. Cunningham's Text-book of anatomy. Anatomy. HYPOGLOSSAL NERVE. 793 the lateral aspect of the spinal medulla, between the anterior and posterior roots of the spinal nerves, its origin extending from the level of the accessory portion as low as the origin of the sixth cervical nerve (for the deep origin, see p. 596). Successively joining together, the fila radicularia (rootlets) form a trunk which ascends in the subdural space of the spinal medulla, posterior to the ligamentum denticulatum, to the foramen magnum. There the two portions unite into a single trunk, which leaves the cranial cavity
. Cunningham's Text-book of anatomy. Anatomy. HYPOGLOSSAL NERVE. 793 the lateral aspect of the spinal medulla, between the anterior and posterior roots of the spinal nerves, its origin extending from the level of the accessory portion as low as the origin of the sixth cervical nerve (for the deep origin, see p. 596). Successively joining together, the fila radicularia (rootlets) form a trunk which ascends in the subdural space of the spinal medulla, posterior to the ligamentum denticulatum, to the foramen magnum. There the two portions unite into a single trunk, which leaves the cranial cavity through the jugular foramen in the same compartment of dura mater as the vagus nerve (Fig. 647, p. 771). Ramus Internus.—In the jugular foramen the accessory portion of the nerve or internal ramus (after furnishing a small branch to the jugular ganglion of the vagus) applies itself to the ganglion nodosum, and in part joins the ganglion, in part the trunk of the nerve beyond the ganglion. By means of these connexions the vagus receives viscero-motor and cardio- inhibitory fibres. Ramus —The spinal portion of the nerve, or external ramus, extends into the neck, where at first it lies along with other nerves, in the interval between the internal carotid artery and the internal jugular vein. Passing obliquely downwards and laterally over the vein, it de- scends close beneath the sterno-mastoid muscle, which it supplies as it pierces it on its deep surface. After crossing the posterior triangle the nerve ends by supplying the trapezius muscle on its deep surface. This portion of the nerve communicates in three situations with nerves from the cervical plexus—(1) in or beneath the sterno-mastoid, with the branch for the muscle derived from the second cervical nerve; (2) in the posterior triangle, with branches from the third and fourth cervical nerves; (3) beneath the trapezius, with the branches for the mUSCle , Accessory nerve ; , First four cervical ner
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1914
