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BRAIN & CRANIAL NERVES The brain and spinal cord develop from ectoderm.

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Presentation on theme: "BRAIN & CRANIAL NERVES The brain and spinal cord develop from ectoderm."— Presentation transcript:

1 BRAIN & CRANIAL NERVES The brain and spinal cord develop from ectoderm

2 The brain and spinal cord develop from the neural tube Prosencephalon (Forebrain) Mesencephalon ( Midbrain) Rhombencephalon (Hindbrain) Primary brain vesicles are present around the 3rd week of development

3 Prosencephalon (forebrain) Differentiates in 5 th week into: Telencephalon – cerebral hemispheres Diencephalon – thalamus; hypothalamus – pineal gland

4 Midbrain Mesencephalon remains the same Brainstem = midbrain

5 Rhombencephalon Metencephalon – cerebellum, pons Myelencephalon – medulla oblongata

6 Meninges Dura mater – dural septa (extensions): falx cerebri, falx cerebelli, tentorium cerebelli Arachnoid Pia mater Cavities – subarachnoid space, subdural space


8 4 Ventricles filled with CSF Lateral ventricles (paired) – Interventricular foramen – connects to 3 rd ventricle Third ventricle – Cerebral aqueduct – connects 3 rd and 4 th ventricles Fourth ventricle – Connects with central canal of spinal cord


10 Cerebrospinal Fluid Clear, colorless fluid that protects brain Formed by the choroid plexus Absorbed by arachnoid villi

11 Parts of the Brain

12 Medulla oblongata Major reflex center for the cardiovascular and respiratory system – vasomotor, vasoconstriction Pyramids - decussation (crossing) center for motor `tracts Non-vital center for coughing, hiccuping, swallowing, vomiting Ascending/descending fibers pass through Cranial nerves VIII-XII arise here


14 PONS Acts as a bridge connecting the spinal cord to the brain Major relay center for voluntary skeletal movements from the cerebral cortex to the cerebellum Coordinates with the medulla to regulate respiration Cranial nerves V-VIII emerge here


16 Midbrain Corpora quadrigemina – Visual and auditory reflex centers Cerebral peduncles - containing large fiber tracts going to and from the brain Houses the cerebral aqueduct Cranial Nerves III-IV emerge here


18 Thalamus Two halves connected by the intermediate mass Relay center for ALL sensory cranial and spinal nerves Interpretation center for crude awareness of pain, temperature and pressure Location of 3rd ventricle


20 Hypothalamus Links the nervous system and endocrine system Major regulator of homeostasis Regulates many ANS functions Regulates appetite, water balance, thirst, body temperature Emotional part of brain - pleasure, fear, rage


22 Cranial Nerves 12 Pairs 1 Olfactory - smell 2. Optic - sight 3. Oculomotor - eye movements 4. Trochlear - eye movements 5. Trigeminal - eyes & face, chewing 6. Abducens - eyes

23 7. Facial -facial expression, taste 8. Vestibulocochlear -equilibrium, hearing 9. Glossopharyngeal -tonge & swallowing 10. Vagus -heart, visceral organs 11. Accessory -neck & back 12. Hypoglossal -tongue Cranial Nerves (continued)


25 Cerebellum Second largest area of the brain 2 cerebellar hemispheres Arbor vitae - branchlike pattern Vermis - wormlike structure that connects left & right side Major coordination of skeletal muscle contraction Assists with posture and balance

26 Cerebrum Cerebral cortex - outer layer of gray matter Two hemispheres separated by longitudinal fissure Gyri - ridges on surface Sulci - grooves on surface Fissures Septum pellucidum - thin wall between ventricles

27 Lobes of the Brain Frontal Parietal Occipital Temporal Central sulcus Lateral sulcus

28 Cerebral Dominance Left hemisphere – Language – Logic – Math Right Hemisphere – Artistic – Musical – Creative

29 Cerebral Cortex Specialization Motor Areas – Control opposite side of body – Control voluntary motor functions Sensory Areas – Detect sensations from opposite side of body Association Areas – Integrate diverse information into purposeful action

30 Association Areas Prefrontal Cortex – intellect, learning, & personality Language Areas – Wernicke’s area – sounding out new words – Brocas’s area – speech General Interpretation Visceral Interpretation

31 Basal Ganglia Cerebral nuclei Islands of gray matter located deep within the white matter Function: controls large automatic skeletal muscle movements and produce dopamine

32 White Matter Commissural fibers (corpus callosum) - connect corresponding parts of two hemispheres Association fibers - connect within the same hemisphere Projection fibers (higher centers to lower ones)

33 Limbic System Includes part of thalamus, hypothalamus, and cerebrum Emotional brain Associated with memory Involuntary behavior for survival Pleasure and pain centers - fear, sorrow, affection

34 Reticular Formation RAS System - reticular activating system Network of gray matter extending from the medulla, pons, midbrain into the cortex Maintains consciousness Awaken from sleep Alerts brain of incoming sensory signals

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