Brain Gross Anatomy

13-1

Brain and Cranial NervesChapter 13

Brain-2

BrainAnterior

Posterior Inferior view

Brain-3

Brain: Gross Anatomy• Brain

– Part of CNS contained in cranial cavity

• Brainstem: connects spinal cord to brain; integration of reflexes necessary for survival

• Cerebellum: involved in control of locomotion, balance, posture

• Diencephalon: thalamus, subthalamus, epithalamus, hypothalamus

• Cerebrum: conscious thought, control

Brain-4

Sagittal Section of Brain

Cerebrum

Cerebellum

Thalamus

Hypothalamus

Midbrain

Pons

Medulla Oblongata

Brainstem

Diencephalon

Brain-5

Brainstem

Pyramid

(a) Anterior view

(b) Posterolateral view

Midbrain

MidbrainPons

Brainstem

Olive

Superior colliculusInferior colliculus

Olive

Pons

Brainstem

Superior cerebellarpeduncleMiddle cerebellarpeduncleInferior cerebellarpeduncle

Medulla oblongata

Medullaoblongata

Pyramidaldecussation

Brainstem

Medulla oblongata Pons Midbrain

Brain-7

BrainstemMedulla Oblongata

• transmits ascending and descending impulses between the brain and spinal cord

• pyramids – nerve tracts – conscious control of skeletal muscle

• center for vital reflexes – heart rate, BP, respiration, swallowing, coughing, sneezing

• olives - nuclei involved in balance, coordination, modulation of sound

• nuclei of cranial nerves V, VII, IX, X, XI, XII

Brain-8

BrainstemPons

• ascending and descending nerve tracts

• nuclei

• sleep centre, respiratory centre

Anterior• Pontine nuclei – communication between

cerebrum and cerebellum

Posterior• nuclei of cranial nerves V, VI, VII, VIII

BrainstemMidbrain• most superior portion of the brainstem

• nuclei of cranial nerves III, IV, V

• Tectum: 4 nuclei - form mounds on dorsal surface of midbrain

- each separate part is a colliculus

- two superior colliculi involved in visual reflexes

- two inferior colliculi involved in hearing

Reticular Formation

• Group of nuclei scattered throughout brainstem

• Cloud throughout the brainstem

• Controls cyclic activities such as sleep-wake cycle

Brainstem

Brain-10

Brain-11

Purkinje cell

Golgicell

Granulecell

Mossy fiberAxon of Purkinje cell

(b) Inferior view

Cerebellum

Lateral hemisphere

FoliaVermis

Anteriorlobe

Posteriorlobe

Vermis

Anterior lobe

FoliaPons

Flocculonodularlobe

Lateralhemisphere

Medullaoblongata

Posteriorlobe

Arborvitae

(a) Medial view

Vermis

Flocculonodular lobe

Cerebellum

Brain-13

CerebellumCommunicates with other regions of the CNS:

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superior cerebellar peduncle – midbrain

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middle cerebellar peduncle – pons

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inferior cerebellar peduncle – medulla oblongata

3 Regions:

1. Flocculonodular lobe – balance2. Vermis – gross motor coordination (Anterior), fine

motor coordination (Posterior)3. Lateral hemisphere – fine motor coordination

Brain-14

Diencephalon• between brainstem and cerebrum• 4 main components:

• Thalamus• Subthalamus• Epithalamus• Hypothalamus

Diencephalon, medial view

ThalamusInterthalamicadhesion

Hypothalamus

Pituitary gland

HabenulaPineal gland Epithalamus

Subthalamus

Diencephalon

Brain-16

DiencephalonThalamus• largest part of the diencephalon

• lateral portions connected by interthalamic adhesion - surrounded by third ventricle

• receives major portion of sensory input – projections to cerebral cortex

• Auditory impulses – medial geniculate nucleus

• Visual impulses – lateral geniculate nucleus

Interthalamicadhesion

Lateral geniculatenucleus

Thalamus

14-17

Brain-18

DiencephalonSubthalamus

• inferior to the thalamus

• ascending and descending nerve tracts

• subthalamic nuclei – controlling motor function

Thalamus

Hypothalamus Subthalamus

Brain-19

DiencephalonEpithalamus

• posterior and superior to the thalamus

• Habenula – emotional and visceral responses to odor

• Pineal gland – may influence the onset of puberty

Thalamus

Hypothalamus

HabenulaPineal gland EpithalamusSubthalamus

Pineal Gland

Brain-21

DiencephalonHypothalamus• most inferior portion of the diencephalon

• contains a stalk – infundibulum connecting the hypothalamus to the pituitary gland

• link between the nervous and endocrine system

• many clusters of nuclei that control bodily functions

• mood and emotion

Paraventricularnucleus

Infundibulum

Supraopticnucleus

Preoptic area

Pituitary gland

Hypothalamus

Brain-23

Cerebrum• outer layer – cerebral cortex (gray matter)

• deep clusters of nuclei (gray matter)

• in between – cerebral medulla (white matter)

Gray matter

White matter

Basal nuclei

Brain-24

Cerebrum

Anterior

Frontal lobe-Motor function-Aggression, mood

Parietal lobe-touch, taste, pressure-blood pH-not smell, vision, hearing

Occipital lobe-reception and integration of visual input

Temporal lobe-olfactory, auditory input-memory

Central sulcus

Lateral fissure

Precentral and Postcentral Gyrus

14-25

Brain-26

CerebrumCerebral Medulla

• nerve tracts connect the cortex to other areas of cortex or other parts of the CNS

• Association fibers – connect areas of cerebral cortex within the same hemisphere

• Commissural fibers – connect the cerebral hemispheres (Corpus Callosum)

• Projection fibers – between the cerebrum and other parts of the brain and spinal cord (Internal capsule)

Brain-27

CerebrumCerebral Medulla

Longitudinalassociationfibers

Commissural fibers(corpus callosum)

NucleiCortex

Shortassociationfibers

Projection fibersInternalcapsule Cerebral

medulla

Association fibersCommissural fibersProjection fibers

(a) Anterior view

Projectionfibers inthe internalcapsule

AnteriorCerebrum

Brainstem

(b) Lateral view Cerebellum

Posterior

Brain-28

Meninges

(a) Anterosuperior view

Skull

Subdural space

Arachnoid mater

Subarachnoid space

Pia mater

Cerebrum

Periosteal duraMeningeal dura

Dura mater

Dural venous sinus(superior sagittal sinus)

Brain-29

Ventricles

Lateral ventricle

Cerebral aqueduct

Fourth ventricle

Third ventricle

Lateral view

Posterior horn oflateral ventricle

Central canalof spinal cord

Anterior horn oflateral ventricleInterventricularforamen

Inferior horn oflateral ventricle

Brain-30

Cerebrospinal Fluid

Ependymalcells

Connectivetissue

Capillarycontainingblood CSF enters

the ventricle

Section of choroidplexus

Choroid plexus oflateral ventricle

1

2

3

4

5

1

• serum-like fluid lacking proteins, but containing nutrients• bathes and protects the brain and spinal cord• most synthesized in the choroid plexus – lateral ventricles

Superiorsagittal sinus

Arachnoid granulation

Subarachnoid space

Median aperture

Lateral aperture

Subarachnoid spaceCentral canal ofspinal cord

i Clicker QuestionThe pyramids are __________ nerve tracts

that are involved in the conscious control of __________ .

A. ascending, smooth muscle B. ascending, skeletal muscle C. descending, smooth muscle D. descending, cardiac muscle E. descending, skeletal muscle

The medulla oblongata does not include the

A. nuclei of some cranial nervesB. OlivesC. PyramidsD. centers for some vital reflexesE. thalamus

i Clicker Question

iClicker Question

The pineal gland is found in the

A. subthalamus. B. thalamus. C. epithalamus. D. hypothalamus. E. pons.

i Clicker Question

The infundibulum connects

A. the hypothalamus and pituitary gland. B. the thalamus and hypothalamus. C. the thalamus and epithalamus. D. the thalamus and subthalamus. E. the medulla and the pons.

i Clicker Question

The primary motor cortex is located in the

A. frontal lobe. B. occipital lobe. C. postcentral gyrus. D. precentral gyrus. E. temporal lobe.

i Clicker Question

Cerebrospinal fluid passes into the blood by way of the

A. arachnoid granulations. B. cerebral aqueduct. C. lateral ventricles. D. choroid plexus. E. brachial plexus.