THE CERVICAL NERVES 



925 



The Coccygeal Nerve (N. Coccygeus). 



The posterior division of the coccygeal nerve (ramus posterior) does not divide 

 into a medial and a lateral branch, but receives, as already stated, a communicating 

 branch from the last sacral ; it is distributed to the skin over the back of the coccyx. 



ANTERIOR DIVISIONS OF THE SPINAL NERVES (RAMI ANTERIORES). 



The anterior divisions of the spinal nerves supply the antero-lateral parts of the 

 trunk, and the limbs; they are for the most part larger than the posterior divisions. 

 In the thoracic region they run independently of one another, but in the cervical, 

 lumbar, and sacral regions they unite near their origins to form plexuses. 



The Cervical Nerves (Nn. Cervicales). 



The anterior divisions of the cervical nerves (rami anteriores), with the exception 

 of the first, pass outward between the Intertransversarii anterior and posterior, 

 lying on the grooved upper surfaces of the transverse processes of the vertebras. 

 The anterior division of the first or suboccipital nerve issues from the vertebral canal 

 above the posterior arch of the atlas and runs forward around the lateral aspect 

 of its superior articular process, medial to the vertebral artery. In most cases it 

 descends medial to and in front of the Rectus capitis lateralis, but occasionally it 

 pierces the muscle. 



The anterior divisions of the upper four cervical nerves unite to form the cervical 

 plexus, and each receives a gray ramus communicans from the superior cervical 

 ganglion of the sympathetic trunk. Those of the lower four cervical, together with 

 the greater part of the first thoracic, form the brachial plexus. They each receive 

 a gray ramus communicans, those for the fifth and sixth being derived from the 

 middle, and those for the seventh and eighth from the lowest, cervical ganglion 

 of the sympathetic trunk. 



The Cervical Plexus (plexus cenicalis) (Fig. 804). The cervical plexus is formed 

 by the anterior divisions of the upper four cervical nerves; each nerve, except 

 the first, divides into an upper and a lower branch, and the branches unite to form 

 three loops. The plexus is situated opposite the upper four cervical vertebrae, in 

 front of the Levator scapulae and Scalenus medius, and covered by the Sterno- 

 cleidomastoideus. 



Its branches are divided into two groups, superficial and deep, and are here 

 given in tabular form; the figures following the names indicate the nerves from 

 which the different branches take origin : 



Smaller occipital 

 Great auricular . 

 Cutaneous cervical 

 .Supraclavicular 



Superficial 



Deep 



Internal 



With hypoglossal 

 " vagus . 

 " sympathetic 

 Rectus capitis lateralis 

 Rectus capitis anterior 

 Longus capitis 

 Communicantes cervi- 



cales 

 Phrenic 

 ("Communicating with accessory 



Communicating 



Muscular 



2,C. 

 2, 3, C. 



2, 3, C. 



3, 4, C. 

 1, 2, C. 



2,C. 

 2,3,4,C. 

 C. 



2,C. 

 2, 3, C. 



External 



Muscular 



Sternocleidomastoideus 

 Trapezius 

 Levator scapulae . 

 Scalenus medius 



3, 4, 5, C. 



2, 3, 4, C. 

 2,C. 



3, 4, C. 

 3,4, C. 

 3, 4, C. 



