THE SACRA MEDIA. 617 



the opposite side, and with the musculo-phrenic and comes nervi phrenici, branches 

 of the internal mammary. The external branch passes toward the side of the 

 thorax and inosculates with the intercostal arteries. The internal branch of the 

 right phrenic gives off a few vessels to the inferior vena cava. and the left one 

 some branches to the oesophagus. Each vessel also sends capsular branches 

 //"/ supr<ir' nal) to the suprarenal capsule of its own side. The spleen on the 

 left side and the liver on the right also receive a few branches from these vessels. 



The Lumbar Arteries. 



The lumbar arteries are analogous to the intercostal. They are usually four 

 in number on each side, and arise from the back part of the aorta, nearly at right 

 angles with that vessel. They pass outward and backward, around the sides of 

 the body of the lumbar vertebra, behind the sympathetic nerve and the Psoas 

 magnus muscle, those on the right side being covered by the inferior vena cava, 

 and the two upper ones on each side by the crura of the Diaphragm. In the 

 interval between the transverse processes of the vertebrae each artery divides into 

 a 'lor&.d and an abdominal branch. 



The dorsal branch gives off, immediately after its origin, a spinal branch, which 

 enters the spinal canal : it then continues its course backward between the trans- 

 verse pr md is distributed to the muscles and integument of the back, 

 anastomosing with the similar branches of the adjacent lumbar arteries and with 

 the posterior branches of the intercostal arteries. 



The spinal branch enters the spinal canal through the intervertebral foramen, 

 to be distributed to the spinal cord and its membranes and to the bodies of the 

 vertebrae in the same manner as the lateral spinal branches from the vertebral 

 page 582). 



The abdominal branches pass outward, having a variable relation to the 

 Quadratus lurnborum muscle. Most frequently the first branch passes in front 

 :>f the muscle and the others behind it ; sometimes the order is reversed and the 

 lowest branch passes in front of the muscle. At the outer border of the Quadratus 

 they are continued between the abdominal muscles, anastomose with branches of 

 the epigastric and internal mammary in front, the intercostals above, and those of 

 the ilio-lumbar and circumflex iliac below. 



The Sacra Media. 



The Middle Sacral Artery is a small vessel about the size of a crow-quill, 

 which arises from the back part of the aorta just at its bifurcation. It descends 

 upon the last lumbar vertebra, and along the middle line of the front of the 

 sacrum, to the upper part of the coccyx, where it anastomoses with the lateral 

 sacral arteries, and terminates in a minute branch, which runs down to the situation 

 of the body presently to be described as " Luschka's gland." From it branches 

 arise which run through the meso-rectum to supply the posterior surface of the rec- 

 tum. Other branches are given off on each side, which anastomose with the lateral 

 sacral arteries, and send off small offsets which enter the anterior sacral foramina. 



The artery is the representative of the caudal prolongation of the aorta of 

 animals, and its lateral branches correspond to the intercostal and lumbar arteries 

 in the dorsal and lumbar regions. 



Coccygeal Gland, or Luschka's Gland. Lying near the tip of the coccyx in a 

 small tendinous interval formed by the union of the Levator ani muscles of each 

 side, and just above the coccygeal attachment of the Sphincter ani, is a small 

 conglobate body about as large as a lentil or a pea. first described by Luschka .' 

 and named by him the coccygeal gland. Its most obvious connections are with the 

 arteries of the part. 



Structure. It consists of a congeries of small arteries with little aneurismal 

 dilatations derived from the middle sacral and freely communicating with each 



1 Der Hirnanhang und die Stelesdruse des Mensehen, Berlin, 1860 ; Anatomie des Menschen, Tubingen, 

 1864, vol. ii. pt. -2, p. 187. 



