Motor Areas

1. Motor Areas • anterior part of each hemisphere • primary motor area • controls voluntary contraction of specific muscles or groups of muscles • more area for muscles of skilled, complex, or delicate movement • Broca’s speech area • left frontal lobe for 97% of population • planning and production of speech • from Broca’s to • premotor area to motors of • larynx, pharynx, mouth • primary motor area to control • breathing muscles

2. Figure 15.5b

3. Association Areas • often adjacent to primary sensory areas • usually receive input from both primary sensory areas and other brain regions • integrate sensory experiences to generate meaningful patterns of recognition and awareness • damage to primary visual area of brain results in loss of vision • damage to visual association area would not recognize what they are seeing

4. Association Areas • somatosensory association area • integrates and interprets sensations • determines shape and texture of object without looking at it • determines orientation of one object with respect to another as they are felt • sense relationship of one body part to another • storage of memories of past experiences to compare current sensations with previous experiences • visual association area • receives sensory impulses from primary visual area and thalamus • relates present and past visual experiences • essential in recognizing and evaluating what is seen

5. Association Areas • auditory association area • allows recognition of sound as speech, music, or noise • Wernicke’s area • broad region in left temporal and parietal lobes • interprets meaning of speech by recognizing spoken words • translates words into thoughts • right hemisphere correspond to Broca’s and Wernicke’s in the left • contribute to verbal communication by adding emotional content like anger, joy, or spoken words

6. Association Areas • common integrative area • integrates sensory interpretations from all sensory association areas • allowing formation of thoughts based on variety of sensory inputs • transmits signals to other parts of brain to cause appropriate response • premotor area • immediately anterior to primary motor area • controls learned, skilled, motor activities of a complex and sequential nature • causes specific groups of muscles to contract in specific sequence • serves as memory bank for specific patterns of movements

7. Association Areas • frontal eye field area • controls voluntary scanning movements of eye • reading for example

8. Hemispheric Lateralization • functional asymmetry • each hemisphere also specializes in performing certain unique functions • appears at about 30 weeks in fetal development • left hemisphere receives somatic sensory signals from controls muscles on the right side of the body • right hemisphere receives and controls the left

9. Hemispheric Lateralization • left hemisphere • reasoning, numerical and scientific skills • spoken and written language • ability to use and understand sign language • right hemisphere • musical and artistic awareness • spatial and pattern perception • recognition of faces • emotional content of language • discrimination of different smells • generating mental images of sight, sound, touch, taste, and smell to compare relationships among them

10. Figure 13.11

11. Table 13.1

12. Concept 13.6Diencephalon

13. Diencephalon • extends from brain stem to cerebrum • surrounds third ventricle • thalamus • hypothalamus • pineal gland

14. Thalamus • 3cm in length • 80% of diencephalon • paired oval masses of gray matter • organized into nuclei • interspersed tracts of white matter • intermediate mass • crosses third ventricle • joins left and right halves of thalamus • relays and processes sensory and motor information

15. Thalamus • with other parts of the brain helps regulate • autonomic activities • emotions • maintains consciousness • pain perception • learning • memory • cognition (thinking and knowing)

16. Figure 13.1a

17. Figure 13.1c

18. Figure 13.9a

19. Figure 13.12

20. Hypothalamus • small part of diencephalon inferior to thalamus • 12 or so nuclei • mammillary bodies • serve as relay stations for reflexes to sense of smell • infundibulum • connects pituitary gland • major regulator of homeostasis • continually monitors conditions within blood • osmotic pressure, glucose levels, hormone concentrations, temperature

21. Important Functions of Hypothalamus • Control of ANS • regulator of visceral activities including heart rate, movement of food through GI tract, contraction of urinary bladder • Production of hormones • through bloodstream and axons to pituitary • Regulation of emotional and behavioral patterns • works with limbic system • Regulation of eating and drinking • insulin passes BBB stimulating or inhibiting food intake • thirst center sensitive to osmotic pressure

22. Important Functions of Hypothalamus • Control of body temperature • stimulates body to promote heat loss if too hot and heat production and retention if too cold • Regulation of circadian rhythms and states of consciousness • sleep and wake cycles

23. Figure 13.13ab

24. Figure 13.13c

25. Pineal Gland • size of a small pea • considered part of endocrine system • secretes melatonin • promotes sleepiness • contributes to setting of body’s biological clock

26. Concept 13.7Brain Stem

27. Brain Stem • between spinal cord and diencephalon • three regions • midbrain • pons • medulla oblongata • contain both tracts and nuclei • act as relay centers for processing and controlling • involuntary of sight and sound processing • eye movement • regulation of autonomic functions • respiration, heart rate, blood pressure, digestion

28. Midbrain • conducts nerve impulses from cerebrum to spinal cord, medulla, and pons • peduncles have axons of sensory neurons • medulla to thalamus • regions • corpora quadrigemina • superior colliculi • reflex centers for some visual activities • inferior colliculi • reflex centers for some reactions to auditory stimuli

29. Pons • anterior to cerebellum • inferior to midbrain • 2.5cm long • tracts that connect parts of brain • e.g. left and right cerebellum • voluntary movements relayed from cerebral cortex to cerebellum • help control breathing • pneumotaxic area • apneustic area

30. Figure 13.1a

31. Figure 13.1c

32. Figure 13.14

33. Figure 13.15

34. Medulla Oblongata • inferior part of brain stem • continuation of spinal cord • 3cm from pons to foramen magnum • all sensory and motor tracts connecting brain and spinal cord • pyramids • white matter bulges • largest motor tracts • 90% of left pass to right & right to left • cardiovascular and medullary rhythmicity areas

35. Reticular Formation • small clusters of neuronal cell bodies within small bundles of myelinated axons • RAS • sensory axons that project cerebral cortex • helps maintain consciousness • active during awakening from sleep • RAS arouses cerebral cortex • motor tracts • help regulate muscle tone

36. Concept 13.8Cerebellum

37. Functions of Cerebellum • anterior and posterior lobes govern subconscious aspects of skeletal muscle movements • flocculondular lobe on inferior surface contributes to equilibrium and balance • main function • cerebellum evaluates movements • smoothes movements • corrects errors • coordinates sequence • regulates posture and balance • makes possible all skilled muscular activities

38. Table 13.2 part 3

39. Concept 13.9Spinal Cord

40. External Spinal Cord Anatomy • roughly circular but flattened slightly in anterior-posterior dimension • ~2cm diameter • larger in cervical and lumbar enlargements • smallest at inferior tip • adult spinal cord length • from 42 to 45 cm • from medulla oblongata to L2 • filum terminale • extension of pia mater • extends inferiorly • anchors spinal cord to coccyx

41. Figure 13.2

42. External Spinal Cord Anatomy 31 pair of spinal nerves • exit vertebral column at intervertebral foramina • each pair called spinal segment • paths of communication • roots • bundles of axons that connect peripheral nerves and spinal cord • posterior or dorsal root • sensory neuron axons • anterior or ventral root • motor neuron axons

43. Figure 13.4b

44. Internal Spinal Cord Anatomy right and left sides • anterior median fissure • deep and wide groove • posterior median sulcus • shallower, narrower • gray matter surrounded by white matter • gray matter shaped like an “H” or a butterfly • gray commissure • crossbar of H connects gray matter L & R sides • central canal • contiguous with 4th ventricle • white commissure • anterior to gray • commissure connects white matter on L & R sides

45. Internal Spinal Cord Anatomy • gray matter • cell bodies, neuroglia, unmyelinated axons of sensor neurons, dendrites of interneurons, motor neurons • divided into horns • anterior horn • cell bodies of somatic motor neurons and motor nuclei • posterior horn • somatic and autonomic sensory nuclei • lateral gray horns • absent in cervical segments • cell bodies of autonomic motor neurons regulating smooth and cardiac muscle, and glands

46. Internal Spinal Cord Anatomy • white matter • bundles of myelinated and unmyelinated axons of sensory neurons, interneurons, and motor neurons • divided into columns • anterior, posterior, and lateral • tracts having common origin or destination and carrying similar information over long distances • sensory tracts • toward CNS • motor tracts • away from CNS

47. Concept 13.10Spinal Cord Impulses

48. Sensory Tracts • spinothalamic tracts and posterior columns • lateral and anterior spinothalamic tracts • pain, warmth, coolness, itching, tickling, deep pressure, crude poorly localized sense of touch • right and left posterior columns • proprioception, discriminative touch, two point discrimination, light pressure and vibration sensations

49. Figure 13.19a

50. Figure 13.19b