Muscle: muscles of mastication, anterior 2/3 of tongue
Nerves: V2 and V3
Arteries: maxillary (branch of external carotid)
Failure of neural crest cells to migrate to first branchial arch
Mandibular hypoplasia, facial abnormalities
Derivatives of second branchial arch
Cartilage: stapes, stylohyoid
Muscles: muscles of facial expression, posterior belly of digastric
Arteries: stapedial and hyoid
Derivatives of third branchial arch
Cartilage: greater horn of hyoid
Congenital pharyngocutaneous fistula
Persistence of third pharyngeal cleft and pouch causes fistula between tonsillar areas and cleft in lateral neck
Derivatives of fourth--sixth branchial arch
Cartilage: thyroid, cricoid, arytenoids
Muscle: pharyngeal constrictors, cricothyroid, intrinsic muscles of larynx
Nerves: X (speaking and swallowing)
Derivatives of first branchial pouch
Derivatives of second branchial pouch
Epithelial lining of palatine tonsils
Derivatives of third branchial pouch
Dorsal wings develop into inferior parathyroids
Ventral wings develop into thymus
Derivatives of fourth pharyngeal pouch
Dorsal wings develop into superior parathyroids, ventral wings degenerate
Di George syndrome
Failure of third and fourth pharyngeal pouches to develop results in thymic aplasia (immunodeficiency) and hypocalcemia
MEN IIa--mutation of germline RET
Hyperplasia of neural crest cell derivatives results in pheo, parathyroid tumor, and medullary carcinoma of the thyroid (tumor of parafollicular, calcitonin producing cells)
Connects primitive thyroid to tongue. Foramen cecum is adult derivative. Failure to degenerate results in thyroglossal duct cyst in midline of neck. Most common site of ectopic thyroid tissue is the tongue.
Central tendon of the diaphragm is derived from...
Septum transversum (most cranial structure in 3-week fetus)
Crura of diaphragm develop from...
Dorsal mesentery of esophagus
Timeline of midgut herniation
Herniates in sixth week, retracts in tenth week, rotating around SMA
Ventral bud becomes pancreatic head, uncinate process, and duct, dorsal bud becomes body, tail, isthmus, and accessory duct
Ureteric bud gives rise to...
Ureter, renal pelvis, collecting duct
Metanephric mesenchyme gives rise to...
Glomerulus and tubules, up to DCT (induced to develop by ureteric bud)
Most common site of obstruction in fetal hydronephrosis
What causes Potter's syndrome?
Malformation of ureteric bud (cannot induce metanephric mesenchyme to form kidneys)