Human Physiology, 14th edition (2016)

234 Chapter 8

Figure 8.24 Ascending tracts carrying sensory information. This information is delivered by third-order neurons to the
cerebral cortex. ( a ) Medial lemniscal tract; ( b ) lateral spinothalamic tract.

Axons of

third-order

neurons

Cerebral

cortex

Medial lemniscal tract

(axons of second-order

neurons)

Fasciculus cuneatus

(axons of first-order

sensory neurons)

Joint stretch receptor

(proprioceptor)

Spinal cord

Fasciculus gracilis

(axons of first-order

sensory neurons)

Medulla oblongata

Touch receptor

Temperature

receptor

Pain receptor

Axons of first-order

neurons (not part of

spinothalamic tract)

Lateral spinothalamic tract

(axons of second-order neurons)

Thalamus

Postcentral gyrus

(a) (b)

Table 8.5 | Descending Motor Tracts to Spinal Interneurons and Motor Neurons

Tract Category Origin Crossed/Uncrossed

Lateral corticospinal Pyramidal Cerebral cortex Crossed

Anterior corticospinal Pyramidal Cerebral cortex Uncrossed

Rubrospinal Extrapyramidal Red nucleus (midbrain) Crossed

Tectospinal Extrapyramidal Superior colliculus (midbrain) Crossed

Vestibulospinal Extrapyramidal Vestibular nuclei (medulla oblongata) Uncrossed

Reticulospinal Extrapyramidal Reticular formation (medulla and pons) Crossed