonomic Nervous System; Controls HPA Axis and stress response - Diencephalon

Tectum

roof of the midbrain

Tegmentum

the "covering" or ventral portion of the midbrain

Descending Axons

contains axons descending from cortex to brain stem and spinal cord (make up corticospinal tract)

Corticospinal tract

motor cortex to spinal motor neurons

Ascending axons

information conduit from spinal cord and brainstem to forebrain (sensory systems)

Tectum differentiates into \________

superior colliculus and inferior colliculus

Superior colliculus

receives sensory info from eye

Inferior colluclus

receives sensory info from ear, relay fro auditory info in route to thalamus

Tegmentum differentiates into \________

substantia nigra, red nucleus, periaqueductal gray (PAG)

Substantia nigra

black substance, cell bodies of dopamine neurons, project to striatum, heavily related to Parkinson's

Red nucleus

rubrospinal tract

Periaqueductal gray (PAG)

rich on opioid receptors, important in pain modulation

Hindbrain differentiates into\_______

cerebellum, pons "bridge," medulla olongata

Rostral Hindbrain (metencephalon)

cerebellum and pons (bridge)

Caudal Hindbrain (myelencephalon)

medulla oblongata

Rhombic lips

fuse to form cerebellum

Pons

90% of descending axons from cortex synapse in the pons\>>>into cerebellum; Some raphe nuclei: 5HT cell bodies; Locus coeruleus: NE cell bodies

Cerebellum

coordination of movements; Receives proprioceptive info from spinal cord; Receives info from the pons (relayed from cortex) specifying the goals of movements; Damage -\> ataxia

Medulla

regulates heart rate, digestion, respiration, blood pressure, coughing, vomiting; Other raphe nuclei: 5HT cell bodies

Corticospinal tract \____________ in the medulla

decussates (Forms the basis ofcontralateral motorcontrol)

Decussation

Crossing of axons from one sideto the other

\_________ do not synapse in the pons

Corticospinal tract fibers...continue toward thespinal cord in the medullarypyramids

Butterfly is \_______ \>> divisible into \______

gray matter, horns

central canal is filled with \_____

CSF

\________ surround butterfly structure

white matter columns

Spinal Cord Structure-Function Relationships General Rules of Thumb: Dorsal horn neurons receive \___________ from \________________

sensory input, dorsal root fibers

Spinal Cord Structure-Function Relationships General Rules of Thumb: Ventral horn motor neurons send axons to \___________ to \________________

ventral roots, innervate muscles

Spinal Cord Structure-Function Relationships General Rules of Thumb: \___________ are interneurons that shape motor output in response to sensory input

Intermediate zones

Differences in rat and human brain

Convolutions on human cerebrum surface called sulci and gyri—why?; Size of olfactory bulb; Growth of cerebral hemisphere: Temporal, frontal, parietal, occipital

Four lobes are so-named for the \_______ that lie above them

skull bones

Common features for all vertebrates

Cell bodies in layers or sheets; a basic cytoarchitecture; Molecular layer lacks neurons (layer1)

Areas of Neocortex - Brodmann's areas

52 areas differ in their cytoarchitecture, guessed that cortical areas that look different perform different functions

BA (Brodman's area) 4

primary motor cortex

BA (Brodman's area) 17

primary visual cortex

3 types of cortex in common ancestors

primary sensory areas, motor areas, secondary sensory areas

Secondary (aka association) cortical areas

adjacent to primary cortex areas; responsible for analyzing information from primary areas, providing perception of the stimulus; Evolution has led to expansion of these areas

\_________ of cortex has changed, \_________________

amount, not structure

Primary M1, Area 4

Initiation of complex voluntary movement

Secondary prefrontal cortex

executive function; Abstract thought; decision making; anticipating consequences of action

Secondary P-T-O Association cortex

Analysis of sensory inputs; Constructs representation of our sensory world