Anatomy and Cell Biology 3319 Lecture : Anatomy Notes
Document Summary
Elements of ascending sensory systems: afferent neuronal signals from skin and deeper structures are segregated in the spinal cord (ex. subthalamic tract vs. dorsal funiculi). Axons of pain and temperature cross the midline in the spinal cord. Axons of discriminative touch and conscious proprioception ascend ipsilaterally to the medulla. After synapsing in the medulla, the axons cross the midline. The ventral posterolateral nuclei (vpl) in the thalamus is the primary site of termination for somatosensory information to the postcentral gyrus. It acts as a relay station for the sensory info ascending to the primary sensory areas of the cerebral cortex. The dorsal column pathway or medial lemniscus sensory system (located at dorsal funiculus) carries information on discriminative touch, pressure, vibratory sensation, and conscious joint position. These are senses that can be localized very precisely on the body surface. Information from the lower limbs enters the lumbar spinal cord at the dorsal horn then ascends via the fasiculus gracilis (medial).