Somatic Efferent Nuclei - Cranial Nerve Nuclei

Somatic Efferent Nuclei

        The somatic efferent column consists of the following nuclei that supply striated (skeletal) muscle of somatic origin.

1.              Theoculomotor nucleusis situated in the upper part of the midbrain at the level of thesuperior colliculus (Figs. 10.1, 10.2 and 10.3F). The nuclei of the two sides form a single complex that lies in the central grey matter, ventral to the aqueduct.

2.              Thetrochlear nucleusis situated in the lower part of the midbrain at the level of the inferiorcolliculus (Figs. 10.1, 10.2 and 10.3E). The nucleus lies ventral to the aqueduct in the central grey matter.

3.              Theabducent nucleusis situated in the lower part of the pons. It lies in the grey matter liningthe floor of the fourth ventricle near the midline (Figs. 10.1, 10.2 and 10.3C)

4.              Thehypoglossal nucleuslies in the medulla. It is an elongated column extending into boththe open and closed parts of the medulla. Its upper part lies deep to the hypoglossal triangle in the floor of the fourth ventricle. When traced downwards it lies next to the midline in the central grey matter ventral to the central canal (Figs. 10.1, 10.2 and 10.3 A,B).