Neurology

Intro

Major components of the nervous system

Central nervous system (CNS) = brain and spinal cord

Peripheral nervous system (PNS)

∙spinal nerves (31 pairs) arise from spinal cord → sensory/motor

∙cranial nerves (12 pairs, all but first arise from brain) are largely concerned with motor and sensation of the head

Visceral nervous system/autonomic nervous system = motor innervations of cardiac muscle, smooth muscle, glands, sensory innervations of viscera

Terms of direction

the axis of direction shifts at an imaginary point w/in skull, so we use different terms

Longitudinal axis of the forebrain

∙rostral = anterior

∙caudal = posterior

∙dorsal = superior

∙ventral = inferior

Longitudinal axis of the brainstem and spinal cord

∙use normal terms of directions

Planes of section

∙Sagittal plane: divides body into two along vertical line

→median plane: specific type of sagittal plane that divides the body into equal halves

∙coronal/transverse plane :divides anterior portion of body from posterior portion along a vertical line

∙horizontal plane: cuts body along horizontal line

Types of tissues in the nervous system

Gray matter: neuronal cell bodies

∙in the brain = located on outer surfaces

∙in spinal cord = innermost tissue (what makes the butterfly)

White matter: glial cells and neuronal processes (Tracts)

∙in brain = located on inner portions of brain

∙in spinal cord = outermost tissue (what surrounds the butterfly)

Layers surround the brain

3 meninges (outside → in): dura mater → arachnoid mater → pia mater

∙dura mater: outer and inner layers, does not touch brain

∙arachnoid mater: does not touch brain

∙pia mater: attaches to brain

2 spaces

∙space b/w the two dura layers (2 sinuses)

→superior/inerior sagittal sinus: contain blood from veins that will drain into jugular veins (remember superior sagittal sinus when we talk about spinal fluid)

∙subarachnoid space: b/w pia and arachnoid mater, contains blood vessels

Terms of cerebrum/cortex

Sulcus/Fissues: allows or increased area to hold more neurons/pathways (sulcus means "ditch")

∙longitudinal fissure = separates left and right hemisphere

∙central sulcus (Fissure of Rolando) = separates frontal lobe from parietal lobe

∙lateral fissure = (Fissure of Sylvius) = separates temporal lobe from frontal/parietal lobe

Gyri (pl.): wave-like curves of cortex, each gurus (singular) has a particular function

∙precentral = motility → if stroke occurs here, movements will be impaired but on contralateral side

∙postcentral

Commissure: connecting fiber tracts for communication in the brain

∙major commissure (corpus callosum): connects left and right

→stroke here will result in problems w/ communication of left and right hemispheres

∙don't confuse w/ tracts, which are tract and not usually able to visualize

Lobes: putting gyri together, each lobe has a different function

∙Frontal lobe

→anterior portion = planning, reasoning

→posterior portion = motor control

∙Temporal lobe

→anterior portion = higher order visual and auditory processing, semantic processing

→medial portion = memory processing

→dorsal/posterior portion = hearing (injury can cause impaired hearing/deafness)

∙Parietal lobe

→primary sensory area - nerve impulses related to pain, temperature, touch and pressure

→attention, spatial processing

∙Occipital Lobe

→processing of visual information

Subcortical structures

remove this structure and you can still do what the cortex wants to do, but not well

∙remove cortex, and you can't think/do higher level functions

basal ganglia: motor control/reward/drug abuse

∙putamen (lateral): looks like "big knots"

∙caudate nucleus (caudal = tail): "c-shaped structure"

∙globus pallidus (medial): darker region within the "big knots"

∙thalamus: all the senses except smell stop here before proceeding into hemispheres

Limbic system: motivation, memory, emotion

∙Hippocampus

→memory

→controls visceral nervous system (which stimulates contraction of muscle fibers and glandular secretions of internal organs, regulates appetite, thirst and temperature)

→controls hormonal secretions via pituitary

∙Amygdala

pineal gland = biological clock

Brainstem

midbrain: relay b/w cerebral cortex and spinal cord, visual and auditory reflex patterns

pons: relay b/w cerebral hemispheres and cerebellum

medulla: lowerst parti - contiguous with spinal cord → respiration, heart rate

Cerebellum

muscle coordination, balance, writing and walking

if you need to figure out anterior and posterior parts of the brain, locate cerebellum

∙will be posterior (longitudinal axis of forebrain)/dorsal (longitudinal axis of brainstem/spinal cord)

Spinal Cord

continuous with the brain in an area called medulla

receives information from all other parts of body (except face) and sends commands for motor activity

Pathways:

∙ascending: generally sensation, toward brain

∙descending: generally motor, away from brain

Ventricular System

cerebrospinal fluid (CSF) formed by choroid plexuses of lateral ventricle, third and fourth ventricles