Which of the following is the nucleus for upwards gaze?
Correct Answer: Nucleus of Cajal
Description: (d) Nucleus of CajalRef: Conjugate Gaze Palsies - Neurologic Disorders." Merck Manuals Professional, Ed., 2015 and Merck Sharp & Dohme Corp, I Mar. 2014. Web. 8 Oct. 2015.* The three key structures in the control of the vertical gaze include the rostral interstitial nucleus ofthe medial longitudinal fasciculus (riMLF), the interstitial nucleus of Cajal (INC), and the posterior commissure (PC).* The riMLF is located in the midbrain and helps with vertical saccades. It normally has bilateral effects on the elevator muscles & unilateral effects on depressor muscles.* Thus, lesions to riMLF will have more effect on downward than up saccades.* The INC is located in the midbrain and helps coordinate all other vertical eye movements except saccades.* Unilateral lesions are selective to impairing gaze-holding and skew deviation, and bilateral lesions cause reduced range in all vertical eye movements except saccades.* The PC is located on the dorsal aspect of the superior end of cerebral aqueduct and is involved with all vertical eye movements, especially upward eye movement.Option 1i.e.,Paramedian Pontine Reticular Formation is responsible for lateral conjugate gaze.Lateral conjugate gaze requires coordination of adduction (medial rectus muscle, CNIII) in one eye and abduction (lateral rectus muscle, CNVI) in the other eye.Option 2i.e.,Nucleus Raphe Magnus are considered in the medial portion of the reticular formation & are the medial part of the brain stem.Neurons in these nuclei are serotonergic & they regulate the release of encephalins & have role in pain transmission.Option 3i.e.,Cuneiform nucleus hasa role in maintaining skeletal muscles tone.Hence answer is d.
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