THE VERTEBRAL VESSELS. 707 



The VERTEBRAL ARTERY has been seen at its origin in the lower Vertebral 

 part of the neck (p. 593) ; and its termination is described with the 

 - of the brain. Entering, usually, the foramen in the sixth 

 cervical vertebra the artery ascends through the corresponding 

 foramina in the other vertebrae. Finally, the vessel winds back- 

 wards round the upper articular process and crosses the neural arch 

 of the atlas, piercing the posterior occipito-atlantal ligament and the 

 dura mater, to enter the skull through the foramen magnnm. In 

 its course upwards the artery lies in front of the anterior trunks of relation to 

 the cervical nerves, except the first, which crosses on the inner side. 



The vessel is accompanied by a vein, and by a plexus of nerves of a vein, and 

 i nerves are 



the same name. with it . 



In the neck the artery furnishes small twigs to the surrounding branches, 

 muscles, the spinal canal, and the spinal cord. 



The vertebral rein begins on the neural arch of the atlas by the Vertebral 

 union of a considerable offset from the intraspinal venous plexuses ^ e 

 with other branches proceeding from a network between the muscles 

 .n the suboccipital region. It is also joined by the emissary vein 

 eaving the skull through the posterior condylar foramen when that 

 aperture is present. In the neck, the vein forms a plexus around course ; 

 the artery in the foramina of the transverse processes ; and it termi- 

 lates below by emptying itself into the innominate trunk. ending ; 



In this course it is joined by branches from the internal and branches, 

 external spinal veins ; its other tributaries are noticed at p. 594. 



The vertebral plexus of nerves is derived from the inferior cervical Vertebral 

 ganglion of the sympathetic. It surrounds the artery, and com- nerves. 

 municates with the spinal nerves which it crosses. 



SECTION XVIII. 



LIGAMENTS OF THE VERTEBRAE AND CLAVICLE. 



Directions. On the remaining part of the spine, the ligaments Directions, 

 connecting the cervical vertebrse to each other and to the occipital 

 bone are to be learnt. 



Dissection. Disarticulate the last cervical from the first dorsal Dissection, 

 vertebra. Then remove altogether the muscles, vessels, nerves, and 

 iireolar tissue and fat from the cervical vertebrse. By sawing through 

 the occipital bone, so as to leave only an osseous ring behind the 

 foramen magnum, the ligaments between the atlas and the occipital 

 bone can be more easily cleaned. 



The COMMON LIGAMENTS attaching together the cervical vertebra Common 

 are similar to those uniting the bones in other parts of the spine, v'frtebne 

 viz., an anterior and a posterior common ligament, bands between 

 the laminae and spines, capsular ligaments lined by synovial mem- 

 brane for the articular processes, and an intervertebral disc between 

 the bodies of the bones. 



z z 2 



