Human Biology (Year 12)
What is the spinal cord?
The spinal cord is a long, thin, tubular structure which is made up of nervous tissue, extending from the medulla oblongata in the brain stem to the lumbar region of the vertebral column. It encloses the central canal of the spinal cord, which contains cerebrospinal fluid. It is a cylindrical structure that exceeds from the foramen magnum to the second lumbar spine. The outer meningeal layer contains fat and connective tissue for protection. The function of the spinal cord is to carry sensory impulses to the brain and motor impulses away from the brain. Another function is the integrate certain reflexes. The spinal cord consists of both ascending and descending tracts.
Ascending tracts consist of sensory axons that carry impulses towards the brain
Descending tracts consist of motor axons that conduct impulses away from the brain
What is grey/white matter? Grey matter is the part of the brain and spinal cord that is made up of nerve cell bodies and unmyelinated fibres. It is located in the spinal cord on the inside (the H band). In the brain, grey matter is on the surface. White matter is the part of the brain and spinal cord which are made up of myelinated fibres. Myelin is white in colour, so the tissue appears white. It is located in the spinal cord on the outside, and in the brain, it is towards the inside.
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