Cns bss
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The document summarizes key aspects of the central nervous system. It describes the protective structures of the brain including the cranium, meninges and cerebrospinal fluid. It then outlines the major regions of the brain - cerebrum, diencephalon, brainstem and cerebellum - and provides details about their structure and function. It also discusses the spinal cord, its protective coverings, gray and white matter structure, and ascending and descending tracts.
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- 1. The Central Nervous System Brain – superiorly Spinal Cord - inferiorly
- 2. Figure 12.3
- 4. Figure 12.24
- 6. Figure 12.5
- 7. Figure 12.26
- 8. Figure 12.27
- 9. Figure 12.12
- 12. Figure 12.6c, d
- 13. Figure 12.6a, b
- 14. Figure 12.7
- 16. Figure 12.6a
- 17. Figure 12.8a
- 19. Figure 12.11b
- 21. 3 Functional areas in the Cerebral Cortex
- 23. Decussation of the Pyramids
- 26. Basal Nuclei
- 29. Ventricles
- 31. Diencephalon
- 33. Brain Stem
- 34. Figure 12.15c
- 35. Table 12.1.1
- 36. Figure 12.14
- 38. Cranial Nerves III - XII
- 39. Figure 12.15b
- 40. 2 pigmented nuclei in the Midbrain
- 41. CEREBELLUM
- 42. The Arbor Vitae
- 44. Table 12.1.2
- 45. The Spinal Cord
- 46. The Spinal Cord
- 48. 3 Protective structures of the Spinal Cord
- 50. Figure 12.29c
- 51. Figure 12.29d
- 53. Lumbar Tap
- 55. Gray Matter and White Matter
- 57. Figure 12.32
- 58. Ascending Tracts - Sensory inputs
- 59. Table 12.2.2
- 60. Descending Tracts – Motor output
- 61. Table 12.3.1
- 64. Lumbar Myelomeningocele – Spina Bifida cystica – incomplete formation of the vertebral arches
Editor's Notes
- Started here, 3 rd bullet… then lobes, then slide 14
- Then 19
- Now here… CEREBRUM – a section through the cerebrum -> 3 regions Outer cerebral cortex Inner cerebral white matter Islands of nuclei called the basal nuclei CEREBRAL CORTEX highly convoluted, appears gray due to the presence of unmyelinated structures = cell bodies, dendrites, supporting cells 2-4 mm thick but it accounts for 40% of the total brain mass composed of 6 layers of billions of neurons has 3 functional areas motor areas sensory areas association areas Motor areas of the cerebral cortex 4 areas (slide 21?) primary motor cortex located in the PRECENTRAL GYRUS in the frontal lobe neurons in the precentral gyrus called the PYRAMIDAL CELLS have large tracts that descend to the spinal cord to control voluntary precise movements The pyramidal tracts (= coricospinal tracts) decossate (cross over) to control voluntary movements of skeletal muscle on opposites of the body Pyramidal cells in the LEFT precentral gyrus control voluntary movement of skeletal muscles on the RIGHT side of the body; and vice versa Hence, the cerebral cortex exhibits contralateral control of voluntary movements of the skeletal muscle Damage to the left precentral gyrus will result in loss of voluntary motor function on the RIGHT side of the body – paralysis of the right side of the body; and vica versa premotor cortex located in the frontal lobe anterior to the precentral gyrus controls voluntary skilled skeletal muscle movements that are patterned or repetitious in nature… ex. Typing Hence, the premotor cortex is referred to as the “memory bank for skilled patterned skeletal muscle activities” broca’s area = speech motor area located in the frontal lobe and is below the premotor cortex controls skeletal muscles involved in speech production damage to the broca’s area results in the loss of speech located in one hemisphere, mostly in the LEFT cerebral hemisphere **Insult (stroke) involving the left cerebral hemisphere involves the left precentral gyrus broca’s area LEADS TO RIGHT SIDE PARALYSIS AND LOSS OF SPEECH frontal eye field (4 th area) located in the frontal lobe of both hemispheres controls skeletal muscles that control eye movements On to slide 21 (we were already on it, just writing stuff there
- Sensory area of the cerebral cortex primary somatosensory corex located in the postcentral gyrus (in the parietal lobe) receives sensory info from receptors in the skin, skeletal muscle, joints, for SPATIAL DISCRIMINATION ability to differentiate areas of the body being stimulated primary visual cortex located in the occipital lobe of both hemispheres receives sensory input from the retinae in the eyes. The primary somatosensory cortex and the primary visual cortex exhibit contralateral inputs Sensory inputs from the left side of the body received by the RIGHT postcentral gyrus and vice versa Sensory inputs from the retinae (vision) in the left eye go to the RIGHT occipital cortex right PRIMARY VISUAL CORTEX 3) primary auditory (hearing) cortex is located in the temporal lobes of both cerebral hemispheres 4) primary gustatory (taste) cortex is located in the insula of both cerebral hemispheres 5) primary olfactory (smell) cortex is located in the temporal lobes; emotional aspect in frontal lobe 3 rd functional area in the cerebral cortex association areas each sensory area has an association area. The association areas integrate/interpret and appreciate the sensory input information
- 2 nd region of the cerebrum cerebral white matter region DEEP to the cerebral cortex cerebral white matter is composed of MYELINATED axons (“whitish”) bundle to form TRACTS 3 types of tracts Commissural tracts = Commissures connect areas of the 2 cerebral hemispheres ex. CORPUS CALLOSUM which connects to cerebral hemispheres medially Association tracts connect areas within the same cerebral hemisphere; ex. ARCUATE FASCICULATE which connects the broca’s area to the Wernicke’s area in the left cerebral hemisphere for language acquisition meaning that you have words that make sense in a coherent sentence See next slide
- 11/10 Cerebral white matter = 3 types of tracts Commissural tracts commissures Association tracts Projection tracts Run vertically between the cerebral cortex… the lower brain regions (=subcortical regions) and the spinal cord 2 types descending projection tracts – come from cerebral cortex ascending projection tracts – TO the cerebral cortex for interpretation, see next slide for picture… now what opoku said descending projection tracts motor tracts carrying efferent impulses from the cerebral cortex EX. Pyramidal (corticospinal) tracts descending from the precentral gyri ascending projection tracts see slide 27 for pictures, sensory inputs = afferent impulses carried TO the cerebral cortex from sensory receptors for interpretation EX. Spinothalamic tract Next slide
- 3 rd region in the cerebrum basal nuclei = islands of gray matter in the cerebral white matter (nucleus = a cluster of neuronal cell bodies in the CNS) 3 major basal nuclei (superior inferior) Caudate Putamen Globus pallidus b&c above = lentiform nucleus All three above = CORPUS STRIATUM As the pyramidal tracts coursing through them give the 3 nuclei a striated appearance (corpus striatum = “striated body”) Function of the basal nuclei involved in the initiation and monitoring of intensity of voluntary movement skeletal muscle movement 2 lateral ventricles are located in the 2 cerebral hemispheres each cerebral hemisphere contains a lateral ventricle 2 lateral ventricles are separated by the septum pellicidum 2 lateral ventricles are connected inferiorly to the 3 rd ventricle by the interventricular foramen (foramen of Monro)
- 2 nd region of the adult (postnatal) brain DIENCEPHALON contains the 3 rd ventricle located below the cerebrum consists of 3 pairs of gray matter structures (on next slide)
- Missed some stuff… thalamus accounts for 80% of the total mass of the diencephalon The cell bodies (gray matter) in the thalamus act as relay centers for sensory info projected to the cerebral cortex. Hence, the thalamus is referred to as the “GATEWAY TO THE CEREBRAL CORTEX” 2 of such relay centers in the thalamus lateral geniculate nucleus (LGN) medial geniculate nucleus (MGN) LGN is the visual relay center MGN is the auditory relay center Hypothalamus is located below the thalamus major endocrime gland 9 hormones controls all body functions to maintain homeostasis Epithalamus dorsal to the thalamus contains an endocrine gland pineal gland secretes a hormone called melatonin “sleep inducting chemical” that works with the suprachiasmatic nucleus in the hypothalamus to bring about sleep
- Midbrain Cerebral peducles Cerebral aqueducts Corpora quadrigemina superior colliculi and the inferior colliculi Superior cerebellar peduncles which connect the motor tracts passing the midbrain to the cerebellum 2 pigmented nuclei red nuclei and the substantia nigra Red nuclei – relay centers for descending motor tracts that control limb flexion Substantia nigra appear black due to high concentration of melanin (melanin used in the production/synthesis of the neurotransmitter DOPAMINE) Hence, the neurons in the substantia nigra are referred to as dopaminergic neurons project to the BASAL NUCLEI (in the cerebrum) to modulate the activities of the basal nuclei for the initiation of skilled, coordinated skeletal muscle movements Damage or degeneration of the dopaminergic neurons from the substantia nigra to the basal nuclei result in the symptoms of parkinson’s disease ========================== -resting tremor -masklike facial expression (expressionless) -slow to initiate voluntary movements -shuffling gait -slurred speech The cell bodies of 2 cranial nerves are located in the midbrain CN III, IV Now, looking at pons
- Pons middle region of the brain stem between the midbrain and the medulla oblongata Pons contains conducting tracts projection tracts between the cerebral cortex and the spinal cord tracts travel through the middle cerebellar peduncles to the cerebellum Pons also contains the respiratory centers apneustic center and pneumotaxic center apneustic center controls the rate of breathing pneumotaxic center controls the depth of breathing Pons will have cell bodies for 3 cranial nerves CN V, VI, VII MEDULLA OBLONGATA most inferior region of the brain stem continued by the spinal cord at the level of the Foramen magnum of the skull contains: inferior cerebellar peduncles that connect the medulla to the cerebellum cell bodies for cranial nerves VIII-XII Ventral aspect of the medulla, the descending pyramidal tracts decussate (cross-over) and the point of crossing over is referred to as the DECUSSATION of the PYRAMIDS explains the contralateral control of voluntary movements in the body explains why the left precentral gyrus controls the voluntary movements (of skeletal muscles) on the right side and vice versa Medulla is responsible for something and contains these structures… Cardiovascular center cardiac center = regulates the heart rate and stroke volume vasomotor center regulates the diameter of blood vessels Cardiovascular center regulates in blood pressure 2) Respiratory center apneustic center and pneumotaxic center 3) Swallowing center 4) Coughing center 5) Emetic (vomiting) center)
- 4 th region of the adult (postnatal) brain CEREBELLUM Accounts for about 11% of the total brain mass Located behind (posterior) to the brain stem and connected to the brain stem via the superior, middle, and inferior cerebellar peduncles Also located inferior to the occipital lobes of the cerebrum (or cerebral hemispheres) The cerebellum is separated from the occipital lobes by the transverse fissure (deep sulcus) Cerebellum divided into 2 cerebellar hemispheres held together medially by the VERMIS Each cerebellar hemisphere is divided into 3 lobes Anterior lobe Posterior lobe Flocculonodular lobe 1&2 can be viewed on the external surface 3 cannot be viewed on the external surface of the cerebellar hemispheres 3 is located deep to the vermis A section through the cerebellum will reveal 2 regions outer gray matter and inner white matter inner white matter branches into a tree-like pattern referred to as ARBOR VITAE (the tree of life) Function of the cerebellum well-coordinated smooth, skillful skeletal muscle movements also involved in balance (equilibrium) involved in maintenance of posture Alcohol intoxication affects the cerebellum the most.
- 11/15 CNS Superior brain and inferior spinal cord In the adult the spinal cord is about 42 cm (17 inches) long and it extends from the foramen magnum to the 1 st lumbar vertebra. 3 protective structures bony structure vertebral column meninges CSF Slide 48
- Spinal cord extends from the foramen magnum L1 appears tapered and ends in cone-shaped structure called the CONUS MEDULLARIS (fibrous extensions from the conus medullaris covered by pia mater) the whole thing in parentheses is called the FILUM TERMINALE attaches to the coccyx to anchor the spinal cord vertically 31 pairs of spinal nerves exit through intervertebral foramina into the PNS 8 pairs of vervical nerves 12 pairs of thoracic 5 lumbar 5 sacral 1 coccyx These 31 pairs of spinal nerves innervate structures outside of the CNS structures in the PNS spinal cord 2 enlargements (slide 52)
- 49
- If you look at the vertebral column C1 to L1 vertebrae provide protection ------------------------- Meninges 3 types Dura mater – outermost meninx, SINGLE-LAYERED and it does not line the internal surface of the vertebrae – there is no contact A space between the verebrae and the dura mater called the EPIDURAL SPACE is present the epidural space contains fat and veins site for epidural anesthesia to block pain the single layered dura mater of the spinal cord is also referred to as the SPINAL DURAL SHEATH Arachnoid mater – middle meninx separated from the spinal dural sheath by a space called the SUBDURAL SPACE The arachnoid mater is separated from the pia mater (innermost meninx) by a space called the SUBARACHNOID SPACE contains CSF Pia mater – innermost meninx forms lateral structures called DENTICULATE ligaments anchor the spinal cord laterally to the spinal dural sheath. Pia mater attaches to the surface of the spinal cord (she showed us a picture on slide 50) went back to slide 48 3 rd protective structure is called the Cerebrospinal fluid (CSF) contained in the subarachnoid space (around the spinal cord) and in the CENTRAL CANAL runs vertically through the core of the spinal cord (inside the spinal cord) The central canal extends and receives CSF from the 4 th ventricle located in the brain stem Function of CSF provide nutrients, remove metabolic wastes, fluid cushion Slide 47
- Cervical enlargement superior enlargement in the cervical region of the spinal cord Spinal nerves from the cervical enlargements will innervate skeletal muscles in the upper limbs nerves control voluntary movements of the upper limbs ================= Lumbar enlargement inferior to cervical enlargement around the lower thoracic and upper lumbar region of the spinal cord spinal nerves from the lumbar enlargement innervate and control voluntary movements of skeletal muscle in the lower limbs Damage or transection of the enlargements will result in paralysis FLACCID paralysis Transection (cutting) of the spinal cord at or above the cervical enlargement will result in paralysis of all 4 limbs both upper and lower limbs quadriplegia Transection of the spinal cord below the cervical enlargement but above the lumbar enlargemnet will only result in paralysis of the lower limbs paraplegia **note hemiplegia paralysis of one side of the body is due to damage to the precentral gyri in the cerebral coretex (BRAIN DAMAGE instead of spinal cord damage) Hemiplegia is also referred to as SPASTIC paralysis =========================== The spinal nerves below L1 form a collection of nerve roots called the CAUDA EQUINA as they exit their foramina below the L1 =========================== Slide 56
- Cross section through the spinal cord outer white matter and inner gray matter The outer white matter composed of mainly myelinated tracts that communicate info between area within the spinal cord and the brain Based on orientation we have 3 areas or columns called funiculi These funiculi contain 3 types of tracts ascending tracts, descending tracts, interneurons Ascending tracts send sensory information to the brain Descending tracts send motor information from the brain to the spinal cord Interneurons communication within the spinal cord Inner gray matter shaped like an “H” or a butterfly mirror images connected by the gray commisure immediately surrounds the central canal Regions with gray matter dorsal horns central horns lateral horns spinal cord at the level of the thoracic or L1 region contain cell bodies of the sympathetic fibers of the autonomic nervous system ============ 11/17 Spinal cord Outer white matter Ascending tracts Descending tracts Interneurons = transverse tracts Inner gray matter shapped like the letter “H” or a butterfly mirror image connected by a band of gray matter called the GRAY COMMISSURE Each side consists of a) DORSAL HORN houses cell bodies for interneurons b) Ventral horn houses cell bodies for somatic neurons that innervate the skeletal muscles c) Lateral horn only present in the spinal cord region of the thoracic and lumbar houses cell bodies of the sympathetic nerve fibers Damage to the cell body of the somatic neurons in the ventral horns Anytrophic Lateral sclerosis (Lov Gehrig’s disease) Hence, in ALS, the patient loses the ability to walk, speak, swallow, breathe breathing lost because the diaphragm (a skeletal muscle) is paralyzed Slide 59
- Slide 62 64
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