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GA2 Test 2 Embryo
Question | Answer |
---|---|
____________ EARLIEST branchial arch composition of the posterior 1/3 of the tongue | Mesoderm from the 2nd, 3rd & 4th Arches |
Anomaly formed when part of the vitelline duct persists at the apex of the primary intestinal loop | Meckels Diverticulum |
Artery whose branches supply the derivatives of the caudal foregut | Celiac Artery |
Artery whose branches supply the derivatives of the midgut. | Superior Mesenteric Artery |
Artery whose branches supply the derivatives of the hindgut. | Inferior Mesenteric Artery |
Branchial arch composition of the anterior 2/3 of the tongue | Mesoderm of the Ventral Mandibular (1st) Arch |
Briefly describe an omphalocele. How does it occur (develop)? | Anomaly of herniation, when mid-gut fails to return and is covered by amnion in the umbilical cord. |
Briefly, what happens to the endodermal epithelium of the esophagus and intestine in the second month of development | Luminal Obliteration followed by recavitation. |
Describe (do not draw) the DEGREES and DIRECTION of rotation of the midgut while it is in the herniated position inside the umbilical cord only. | Primary Intestinal Loop rotates 90 Degrees counter-clockwise around the axis of the superior mesenteric artery. Causes the cephalic limb to move to the right and the caudal limp to move to the left. |
Discuss in detail the development of an INTERNAL branchial fistula. | Abnormal regression of the tissue between the 2nd arch & 2nd Pouch |
Discuss in detail the formation of a cervical sinus | 2nd Branchial arch grows caudally overlaping the 3&4 Branchial arches, 2nd arch fuses with Epicardial Ridge Thus, 2nd, 3rd, 4th clefts are buried forming the cervical sinus. |
Discuss the development of the falciform ligament and lesser omentum | Liver grows out of the septum transversum, the mesoderm that is pulled out then becomes lesser omentum and falciform ligaments. |
Discuss the rotational movements of the STOMACH. | 90 Degress clockwise on vertical axis & clockwise on Anteroposterior (A to P) axis |
Draw 2 diagrams (x-sections through the gut loop) showing positional changes of the proximal (cephalic) limb of the primary intestinal loop during REDUCTION (return) of the midgut hernia ONLY. | Draw Diagrams |
Exactly where does the midgut end in the ADULT? | Junction of Right 2/3 and left 1/3 transverse colon |
Explain why the right recurrent laryngeal n. loops under the right subclavian a. but the left loops under the arch of the aorta. BE SPECIFIC AND COMPLETE! | Distal part of Right 6th arch drops out allowing the right recurrent laryngeal to move up underneath the right 4th aortic arch. |
From what embryonic components do the following parts of the liver develop? Be sure to also mention the germ layer in your answer. a) parenchyma (functional part) b) Connective tissue | a) Gut Endoderm b) Mesodermal partition of septum transversum |
Give the derivatives if any of : (BE SPECIFIC) a) distal part of right 6th aortic arch- b) left 4th aortic arch- c) 3rd aortic arch- | a) regresses b) Part of Aortic Arch between left common carotid & left subclavian artery c)Common carotid arteries and proximal 1/3 of internal carotid arteries |
Give the derivatives if any of : (BE SPECIFIC) a) right 4th aortic arch- b) left 1st aortic arch- | a) Proximal Part of Subclavian Artery b) regresses |
Give the embryonic component that forms: a) the left subclavian artery b)the portion of the right subclavian IMMEDIATELY proximal to the vertebral artery | a) Left 7th Intersegmental artery b) Right 4th aortic arch & some of right dorsal aorta |
Give the embryonic derivation of the INTERNAL carotid a. | Proximal 1/3 - 3rd Aortic Arch & Distal 2/3 - Anterior Extensions of dorsal aortae |
Give two structures derived from the CAUDAL limb of the primary intestinal loop. | Ascending Colon, Cecum (distal 2-3 feet of ileum & proximal right 2/3 transverse colon) |
In detail, how does a left- sided cecum develop? | Only the 1st 90 degree counter-clockwise rotation occurs instead of the 270 degree counter-clockwise rotation. |
List the degrees and direction of rotation of the gut during its RETURN to the abdominal cavity ONLY. | 180 Degrees counter-clockwise |
List the EMBRYONIC components that collectively form the definitive ARCH of the AORTA | 1. Aortic sac 2. Left 4th Arch 3. Left Dorsal Aorta |
Name two derivatives of the CAUDAL limb of the primary intestinal loop | Distal 2-3 feet of ileum, cecum, ascending colon, proximal right 2/3 of transverse colon |
Name the ADULT derivatives of the following: a) 2nd cleft b) 2nd pouch c) Ventral 3rd pouch d) Copula (hypobranchial eminence) | a) No derivatives b) tonsilar fossa & palatine tonsils c)Thymus d)Posterior 1/3 of tongue |
Name the ADULT derivatives of the following: a) dorsal fourth pouch b) third cleft | a)Superior Parathyroid b) Regresses - No Derivatives (2,3,4 can produce cervical sinus) |
Name the ADULT derivatives of the following: a) Dorsal third pouch b) Ventral 4th pouch | a) Inferior Parathyroid b) Ultimobranchial body |
Name the ADULT derivatives of the following a) dorsal 3rd pouch b) first pouch | a) Inferior Parathyroid b) tubotympanic recess containing, typanic cavity, auditory tube & tympanic membrane |
Name the primordium (NOT arches) responsible for each part of the tongue listed below: a) Anterior 2/3rds b) Posterior 1/3rd | a) Lateral Lingual Swellings B) Copula (Hypobranchial Eminence) |
Name two derivatives of the CEPHALIC limb of the primary intestinal loop | Distal part of the duodenum, jejunum, jejunum and most of ileum |
Name two FETAL vessels which carry highly oxygenated blood and close at birth. What adult structures do they form? | Umbilical Vein - Ligamentum Teres Hepatis & Ductus Arteriosus - Ligamentum Arteriosum |
SPECIFICALLY, how does a structure become secondarily retroperitoneal? | A structure becomes retroperitoneal when its mesentery fuses with the posterior wall of the abdomen. |
Specifically, where does the midgut end in the adult? | Between the Right 2/3 and Left 1/3 of transverse colon |
Specifically, where does the hindgut end in the adult? | Pectinate Line of Anal Canal |
The brachiocephalic artery specifically develops from what embryonic component? | Aortic Sac of the Truncus Arteriosus |
What develops from the: a) right 4th aortic arch b) left 2nd aortic arch | a) Proximal Part of Right Subclavian b) Regresses except for small stapedial and hyoid arteries |
What happens to: a) 2nd aortic arch b) Distal left 6th arch | a) Regresses b) Forms ductus arteriosus |
When (week) and why does the midgut undergo physiological umbilical herniation? | 6th week, due to rapid growth of cephalic limb the abdominal cavity is temporarily too small |