embryology Flashcards
1st aortic arch
maxillary artery
2nd aortic arch
stapedial artery and hyoid artery
3rd aortic arch
common carotid artery and proximal part of internal carotid artery
4th aortic arch
on left–>aortic arch
on right–>proximal right subclavian
6th aortic arch
proximal part of pulmonary arteries
ductus arteriosus
branchial clefts
derived from ectoderm
branchial arches
derived from mesoderm (muscles, arteries) and neural crest (bones, cartilage)
branchial pouches
derived from endoderm
1st branchial cleft
external auditory meatus
2nd-4th branchial clefts
temporary cervical sinuses, which are obliterated by proliferation of 2nd arch mesenchyme
persistent cervical sinus
branchial cleft cyst in lateral neck
1st branchial arch
Cartilage: meckel’s cartilage, mandible, malleus, incus, spheno-mandibular ligament
Muscles: muscle of mastication (masseter, lateral and medial pterygoids), mylohyoid, anterior belly of digastric, tensory tympani, tensor veli palatini
nerves: CN V2 and V3 (chew)
Treacher collins syndrome: 1st arch neural crest cells fail to migrate–>mandibular hypoplasia
2nd branchial arch
Reichert’s cartilage: stapes, styloid process, lesser horn of hyoid, stylohyoid ligament
Muscles: facial expression, stapedius, stylohyoid, posterior belly of digastric
CN 7 (facial expression)
3rd branchial arch
Cartilage: greater horn of hyoid
Muscles: stylopharyngeus
Nerve: CN9=glossopharyngeal nerve
*congenital pharyngocutaneous fistula: persistence of cleft and pouch–>fistula between tonsillar area and cleft in lateral neck
4th-6th branchial arches
Cartilages:thyroid, cricoid, arytenoids, corniculate, cuneiform
4th arch muscles: most pharyngeal constrictors, cricothyroid, levator veli palatini
6th arch muscles: all intrinsic muscles of the larynx except cricothyroid
4th arch nerve: CN 10 (superior laryngeal branch)
6th arch nerve: CN 10 (recurrent laryngeal br)
