1072 



THE NERVE SYSTEM 



nerves composing which small ganglia are occasionally found. The plexuses 

 accompanying some of these arteries have important communications with other 

 nerves. That surrounding the external carotid artery (plexus caroticus externus) 

 is connected with the branch of the facial nerve to the Stylohyoid muscle; that 

 surrounding the facial artery communicates with the submaxillary ganglion by 

 one or two filaments; and that accompanying the middle meningeal artery sends 

 an offshoot which passes to the otic ganglion and a second, the external superficial 

 petrosal nerve (Fig. 740), to the geniculate ganglion of the facial nerve. 



The middle cervical ganglion (ganglion cervicale medium) (Figs. 780 and 782) 

 is the smallest of the three cervical ganglia, and is occasionally altogether wanting. 

 It is placed opposite the sixth cervical vertebra, usually upon, or close to, the 

 inferior thyroid artery. It is probably formed by the coalescence of two ganglia 

 corresponding to the fifth and sixth cervical nerves. 



It is joined by gray rami communicantes to the fifth and sixth cervical nerves. 



It gives off the thyroid and middle cardiac nerves. 



The thyroid branches are small filaments which accompany the inferior thyroid 

 artery to the thyroid gland, forming the inferior thyroid plexus (plexus thyroideus 

 inferior)', they communicate, on the artery, with the superior cardiac nerve, and, 

 in the gland, with branches from the recurrent and external laryngeal nerves. 



The middle or great cardiac nerve (n. cardiacus medius) (Fig. 780), the largest 

 of the three cardiac nerves, arises from the middle cervical ganglion or from the 

 cord between the middle and inferior ganglia. On the right side it descends behind 

 the common carotid artery, and at the root of the neck passes either in front of 

 or behind the subclavian artery; it then descends on the trachea, receives a few 

 filaments from the recurrent laryngeal nerve, and joins the right side of the deep 

 cardiac plexus. In the neck it communicates with the superior cardiac and re- 

 current laryngeal nerves. On the left side the middle cardiac nerve enters the 

 thorax between the left carotid and subclavian arteries, and joins the left side of 

 the deep cardiac plexus. If the middle cervical ganglion is absent, the above- 

 named branches arise from the gangliated cord. 



The inferior cervical ganglion (ganglion cervicale inferius) (Figs. 780 and 782) 

 is situated between the base of the transverse process of the last cervical vertebra 

 and the neck of the first rib on the inner side of the superior intercostal artery. 

 Its form is irregular; it is larger in size than the preceding, and is frequently joined 

 to the first thoracic ganglion. It is probably formed by the coalescence of two 

 ganglia which correspond to the last two cervical nerves. It is connected to 

 the middle ganglion by two or more cords, one of which forms a loop around 

 the subclavian artery and supplies offshoots to it. This loop is named the ansa 

 subclavii (Vieussenii). 



The ganglion is joined to the seventh and eighth cervical nerves by gray rami 

 communicantes. 



It gives off the inferior cardiac nerve and offshoots to bloodvessels. 



The inferior cardiac nerve (n. cardiacus inferior) arises from the inferior cervical 

 or first thoracic ganglion. It passes down behind the subclavian artery and along 

 the front of the trachea to join the deep cardiac plexus. It communicates freely 

 behind the subclavian artery with the recurrent laryngeal and middle cardiac 

 nerves. 



The offshoots to bloodvessels accompany the vertebral artery, and form a plexus 

 around it; this plexus (plexus vertebrates) supplies filaments to the vessel, and is 

 continued up the vertebral and basilar arteries to the cerebral and cerebellar 

 arteries. 



Applied Anatomy. The situation of the cervical sympathetic makes wounds of it rare. 

 Thirteen cases of traumatic injury to the cervical sympathetic* were collected by Seeligmiiller. 

 In ten cases paralysis existed; in three, irritation. Tumors of the neck may cause irritation or 



