Biology 322 Human Anatomy I Spinal Cord

Human Central Nervous System Recall: Starts as a fold which forms 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.

Coronal Section of Brain Cross Section of Spinal Cord

Embryology of nervous system

Spinal cord surrounded by 3 layers of connective tissue:

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

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

Embryology of nervous system

Recall: In brain and spinal cord Gray Matter: White Matter:

Embryology of nervous system 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 skeletal myocytes (somatic motor innervation) 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 White Matter of Spinal Cord Within each column, axons with same functions organized into bundles called

Individual tracts of the spinal cord are described in your Marieb / Mallatt / Wilhelm text 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 decussates 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

Each nerve connects with spinal cord through two roots:

Embryology of nervous system Spinal nerves named according to which vertebrae they pass between: Levels of the spinal cord named

Embryology of nervous system 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.