Biology 211 Anatomy & Physiology I Spinal Cord

Human Central Nervous System Starts as a hollow tube in the embryo; Remains hollow & fluid-filled throughout life; These spaces form the ventricles of the brain and the central canal of the spinal cord. Cranial end of this hollow tube enlarges & folds to form brain and its various parts Caudal end of this hollow tube does not enlarge or fold; Develops into spinal cord

Embryology of nervous system

Coronal Section of Brain Cross Section of Spinal Cord

Embryology of nervous system

Spinal cord surrounded by 3 layers of connective tissue:

Space (Vertebrae) Mater

The spinal cord is protected in three ways: 1) 2) 3) Floats in

Cerebrospinal fluid produced within ventricles by Exits from fourth ventricle through three openings (apertures or foramina) into the subarachnoid space. Two Surrounds brain & spinal cord. Reabsorbed into blood through arachnoid villi on surface of brain

Embryology of nervous system

Recall: In brain and spinal cord Nervous tissue of the CNS consisting of neuron cell bodies, their supporting glia, and unmyelinated axons & dendrites. Nervous tissue of the CNS consisting of myelinated axons & dendrites and their supporting glia

Gray Matter of Spinal Cord Cell bodies of neurons which receive afferent information from spinal nerves and send it toward the brain Cell bodies of neurons which receive efferent information from the brain and send it to smooth myocytes, cardiac myocytes, and glands (autonomic motor innervation) Embryology of nervous system Cell bodies of neurons which receive efferent information from the brain and send it to skeletal myocytes (somatic motor innervation)

White Matter of Spinal Cord Myelinated axons carrying information between brain and gray matter of spinal cord (both directions). Embryology of nervous system Within each column, axons with same functions organized into bundles called

Individual tracts of the spinal cord are described on pages 486 to 490 of your Saladin text (4th ed). You should be able to describe, in moderate detail, at least one ascending tract and one descending tract: Where it begins Where it ends If it deccusates Where it is located in the spinal cord What type of information it carries What would happen if it were damaged

Spinal cord gives rise to spinal nerves. A pair of spinal nerves (one on each side) exits between each pair of vertebrae from the atlas (cervical 1) to the first vertebra of the coccyx

Each nerve connects with spinal cord through two roots: Carries afferent information into dorsal horn of gray matter Carries efferent information away from ventral horn of gray matter

Spinal nerves named according to which vertebrae they pass between: cervical nerves thoracic nerves lumbar nerves sacral nerves coccygial nerve Levels of the spinal cord named according to which spinal nerve carries information in/out of it. Embryology of nervous system

Spinal nerves named according to which vertebrae they pass between: cervical nerves thoracic nerves lumbar nerves sacral nerves coccygial nerve Levels of the spinal cord named according to which spinal nerve carries information in/out of it. Thus: Spinal cord level "cervical 5" is defined as the region where spinal nerve "cervical 5" connects Embryology of nervous system

Next: Let's follow the spinal nerves distally as they form the peripheral nervous system. Embryology of nervous system