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BIO 210 Lab Instructor: Dr. Rebecca Clarke

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1 BIO 210 Lab Instructor: Dr. Rebecca Clarke
Chapter 14: The Brain BIO 210 Lab Instructor: Dr. Rebecca Clarke

2 Human Brain Contains almost 98% of body’s neural tissue
Average weight about 3 lb (1.4 kg)

3 6 Major Regions of the Brain
Cerebrum Cerebellum Diencephalon Mesencephalon Pons Medulla oblongata

4 The Brain Embryological Development
Determines organization of brain structures Neural tube Origin of brain Enlarges into three primary brain vesicles prosencephalon mesencephalon rhombencephalon

5 The Brain Five Secondary Brain Vesicles Telencephalon Diencephalon
Mesencephalon Metencephalon Myelencephalon

6 The Brain Origins of Brain Structures
Diencephalon and mesencephalon persist Telencephalon: Becomes cerebrum Metencephalon Forms cerebellum and pons Myelencephalon Becomes medulla oblongata

7 The Brain

8 Cerebrum Controls higher mental functions
Largest part of brain (80% of volume)

9 Cerebrum Divided into large L and R cerebral hemispheres
Longitudinal fissure: Separates upper part of R & L hemispheres Corpus callosum: Thick, crescent-shaped band of white matter Connects R & L hemispheres

10 Cerebrum Corpus Callosum Figure 14–11a

11 Cerebral Cortex Surface layer of gray matter on cerebrum
Also called neural cortex Folded surface: Increases surface area Provides space for more cortical neurons

12 Cerebral Cortex Folded surface has:
Gyri (sing: gyrus) = elevated ridges Sulci (sing: sulcus) = hollow depressions Fissures = deep grooves

13 Cerebrum Sulci and fissures divide cerebral hemispheres into distinct lobes (regions) (named for overlying bones of skull)

14 Cerebral Structures Central sulcus Postcentral gyrus Precentral gyrus
Groove across hemi-sphere Separates motor and sensory areas Postcentral gyrus Upfold posterior to central sulcus Primary sensory cortex Precentral gyrus Upfold anterior to central sulcus Primary motor cortex

15 Cerebral Lobes Frontal lobe Parietal lobe Occipital lobe Temporal lobe
Motor cortex Parietal lobe Sensory cortex Occipital lobe Visual cortex Temporal lobe Auditory cortex Olfactory cortex

16 Cerebral Structures: Insula
“5th lobe;” deep “island” of cortex medial to lateral sulcus Exposed when temporal lobe pushed to side Site of gustatory cortex

17 Cerebral Gray Matter Found in: Cerebral cortex Cerebral nuclei

18 Cerebral White Matter Myelinated nerve fibers
Makes up most of interior of cerebrum Located: Deep to cerebral cortex Around cerebral nuclei

19 Ventricles of the Brain
Chambers lined with ependymal cells  CSF 4 ventricles: 2 lateral (R & L), 3rd, 4th

20 Ventricles of the Brain: Lateral Ventricles (First 2)
1/cerebral hemisphere

21 Ventricles of the Brain: 3rd Ventricle
In diencephalon between R & L thalami Connects to lateral ventricles via interventricular foramen (of Monro)

22 Ventricles of the Brain: 4th Ventricle
Extends between pons and cerebellum into medulla oblongata; becomes continuous with central canal of spinal cord Connects to 3rd ventricles via mesencephalic (cerebral) aqueduct

23 CSF Circulation Choroid Plexus Through ventricles
To central canal of spinal cord Into subarachnoid space around brain, spinal cord, and cauda equina Enters venous circulation

24 Cranial Meninges Have 3 layers (like spinal meninges):
Dura mater Arachnoid mater Pia mater Are continuous with spinal meninges Protect the brain from cranial trauma (act as “air bags”)

25 Cranial Meninges: Dura Mater
2 Fibrous layers Outer (endosteal) layer Fused to periosteum of cranial bones No epidural space (vs. spinal cord) Inner (meningeal) layer In some locations folds into cranial cavity between hemispheres  dural folds Venous (dural) sinus between layers

26 Cranial Meninges: Dural Folds
Folded inner layer of dura mater Extend into cranial cavity Stabilize and support brain (act like “seat belts”) Contain collecting veins (dural sinuses) [FYI: falx cerebri, tentorium cerebelli, falx cerebelli]

27 Cranial Meninges: Arachnoid Mater
Consists of: Arachnoid membrane Epithelial layer Covers brain (does not follow folds) Arachnoid trabeculae Cells and fibers that cross subarachnoid space to pia mater

28 Cranial Meninges: Pia Mater
Attached to brain surface by astrocytes

29 Cerebellum Coordinates repetitive body movements
Second largest part of brain 10% of volume but 50% of neurons

30 Cerebellum R & L cerebellar hemispheres: Vermis:
Separated at midline by vermis Vermis: Narrow band of cortex

31 Cerebellum Highly folded cerebellar cortex
 folia (less prominent than gyri) Arbor vitae: central, tree-like branching mass of white matter deep to cortex

32 Diencephalon Located in central region of brain deep to cerebrum
Links cerebrum with brain stem

33 Diencephalon 4 Regions: Thalamus – L & R: Hypothalamus:
Masses of gray matter (nuclei) Forms walls of third ventricle Hypothalamus: Below thalamus Forms floor and part of walls of thalamus

34 Diencephalon Third ventricle: Pineal gland: Separates L & R thalamus
Secretes hormone melatonin

35 Diencephalon Intermediate mass: Projection of gray matter
Extends into ventricle from each side of thalamus

36 Hypothalamus Has neural and endocrine functions Infundibulum
Stalk that connects pituitary gland to hypothalamus Pituitary Gland

37 Brain Stem Processes information between:
Spinal cord and cerebrum or cerebellum Includes: mesencephalon, pons, medulla oblongata

38 Mesencephalon (Midbrain)
2 pairs of sensory nuclei (corpora quadrigemina): Superior colliculi (visual) Inferior colliculi (auditory)

39 Pons Links cerebellum with mesencephalon, diencephalon, cerebrum, and spinal cord Involved in motor control

40 Medulla Oblongata Connects brain to spinal cord
Regulates complex autonomic functions: Heart rate, blood pressure, respiration Continuous with spinal cord

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