634 THE SPINAL NERVES. 



cervicalis ascendens, and the trans versa! is colli with the trachelo-mastoid. 

 That of the second nerve is the largest of the series of external branches, 

 and is often united to the corresponding branch of the third ; it supplies 

 the complexus muscle which covers it, and ends in the splenius and trachelo- 

 inastoid muscles. 



The internal branches, larger than the external, are differently disposed at 

 the upper and the lower parts of the neck. That of the second cervical 

 nerve is named, from its size and destination, the great occipital, and 

 requires separate notice. The rest are directed inwards to the spinous pro- 

 cesses of the vertebrae. Those derived from the third, fourth, and fifth 

 nerves pass over the semispinalis and beneath the complexus muscle, and, 

 having reached the spines of the vertebrae, turn transversely outwards and 

 are distributed in the integument over the trapezius muscle. From the 

 cutaneous branch of the third nerve a branch passes upwards to the integu- 

 ment on the lower part of the occiput, lying at the inner side of the great 

 occipital nerve, and is sometimes called third occipital nerve. 



Between the inner branches of the first three cervical nerves, beneath the complexus, 

 there are frequently communicating fasciculi ; and this communication Cruveilhier 

 has designated as " the posterior cervical plexus." 



The internal branches from the lowest three cervical nerves are placed 

 beneath the semispinalis muscle, and end in the muscular structure, without 

 furnishing (except occasionally the sixth) any offset to the skin. These 

 three nerves are the smallest of the series. 



The great occipital nerve is directed upwards on the lower oblique muscle, 

 and is transmitted to the surface through the complexus and trapezius 

 muscles, giving twigs to the complexus. Ascending with the occipital 

 artery, it divides into branches, which radiate over the occipital part of the 

 occipito-frontalis muscle, some appearing to enter the muscle, and others 

 joining the smaller occipital nerve. 



An auricular branch is sometimes supplied to the back of the ear by the great 

 occipital nerve. 



DORSAL NERVES. The external branches increase in size from above 

 downwards. They are directed through or beneath the longissiinus dorsi to 

 the space between that muscle and the ilio-costalis and accessory ; they supply 

 both those muscles, together with the small muscles continued upwards from 

 the erector spinse to the neck, and also the levatores costarum. The lower 

 five or six nerves give cutaneous twigs, which are transmitted to the integu- 

 ment in a line with the angles of the ribs. 



The internal branches of the upper six dorsal nerves appear in the interval 

 between the multifidus spinee and the semispinalis dorsi ; they supply 

 those muscles, and become cutaneous by the side of the spinous processes of 

 the vertebras. The cutaneous branch from the second nerve, and sometimes 

 others, reach as far as the scapula. The internal branches of the lower six 

 dorsal nerves are placed between the multifidus spinso and longissimus dorsi, 

 and end in the multifidus without giving branches to the integument. 

 Where cutaneous nerves are supplied by the internal branches, there are 

 none from the external branches of the same nerve, and vice versa. 



LUMBAR NERVES. The external branches enter the erector spinse, and 

 give filaments to the intertrans verse muscles. From the upper three, 

 cutaneous nerves are supplied ; and from the last, a fasciculus descends to 

 the corresponding branch of the first sacral nerve. The cutaneous nerves 

 given from the external branches of the first three lumbar nerves, pierce the 



