November 8

Question 1

External Carotid Artery

Answer 1

The common carotid artery bifurcates at the level of C3 - C5 into external and internal carotid artery. the external carotid lies median and anterior to the internal caroitd artery but behind the stylohyoid and the posterior belly of digastric. It is covered by the sternocleidomastoid at some point. It then pierces the parotid gland to give the Maxillary artery and the superficial temporal artery.

Question 2

Embryology of the Kidney

Answer 2

1) the ureter, the pelvis, calyces and the collecting tubules of the kidney are formed from the ureteric bud of the mesonephric duct.
2) From the calyces numerous collecting tubules grow and acquire connections with the renal tubules, which arise independently in the metanephric cap- a condensation of the intermediate mesoderm covering the expanded ureteric bud.
3) The metanephric cap, in which the renal tubules arise, lies at first on the medial side of the ureteric bud and later on its dorsal aspect. The ureteric bud and metanephric duct grow in a cephalic direction dorsal to the mesonephros.** If this process fails to occur, the kidney retains its pelvic location (the so called pelvic kidney).**
4) The close relationship of the two metanephric caps at their caudal ends can result in the development of horseshoe kidney in some cases. As the kidney ascends cranially,** its blood supply changes from the iliac vessels to the renal arteries from the aorta.**
5) As the ureteric bud divides to form the calyces, the metanephric cap breaks up into numerous cell masses- one for each calyx, and later one for each of the collecting tubules which grow out from the calyces. This results in the kidney having a lobulated appearance which is seen in the kidneys of neonates.

Question 3

Embryology of the diaphragm

Answer 3

1) The diaphragm is formed between the 5th and 7th weeks of gestation through the progressive fusion of the septum transversum, pleuroperitoneal folds and via lateral muscular ingrowth.
2) The muscular origins of the diaphragm are somites located in cervical segments 3 to 5, which accounts for the long path taken by the phrenic nerve.
3) The components contribute to the following diaphragmatic segments:
* Septum transversum - Central tendon
* Pleuroperitoneal membranes - Parietal membranes surrounding viscera
* Cervical somites C3 to C5 - Muscular component of the diaphragm

Question 4

Types of diaphragmatic Hernia

Answer 4

1) Morgagni
Anteriorly located
Minimal compromise on lung development
Minimal signs on antenatal ultrasound
Usually present later
Usually good prognosis
2) Bochdalek hernia
Posteriorly located
Larger defect
Often diagnosed antenatally
Associated with pulmonary hypoplasia
Poor prognosis

Question 5

Surgical Importance of Bochdalek Hernia

Answer 5

1) most common type
2) if not diagnosed antenatally will typically present soon after birth with respiratory distress
3) scaphoid abdomen on clinical examination because of herniation of the abdominal contents into the chest.
4) associated with a number of chromosomal abnormalities such as Trisomy 21 and 18.
5) Infants have considerable respiratory distress due to hypoplasia of the developing lung.
6) The pulmonary hypoplasia is associated with pulmonary hypertension and abnormalities of pulmonary vasculature.
7) The pulmonary hypertension renders infants at risk of right to left shunting (resulting in progressive and worsening hypoxia).
8) Diagnostic work up of these infants includes chest x-rays/ abdominal ultrasound scans and cardiac echo.

Question 6

Embryology of Adrenal Gland

Answer 6

1) First detected at 6 weeks’ gestation.
2) adrenal cortex is derived from the mesoderm of the posterior abdominal wall.
3) Steroid secretion from the fetal cortex begins shortly thereafter.
4) The adrenal medulla is of ectodermal origin, arising from neural crest cells that migrate to the medial aspect of the developing cortex.
5) At 4 months’ gestation, it is 4 times the size of the kidney; however, at birth, it is a third of the size of the kidney. This occurs because of the rapid regression of the fetal cortex at birth. It disappears almost completely by age 1 year; by age 4-5 years, the permanent adult-type adrenal cortex has fully developed.
6) Because the development of the adrenals is closely associated with that of the kidneys, agenesis of an adrenal gland is usually associated with ipsilateral agenesis of the kidney, and fused adrenal glands (whereby the 2 glands join across the midline posterior to the aorta) are also associated with a fused kidney.
7) Adrenal hypoplasia occurs in the following 2 forms: (1) hypoplasia or absence of the fetal cortex with a poorly formed medulla and (2) disorganized fetal cortex and medulla with no permanent cortex present.
8) Accessory adrenal tissue (adrenal rests), which is usually comprised only of cortex but seen combined with medulla in some cases, is most commonly located in the broad ligament or spermatic cord but can be found anywhere within the abdomen.

Question 7

Duodenum

Answer 7

1st part - L1
2nd part - L2
3rd Part- L3
4th part - L2

Question 8

Ductus Arterious

Answer 8

If it does not close after brith, administration of indomethacin can help.