SPINAL CORD BY : LEMA GEMEDA(M.Tech) DECENBER 26/2017

Outline Overview of spinal cord Function of spinal cord Structures of the spinal cord Spinal cord injury Reflection of spinal cord conclusion

Overview of Spinal Cord  Information highway between brain and body  Extends through vertebral canal from foramen magnum to L1  Each pair of spinal nerves receives sensory information and issues motor signals to muscles and glands  Spinal cord is a component of the Central Nervous System and Peripheral Nervous System

Functions of the Spinal Cord  Conduction  bundles of fibers passing information up and down spinal cord  Locomotion  repetitive, coordinated actions of several muscle groups  central pattern generators are pools of neurons providing control of flexors and extensors (walking )  Reflexes  involuntary, stereotyped responses to stimuli (remove hand from hot stove)  involves brain, spinal cord and peripheral nerves

Structure of the Spinal Cord About 18 inches long Extends from the foramen magnum to the level of the 1st-2nd lumbar vertebrae Very well protected by the vertebral column, meninges, CSF, vertebral ligaments 31 pairs of spinal nerves

A cross-section of the spinal cord

Grey Matter in the Spinal Cord Pair of dorsal or posterior horns dorsal root of spinal nerve is totally sensory fibers Pair of ventral or anterior horns ventral root of spinal nerve is totally motor fibers

White Matter in the Spinal Cord  White column = bundles of myelinated axons that carry signals up and down to and from brainstem  3 pairs of columns or funiculi - dorsal, lateral, and anterior columns  Each column is filled with named tracts or fasciculi (fibers with a similar origin, destination and function)  functions ascending tracts - sensory toward brain descending tracts - motor from brain

Meninges of the Spinal Cord  A three layered covering of connective tissue  Dura mater ( is tough out layer)  tough collagenous membrane surrounded by epidural space filled with fat and blood vessels  Arachnoid mater  layer of simple squamous epithelium lining dura mater and loose mesh of fibers filled with CSF(creates subarachnoid space)  Pia mater  delicate membrane adherent to spinal cord  folium terminale and denticulate ligaments anchor the cord

Pia mater Arachnoid mater Dura mater Body of vertebra Body of vertebra Vertebral vein & artery Subarachnoid Subarachnoid space space Meninges of the Spinal Cord

Spinal cord injuries  The most common of spinal cord injury is a broken neck or back neck(causing damage to the bones of the spine that surround the spinal cord).  Total number of people with Spinal Cord Injury  Current estimates are 250, ,000 individuals living with Spinal Cord Injury or Spinal Dysfunction.  82% male and 18% female

Cont.  Highest per capita rate of injury occurs between ages  Average age at injury  Median age at injury - 26  Mode (most frequent) age at injury 19

Causes of Spinal Cord Injury Motor vehicle accidents (44%) Acts of violence (24%) falls (22%) sports (8%) (2/3 of sports injuries are from diving) other (2%)

What are reflexes?  Rapid, involuntary, automatic responses to stimuli There are basically 5 components to a reflex: Receptor  Its responds to a stimulus by producing an electrical signal called an action potential Afferent pathway  afferent means “towards”. The afferent pathway sends the action potential towards the integrating centre.

Integrating centre  the integrating centre is usually the central nervous system, and processes all action potentials it receives  It processes all this information, and then “decides” how the body should response Efferent pathway  the response is transmitted through the efferent pathway to the effector organ Effector organ  the effector organ carries out the desired response This organ is usually a muscle or gland in the body

conclusion  Spinal cord is the highway for connection and transfers information between brain and body  It’s well protected structures by the vertebral column, meninges, CSF, vertebral ligaments  It is a large hole in the base of the skull and is enclosed by the protective vertebral column  It have pair of spinal nerves which is receives sensory information and issues motor signals to muscles and glands  And it affected by injuries. Therefore, kept spinal cord health should have properly involves and protect from any damaging

Reference (of Anatomy and physiology sc)