Anatomy - Overview

Anatomically, a distinction is made ^[160] between the central nervous system (CNS) ^{[95, 225]} (or neuraxis) and the peripheral nervous system (PNS) ^[125].

The central nervous system:

The brain :

The brain ^[157] is located in the skull and contains: the two cerebral hemispheres ^[224] (which hold the cerebral cortex), the cerebral ventricles ^[37] where cerebrospinal fluid (CSF) circulates ^[95] , the basal ganglia ^[4] , the thalamus ^[75] , the hypothalamus ^{[4, 50]} , the cerebellum ^{[4, 54]} , and the brainstem ^{[32, 38]}.

The spinal cord :

The spinal cord ^{[38, 160]} is the extension of the brainstem outside the skull; it is protected within the spinal canal ^[43] in the center of the spine. Anterior and posterior roots emerge from it to form the spinal nerves ^{[38, 125]}.

The peripheral nervous system :

The PNS consists of various nerves and nerve ganglia located outside the neuraxis. It essentially comprises 11 pairs of cranial nerves ^[64] emerging at the level of the skull (the optic nerve is considered part of the CNS ^[41] ), and 31 pairs of spinal nerves ^{[6, 7, 8, 9, 10, 11, 12, 13]} which emerge from the intervertebral foramina located in the spine.