1. White matter is found on the outside or surface of the cord. It connects the cord and the brain and is made up of nerve fibres. White matter contains motor fibres which run down from the motor centre of the brain, the cerebrum and the cerebellum to the motor cells of the cord Sensory fibres also run up the cord from the sensory cells of the cord to the sensory centre of the brain.
2. ANTERIOR HORNS – The anterior horns of the spinal cord is the front grey matter section of the spinal cord. It contains motor neurons that affect the axial muscles. The cell bodies of the alpha motor neurons are located here. A motor impulse from the motor centre in the brain is carried down to the motor cell in the spinal cord by an efferent fibre. POSTERIOR HORNS – The posterior horns of the spinal cord is the rear grey matter section of the spinal cord. It receives several types of sensory information from the body including vibration and touch.
3. Two main functions of the spinal cord
a) The spinal cord acts as a coordinating centre responsible for reflexes for example the withdrawal reflex. b) It connects a large portion of the nervous system to the brain. Nerve impulses reaching the spinal cord through sensory neurons are transmitted up to the brain.
4. Two types of peripheral nerves
a) CRANIAL NERVES – These are nerves that emerge directly from the brain. These supply the organs of the head and neck. They include nerves which control smell, taste, sight and hearing and also include the vagus nerve. The vagus nerve helps regulate the heart beat, controls muscle movement, keeps a person breathing and also transmits a variety of chemicals through the body. b) SPINAL NERVES – These nerves supply the muscles of the limbs and trunk with movement. There are 31 pairs of spinal nerves which are in groups; cervical 8, thoracic 12, lumbar 5, sacral 5 and coccygeal 1. These are mixed nerves so contain both sensory and...
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