Search results
Results From The WOW.Com Content Network
The lateral rectus is the only muscle supplied by the abducens nerve (CN VI). The neuron cell bodies are located in the abducens nucleus in the pons.These neurons project axons as the abducens nerve which exit from the pontomedullary junction of the brainstem, travels through the cavernous sinus and enter the orbit through the superior orbital fissure.
The last muscle is the inferior oblique, which originates at the lower front of the nasal orbital wall, passes inferiorly over the inferior rectus muscle on its path laterally and posteriorly, and inserts under the lateral rectus muscle on the lateral, posterior part of the globe. Thus, the inferior oblique pulls the eye upward and laterally.
The PPRF mediates horizontal conjugate gaze (i.e. simultaneous horizontal movement of both eyes) by projecting to both: [6] [7] the ipsilateral abducens (CN VI) nucleus (which controls the ipsilateral lateral rectus muscle),
The abducens nucleus contains two types of cells: motor neurons that control the lateral rectus muscle on the same side, and interneurons that cross the midline and connect to the contralateral oculomotor nucleus (which controls the medial rectus muscle of the opposite eye). In normal vision, lateral movement of one eye (lateral rectus muscle ...
Diplopia is also increased on looking to the affected side and is partly caused by overaction of the medial rectus on the unaffected side as it tries to provide the extra innervation to the affected lateral rectus. These two muscles are synergists or "yoke muscles" as both attempt to move the eye over to the left or right. The condition is ...
Three reactions occur simultaneously; the eyes adduct, the ciliary muscles contract, and the pupils become smaller. [5] This action involves the contraction of the medial rectus muscles of the two eyes and relaxation of the lateral rectus muscles. The medial rectus attaches to the medial aspect of the eye and its contraction adducts the eye.
The term gaze is frequently used in physiology to describe coordinated motion of the eyes and neck. The lateral gaze is controlled by the paramedian pontine reticular formation (PPRF). [1] The vertical gaze is controlled by the rostral interstitial nucleus of medial longitudinal fasciculus and the interstitial nucleus of Cajal. [2]
From this nuclei excitatory fibres cross to the left abducens nucleus. There they project and stimulate the lateral rectus of the left eye via the abducens nerve. In addition, by the medial longitudinal fasciculus and oculomotor nuclei, they activate the medial rectus muscles on the right eye. As a result, both eyes will turn counter-clockwise.