Lab Activity 15The Brain Portland Community CollegeBI 2322Brain 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 veins3Dural Folds• The inner layer of dura mater that extends into the cranial cavity.• Provide additional stabilization and support for the brain• Contain the dural sinuses4Dural 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 hemispheres56Brain 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 space7Ventricles83 Structures:• Midbrain (mesencephalon)• Pons• Medulla oblongataBrainstemCorpora quadrigemina9PonsMedullaMidbrainCorpora quadrigemina101112Brainstem: 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 tracts13Brainstem: 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 cerebellum14Brainstem: Midbrain• Functions:• Connects pons to cerebellum• Superior colliculi: visual reflex centers• Inferior colliculi: auditory reflex centers15DiencephalonStructures• Thalamus • Hypothalamus• Epithalamus16Diencephalon: Epithalamus• Superior to the third ventricle, contains the pineal glandPineal gland17Diencephalon: Thalamus• Relay station for sensory input18Diencephalon: Hypothalamus• Pituitary gland: Attaches to the hypothalamus via the infundibulum • Mamillary bodies: Process olfactory sensations.Pituitary gland (not in this picture) would be hanging hereMamillary body19Diencephalon: Hypothalamus• Major Functions:1. Controls somatic motor activities at the subconscious level2. Controls autonomic function3. Coordinates activities of the nervous and endocrine systems4. Secretes hormones5. Produces emotions and behavioral drives6. Coordinates voluntary and autonomic functions7. Regulates body temperature8. Coordinates circadian cycles of activity20Cerebellum• Functions:• Coordination of movements• Adjustment of postural musclesVermisArbor Vita (white matter that looks like a leaf)21Cerebral Cortex• The superficial layer/rim of gray matter in the cerebral hemispheres• Gray matterconsists of cell bodies, dendrites, and unmyelinated axons.22White 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 patterns23White Matter & Basal NucleiWhite MatterBasal NucleiCorpus Callosum24Sulci & 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 areaSulci25Lateral SulcusCentral Sulcus26Transverse fissureLongitudinal FissureTransverseFissure27Central SulcusPrecentral Gyrus:(frontal lobe) contains the primary motor areaPostcentral Gyrus:(parietal lobe) contains the primary somatosensory area.28Cerebrum• Frontal lobe• Motor, speech (usually left lobe), personality• Parietal lobe• Sensation (except smell), language• Occipital lobe• Vision• Temporal lobe• Hearing, smell, language2930The