Clinical Embryology

Question 1

describe branchial cysts

Answer 1

• persistence of parts of cervical sinus and/or 2nd pharyngeal groove
• cystic swelling along anterior border of SCM

Question 2

describe the 2 types of branchial sinus

Answer 2

• external
  
  • open externally along anterior border of SCM
• internal
  
  • opens internally into the tonsillar fossa

Question 3

describe a branchial fistula

Answer 3

• persistence of the 2nd groove and 2nd pouch
• abnormal tract passing between ext. and int. carotid arteries
• opening on the side of neck externally and in the tonsillar sinus internally

Question 4

describe first arch syndrome

Answer 4

• occurs due to a faulty migration of NCCs to 1st arch
• includes Treacher Collins and Pierre Robin syndromes
• symptoms:
  
  • preauricular appendage
  • defective cheek
  • macrostomia
  • hypoplasia of the mandible

Question 5

describe a thyroglossal cyst

Answer 5

cystic remnant of the tyroglossal duct and may open to the exterior, forming a thyroglossal fistula

Question 6

describe the 2 types of cleft palates

Answer 6

• anterior:
  
  • cleft lip, cleft upper jaw and cleft between primary and secondary palates
  • due to partial/complete lack of fusion of maxillary and medial nasal prominences
• posterior:
  
  • cleft secondary palate and cleft uvula
  • failure of fusion of palatine processes of maxillary prominences

Question 7

describe a median cleft upper lip

Answer 7

failure of fusion of the 2 medial nasal processes to form the intermaxillary segment

Question 8

describe a unilateral cleft upper lip

Answer 8

failure of fusion of left maxillary prominence with the intermaxillary segment (medial nasal prominence)

bilateral cleft upper lip = ^^ happens on both sides

Question 9

describe an oblique facial cleft

Answer 9

falure of maxillary prominence to fuse with lateral nasal prominence

Question 10

describe the cause of anencephaly/meroanencephaly

Answer 10

• caused by failure of closure of the rostral neuropore in the 4th week
• elevated AFP and polyhydramnios seen
• 70% of these can be prevented bt taking folic acid during pregnancy

Question 11

contrast obstructive vs non-obstructive hydrocephalus

Answer 11

• obstructive/non-communicating
  
  • congenital stenosis of apertures between the ventricles or the subarachnoid space
  • dilatation of ventricles, pressure from the accumulated CSF enlarges the head, thinning of the bones and cerebral cortex
• non-obstructuve (communicating)
  
  • obliteration of subarachnoid cistern or arachnoid villi malfunction

Question 12

describe cranium bifidum

Answer 12

defect in the formation of cranium (usually occipital bone)

Question 13

describe Arnold-Chiari malformation

Answer 13

• inferior displacement of the vermis of the cerebellum and medulla through the foramen magnum
• most common anomaly of the cerebellum
• usually associated with hydrocephalus

Question 14

describe holoprosencephaly

Answer 14

• alcohol, maternal diabetes, genetic factors, etc. contribute to causes
• thought to be related to SHH gene signaling defects associated with cholesterol metabolism

Question 15

describe what is seen in this ultrasound

Answer 15

cranium bifidum: defect in the formation of the cranium, usually the occipital bone