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Nervous System lecture 2 BS Nursing 2nd semester
- 1. Anatomy & Physiology-II TheNervous System Mr. Salman Ahmad BSN, MSN
- 2. Central Nervous System(CNS) Central Nervous System (CNS) • Adult brain has 100 billion neurons. • Weight of brain---1300 g • Lies in cranial cavity • That provide it protection from damage and injury.
- 3. Protection of theCentral Nervous Protection of the Central Nervous System System Brain is enclosed within skull and spinal cord by the vertebrae. Scalp and skin Skull and vertebral column Meninges Figure 7.16a
- 4. Protection of theCentral Nervous Protection of the Central Nervous System System Cerebrospinal fluid Blood brain barrier Figure 7.16a
- 5. Meninges Meninges The brain andspinal cord are completely surrounded by 3 layers of tissue, The Meninges; Dura mater Double-layered external covering: Periosteum – attached to surface of the skull Meningeal layer – outer covering of the brain
- 6. Meninges Meninges Arachnoid mater Middle layer CSF is present in the space below arachnoid mater (Sub arachnoid space) Pia mater Internal layer Adheres to the surface of the brain Pia mater & Arachnoid mater are collectively called Lepto meninges.(thin, or delicate.)
- 7. Cerebrospinal fluid (CSF) •Fluid found in and around the central nervous system (CNS), the brain and spinal cord. • 80- 90 % CSF is produced by ependymal cells within the lateral ventricles; remainder is produced by similar cells in third and fourth ventricles. • These ependymal cells, their supporting tissue , and the associated blood vessels are called choroid plexuses.
- 8. Ventricles and Locationof the Ventricles and Location of the Cerebrospinal Fluid Cerebrospinal Fluid Figure 7.17a
- 9. Ventricles and Locationof the Ventricles and Location of the Cerebrospinal Fluid Cerebrospinal Fluid Figure 7.17b
- 10. CSF Composition CSF Composition Secretedcontinuously at a rate of about 0.5ml per minute; 720ml per day. The volume remains fairly constant at about 150ml, as absorption keeps pace with the secretion. CSF pressure Normal 8 -10cm H2O Appearance; clear, colorless Water Mineral salts Glucose: 40–85 mg/dL. Protein (total): 15–45 mg/dL. Leukocytes (WBC): 0–5/µL (adults / children) Specific gravity: 1.005–1.009
- 11. CSF circulation: • Choroidplexus produces ~720ml/day of CSF • body produces, absorbs and replenishes the total volume of CSF about 3-4 times daily.) • CSF produced in the lateral ventricles flows into the 3rd ventricle through an opening called interventricular foramen • Flows into through a canal called cerebral aqueduct into the 4th ventricle • Passes through paired lateral apertures and a median aperture into the subarachnoid space • Flows through the subarachnoid space surrounding the brain (small amount enters the central canal of the SC)
- 14. Functions of CSF Functionsof CSF Supports and protects the brain & spinal cord. Keeps the brain and spinal cord moist Supplies nutrients to the nervous system tissue. Removes waste products from cerebral metabolism.
- 15. Brain Anatomy Brain Anatomy TheBrain constitutes about one fiftieth of the The Brain constitutes about one fiftieth of the body weight & lies within the cranial cavity. body weight & lies within the cranial cavity.
- 16. Regions of theBrain Regions of the Brain Cerebrum(Cerebral hemispheres) Diencephalon Thalamus Hypothalamus Epithalamus Brain stem Midbrain Pons Medulla Oblangata Cerebellum Figure 7.12
- 17. Cerebrum -The largestpart of the brain. It is divided into two hemispheres, each of which is divided into four lobes. Cerebrum Cerebrum Cerebellum It is comprised of right and left hemispheres connected by the a band of white mater called as corpus callosum. The surface of the brain is convoluted to create more surface area.
- 18. Cerebral Cortex Cerebral Cortex CerebralCortex - The outermost layer of gray matter making up the superficial aspect of the cerebrum.
- 19. CEREBRAL FEATURES Gyri orConvulsions– Elevated ridges “winding” around of the brain. Sulci – Small grooves dividing the gyri e.g. 1) Central Sulcus – Divides the Frontal Lobe from the Parietal Lobe 2) Parietal-occipital sulcus Fissures – Deep grooves, generally dividing large regions/lobes of the brain 1) Longitudinal Fissure – Divides the two Cerebral 2) Transverse Fissure – Separates the Cerebrum from the Cerebellum 3) Sylvian/Lateral Fissure – Divides the Temporal Lobe from the Frontal and Parietal Lobes
- 21. Lobes of theCerebrum Lobes of the Cerebrum Fissures (deep grooves) divide the cerebrum into 4 lobes Lobes of the cerebrum Frontal lobe Parietal lobe Occipital lobe Temporal lobe
- 22. Cerebral Lobes andtheir General Functions Frontal lobe. The top, front regions of each of the cerebral hemispheres used for reasoning, emotions, judgment, and voluntary motor movement Parietal lobe. The middle lobe of each cerebral hemisphere between the frontal and occipital lobes; it contains important sensory centers. Occipital lobe. The region at the back of each cerebral hemisphere that contains the centers of vision and reading ability (located at the back of the head). Temporal lobe. The region at the lower side of each cerebral hemisphere; contains centers of hearing and smell (located at the sides of the head).
- 23. Functional Areas ofthe Cerebrum Functional Areas of the Cerebrum Sensory areas – receives impulses from the body’s sensory receptors Motor areas – sends impulses to skeletal muscles Association areas – concerned with integration and processing of complex mental functions such as intelligence, memory, reasoning, judgement & emotions.
- 24. Functional Areas ofCerebral Cortex Functional Areas of Cerebral Cortex Motor areas of Cerebral Cortex Primary motor area – lies in the frontal lobe ant. To central sulcus Broca’s area – motor speech area, lies in frontal lobe above lateral sulcus Sensory areas of Cerebral Cortex The somatosensory area – lies immediately behind the central sulcus in the parietal lobe. The auditory area - Hearing area, lies in temporal lobe The Olfactory area – Smell area, lies deep within the temporal lobe The Gustatory area – Taste area, lies just above the lateral sulcus The visual area – lies in occipital lobe Association Areas The Premotor area – lies in frontal lobe anterior to motor area The prefrontal area - extend anteriorly from premotor area. Wernicke’s area – Sensory speech, area lies in temporal lobe.
- 26. Sensory and MotorAreas of the Sensory and Motor Areas of the Cerebral Cortex Cerebral Cortex Figure 7.14
- 27. Layers of theCerebrum Layers of the Cerebrum Gray matter Outer layer Composed of neuron cell bodies Figure 7.13a
- 28. Layers of theCerebrum Layers of the Cerebrum White matter Middle part of the cerebrum Composed of nerve cell processes Figure 7.13a
- 29. Layers of theCerebrum Layers of the Cerebrum Basal Ganglia Groups of cell bodies (nuclei) deep within the cerebral hemispheres. Act as a unified functional unit. Their functions include initiation and fine control of complex movement & learned coordinated activities such as posture and walking Figure 7.13a
- 30. Functions of CerebralCortex Functions of Cerebral Cortex Mental activities involved in memory, intelligence, sense of responsibility, thinking, reasoning, moral sense and learning. Sensory perception, including the perception of pain, touch, sight, hearing, taste & smell. Initiation and control of skeletal muscle contraction (voluntary movement) Figure 7.13a
Editor's Notes
- #24 1. Premotor Area: Responsible for planning, sequencing, and coordinating movements. Helps in learning skilled and patterned motor activities (e.g., writing, playing piano). 2. Prefrontal Area: Involved in higher cognitive functions: reasoning, decision-making, planning, judgment. Wernicke’s Area :Responsible for language comprehension (understanding spoken and written language).