1. The CNS The Brain, Spinal Cord, and Nerves Human Anatomy and Physiology CHS

2. In the CNS, the brain helps to control all the body systems and organs. The brain also allows us to think, feel, remember, and imagine. The brain communicates with the rest of the body through the spinal cord and the nerves. Nerves tell the brain what is going on in the body at all times. This system also gives instructions to the body about what to do and when to do it. The spinal cord is a thick bundle of nerves, connecting your brain to the rest of your body. It is protected by the backbone and carries messages to and from your arms, legs, and trunk of the body.

3. The Brain Appearance: 2 fist-fulls of pinkish gray tissue, wrinkled like a walnut with the texture of cold oatmeal. It weighs a little over 3 pounds. It is made up of 4 major regions.

4. BRAIN—4 main parts – Cerebrum ( 2 cerebral hemispheres) – --largest portion (larger than other 3 together). As it grows, covers most of brainstem. --most superior, largest, 85% of mass --4 lobes --receives messages about senses, controls speech, learning, intelligence, and personality. “thinking part” – Diencephalon –superior to brain stem (can only see from cross section) Thalamus Hypothalmus – Brain stem /medulla—controls autonomic system; connects cerebrum to spinal cord. Medulla oblongata Pons Midbrain – Cerebellum – “little brain”—controls balance and movement of muscles

6. Cerebrum Wrinkly, large part of the brain. Higher mental functioning, problem solving.

7. CEREBRUM Cerebral Cortex – dark outer area consists of gray matter; contains cell bodies of 75% of all neurons in the nervous system. This is outermost tissue layer on the cerebrum and is the most evolved portion of the brain. This area controls conscious thought, reasoning, and abstract mental functioning. Gyri (gyrus)–elevated regions (bumps) Sulci (sulcus)– grooves or furrows. Fissures – deeper grooves; divide brain into lobes. Longitudinal fissure – separates brain into Right and left cerebral hemispheres Corpus callosum – connects both hemispheres

8. Cerebrum has 3 basic regions: a superficial (outside) cortex of gray matter (cerebral cortex), an internal white matter, and the basal nuclei, islands of gray matter situated deep within the white matter.

9. Gray Matter vs. White Matter Gray matter—pinkish-gray color—contains cell bodies, dendrites, and axon terminals of neurons…so this is where all the synapses are; nonmyelinated axons. – Cerebral cortex – Specialized regions of the brain involved in computation, thinking, memory storage, muscle control, sensory perceptions, such as seeing and hearing, emotions, and speech. White matter—made of long myelinated axons connecting different parts of gray matter to each other. – Diencephalon (between brainstem and cerebellum) – Relays sensory information from the rest of the body to the cerebral cortex (allows NS to communicate), ANS functions, expression of emotions, release of hormones, and regulation of food and water intake. – Limbic system Youtube video: Gray vs White matter www.youtube.com/watch?v=AubAJx7-BcI

10. The cerebrum is divided into two hemispheres, right and left. Left hemisphere —responsible for speech, reading, writing, and logical thinking. These are more linear and analytical functions. Right hemisphere —responsible for emotions, creativity, musical, and artistic ability. These are more intuitive, creative, and holistic functioning.

11. Cerebral Cortex—speech, memory, logical, and emotional response, as well as consciousness, interpretation of sensation, and voluntary movement. White matter of brain lies under cortex and makes up bulk of cerebrum – Contains tracts (nerve fibers within the CNS) inside gray matter.

13. Cerebrum is divided into 4 lobes: – Frontal - forehead – Temporal – above ears – Parietal – top sides – Occipital – back Lateral fissure divides temporal lobe from frontal & parietal lobes Central sulcus divides frontal & parietal lobes No distinct boundary between parietal & occipital lobes Transverse fissure – separates cerebrum & cerebellum

15. Lobes of cerebrum

16. Functional Areas of Frontal Lobe Function: Higher order thinking skills, problem solving, planning, behavior, attention, creative thought, judgment, initiative, intelligence, inhibition, personality, emotional traits and smell. Broca’s Area—coordinated muscle movement for speech; language production Primary motor cortex – Controls voluntary actions of specific muscles or groups of muscles on the opposite side of body; Storage of motor patterns.

17. Functional Areas of Parietal Lobe Functions: Sense of touch, processing visual information, language, and math; learning comprehension; body orientation Primary somatosensory cortex – Behind central sulcus in postcentral gyrus – Receives impulses for touch, proprioception (self awareness), pain, & temperature

18. Functional Areas of Occipital Lobe Functions: Visual processing, recognition, reading.

19. Functional Areas of Temporal Lobe Major Functions: Hearing and speech, auditory and visual memory, music, fear, and sense of identity; expressed behavior. Olfactory area – smell Auditory area – hearing Wernicke Area--

20. Right and Left Hemispheres

21. Corpus callosum The right and left hemispheres are connected by the corpus callosum. 200 million axons. It’s function is to facilitate communication between the two hemispheres. The largest collection of white matter in the brain—so faster transmission of information.

22. DIENCEPHALON Sits atop the brainstem and is enclosed by the cerebral hemispheres; the interbrain. (Thalamus, hypothalamus, epithalamus) – Relay station for sensory impulses to cerebral cortex (white matter) – Plays a role in emotions, memory, awareness and cognition

23. Thalamus Relay station (connections) for sensory impulses passing upward to the sensory cortex. As impulses surge through thalamus, we have a crude recognition of whether the sensation we are about to have is pleasant or unpleasant. It is the neurons of sensory cortex that actually localize and interpret the sensation.

24. Hypothalamus – “under the thalamus” (controls ANS) – Controls regulation eating & drinking (water balance and metabolism/apetite) – Controls body temperature – Regulation of consciousness, emotional and behavior, response to anxiety, diurnal (circadian) rhythms – synchronizes day- night cycle (sleep patterns) – Regulates the pituitary gland.

25. Epithalamus contain Pineal gland (part of endocrine system)— produces – Melatonin- sleep/wake patterns, seasonal functions. Choroid plexus (knots of capillaries forming the cerebrospinal fluid) Pituitary Gland—(hangs off hypothalamus) produces hormones that control many functions of other endocrine glands.

26. Limbic System – Not a structure, but a series of nerve pathways incorporating structures deep in the temporal lobe. – Thalamus, hypothalamus, amygdala, hippocampus. – Emotional aspects of behavior; Control and expression of mood and emotion, processing and storage of recent memory, control of appetite and emotional response to food; thirst, sex, pain, and pleasure centers. – Produces hormones. – Linked to depression; some psychiatric disorders, such as anxiety.

27. Amygdala – almond-shape set of neurons located deep in the brain's medial temporal lobe. – integrative center for emotions, emotional behavior, and motivation; intense emotion, such as panic and fear, panic attacks, pleasure.

28. Hippocampus – Forming, organizing, and storing memories. – Connecting smell and sound to memories. – Spatial orientation. – Horseshoe shaped. – Acts as a memory indexer by sending memories out to the appropriate part of the cerebral hemisphere for long-term storage and retrieving them when necessary.

30. BRAIN STEM About the size of the thumb in diameter and 3 inches long. Connects spinal cord to white matter to cerebral cortex. Regulate visceral functions (autonomic systems).

31. Pons – Pons means “bridge” – Relaying sensory information; Connects spinal cord with brain & links parts of brain with one another by way of tracts ( nerve fibers within the CNS) – Aid in control of breathing and other autonomic functions. – Sleep

32. Medulla Oblongata – Most inferior part of the brainstem. – Merges into spinal cord. – Fiber tracts – Regulates: Cardiac center – heart rate Vasomotor center – constricts blood vessels (blood pressure) Respiratory center – rate and depth of breathing Swallowing Vomiting

33. Midbrain Cerebral aqueduct—tiny canals that travel through the midbrain. Cerebral peduncles--Convey ascending and descending impulses. Corpora quadrigemina—reflex centers involved with vision and hearing.

34. Reticular (Activating) Formation Extends entire length of brain stem. Receives input from most of the bodies sensory systems (sight, sound, etc) Diffuse mass of gray matter. – Responsible for maintaining consciousness & awakening from sleep; focus. – Damage to this area can result in coma.

36. CEREBELLUM White matter tracts are called “arbor vitae” tree of life. (cauliflower) 2 hemispheres, convoluted surface. Outer cortex (gray matter) and inner region (white matter). Coordination, balance, and posture; coordinates sensory input from inner ear and the muscles to provide accurate control of position and movement. Damage would show loss of muscle tone and inaccurate movements Located in the back of the brain.

38. Cerebellum Cerebellar peduncles – connect cerebellum to other parts of brain; convey impulses.

42. PROTECTIONS & COVERINGS The CNS is protected by: – Bone – cranium and vertebral column – Meninges – 3 connective tissue layers located between the bone and the soft tissue of the nervous system. Dura mater – outermost layer; attached to periosteum; many blood vessels and nerves. Arachnoid mater – “spiderweb” middle layer; no blood vessels Pia mater – inner, nearly transparent membrane, contains nerves and blood vessels to nourish cells. Follows contours of brain and spinal cord.

43. MENINGES Meningitis – inflammation of meninges Subdural space – fluid filled area between dura and subarachnoid maters (cerebral spinal fluid).

44. Cerebralspinal fluid (CSF) and ventricles Watery “broth” similar to blood plasma surrounding the outer surface of the brain. Provides cushion and protection for fragile nervous tissue from blows and other trauma. The CSF also maintains and controls the extracellular environment and circulates endocrine hormones. Within the brain, there are a number of cavities called ventricles (4). They are filled with CSF. Continually moving through brain and spinal cord. Changes in CSF indicate meningitis or other brain inflammation. The test for this is a lumbar (spinal) tap. Watch a video of a lumbar puncture: https://www.youtube.com/watch?v=yYZxNsnf18Y&feature=youtu.be

45. Cranial Nerves 1. Olfactory 2. Optic 3. Oculomotor 4. Trochelear 5. Trigeminal 6. Abducens 7. Facial 8. Vestibulocochlear/Acoustic 9. Glossopharyngeal 10. Vagus 11. Accessory (spinal accessory) 12. Hypoglossal

47. Cranial Nerve Functions

49. Spinal Nerves