Branchial Apparatus

Question 1

Clefts v Pouches v Arches

Answer 1

Clefts - from ectoderm

Arches - mesoderm and neural crest cells

Pouches - endoderm

CAP from out to in

Question 2

Branchial Cleft Derivatives

Answer 2

1- external auditory meatus

2-4 cervical sinuses eventually obliterated but if persist form cysts that are NOT mobile when swallowing

Question 3

1st Arch

Answer 3

Maxillary process- maxilla and zygomatic bone

Mandibular process - Meckel cartilage –> mandible, malleus, incus, sphenomandibular ligament

Muscles of mastication, mylohyoid, anterior belly of digastric, tensor tympani, anterior 2/3 tongue

CN V2 and V3

Question 4

2nd Arch

Answer 4

Reichert cartilage - stapes, styloid process, lesser horn of hyoid, styloid ligament

Muscles of facial expression, stapedius, stylohyoid, posterior belly of digastric

CN VII

Question 5

3rd Arch

Answer 5

Greater horn of hyoid

Stylopharyngeus

CN IX

Question 6

4-6th Arches

Answer 6

Arytenoids, cricoid, corniculate, cuneiform, thyroid cartilage

4- pharyngeal constrictors, crycothyroid, levator veli palatini (CN X - superior laryngeal branch)

6- all intrinsic muscles of larynx except cricothyroid (CN X - recurrent laryngeal branch)

Question 7

1st Pouch

Answer 7

Middle ear cavity, Eustachian tube, mastoid air cells

Question 8

2nd Pouch

Answer 8

Epithelial lining of palatine tonsils

Question 9

3rd Pouch

Answer 9

Dorsal wings become inferior parathyroids

Ventral wings become thymus

Question 10

4th Pouch

Answer 10

Dorsal wings become superior parathyroids

Ventral wings become parafollicular C cells of thyroid

Question 11

Pierre Robin Sequence

Answer 11

1st and 2nd Arch problem

Micrognathia, glossoptosis, cleft palate, airway obstruction

Question 12

Treacher Collins Syndrome

Answer 12

1st and 2nd Arch problem

Neural crest cell problem leading to mandibular hypoplasia, facial abnormalities