somatosensory tract

Examples of somatosensory tract in the following topics:

• Sensory and Motor Tracts

  • The spinothalamic tract is a somatosensory tract and the corticospinal tract is a motor tract.
  • The spinothalamic tract is a sensory pathway originating in the spinal cord.
  • Somatosensory organization is divided into the dorsal column–medial lemniscus tract (the touch/proprioception/vibration sensory pathway) and the anterolateral system, or ALS (the pain/temperature sensory pathway).
  • The corticospinal tract is made up of two separate tracts in the spinal cord: the lateral corticospinal tract and the anterior corticospinal tract.
  • However, connections to the somatosensory cortex suggest that the pyramidal tracts are also responsible for modulating sensory information from the body.

• Somatic Sensory Pathways to the Cerebellum

  • It is part of the somatosensory system and runs in parallel with the dorsal spinocerebellar tract.
  • Both tracts involve two neurons.
  • The dorsal spinocerebellar tract (also called the posterior spinocerebellar tract, Flechsig's fasciculus, or Flechsig's tract) conveys inconscient proprioceptive information from the body to the cerebellum.
  • It is part of the somatosensory system and runs in parallel with the ventral spinocerebellar tract.
  • The anterior and posterior spinocerebellar tracts are the major somatosensory pathways communicating with the cerebellum.

• Somatic Sensory Pathways

  • The somatosensory pathway is composed of three neurons located in the dorsal root ganglion, the spinal cord, and the thalamus.
  • A somatosensory pathway will typically have three long neurons: primary, secondary, and tertiary.
  • In the spinal cord, the somatosensory system includes ascending pathways from the body to the brain .
  • Other ascending pathways, particularly those involved with control of posture, are projected to the cerebellum, including the ventral and dorsal spinocerebellar tracts.
  • The primary somatosensory area in the human cortex is located in the postcentral gyrus of the parietal lobe.

• Cutaneous Sensation

  • The somatosensory system is composed of the receptors and processing centers to produce the sensory modalities, such as touch and pain.
  • The somatosensory is the system of nerve cells that responds to changes to the external or internal state of the body, predominately through the sense of touch, but also by the senses of body position and movement.
  • Transmission of information from the receptors passes via sensory nerves through tracts in the spinal cord and into the brain.
  • Processing primarily occurs in the primary somatosensory area in the parietal lobe of the cerebral cortex.

• General Organization of the Somatosensory System

  • The somatosensory system is composed of the neurons that make sensing touch, temperature, and position in space possible.
  • The somatosensory system is distributed throughout all major parts of our body.
  • A somatosensory pathway will typically consist of three neurons: primary, secondary, and tertiary.
  • Somatosensory information involved with proprioception and posture is processed in the cerebellum.
  • The somatosensory system functions in the body’s periphery, spinal cord, and the brain.

• Thalamus

  • The thalamus is connected to the hippocampus via the mammillothalamic tract.
  • The ventral posterior nucleus is a key somatosensory relay, which sends touch and proprioceptive information to the primary somatosensory cortex.

• Cerebral Hemispheres and Lobes of the Brain

  • The visual cortex receives raw sensory information through sensors in the retina of the eyes, which is then conveyed through the optic tracts to the visual cortex.
  • The parietal lobe is comprised of the somatosensory cortex and part of the visual system.
  • The somatosensory cortex consists of a "map" of the body that processes sensory information from specific areas of the body.

• Mapping the Primary Somatosensory Area

  • Typically, the area of the body corresponds to a point on the primary somatosensory cortex (postcentral gyrus).
  • Areas such as the appendages, digits, and face can draw their sensory locations upon the somatosensory cortex.
  • Areas that are finely controlled, such as the digits, have larger portions of the somatosensory cortex, whereas areas that are coarsely controlled, such as the trunk, have smaller portions.
  • The idea of the cortical homunculus was created by Wilder Penfield and serves as a rough map of the receptive fields for regions of primary somatosensory cortex.
  • The postcentral gyrus is located in the parietal lobe of the human cortex and is the primary somatosensory region of the human brain.

• Organization of Motor Neuron Pathways

  • These are the upper motor neurons of the corticospinal tract.
  • They then descend as the lateral corticospinal tract.
  • These are the rubrospinal tract, the vestibulospinal tract, the tectospinal tract, and the reticulospinal tract.
  • The function of lower motor neurons can be divided into two different groups: the lateral corticospinal tract and the anterior corticalspinal tract.
  • Included in the diagram are the following motor pathways: corticospinal tracts (pyramidal tract), and extrapyramidal tracts (tectospinal tract not delineated).

• Somatosensation: Pressure, Temperature, and Pain

  • The somatosensory system allows the human body to perceive the physical sensations of pressure, temperature, and pain.
  • The human sense of touch is known as the somatic or somatosensory system.
  • The somatosensory system uses specialized receptor cells in the skin and body to detect changes in the environment.
  • Sensory cell function in the somatosensory system is determined by location.
  • Summarize the stages of the somatosensory system in which physical stimuli are detected and processed