Thoracic part of spinal cord

The thoracic part of spinal cord lies between the cervical part above and the lumbar, sacral, and coccygeal spinal regions below.

Like all other regions, the thoracic part of spinal cord consists of a central butterfly shaped gray matter with anterior (motor) and posterior (sensory) gray columns or horns. Unlike the cervical and lumbosacral regions, the thoracic part of spinal cord does not contain the additional gray matter to innervate the limb musculature (hence, smaller anterior and posterior horns).

In the anterior gray horn of the thoracic spinal cord, only the medial cell group is prominently visible, which innervate the trunk musculature, including the intercostal muscles. Unlike the cervical region, there is no distinct central cell group, nor is there a prominent lateral cell group, as limb innervation is not required at the thoracic level.

The posterior gray horn contains four distinct groups of nuclei. Two of these extend throughout the length of the spinal cord and include substantia gelatinosa group (receiving pain and temperature sensations) and nucleus proprius group (receiving sensory information of proprioception, vibration, and 2-point discrimination). The remaining two groups of nuclei do not extend throughout the spinal cord length and include the dorsal nucleus of Clarke (receiving subconscious proprioceptive information from cerebellum) and visceral afferent nucleus (linked with autonomic innervation).

A prominent lateral gray horn can be seen in the thoracic part of spinal cord (extending from T1 to L2 spinal segments). It contains preganglionic nerve cell bodies for the sympathetic neuronal outflow.

The gray matter on both sides–right and left–are connected by a gray commissure that surrounds a central canal.

The gray matter is surrounded by bundles of white matter fibers or tracts (or funiculi). These include the anterior, posterior and lateral white columns.

The anterior white column (a.k.a. anterior funiculus) contains sensory and motor tracts, such as, anterior spinothalamic, anterior corticospinal, tectospinal, vestibulospinal and pontine reticulospinal tracts.

The lateral white column (a.k.a. lateral funiculus) also contains a mixture of sensory and motor tracts, including anterior and posterior spinocerebellar, lateral spinothalamic, lateral corticospinal, lateral reticulospinal and rubrospinal tracts.

In the posterior or dorsal white column of thoracic part of spinal cord, the fasciculus gracilis can be seen throughout the length of the spinal cord, while the fasciculus cuneatus can be spotted only as far below as the T6 spinal segment. It is absent in the lower thoracic spinal cord.