Part 1 - Nervous System

• Sensory information pathway


  1. Sensory information reaches the brain

  2. Thalamus conveys messages to specific areas

  3. Except for CN olfactory which exits from the hypothalamus
• Basal ganglia & substantia nigra


  A group of subcortical nuclei that form important connections, responsible primarily for motor control, as well as other roles such as motor learning, executive functions and behaviors, and emotions
• Parkinson's Disease


  Caused by a loss of nerve cells in the substantia nigra resulting in decrease in DOPAMINE
• Nerve cells in substantia nigra

  Responsible for producing a chemical called dopamine
• Decrease in dopamine


  Results in poor motor functions, typically in the hands
• Pituitary gland


  Master gland that regulates growth, metabolism, and reproduction through the hormones it produces
• Pituitary hormone production


  Production of hormones is either stimulated or inhibited by chemical messages sent from the hypothalamus to the pituitary
• Pituitary lobes


  • Anterior lobe - secretes majority of the hormones which target the endocrine glands
  • Posterior lobe - secretes 2 hormones: oxytocin and antidiuretic hormone
• Functional Divisions of the Peripheral Nervous System (PNS)

  • Somatic Nervous System
  • Autonomic Nervous System
  • Enteric Nervous System
• Somatic Nervous System


  Controls the skeletal muscles, consists of nerves that go to the skin and muscles, involved in conscious activities
• Autonomic Nervous System


  Controls the visceral organs, consists of nerves that connect the CNS to the visceral organs such as the heart, stomach, and intestines, mediates unconscious activities
• Enteric Nervous System


  Controls the functions of the GIT, sometimes considered part of the autonomic nervous system, sometimes considered an independent system that controls digestive activities
• Central Nervous System (CNS)

  The brain and the spinal cord
• Peripheral Nervous System (PNS)


  The cranial nerves and spinal nerves
• Nervous System is composed of the Central Nervous System (CNS) and the Peripheral Nervous System (PNS)
• Circle of Willis


  A ring of vessels connecting the anterior and posterior circulations of the brain
• Cerebral Aneurysm


  • Occurs commonly in the Circle of Willis area
• Vessels in the Circle of Willis

  • Anterior cerebral
  • Anterior communicating
  • Middle cerebral
  • Posterior communicating
  • Posterior cerebral
  • Basilar
• Arachnoid space


  The space in between the arachnoid and pia mater
• Contents of the arachnoid space

  • Blood
  • Dura mater
  • Arachnoid
  • Pia mater
• Spinal cord


  A long cylindrical structure extending from the foramen magnum to the L1 in adult, 3/L4 in pedia
• Cross section of the spinal cord

  • Gray matter contains neurons
  • White matter consists of nerve fibers
• Spinal nerves


  • 31 pairs that exit the spinal cord
• Spinal nerve


  Formed by the dorsal root (sensory) and the ventral root (motor)
• Spinal nerve segments


  • Cervical 8 pairs
  • Thoracic 12 pairs
  • Lumbar 5 pairs
  • Sacral 5 pairs
  • Coccygeal 1 pair
• Ventricles


  CSF filled cavities in the brain
• Ventricles


  • Lateral ventricle
  • Third ventricle
  • Fourth ventricle
• The body is able to produce approximately 500ml of CSF at a constant amount the whole time
• As CSF circulates, some is absorbed by the tissues of the brain and spinal cord (approximately 50ml within 24 hours), while there is also a constant replenishing or replacement of the loss, maintaining the 500ml
• Intracranial Pressure (ICP)


  The pressure inside the skull, maintained by the CSF
• Normal ICP is 10-15 mmHg for adults, 3-7 mmHg for young children
• If ICP reaches beyond 15 mmHg, it causes headache and projectile vomiting
• CSF pathway


  1. Lateral ventricle

  2. Interventricular foramen of Monro

  3. Third ventricle

  4. Cerebral aqueduct of Sylvius

  5. Fourth ventricle

  6. Exits through median foramen of Magendie or lateral foramen of Luscka

  7. Subarachnoid spaces in the cisterna magna, spinal cord, and brain
• Parts of the nervous system

  • Central nervous system (brain and spinal cord)
  • Peripheral nervous system
• Divisions of the autonomic nervous system

  • Sympathetic nervous system
  • Parasympathetic nervous system
• Sympathetic nervous system


  Originates from the T1-L2/L3 segments of the spinal cord, utilized for flight and fight response, uses neurotransmitters epinephrine and norepinephrine
• Sympathetic responses


  • Increased heart rate, respiratory rate, blood pressure, visual acuity, smooth muscle tone, metabolism, decreased peristalsis, salivary secretions, ejaculation
• Parasympathetic nervous system


  Cranio-sacral location, uses neurotransmitter acetylcholine, responsible for feed and breed responses
• Parasympathetic responses


  • Increased peristalsis, salivary secretions, pupillary constriction, smooth muscle tone, erection
• Cranial nerves


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