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Chapter 2a CNS Gross Anatomy

Chris RordenUniversity of South CarolinaNorman J. Arnold School of Public HealthDepartment of Communication Sciences and DisordersUniversity of South Carolina

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Multiple choice

What is the image plane?A. Axial.

B. Coronal.

C. Oblique.

D. Sagittal.

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Multiple choice

What is unusual about this brain?A. Too much gray matter

B. Too much white matter

C. Too much cerebral spinal fluid

D. Too much bone

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Roles of the CNS

Functions of neurons in the CNS (brain and spinal cord) include:– Sensor: Receives environmental and body stimuli– Integrator: Combines information received– Effector: Initiates body movements– Regulator: Maintains homeostatic state for body

function

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Nervous System

The CNS is protected and isolated.– Bone offers protection from injury

Skull covers brainVertebral Column covers spinal cord

– The is encased in soft-tissue membranes – The brain’s blood vessels stop many subastances

from entering the brain (blood-brain barrier)Protects from contamination/infection

– The brain floats in cerebral spinal fluidOffers protection from impact

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The Meninges

Dura Mater: Tough outer covering Arachnoid Mater: Middle layer Pia Mater: Inner closely formed

layer

Latin - English Dura – strong Arachnoid – spider Pia – tender Mater -mother

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Cerebrospinal Fluid (CSF)

Located between the meninges and in the ventricular cavities of the brain

Produced in the ventricular cavities by the choroid plexus

Functions– mechanical buffer – fluid for metabolic functions

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CSF

CSF is in ventricles, subarchnoid space, interventricular foramens, and around the spine.

Circulates from ventricles around brain and spinal column

Is finally absorbed by venous system Replenishes at ventricles every 7

hours

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Divisions of the PNS

Somatic Nervous System (under voluntary control)– Sensory and Motor – Skin and Muscles

Autonomic Nervous System (can not be voluntarily controlled).– Sensory and Motor– Visceral organs and glands– Two main subdivisions:– Sympathetic: Fight, Flight, Fear

Prepare to expend energy– Parasympathetic: Regulates normal function

Prepare to conserve energy

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Major Structures of the Brain

Longitudinal Fissure– Separates Two Hemispheres of the Brain– Aka ‘Interhemispheric Fissure’

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The folds of your brain are like a fingerprint – there are a few general patterns, with individual variability.

Two main folds– Central Sulcus

Fissure of RolandoRolandic sulcus

– Lateral sulcusSylvian fissure

The central sulcus separates the frontal and parietal lobes.

The lateral sulcus separates the temporal lobe from frontal, parietal, insula

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The major cortical lobes

Insular Lobe – Tucked away, but often injured in patients seen by speech pathologists

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Major medial sulci

Central Sulcus

Preoccipital Notch

Calcarine Sulcus

Parieto-occipital Sulcus

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Landmarks of the frontal lobe

Frontal PolePrecentral GyrusPrecentral SulcusPremotor Cortex Speech, Fine MotorPrefrontal Cortex

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Frontal Lobe Functions

Motor FunctionCognitive Functions Reasoning, Abstract

Thinking, Self-Monitoring, Decision Making, Planning, Inhibition

Organization of Spoken Language

Frontal Motoric Areas

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Broca’s Area – speech production

Pars opercularis

(Inferior frontal gyrus)

Pars triangularis(Inferior fronal gyrus)

Pars orbitalis(Inferior frontal gyrus)

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Parietal Lobe Landmarks

Post Central Gyrus (PoCG)– Primary Sensory Cortex

Superior and Inferior Parietal Lobules (SPL, AnG,SmG)– Perceptual Synthesis, Spatial

Orientation, Memory Angular Gyrus (AnG)

Supramarginal Gyrus (SMG)– In Dominant Hemisphere:

Reading, Writing and Calculation

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The homunculus (little man)

The motor strip (red, frontal cortex) and primary sensory cortex (green, parietal) spatially map corresponding portions of the contralateral hemisphere.

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Temporal Lobe – Major External Gyri

Superior Temporal GyrusMiddle Temporal Gyrus Inferior Temporal Gyri

Temporal Pole

Temporal Operculum

Dorsal surface of STG is called the ‘Temporal Operculum’ (Lip) – Middle section: Heschel’s Gyri

(Brodmann Areas 41 + 42) Auditory Reception Cortex

– Posterior section: Wernicke’s Area (Brodmann 22)

Auditory Association Cortex

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Heschl’s Gyrus

Primary auditory cortex found in Heschl’s gyrus

This is organized tonotopically – a high pitched sound excites a different region than low pitched sounds.

Superior Temporal Gyrus

Auditory Cortex lies inside the Superior Temporal Sulcus

Part of the superior temporal gyrus that is imperative for the perception of speech is Heschl’s gyrus

Heschl’s gyrus (primary AC)

planum temporale (nonprimary AC) planum

polare (nonprimary AC)

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Ventral-Medial Structures

Temporal Lobe– Fusiform gyrys (Face

Recognition)– Hippocampal Gyrus

(places, memory)– Uncus (smell)

Occipital lobe– Cuneus and Lingual

gyrus (primary vision)

Medial View

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Ventral-Medial Structures

UncusParahippocampal GyrusFusiform GyrusLingual Gyrus

Cerebellum and Brainstem removed

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Occipital Lobe

Occipital Pole (medial)– Medially: cuneus and lingual

gyrus: primary visual cortex– Clinically: field cuts, blindsight

Lateral occipital structures:– Superior, Lateral and Superior

Occipital Gyris: Secondary Visual Cortex (Association)

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Language Areas

Insular Lobe (Isle of Reil)

Deep in Lateral Fissure– Functions: Language(?), taste, disgust,

cravings (e.g. smoking)

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Midsagittal Surface

Corpus Callosum – Connects Hemispheres

Limbic System– Emotions

Cingulate Gyrus Fornix Thalamus Hypothalamus

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Midsagittal Surface

Uncus Fornix

Septum

Corpus Callosum

CingulateGyrus

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Transverse Slice

Fornix

ThalamusPutamen

Caudate Nucleus

Globus Pallidus

Claustrum

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Brain Stem

Midbrain

Pons

Medulla

OpticNerve

OpticChiasm

OpticTract

PituitaryStalk

Pes Pedunculi

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Basal Ganglia

Caudate Nucleus Putamen Globus Pallidus (Pallidum) Caudate Nucleus

+Putamen = Striatum Putamen + Globus

Pallidus = Lenticular Nucleus

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Striatum

Cleft forInternal Capsule

Head ofCaudateNucleus

Thalmus

Putamen

AmygdaloidNucleus

Tail ofCaudate Nucleus

Lateral View