Veterinary obstetrics, including the diseases of breeding animals and of the new-born . umbilical cord. (Heisler). 322 Veterinary Obstetrics The aortse continue forward beyond the aortic arches and runalongside the brain, to constitute the internal carotid arteries. Changes now begin to appear, looking toward the foundationof the adult plan of circulation. The middle portions of theaortic arches in the mandibular and hyoidean arches disappear ;the connection between the truncus arteriosus and the aortae,through these arches, ceases to exist and the proximal ends ofthese vessels remain as the e
Veterinary obstetrics, including the diseases of breeding animals and of the new-born . umbilical cord. (Heisler). 322 Veterinary Obstetrics The aortse continue forward beyond the aortic arches and runalongside the brain, to constitute the internal carotid arteries. Changes now begin to appear, looking toward the foundationof the adult plan of circulation. The middle portions of theaortic arches in the mandibular and hyoidean arches disappear ;the connection between the truncus arteriosus and the aortae,through these arches, ceases to exist and the proximal ends ofthese vessels remain as the external carotid arteries. The third aortic arch remains and retains its connection withthe anterior portion of the aorta and its proximal end or stemconstitutes the common carotid artery. The connection betweenthe portion of the aorta posterior to the junction with the thirdaortic arch and anterior to the fourth disappears, thus .separatingthe carotid system from the aortic vessels. Common carotid —;-Recurrent laryngealnerve (right)Right subclavian innominate arteryAscending aorta. Internal carotid I erfebralarteryArch of aortaLeft subclavianDuctus arteriosus Pulmonary trunk Fig. 50. Diagram illustrating the fate of the aortic arches.(Modified from Heisler.) The left fourth aortic arch persists, to eventually become theaorta, while the fifth, or, according to those authors who re-cognize six aortic arches, the .sixth, arch ultimately becomes thepulmonary artery. See Figs. 49 and 50. The Arteries 323 At approximately the fifth or sixth week of embryonic life,the heart leaves the region of the pharynx and passes backward,while the neck becomes elongated and the head extended for-ward, which causes a great lengthening of the common carotidartery.
Size: 1221px × 2048px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectveterinaryobstetrics
