A&P Exam 4

• Spinal cord


  31 segments with spinal nerves
• Spinal nerve


  Fusion of dorsal and ventral roots
• Dorsal root


  Axons of sensory neurons in the dorsal root ganglia connecting to sensory neurons in dorsal/posterior gray matter horns
• Ventral root


  Axons from somatic and autonomic motor neurons from ventral/anterior gray matter horns
• Grey matter areas


  • Dorsal/posterior gray horns, sensory
  • Ventral/anterior gray horns, somatic motor
  • Dorsal and ventral, gray commissures
  • Th/Lu lateral gray horns, autonomic motor, sympathetic
• White matter


  • Posterior/dorsal funiculi
  • Lateral tracts/fasciculi
  • Anterior/ventral funiculi
  • Anterior white commissure
  • Posterior white commissure
• Spinal pathways


  • Decussation - most pathways cross to the contralateral side of the CNS
  • Relay - most pathways involve two or more synapses
  • Somatotopy - space relationship among tract fibers that reflects orderly mapping on the body
  • Symmetry - all pathways and tracts paired symmetrically

  
• Spinal nerves


  Leave the vertebral bones and then project to the body by branching (rami). Dorsal rami are short and project to posterior side, ventral rami are longer and project to front and lateral side of body
• Spinal nerves are organized in plexus
• Spinal nerves have associated connective tissue: epineurum, perineurum and endoneurum

  
• Paresthesia


  Damage to dorsal roots
• Paralysis


  Damage to ventral roots
• Flaccid paralysis


  Spinal cords or ventral cords are injured
• Spastic paralysis


  Upper motor neurons on motor cortex, or their axons on spinal cord are injured
• Transections of spinal cord

  Total motor and sensory loss in body regions inferior to site of damage
• Paraplegia


  Damage between T1 and L1
• Quadriplegia


  Damage in cervical region
• Spinal shock


  Transient period of functional loss after injuries. Immediate depression of reflex caudal to the injurie site
• Poliomyelitis


  Destruction of motor neurons on ventral horns
• Amyotrophic lateral sclerosis (ALS, Lou Gehrig Disease)


  Progressive destruction of motor neurons on ventral horns and fibers of the pyramidal tract. Glutamate and ROS-dependent
• Prosencephalon (Forebrain)


  Telencephalon + Diencephalon
• Telencephalon


  Cerebrum cortex, white tissue, and basal ganglia
• Cerebral cortex


  • Contains 3 kinds of functional areas: Motor areas, sensory areas and association areas
  • Each hemisphere is chiefly concerned with the sensory and motor functions of the contralateral (opposite) side of the body
  • Although largely symmetrical in structure, the two hemispheres are not entirely equal in function. There is lateralization (specialization) of cortical functions
  • No functional area of the cortex works alone, and conscious behavior involves the entire cortex in one way or another

  
• White tissues


  Nerve cell processes (axons). Forms tracts: association fibers, projection fibers, and commissures fibers
• Basal nuclei


  Subcortical nuclei involved in the control of the movements of skeletal muscles
• Diencephalon


  Epithalamus, Thalamus, and Hypothalamus
• Epithalamus


  Pineal gland, secretion of melatonin (metabolic setting of circadian rhythm)
• Thalamus


  Center of integration of many sensory afferent pathways (with the exception of olfaction)

  
• Hypothalamus


  Center of integration of cortex with autonomous and endocrine system. It sustains to the pituitary gland (Hypophysis)
• Limbic system


  Functional association of neurons across the brain, including nuclei on the border of cortex and inferior structures. Functions include learning, memory, motivation, emotions, and social interactions
• Mesencephalon (Midbrain)


  Tectum: optic lobes, superior and inferior colliculi. Tegmentum: substantia nigra, dopaminergic neurons controlling basal nuclei
• Reticular formation


  Functional association of neurons across the brainstem. Functions include automatic processing of motor and sensory commands/information, regulating vital autonomic functions, and part of the extrapyramidal system

  
• Rhombencephalon (Hindbrain)


  Metencephalon: Cerebellum and pons. Myelencephalon: Medulla oblongata
• Cerebellum


  Adjustment of motor output, ensuring coordination and balance. Part of the extrapyramidal system
• Pons


  Contains respiratory centers, controls rate and pattern of breathing. Also involved in alertness and sleep
• Medulla oblongata


  Contains vital centers for respiratory rhythmicity, cardiovascular control, and centers for vomiting, hiccupping, swallowing, coughing and sneezing
• Pyramidal system


  Direct pathways from the upper brain motor cortex. Control skilled voluntary movements
• Extrapyramidal system


  Indirect pathways from the brain motor cortex. Regulates fast and fine (or skilled) movements, muscle tone, axial muscles, coarse limb movements, and head/neck/eye movements

  
• Autonomic nervous system


  Division of the efferent nervous system that regulates visceral activity (heart and smooth muscle of inner organs)
• Sympathetic division


  Moves energy in the body (fight and fly response). Ganglia have acetylcholine, nicotinic receptors. Postganglionic fibers release adrenaline, noradrenaline on target organs