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Preganglionic neurons of the parasympathetic nervous system originate in the nuclei of the craniosacral region (cranial nerves and in the spinal cord segments of S2-S4). Those of the sympathetic nervous system originate in the thoracolumbar region (spinal cord segments of T1-L3).

The spinal cord consists of 31 segments/pairs. The cervical contains 8, thoracic contains 12, lumbar contains 5, sacral contains 5, and coccygeal contains 1.

The anterior roots are where outgoing instructions leave the spinal cord. The posterior roots are where incoming sensory information enter the spinal cord. Grey matter contains the cell bodies of neurons, while the white matter contains the axons of nerves.

The dorsal column track is an ascending system conveying somatic sensory information to the brain. The dorsal column tracts ascend in the fasiculus gracilis and fasiculus cuneatus. They synapse in the medulla so that signals from the left side of the body are transmitted to the right side, and vice versa.

The correct order of CSF flow is as follows:

Lateral ventricals, foramen of Monro, third ventricle, cerebrel aqueduct of Sylvius, fourth ventricle, foramen of Magendie (medial) and foramen of Lushka (lateral), central canal and subarachnoid space, superior sagittal sinus

A delta fibers are responsible for signaling "new" sharp pain. The body sends this sensory information to Rexed Laminae I and II. *I and II are called the substantia gelatinosa.

The somatic nervous system is the voluntary nervous system and part of the peripheral nervous system. It is associated with voluntary skeletal muscle control over body movements and is associated with involuntary reflex arcs. The somatic nervous system consists of afferent (relay sensations to central nervous system) and efferent (relays commands from central nervous system to the body) nerves stimulating muscle contractions. Thus muscle contraction ceases when neural stimulation ceases.

The conus medullaris is the cone-shaped ending of the spinal cord and it is found at the level of the second lumbar vertebrae (L2). It is located superior to the cauda equina.

Fasciculus gracilus is one of the component to the dorsal columns. Remember that anything that is dorsal of the spinal cord is associated with sensation. In addition, the dorsal columns control touch while the spinothalamic tract carries pain and temperature information.

The cauda equina is the bottom of the conus medullaris. It extends from the conus medullaris and terminates at C0 vertebrae.