5.1 The spinal cord
5.2 Brainstem
5.3 Midbrain
5.4 Cerebellum functions
5.5 Limbic system
5.6 Basal ganglia
5.7 Cerebral cortex
5.8 Blood-brain barrier
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5.1. The spinal cord
Structural characteristics of the spinal cord The spinal cord is located in the spinal canal from the first cervical vertebra (CI) to between the first and second lumbar vertebra (LI-LII), inclusively. The spinal cord does not extend below LII in the spinal canal, only the lower lumbar and sacral nerves are located there. This zone is used for spinal punctures, spinal fluid analysis, and spinal anesthesia. The spinal cord consists of 31-33 segments: eight cervical (CI-CVIII), twelve thoracic (ThI-ThXII), five lumbar (LI-LV), and one to three coccygeal (CoI-CoIII) vertebrae. A metamere innervates each segment of the spinal cord and consists of an area of skin (a dermatome) and skeletal muscle. The spinal cord consists of gray and white matter. The gray matter is made up of neurons, while the white matter is made of nerve fibers (neuron axons). Gray matter is located in the middle of the spinal cord, anterior and posterior horns are present throughout its length, in the CVIII-LIII
region there are lateral horns. The white matter of the spinal cord forms three cord pairs: anterior, lateral, and posterior. There are 31 pairs of spinal nerves. Afferent (sensitive) impulses enter the spinal cord through the nerve fibers that form posterior roots. Afferent neuron bodies are located in the spinal ganglia. Efferent impulses to effector organs depart from the spinal cord along its anterior roots formed by axons of the motor somatic and autonomic neurons of the spinal cord. According to the Bell-Magendie law, the anterior roots fulfil motor functions, while posterior roots fulfil sensitive functions.