corticospinal tract

Examples of corticospinal 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 corticospinal tract conducts impulses from the brain to the spinal cord.
  • The corticospinal tract is made up of two separate tracts in the spinal cord: the lateral corticospinal tract and the anterior corticospinal tract.
  • The corticospinal tract also contains the Betz cell (the largest pyramidal cells) that are not found in any other region of the body.
  • The primary purpose of the corticospinal tract is to maintain voluntary motor control of the body and limbs.

• Organization of Motor Neuron Pathways

  • There are upper and lower motor neurons in the corticospinal tract.
  • These are the upper motor neurons of the corticospinal tract.
  • They then descend as the lateral corticospinal tract.
  • The remaining 10% of axons descend on the ipsilateral side as the ventral corticospinal tract.
  • Included in the diagram are the following motor pathways: corticospinal tracts (pyramidal tract), and extrapyramidal tracts (tectospinal tract not delineated).

• Axon Bundles

  • A bundle of axons is called a nerve in the peripheral nervous system and a tract in the central nervous system.
  • Bundles of neurons processes are called tracts in the CNS and nerves in the PNS.  
  • Some examples of CNS tracts are the large pyramidal (corticospinal) tracts descending from the motor cortex to the medulla while continuing into the spinal cord.

• Functions of the Brain Stem

  • This includes the corticospinal tract (motor), the posterior column-medial lemniscus pathway (fine touch, vibration sensation, and proprioception) and the spinothalamic tract (pain, temperature, itch, and crude touch).
  • It contains tracts that carry signals from the cerebrum to the medulla and to the cerebellum.
  • It also has tracts that carry sensory signals to the thalamus.
  • The facial sensations have similar pathways and also travel in the spinothalamic tract and the medial lemniscus.
  • Descending tracts are upper motor neurons destined to synapse on lower motor neurons in the ventral horn and intermediate horn of the spinal cord.

• Medulla Oblongata

  • A stroke can injure the pyramidal tract, medial lemniscus, and the hypoglossal nucleus.
  • This elevation is caused by the corticospinal tract.
  • The posterior part of the medulla between the posterior median and posterolateral sulci contains tracts that enter it from the posterior funiculus of the spinal cord.
  • The gray matter of this nucleus is covered by a layer of nerve fibers that form the spinal tract of the trigeminal nerve.

• Amyotrophic Lateral Sclerosis

  • MRI (parasagittal FLAIR) demonstrates increased T2 signal within the posterior part of the internal capsule and can be tracked to the subcortical white matter of the motor cortex, outlining the corticospinal tract), consistent with the clinical diagnosis of ALS.

• Somatic Sensory Pathways to the Cerebellum

  • Both tracts involve two neurons.
  • There it makes a synapse with the dendrites of two neurons that send their axons bilaterally to the ventral border of the lateral funiculi (transmit the contralateral corticospinal and spinothalamic tracts).
  • This is one of the few afferent tracts through the superior cerebellar peduncle.
  • 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.
  • This tract involves two neurons and ends up on the same side of the body.

• Anatomy of the Digestive System

  • The upper gastrointestinal tract consists of the esophagus, stomach, and duodenum.
  • The lower gastrointestinal tract includes most of the small intestine and all of the large intestine .
  • It contains the plicae circulares and villi to increase the surface area of that part of the GI Tract.
  • The ligament of Treitz is sometimes used to divide the upper and lower GI tracts.
  • This image shows the position of the small intestine in the gastrointestinal tract.

• Mucosa

  • The mucosa is the innermost layer of the gastrointestinal (GI) tract, composed of simple epithelium cells.
  • It is the absorptive and secretory layer of the GI tract.
  • The GI tract is composed of four layers.
  • The mucosae (singular: mucosa) are highly specialized in each organ of the gastrointestinal tract, in order to deal with the different digestive tract conditions.
  • Describe the structure and function of the mucosa of the GI tract

• Muscularis

  • The muscularis is responsible for segmental contractions and peristaltic movement in the GI tract.
  • The GI tract is composed of four layers or also know as tunics.
  • These muscles cause food to move and churn with digestive enzymes down the GI tract.
  • The thickness of muscularis externa varies in each part of the tract.
  • Alone among the GI tract, the stomach has a third layer of muscularis externa.