266 HEAD AND NECK 



highest pair of muscular slips lies between the atlas and the 

 epistropheus ; the lowest pair connects the transverse process 

 of the seventh cervical vertebra with the transverse process 

 of the first thoracic vertebra. 



Nervi Cervicales. The cervical spinal nerves have a 

 very definite relation to the intertransverse muscles. The 

 anterior rami of the lower seven nerves make their appearance, 

 by passing laterally, between the two corresponding muscles. 

 The posterior divisions of the same nerves turn backwards, 

 medial to the posterior muscles. 



The upper two cervical nerves emerge from the vertebral 

 canal differently from the others. They pass laterally over 

 the posterior arch of the atlas and the vertebral arch of the epi- 

 stropheus, respectively, behind the articular processes, whilst 

 the lower nerves are situated in front of the articular processes. 



The anterior ramus of the first cervical nerve passes for- 

 wards medial to the rectus capitis lateralis, and then turns 

 downwards to join the anterior ramus of the second cervical 

 nerve, with which it forms the first loop of the cervical plexus. 

 The posterior ramus passes backwards into the sub-occipital 

 triangle. The anterior ramus of the second cervical nerve 

 passes laterally between the first pair of intertransverse 

 muscles, and the posterior ramus runs backwards medial 

 to the first posterior intertransverse muscle. 



Dissection. The vertebral artery as it traverses the succession 

 of foramina in the transverse processes of the cervical vertebrae 

 should now be exposed. Remove the intertransverse muscles 

 as well as the muscles still attached to the transverse process 

 of the atlas viz., the rectus lateralis, the inferior oblique, and 

 the superior oblique. The anterior tubercles and the costal 

 portions of the transverse processes of the third, fourth, fifth, 

 and sixth cervical vertebras should then be snipped off with the 

 bone forceps. 



Arteria Vertebralis. The vertebral artery is a vessel of 

 great importance, for, together with its fellow of the opposite 

 side and the basilar artery, which is formed by their union, it 

 supplies the hind-brain, the mid-brain, and the posterior parts 

 of the cerebral hemispheres, and it helps to supply the spinal 

 medulla. It commences at the root of the neck, as a branch 

 of the first part of the subclavian artery, and it runs upwards, 

 through the transverse processes of the upper six cervical 

 vertebrae, to the base of the skull. It enters the skull through 

 the foramen magnum and unites, in the posterior fossa of the 



