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