spinal cord and nerve root

Cervical enlargement

spinal cord region corresponding to upper extremity spinal nerves

Lumbar (lumbosacral) enlargement

spinal cord region corresponding to lower extremity spinal nerves

Conus medullaris

pointed tip of the spinal cord, at vertebral level L2

Cauda equina

collection of lumbosacral and coccygeal spinal nerves located within the subarachnoid space inferior to the conus medullaris

Posterior median sulcus

shallow indentation along posterior midline of spinal cord

Anterior median fissure

deep indentation along anterior midline of spinal cord

Central Canal of spinal cord

contains small amount of CSF

Posterior gray horn

location of somatic and visceral sensory nuclei within all spinal cord segments

Lateral gray horn

origin of sympathetic visceral motor neurons of autonomic nervous system (ANS); located in T1-L2 spinal cord segments only

Anterior gray horn

location of somatic (lower) motor neurons within all spinal cord segments

Gray commissure

gray matter between left and right sides of spinal cord, surrounding central canal

Posterior white column

location of fasciculus gracilis (gracile fasciculus) & fasciculus cuneatus (cuneate fasciculus) for transmitting proprioception (conscious awareness), fine touch, pressure and vibration

Anterior white column

location of anterior spinothalamic tract (for crude touch & pressure), anterior corticospinal tract (for conscious motor commands), and medial pathway tracts (for subconscious and reflexive motor control)

Lateral white column

location of spinocerebellar tracts (for “unconscious” proprioception), lateral spinothalamic tract (for pain and temperature sensations), lateral corticospinal tract (for conscious motor commands), lateral pathway tracts (for subconscious and reflexive motor control)

Dorsal (posterior) root of spinal nerve

contains axons of somatic sensory neurons

Dorsal (posterior) root ganglion

contains the cell bodies of somatic sensory neurons

Ventral (anterior) root of spinal nerve

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Dorsal ramus

axons that receive sensory innervation from the back, and transmits motor innervation to deep back muscles

Ventral ramus

axons that receive sensory innervation from, and transmits motor innervation to anterior and lateral body wall, and extremities

Rami communicantes

found at T1- L2 spinal nerves only, contains axons of sympathetic visceral motor fibers

Sympathetic chain (sympathetic trunk)

contains axons of sympathetic pre-ganglionic neurons

Sympathetic chain ganglia (aka paravertebral ganglia)

contain cell bodies of sympathetic post- ganglionic neurons