Spinal cord Domina Petric, MD

White and grey matter of the spinal cord https://media1.britannica.com/eb- media/75/2975-004-7891D6AA.jpg DORSAL COLUMN VENTRAL COLUMN LATERAL COLUMN White matter

White matter Dorsal column is sensory zone. Lateral column is mixture of sensory axons and motor pathways. Ventral column is mixture of sensory and motor pathways. Pain pathways are in the ventral column.

Rexed laminae VirtualMedStudent.com DORSAL HORN: laminae 1-6, sensory neurons. VENTRAL HORN: laminae 7-9, motor neurons.

Substantia gelatinosa is Rexed lamina number 2 It is located in the apex of the horn. Extends throughout the length of spinal cord. These dorsal root fibres are responsible for sensations of pain, temperature and touch. http://www.neuroscientificallychallenged.com/glossary/substantia-gelatinosa

Nucleus proprius is Rexed laminae 3 and 4 It is located anterior to substantia gelatinosa. Extends throughout the length of spinal cord. These dorsal root fibres are responsible for senses of position and movement (proprioception).

Cell organisation Dorsal horn is organised in long strips of cells (laminar organisation). Ventral horn is organised more into columns (rod-shaped organisation).

Longitudinal organisation of spinal cord In the cervical and lumbosacral enlargement of the spinal cord there is a greater amount of grey matter in ventral horn to provide motor neurons for both hands (cervical enlargement) and legs (lumbosacral enlargement). In the thoracal region amount of grey matter in the ventral horn is reduced. White matter amount is decresing in the direction from cervical to sacral regions because: the axons that are comming down from the brainstem, cerebral cortex, lateral and anterior column of the white matter are terminating along the way ascending pathways (pain, temperature, mechanosensation) are collecting at various levels up through the spinal cord providing more axons in the cervical region in comparison to the sacral region

Lateral horn It is a protrusion between the ventral and dorsal horn in the thoracal region of spinal cord. In the lateral horn there are preganglionic sympathetic neurons providing outflow from the nervous system to the viscera. In the sacral portion of the spinal cord there is also a collection of preganglionic visceral motor neurons which are parasympathetic and do not form a lateral horn.

Dorsal column In the cervical portion of spinal cord there is a distinction between the lateral and medial component. Medial component is found in the lower portions of the spinal cord.

Dorsal column Gracile tract (the medial component) starts to build up in the spinal cord white matter from lower extremities up to cervical segment. Cuneate tract (the lateral component) is present from the upper portion of the thoracic segment up to the cervical segment. Both tracts are ascending sensory pathways.

Antero-lateral system Conveys pain and temperature signals from the body up into the brainstem and forebrain.

Motor descending tracts Lateral corticospinal tract is the major motor control pathway. Descends with a progressive termination of the axons from cervical to sacral spinal cord. Lateral corticospinal tract controls our voluntary movements. Ventral corticospinal tract is the smaller motor control pathway. In the ventral corticospinal tract axons project along the length of the spinal cord.

Literature https://www.coursera.org/learn/medical- neuroscience/lecture: Leonard E. White, PhD, Duke university www.britanica.com VirtualMedStudent.com www.neuroscientificallychallenged.com Wikipedia.org