nervous system

• Main parts of the nervous system

  • CNS (central nervous system)
  • PNS (peripheral nervous system)
• CNS


  Consists of the brain and the Spinal cord
• PNS


  Consists of 12 cranial nerves, 31 spinal nerves and other associated ganglia
• Functional divisions of the nervous system

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


  Responsible for voluntary activities
• Autonomic Nervous System


  Responsible for involuntary activities
• Central Nervous System


  • Composed of a large number of cells and their processes, supported by specialized tissue called Neuroglia
• Neuron


  The nerve cell and all its processes
• Dendrites


  • The short processes of the cell body
• Axons


  • The longest process of the cell body
• Grey Matter


  Consists of nerves cells embedded in neuroglia
• White Matter


  Consists of nerve fibers (axons) embedded in neuroglia
• Peripheral Nervous System


  • Consists of the cranial and spinal nerves and their associated ganglia
• Cranial Nerves


  There are 12 pairs of cranial nerves that leave the brain and pass through the foramina in the skull. All nerves are distributed in the head and neck EXCEPT the CN X (Vagus), which also supplies structures in the thorax and abdomen
• Spinal Nerves


  A total of 31 pairs of spinal nerves leave the spinal cord and pass through intervertebral foramina in the vertebral column. They are named according to the region of vertebra they are found in: 8 Cervical, 12 Thoracic, 5 Lumbar, 5 Sacral, 1 Coccygeal
• Spinal nerve roots in the cervical region

  • Short and run almost horizontally
• Spinal nerve roots in the lumbar and sacral regions

  • Form a vertical bundle of nerves that resembles a horse's tail and is called the cauda equina
• Plexuses


  At the root of the limbs, the anterior rami join one another to form complicated nerve plexuses
• Brachial Plexus


  C5 to T1, innervates the Upper Limb Muscles, Shoulder muscles, and some muscles of the back and thorax
• Lumbar Plexus


  T12 to L4, innervates the Muscles of the Lower Limb and Buttocks
• Sacral Plexus


  L4 to S4, innervates the muscles of the Lower Limb as well as genital area
• Autonomic Nervous System


  The part of the nervous system concerned with the innervation of involuntary structures such as the heart, smooth muscle, and glands throughout the body
• Parts of the Autonomic Nervous System

  • Sympathetic part
  • Parasympathetic part
• Sympathetic part


  Prepares the body for an emergency (fight or flight), causes adrenergic/adrenal response, accelerates heart rate, constricts peripheral blood vessels, raises blood pressure, redistributes blood, inhibits intestinal peristalsis, closes sphincters
• Parasympathetic part


  Aims at conserving and restoring energy, slows heart rate, increases intestinal peristalsis and glandular activity, opens sphincters
• Hypothalamus


  Controls the autonomic nervous system and integrates the activities of the autonomic and neuroendocrine systems, thus preserving homeostasis in the body
• Craniosacral Division

  • S2-S4 - Urinary bladder
  • CN10 - Dorsal Motor Nucleus - Lungs/GIT
  • CN 3 - Edinger-Westphal - PERRLA
• Parasympathetic Nervous System

  "Rest and Digest"
• Bones


  • Living tissue capable of changing its structure as a result of the stresses to which it is subjected, consist of cells, fibers, and matrix, hard due to calcification of extracellular matrix, possess elasticity due to organic fibers
• Types of Bone Marrow

  • Red bone marrow
  • Yellow bone marrow
• Red Bone Marrow


  Where hematopoiesis or the production of RBCs take place
• Yellow Bone Marrow


  Contains adipose tissue, triglycerides stored in the adipocytes can be released to serve as a source of energy for other tissues
• Forms of Bone

  • Compact
  • Cancellous
• Compact Bone


  Appears as a solid mass
• Cancellous Bone


  Consists of a branching network of trabeculae
• Long Bones


  • Found in the limbs, length greater than breadth, have a tubular shaft (diaphysis) and an epiphysis at each end, metaphysis is the part of the diaphysis adjacent to the epiphyseal cartilage, covered by periosteum, articular surfaces covered by hyaline cartilage
• Short Bones


  • Found in the hand and foot, roughly cuboidal in shape, composed of cancellous bone surrounded by a thin layer of compact bone, covered with periosteum, articular surfaces covered by hyaline cartilage
• Flat Bones


  • Found in the vault of the skull, composed of thin inner and outer layers of compact bone (tables) separated by a layer of cancellous bone (diploë), include the scapulae
• Irregular Bones


  • Not assigned to the previous groups, composed of a thin shell of compact bone with an interior made up of cancellous bone, include the bones of the skull, vertebrae, and pelvic bones
• Sesamoid Bones


  Small nodules of bone found in certain tendons where they rub over bony surfaces, largest is the patella, reduce friction on tendons and can alter the direction of pull