Nervous system 2

• Brain

  • The adult brain contains 95% of the body's nervous tissue
  • The adult brain consists of 6 major regions: medulla oblongata, pons, mesencephalon, diencephalon, cerebellum, cerebrum

  
• Cerebrum


  The largest part of the brain, consists of two hemispheres, several lobes (frontal, parietal, occipital, temporal), gyri and sulci to increase surface area

  
• Hemispheric Specialization

  • Left hemisphere: speech center, writing, language, mathematics
  • Right hemisphere: analysis by touch, spatial visualization
• Cerebral Lobes


  • Frontal lobe: conscious control of skeletal muscles
  • Occipital lobe: perception of visual stimuli
  • Parietal lobe: conscious perception of touch, pressure, vibration, pain, temperature, and taste
  • Temporal lobe: conscious perception of auditory and olfactory stimuli

  
• Cerebellum


  • Coordinates complex somatic motor patterns
  • Adjusts output of other somatic motor centers in brain and spinal cord
• Brain Stem


  • Relays sensory information to thalamus and brain stem
  • Autonomic centers for regulation of visceral function (cardiovascular, respiratory, and digestive system activities)
  • Relays sensory information to cerebellum and thalamus
  • Subconscious somatic and visceral motor centers
  • Processing of visual and auditory data
  • Generation of reflexive somatic motor responses
  • Maintenance of consciousness
  • Centers controlling emotions, autonomic functions, and hormone production
  • Relay and processing centers for sensory information
• Thalamus

  • Relay and processing centers for sensory information
• Hypothalamus

  • Centers controlling emotions, autonomic functions, and hormone production
• Medulla Oblongata


  • Subconscious somatic and visceral motor centers
  • Processing of visual and auditory data
  • Generation of reflexive somatic motor responses
  • Maintenance of consciousness
• Pons

  • Relays sensory information to thalamus and brain stem
  • Autonomic centers for regulation of visceral function (cardiovascular, respiratory, and digestive system activities)

  
• Mesencephalon


  • Relay and processing centers for sensory information
• Diencephalon


  • Relay and processing centers for sensory information
• Cranial Meninges


  • Protects & supports the brain
  • Surround the brain and the spinal cord

  
• Dura Mater


  Has 2 fibrous layers: endosteal and meningeal (dural sinus contained between these two)
• Arachnoid Mater


  • Smooth, does not follow sulci and gyri
  • Deep to the arachnoid mater is the Subarachnoid space
  • Arachnoid trabeculae: network of collagen and fibres that extend from the inner surface of the arachnoid mater to the pia mater outer surface
• Pia Mater


  • Tightly attached to the surface of the brain
  • Follows the sulci and gyri of the brain
  • Helps to anchor the larger blood vessels of the cerebrum

  
• Ventricles


  • Fluid-filled cavities within the brain
  • Filled with cerebrospinal fluid (CSF)
  • Lined with ependymal cells
  • Fluid transports nutrients to the CNS and transports waste away from the CNS
  • CSF also provides cushion for the CNS
• CSF Circulation


  1. Made in the choroid plexus

  2. ~500ml/day

  3. Circulating CSF ~150ml, so CSF is replaced every 8 hours
• Circle of Willis


  Arteries that supply blood to the brain: anterior communicating, anterior cerebral, internal carotid, posterior communicating, posterior cerebral, basilar, vertebral
• Cranial Nerves


  • Olfactory nerve (N I)
  • Optic Nerve (N II)
  • Oculomotor Nerve (N III)
  • Trochlear Nerve (N IV)
  • Trigeminal Nerve (N V)
  • Abducens nerve (N VI)
  • Facial nerve (N VII)
  • Vestibulocochlear nerve (N VIII)
  • Glossopharyngeal nerve (N IX)
  • Vagus nerve (N X)
  • Accessory nerve (N XI)
  • Hypoglossal nerve (N XII)

  
• Cranial Nerves


  • Innervate the periphery emerging from the brain (not the spinal cord)
  • Found on the ventrolateral surface of the brain
  • Numbered beginning at the anterior aspect of the brain

  
• There are 12 pairs of cranial nerves
• The Cranial Nerves


  • There are 12 pairs of cranial nerves
  • Innervate the periphery emerging from the brain (not the spinal cord)
  • Found on the ventrolateral surface of the brain
  • Numbered beginning at the anterior aspect of the brain
  • They are numbered CN I to CN XII

  
• Cranial Nerves


  • Olfactory nerve (N I)
  • Optic Nerve (NII)
  • Oculomotor Nerve (N III)
  • Trochlear Nerve (N IV)
  • Trigeminal Nerve (N V)
  • Abducens Nerve (N VI)
  • Facial Nerve (N VII)
  • Vestibulocochlear Nerve (N VIII)
  • Glossopharyngeal Nerve (N IX)
  • Vagus Nerve (N X)
  • Accessory Nerve (N XI)
  • Hypoglossal Nerve (N XII)

  
• Olfactory nerve (N I)


  Special sensory (smell)
• Optic Nerve (NII)


  Special sensory (vision). Retina of the eye
• Oculomotor Nerve (N III)


  Motor, eye movements. Intrinsic eye muscles (diameter of the pupil). External muscles
• Trochlear Nerve (N IV)


  Motor, eye movements
• Trigeminal Nerve (N V)


  Sensory and motor, opthalmic branch (sensory), maxilary branches (sensory), mandibular branch

  
• Abducens Nerve (N VI)

  Motor, eye movements, lateral movements
• Facial Nerve (N VII)


  Sensory and motor, taste receptors on the tongue, and motor nuclei of pons, motor control of facial expression
• Vestibulocochlear Nerve (N VIII)


  Special sensory, balance and equilibrium, and hearing
• Glossopharyngeal Nerve (N IX)


  Sensory and motor, sensory on the tongue, pharynx, and palate, carotid arteris, motor form the motor nuclei of the medulla oblongata, pharynx and parotid salivary gland
• Vagus Nerve (N X)


  Sensory and motor. Sensory of the pharynx, auricle, diaphragm, visceral organs. Visceral motor and motor nuceli in the medulla oblongata. Motor to muscles of the palate and pharynx, motor to respiratory, cardiovascular, and digestive organs

  
• Accessory Nerve (N XI)

  Motor. Voluntary swallowing muscles of the soft palate and pharynx and muscles that control the vocal cords. Controls muscles of the neck and back.
• Hypoglossal Nerve (N XII)


  Motor, tongue movements
• Outline of the Autonomic Nervous System

  • Somatic vs autonomic
  • Sympathetic vs parasympathetic
• The autonomic nervous system (ANS) regulates body temperature and coordinates cardiovascular, respiratory, digestive, excretory, and reproductive functions. Routine physiological adjustments to systems are made by the autonomic nervous system operating at the subconscious level.
• Sympathetic

  The sympathetic division of the autonomic nervous system operates through a series of interconnected neurons. Efferent sympathetic neurons originate from thoracic and lumbar spinal nerves and synapse with neurons in the peripheral nervous system at a series of sympathetic ganglia. "fight or flight"
• Parasympathetic


  "rest and digest" The parasympathetic division consists of (1) preganglionic neurons in the brainstem and in sacral segments of the spinal cord and (2) ganglionic neurons in peripheral ganglia located within or immediately next to target organs.