Lab Activity 15 The Brain Portland Community College BI 232

2 Brain Meninges: Dura Mater Continuous with the spinal meninges Dura mater: An outer and inner fibrous connective tissue Outer later is fused to the periosteum of the cranial bones (no epidural space) Between the layers are tissue fluids, blood vessels and venous sinuses. Venous sinuses are large collecting veins. Venous sinuses drain into the internal jugular veins

3 Dural Folds The inner layer of dura mater that extends into the cranial cavity. Provide additional stabilization and support for the brain Contain the dural sinuses

4 Dural Folds Falx cerebri projects between the cerebral hemispheres in the longitudinal fissure Superior sagittal sinus & inferior sagittal sinus Tentorium cerebelli separates the cerebellar hemisphere from the cerebrum Transverse sinus Falx cerebelli divides the cerebellar hemispheres

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6 Brain Meninges: Arachnoid & Pia Mater Arachnoid mater consists of the arachnoid membrane and fibers of the arachnoid trabeculae that attach to the pia mater Pia mater: attached to the surface of the brain, anchored by processes of astrocytes Contains branches of cerebral blood vessels that penetrate the surface of the brain. CSF is between these two membranes in the subarachnoid space

7 Ventricles

8 3 Structures: Midbrain (mesencephalon) Pons Medulla oblongata Brainstem Corpora quadrigemina

9 Pons Medulla Midbrain Corpora quadrigemina

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12 Brainstem: Medulla Oblongata Functions: Center for the coordination of complex autonomic reflexes (heart rate, respiratory rhythm, blood pressure) Control of visceral functions (vomiting, swallowing) Decussation of pyramids: a crossover point for the major motor tracts

13 Brainstem: Pons Functions: Sensory and motor nuclei of Cranial nerves V, VI, VII, and VIII Respiratory control: Apneustic center and pneumotaxic center to modify the activity of the respiratory rhythmicity center in the medulla Nuclei and tracts that process and relay information to and from the cerebellum

14 Brainstem: Midbrain Functions: Connects pons to cerebellum Superior colliculi: visual reflex centers Inferior colliculi: auditory reflex centers

15 Diencephalon Structures Thalamus Hypothalamus Epithalamus

16 Diencephalon: Epithalamus Superior to the third ventricle, contains the pineal gland Pineal gland

17 Diencephalon: Thalamus Relay station for sensory input

18 Diencephalon: Hypothalamus Pituitary gland: Attaches to the hypothalamus via the infundibulum Mamillary bodies: Process olfactory sensations. Pituitary gland (not in this picture) would be hanging here Mamillary body

19 Diencephalon: Hypothalamus Major Functions: 1.Controls somatic motor activities at the subconscious level 2.Controls autonomic function 3.Coordinates activities of the nervous and endocrine systems 4.Secretes hormones 5.Produces emotions and behavioral drives 6.Coordinates voluntary and autonomic functions 7.Regulates body temperature 8.Coordinates circadian cycles of activity

20 Cerebellum Functions: Coordination of movements Adjustment of postural muscles Vermis Arbor Vita (white matter that looks like a leaf)

21 Cerebral Cortex The superficial layer/rim of gray matter in the cerebral hemispheres Gray matter consists of cell bodies, dendrites, and unmyelinated axons.

22 White Matter & Basal Nuclei White matter consists primarily of myelinated axons Is beneath the gray matter cortex Notice how it is the opposite arrangement from the spinal cord (Spinal cord: white matter is on the outside and gray matter is on the inside.) Corpus callosum: Connects the right and left hemispheres Basal nuclei: Islands of gray matter within the white matter. Function: Involved in the subconscious control of skeletal muscle tone and the coordination of learned movement patterns

23 White Matter & Basal Nuclei White Matter Basal Nuclei Corpus Callosum

24 Sulci & Gyri Sulci: Shallow depressions of the cerebral cortex Central sulcus is between the frontal and parietal lobes Lateral sulcus is between the parietal lobes and temporal lobes. Fissures: Deep grooves Longitudinal: separates cerebral hemispheres Transverse: separates cerebrum form the cerebellum Gyri: The elevated ridges of the cerebral cortex Serve to increase the surface area Sulci

25 Lateral Sulcus Central Sulcus

26 Transverse fissure Longitudinal Fissure Transverse Fissure

27 Central Sulcus Precentral Gyrus: (frontal lobe) contains the primary motor area Postcentral Gyrus: (parietal lobe) contains the primary somatosensory area.

28 Cerebrum Frontal lobe Motor, speech (usually left lobe), personality Parietal lobe Sensation (except smell), language Occipital lobe Vision Temporal lobe Hearing, smell, language

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30 The End