Central Nervous System The Spinal Cord Spinal Cord
- Slides: 12
Central Nervous System: The Spinal Cord
Spinal Cord • It is about 18 inches long. • Extends from the brain to the 1 st or 2 nd lumbar vertebrae. • Long cylinder, 31 continuous segments. • Each segment contains a pair of spinal nerves. – Relay information from PNS to CNS. • Cervical Enlargement: Swelling in the spinal cord that serves the upper appendages. • Lumbrosacral Enlargement: Swelling in the spinal cord that serves the lower appendages.
Connective Tissue Coverings of the Spinal Cord • Dura Matter: outer most covering of the spinal cord – Not attached to the vertebral column, has a space(epidural block) filled with; connective tissue, blood vessel, and adipose tissue. – Epidural Block: injection of anesthesia to the epidural space to block pain from spinal nerves in that area. • Archnoid: Middle layer, contains collagen & elastic fibers. • Pia Matter: Inner layer attached to the neural tissue, contains a network of blood vessels.
Structures of the Spinal Cord • External Structures: – Conus Medularis: Location where spinal cord tapers(L 2). – Caudia Equina: “Horse’s Tail”; collection of nerves that extend beyond the end of the spinal cord.
Structures of the Spinal Cord • Internal Structures: – Anterior & Posterior Medial Sulcus: Fissures(grooves) that divide the spinal cord into right and left halves. – Central Canal: Narrow passageway filled with cerebrospinal fluid (center of cord). – Gray Matter: • Forms “H” or butterfly shape in the center of the cord. • Contains unmyelinated fibers & neuroglia that “integrate” • Contains; motor, sensory, & association neurons.
Structures of the Spinal Cord • Internal Structures (cont. ) – White Matter • Surrounds the gray matter. • Contains mostly myelinated neurons that relay information from sensory to motor neurons. • Contains two tracts that carry information to and from the brain. (Ascending Tract, Descending Tract)
Anatomical Structures of the Spinal Cord
Function of the Spinal Cord • Conduction Pathways: – Ascending Tract: Carries sensory information to the brain. – Descending Tract: Conveys motor commands from the brain.
Function of the Spinal Cord • Reflex Arc: Rapid way of responding to an emergency situation, impulse only travels through the spinal cord, not to the brain. – Receptor: Sensory receptor end of dendrite that senses change. – Sensory Neuron: Carries impulse to spinal cord. – Association Neuron: Connects sensory neruron to motor neuron (carries out response) to illicit response.
Function of the Spinal Cord • Reflex Arc: – Somatic Reflex: Effect skeletal muscle (withdrawal reflex, patellar reflex). – Visceral Reflex: Effects smooth or cardiac muscle (heart rate, breathing, vomiting, sneezing, coughing).
Reflex Arc
Damage & Disease • Quadriplegia- Damage to the 4 th or 5 th cervical vertebrae that produces paralysis to the upper and lower limbs. • Paraplegia- Damage to the thoracic vertebrae that produces paralysis to the lower limbs. • Meningitis (spinal or cerebral)- Bacterial or viral infection of the coverings of the spinal cord or brain, affects the blood supply or cerebrospinal fluid resulting in the death of neurons.
- Brain and spinal cord nervous system
- Brain regions
- Spinal nerves labeled
- Spine meninges
- Lateral pectoral nerve
- Inferior gluteal nerve
- Neuronal pools
- Nervous
- Neuron processes
- Division of central nervous system
- Central nervous system amusement park
- Building vocabulary activity: the central nervous system
- Arthropod nervous system