Development Of Aortic Arches PDF 2024-2025

Development Of Aortic Arches By: Dr. ABDELHAMID ELSIFY MBBCH, M.SC. MD ASSOCIATE PROFESSOR OF ANATOMY & EMBRYOLOGY HEAD OF ANATOMY-HISTOLOGY DEPARTMENT 9/11/2023 Dr.ABDEL...

Development Of Aortic Arches By: Dr. ABDELHAMID ELSIFY MBBCH, M.SC. MD ASSOCIATE PROFESSOR OF ANATOMY & EMBRYOLOGY HEAD OF ANATOMY-HISTOLOGY DEPARTMENT 9/11/2023 Dr.ABDELHAMID 1  Learning Objectives Knowledge & understanding By the end of this lecture the student should be able to: ❑ Describe the Development of Aortic Arches & their anomalies. Accordingly the following embryological &anatomical points become clear: 1. Pharyngeal arches and their relation to the aortic arches. 2. The developmental source of the main arteries. 3. The difference between the anatomical course of RLNs on both sides. 4. Explanation of some important congenital anomalies as: A. Ductus arteriosus. B. Coarctation of aorta C. Double aortic arch. 9/11/2023 Dr.ABDELHAMID 2 Remember the Anatomy of arch of aorta, its branches &RLNs 9/11/2023 Dr.ABDELHAMID 3 Remember the types of early blood vessels ❑ 2 Sets of blood vessels appear: 1-Extra-embryonic vessels(appear earlier) include: a) Vitelline vessels. b) Umbilical vessels. 2-Intra-embryonic vessels(appear 2 days later) include: 2 dorsal aortae. 9/11/2023 Dr.ABDELHAMID 4 Remember the Endocardial heart tube: Remember the Truncus arteriosus Truncus arteriosus & spiralized aortico-pulmonary septum Pharyngeal Arches 9/11/2023 Dr.ABDELHAMID 7 Pharyngeal Arches 9/11/2023 Dr.ABDELHAMID 8 Aortic arches ( anteroposterior view ) 9/11/2023 Dr.ABDELHAMID 9 Side view of Aortic Arches 9/11/2023 Dr.ABDELHAMID 10 Pharyngeal arches & their corresponding nerve supply 9/11/2023 Dr.ABDELHAMID 11 Skeletal derivatives of the Pharyngeal Arches 9/11/2023 Dr.ABDELHAMID 12 Fate of aortic sac, aortic arches & 2 dorsal aortae 9/11/2023 Dr.ABDELHAMID 13 Fate of aortic sac, aortic arches , 2 dorsal aortae& relation of RLNs 9/11/2023 Dr.ABDELHAMID 14 Final vascular tree & its relations with 2 RLNs 9/11/2023 Dr.ABDELHAMID 15 3 Sets of aortic vessels 1. Ventral aortic sac: which is the dilated cranial part of the truncus arteriosus. 2. Two dorsal aortae (Right&Left): both unite caudally forming a single dorsal aorta. 3. Six pairs of aortic arches: connect the dorsal aorta with the ventral aortic sac. Each aortic arch runs in the corresponding pharyngeal arch. ❑ The aortic arches are embedded in the mesenchyme of the pharyngeal arches and terminate in the right and left dorsal aortae. In the region of the arches, the dorsal aortae remain paired, but caudal to this region, they fuse to form a single dorsal aorta. 9/11/2023 Dr.ABDELHAMID 16 Continue ❑The pharyngeal arches and their vessels appear in a cranial-to-caudal sequence, so that they are not all present simultaneously. The aortic sac contributes a branch to each new arch as it forms, giving rise to a total of five pairs of arteries. The dorsal aortae give 3 sets of branches: ❑Intersegmental arteries ❑Lateral splanchnic arteries (visceral) ❑Ventral splanchnic arteries (visceral) 9/11/2023 Dr.ABDELHAMID 17 Fate of aortic sac, aortic arches & dorsal aortae ❑The following parts disappear: 1.The first &second arches (almost totally) disappear. 2.The fifth arch totally disappears on both sides. 3.The distal part of the right 6th aortic arch disappears. 4.Parts of dorsal aortae: -The segment between 3rd &4th arches on both sides named(carotid duct). -The part of right dorsal aorta between the 7th intersegmental artery and the junction of the two dorsal aortae. 9/11/2023 Dr.ABDELHAMID 18 Fate of aortic sac, aortic arches & dorsal aortae ❑ The aortic sac is divided into 2 parts by upward extension of the aortico-pulmonary septum: 1. Large upper part connected to ascending aorta. This part divides into right and left horns , each is connected to the 3rd & 4th aortic arches. 2. Small lower part connected to the pulmonary trunk. This part is connected to the 6th pair of aortic arches which is also named pulmonary arch. ❑ The remaining arteries give the following: 1. The arch of aorta which is derived from: a) Left horn of aortic sac gives → the proximal part. b) 4th Left aortic arch gives → the middle part. c) The part of the left dorsal aorta gives → the distal part ( between the 4th arch and the 7th intersegmental artery) 2. The brachiocephalic artery is derived from right horn of aortic sac. 9/11/2023 Dr.ABDELHAMID 19 Fate of aortic sac, aortic arches & dorsal aortae 3. The common carotid artery on each side is derived from the proximal part of the corresponding 3rd aortic arch. The external carotid arises as a bud (sprout) from the 3rd arch. The internal carotid artery is derived from the distal part of the 3rd aortic arch and the cranial part of the dorsal aorta. 4. The subclavian arteries: The right is derived from the right 4th aortic arch + part of the right dorsal aorta+ the right 7th intersegmental artery. The left is derived from the left 7th segmental artery only. 9/11/2023 Dr.ABDELHAMID 20 Fate of aortic sac, aortic arches & dorsal aortae 5. The descending aorta: is derived from the part of the left dorsal aorta caudal to the left 7th segmental artery + the single distal aorta. 6. Small remnants of the 1st & 2nd arches: -maxillary artery is derived from the 1st arch. -stapedial and hyoid arteries are derived from the 2nd arches. 7. The right &left pulmonary arteries: are derived from the proximal parts of the 6th aortic arches. The left pulmonary artery is connected to the arch of aorta by the ductus arteriosus which is derived from the distal part of the left 6th aortic arch 9/11/2023 Dr.ABDELHAMID 21 3 Fate of aortic sac, aortic arches&dorsal aortae N.B: The recurrent laryngeal nerve is the nerve of the 6th pharyngeal arch. Due to caudal migration of the heart, the nerve is pulled down by the 6th aortic arch forming a loop before it returns to the neck. ❑ On the left side: The recurrent laryngeal nerve hooks around the ductus arteriosus near to the arch of aorta (i.e., in the thorax). ❑ On the right side: the distal part of the right 6th aortic arch disappears + the 5th aortic arch also disappear. Therefore, the recurrent laryngeal nerve hooks around the right subclavian artery in the neck (i.e,. The derivative of the right 4th arch). 9/11/2023 Dr.ABDELHAMID 22 3 Fate of aortic sac, aortic arches&dorsal aortae Right Left 1st arch Its major part disappears. A small portion gives the maxillary artery 2nd arch Its major part disappears. A small portion gives the stapedial and hyoid arteries 3rd arch Its Proximal part gives → common carotid artery , Its distal part gives → internal carotid artery. (The external carotid arises as a sprout from the end of the common carotid 4th arch Part of the right subclavian artery Middle part of the arch of aorta (between the left common carotid &left subclavian artery 5th arch Disappears completely (50%) or never develops (50%) 6th arch Proximal part gives →right pulmonary artery Proximal part gives →left pulmonary artery Distal part disappears Distal part → ductus arteriosus 9/11/2023 Dr.ABDELHAMID 23 Patent ductus arteriosus Patent ductus arteriosus The ductus arteriosus does not close after birth. May occur alone or associated and secondary to preductal coarctation of aorta. 9/11/2023 Dr.ABDELHAMID 24 Coarctation of Aorta Narrowing of a segment of aorta, it has 2 types: A-Preductal with PDA B-Postductal no PDA (Ligamentum arteriosum) Cause: unknown but may be foetal hypoxia causes proliferation of endothelium and hypertrophy of the muscle layer. Clinical picture: Brachial artery pressure is markedly increased, femoral artery pressure is decreased, and femoral pulses are delayed. 9/11/2023 Dr.ABDELHAMID 25 Double aortic arch Right &left aortic arches arise from the ascending aorta. Both form a vascular ring around trachea &esophagus , then unite to form single descending aorta, causing difficulties in breathing and swallowing. Cause: due to persistence of the part of right dorsal aorta between the 7th intersegmental artery and the junction of the 2 aortae. 9/11/2023 Dr.ABDELHAMID 26  Conclusion: ❑ Arch of aorta is derived from: ▪ Left horn of aortic sac gives → the proximal part. ▪ 4th left aortic arch gives → the middle part. ▪ The part of the left dorsal aorta gives → the distal part ( between the 4th arch and the 7th intersegmental artery) 9/11/2023 Dr.ABDELHAMID 27  Case Problem : During cardiac catheterization of a 6-year-old child, the radiologist notes that the contrast medium released into the arch of the aorta is also visible immediately in the left pulmonary artery. What is the most likely explanation for this finding? a) Patent ductus arteriosus b) Atrial septal defect c) Ventricular septal defect d) Patent ductus venosus 9/11/2023 Dr.ABDELHAMID 28  Any Questions? 9/11/2023 Dr.ABDELHAMID 29  References: 1-Langmans Medical Embryology - 13th Edition, 2015 2-https://www.amboss.com/ 9/11/2023 Dr.ABDELHAMID 30  Thank You 9/11/2023 Dr.ABDELHAMID 31