Of these there are eight pairs. The first cervical nerve leaves the spinal canal through the antero-internal foramen of the atlas. The superior branches accompany the occipital artery and vein to between the rectus capitis posticus and the obliquus capitis superior. At its origin it gives branches to the small muscles about the poll. The inferior branch passes downwards and is distributed to the thyrodiyoid, subscapulo-hyoid, sterno-thyroid, and sternodiyoid muscles. It sends a small branch to the hypoglossal nerve, and another to the superior cervical ganglion of the sympathetic. It also supplies the skin of the ear on the inner and lower part.
The second cervical nerve leaves the spinal canal through an opening at the anterior part of the dentata, under cover of the obliquus capitis inferior. The inferior branches of this nerve are distributed to the mastoido-humeralis and skin of the ears; the superior branches go to the superior and inferior oblique muscles of the neck. The sixth and seventh, and sometimes the fifth, together with a branch from the brachial plexus, form the diaphragmatic nerve.
From the second to the sixth they communicate with each other, and then divide into three sets of branches; one set joins the vertebral nerve, and goes to the sympathetic or middle cervical ganglion, another is distributed to the mastoido-humeralis, longus colli, rectus capitis anticus major, the scalenus, and to the phrenic nerve, and a third to the skin. The sixth nerve also furnishes branches to the levator anguli scapulas and rhom-boideus muscles, and the brachial plexus receives a twig from its phrenic branch. The superior branches of the last six cervical nerves supply the splenius, trachelo-mastoideus, semi-spinalis colli, and complexus muscles, and the skin in the region of the mane.
The seventh and eighth cervical nerves are expended in the formation of the brachial plexus. Each nerve supplies a branch to the middle cervical ganglion, the former joins the vertebral nerve, the latter passes directly to the ganglion.