Vestibular pathway

From WikiCNS
Jump to: navigation, search
  1. Vestibular nuclei are located in the dorsal pons and medulla and receive input from the vestibular labyrinth
    1. four vestibular nuclei
      1. lateral vestibular nuclei (Deiters’ nucleus) which gives rise to the lateral vestibulospinal tract which projects ipsilaterally to all levels of the spinal cord (medial, superior and inferior vestibular nuclei give rise to the medial vestibulospinal tract which only descends to the cervical segments – medial vestibulospinal tract is the caudal extension of the medial longitudinal fasciculus (MLF) that controls eye movements)(See Figure 6a)
        1. Deiter’s nucleus is normally inhibited from above by the cerebellum; a lesion above the nucleus releases inhibitions and causes decorticate posturing while lesions below the nucleus result in decerebrate posturing
        2. Lateral vestibulospinal tract runs in the lateral/anterior portion of the spinal cord just lateral to the anterior corticospinal tract; medial vestibulospinal tract runs very medial just anterior to the anterior commissure
        3. Cells of the superior vestibular ganglion (which innervate the utricular macula) project to the lateral vestibular nuclei
      2. medial vestibular nuclei – largest of the nuclei
        1. sends crossed fibers to both the extraocular nerve nuclei and to the cerebellum (Remember: the medial vestibular nuclei is closest to the midline and therefore can send crossed fibers most readily)
        2. sends most of the fibers to the medial vestibulospinal tract (bilateral)
        3. sends many fibers to the descending MLF (a.k.a. medial vestibulospinal tract)
          1. function of MLF is to coordinate changes in position and balance of the head
          2. descends to cervical spine in the exact center of the medulla and contains fibers arising from the intersitital nucleus of Cajal, medial vestibular nucleus, pontine reticular formation, and superior colliculus
          3. MLF is found in the pons and nucleus of CN 6 (NOTE: MLF ends in the pons and not in the midbrain)
          4. blood supply of the MLF are paramedian penetrating branches of the basilar artery
      3. superior vestibular nuclei
        1. sends uncrossed fibers to CN 3 and 4 via the MLF
      4. inferior vestibular nuclei
        1. integrates input from the vestibular system and cerebellum (fastigial nucleus)
        2. cells of the inferior vestibular ganglion (which innervate the posterior part of the saccular macule) project to the inferior vestibular nucleus; Remember: inferior vestibular ganglion goes to the inferior vestibular nucleus while superior vestiublar ganglion projects to the lateral vestibular nucleus
    2. primary vestibular cortex (Brodmann areas 2 and 3) receives input from the VPL and VL nuclei of the thalamus
Personal tools