Anatomy & Physiology Part 2: Nervous System

The Brain: ~100 billion multipolar neurons 3 major components: The cerebrum largest part (associated with sensory & motor functions, higher mental functions) The cerebellum (voluntary muscle movement & coordination) The brain stem (connects & regulates viscera) Another part of the brain is the diencephalon. This is also associated with sensory functions.

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Cerebrum: There are 2 cerebral hemispheres. This is collectively called the cerebrum. Gyri are ridges; sulci are grooves. Fissures are deep grooves Fissures divide the cerebrum into lobes. http://www.google.com/imgres

Cerebrum Lobes: These are named for the bones they are under. Frontal lobe Parietal lobe Temporal lobe Occipital lobe Insula

The corpus callosum is a “bridge” of nerve fibers that connect the 2 hemispheres. The hemispheres generally mirror each other. There are 3 main areas of the cerebrum: Cerebral Cortex White Matter Basal Nuclei

Cerebrum: Cerebral Cortex: Functions: speech, memory, logic, emotional responses, & voluntary movement The cortex includes: Broca’s area: vocalization/formation of words Speech area: language comprehension (meanings of words)

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Cerebrum: White Matter: Basal Nuclei: Contains nerve tracts that allow communication to occur between hemispheres and brain stem a.k.a. basal ganglia Gray matter Regulate voluntary motor functions

Diencephalon: It contains the thalamus, hypothalamus, optic tracts pituitary gland, mammillary gland & pineal gland. The thalamus is the central region of message relays; receiving all sensory info (except smell) & transmitting the signals to the appropriate location. It produces awareness of sensations. http://www.google.com/imgres

The hypothalamus maintains homeostasis & links the NS to the endocrine system. It regulates: Heart rate & blood pressure Body temperature Water & electrolyte balance Hunger & body weight Stomach & intestinal secretions & movement Sleep & wakefulness Production of stimulants for the pituitary gland

Diencephalon: Other glands part of the Diencephalon: Pituitary gland (hormones) Pineal gland (sleep regulation) Choroid plexuses (capillaries that secrete CSF) The hypothalamus includes the limbic system and controls emotional responses & expression; as a result, it guides behavior to increase the chance of survival.

Brain Stem: Connects the spinal cord to the cerebrum Includes the midbrain, pons & medulla oblongata The midbrain contains reflex centers (visual & auditory Midbrain http://www.google.com/imgres

The pons is between stem & oblongata; relays sensory impulses & regulates rate & depth of breath. The medulla oblongata is below the pons The medulla oblongata is associated with coughing, sneezing, swallowing & vomiting reflexes. It controls heart rate, blood pressure, and breathing

The reticular formation is a network of nerve fibers that are throughout the midbrain, pons & medulla oblongata. This regulates wakefulness (increased activity increases awareness; decreased activity induces sleep). If this is injured, this causes unconsciousness; if the person cannot be aroused, a comatose state (coma) results.

Cerebellum: Integrates & coordinates sensory info & skeletal muscles; helps to maintain posture. Injury to this area will cause tremors (involuntary movements), inaccurate movements, staggering walk, muscle tone loss or equilibrium disturbance.

Protection of CNS: Meninges The CNS is surrounded by bones, membranes & fluids (skull contains the cranial cavity which contains the brain, etc.). The membranes of the CNS are the meninges (between bones & soft tissues). These protect the brain & spinal cord. There are 3 layers to the meninges: dura mater, arachnoid mater, & pia mater.

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Meninges: Arachnoid Mater: Dura Mater: outermost layer found within the cranial cavity, surrounds skull bones, & extends inward between brain lobes Surrounds the spinal cord & ends as a sac right below the cord (but is not attached to the vertebrate). Thin membrane without a blood supply Between dura mater & pia mater Covers brain & spinal cord

The innermost layer of the meninges Between the arachnoid mater & pia mater is the subarachnoid space. The cerebrospinal fluid (CSF) is contained here. This is a clear watery fluid that bathes the brain & spinal cord. Pia Mater: The innermost layer of the meninges Covers the brain & spinal cord and follows their surfaces closely

Spinal Cord: This is a nerve column that goes from the brain into the vertebral canal. Consists of 31 segments & 31 pairs of spinal nerves There are 2 enlargements: the cervical enlargement contains the nerves for the upper limbs; the lumbar enlargement contains the nerves for the lower limbs. http://www.google.com/imgres

Spinal Cord with Meninges: http://www.google.com/imgres

PNS: Cranial Nerves: There are 12 pairs of cranial nerves: 1. Olfactory nerves (I): sense of smell 2. Optic nerves(II): vision (eyes to brain) 3. Oculomotor nerves (III): eye muscle movement (somatic & autonomic) 4. Trochlear nerves (IV): eye movement; smallest cranial nerves 5. Trigeminal nerves (V): contain ophthalmic, maxillary, & mandibular nerves; mixed nerves; largest cranial nerves.

See textbook for summary of cranial nerves. 6. Abducens nerves (VI): aids in eye muscle movement 7. Facial nerves (VII): taste receptors; stimulate salivary & tear gland secretions (autonomic) 8. Vestibulocochlear nerves (VIII): maintain equilibrium & enable hearing (ear) 9. Glossopharyngeal nerves (IX): swallowing; mixed nerves; associated with the tongue & pharynx. 10. Vagus nerves (X): speech & swallowing; mixed (autonomic & somatic) 11. Accessory nerves (XI): cranial & spinal 12. Hypoglossal nerves (XII): tongue, speaking, chewing & swallowing. See textbook for summary of cranial nerves.

PNS: Spinal Nerves: Come from the spinal cord Grouped according to their location: Cervical nerves (#C1 to C8): 8 pairs Thoracic nerves (#T1 to T12): 12 pairs Lumbar nerves (#L1 to L5): 5 pairs Sacral nerves (#S1 to S5): 5 pairs Coccygeal nerves (Co): 1 pair See textbook summary of these spinal nerves.

Autonomic Nervous System: Functions independently (autonomous), meaning without conscious thought Controls visceral functions Contains the parasympathetic & sympathetic divisions The parasympathetic division functions during restful conditions while the sympathetic division functions during emergency, stressful & energy spending situations.

Look up in text or online! Know the following: Huntington’s Disease, Parkinson’s Disease, Ataxia, Meningitis, Encephalitis, Hydrocephalus, Blood brain barrier, Concussion, Contusion, Intracranial hemorrhage, cerebral edema, CVA, hemiplegia, TIA, Cerebral palsy, Spina bifida, and Senility

This slide show was developed by Dana Halloran, Cardinal Mooney High School, Sarasota, FL. Used with her personal permission, adapted and amended by Rosa Whiting, Manatee School for the Arts, Palmetto, FL.