Henry Gray (18251861). Anatomy of the Human Body. 1918.
and form a plexus with the cervical branch of the facial nerve beneath the Platysma; others pierce that muscle, and are distributed to the skin of the upper and front part of the neck.
The descending branches (rami inferiores) pierce the Platysma, and are distributed to the skin of the side and front of the neck, as low as the sternum.
The Supraclavicular Nerves (nn. supraclaviculares; descending branches) arise from the third and fourth cervical nerves; they emerge beneath the posterior border of the Sternocleidomastoideus, and descend in the posterior triangle of the neck beneath the Platysma and deep cervical fascia. Near the clavicle they perforate the fascia and Platysma to become cutaneous, and are arranged, according to their position, into three groupsanterior, middle and posterior.
The anterior supraclavicular nerves (nn. supraclaviculares anteriores; suprasternal nerves) cross obliquely over the external jugular vein and the clavicular and sternal heads of the Sternocleidomastoideus, and supply the skin as far as the middle line. They furnish one or two filaments to the sternoclavicular joint.
The middle supraclavicular nerves (nn. supraclaviculares medii; supraclavicular nerves) cross the clavicle, and supply the skin over the Pectoralis major and Deltoideus, communicating with the cutaneous branches of the upper intercostal nerves.
The posterior supraclavicular nerves (nn. supraclaviculares posteriores; supra-acromial nerves) pass obliquely across the outer surface of the Trapezius and the acromion, and supply the skin of the upper and posterior parts of the shoulder.
Deep Branches of the Cervical Plexus. INTERNAL SERIES.The Communicating Branches consist of several filaments, which pass from the loop between the first and second cervical nerves to the vagus, hypoglossal, and sympathetic. The branch to the hypoglossal ultimately leaves that nerve as a series of branches, viz., the descending ramus, the nerve to the Thyreohyoideus and the nerve, to the Geniohyoideus (see page 916). A communicating branch also passes from the fourth to the fifth cervical, while each of the first four cervical nerves receives a gray ramus communicans from the superior cervical ganglion of the sympathetic.
Muscular Branches supply the Longus capitis, Rectus capitis anterior, and Rectus capitis lateralis.
The Communicantes Cervicales (communicantes hypoglossi)(Fig. 804) consist usually of two filaments, one derived from the second, and the other from the third cervical. These filaments join to form the descendens cervicalis, which passes downward on the lateral side of the internal jugular vein, crosses in front of the vein a little below the middle of the neck, and forms a loop (ansa hypoglossi) with the descending ramus of the hypoglossal in front of the sheath of the carotid vessels (see page 916). Occasionally, the loop is formed within the sheath.
The Phrenic Nerve (n. phrenicus; internal respiratory nerve of Bell) contains motor and sensory fibers in the proportion of about two to one. It arises chiefly from the fourth cervical nerve, but receives a branch from the third and another from the fifth; (the fibers from the fifth occasionally come through the nerve to the Subclavius.) It descends to the root of the neck, running obliquely across the front of the Scalenus anterior, and beneath the Sternocleidomastoideus, the inferior belly of the Omohyoideus, and the transverse cervical and transverse scapular vessels. It next passes in front of the first part of the subclavian artery, between it and the subclavian vein, and, as it enters the thorax, crosses the internal mammary artery near its origin. Within the thorax, it descends nearly vertically in front of the root of the lung, and then between the pericardium and the mediastinal pleura, to the diaphragm, where it divides into branches, which pierce that muscle, and are distributed to its under surface. In the thorax it is accompanied by the pericardiacophrenic branch of the internal mammary artery.
The two phrenic nerves differ in their length, and also in their relations at the upper part of the thorax.