Branchial Apparatus Flashcards
Cleft/Arches/Pouches Derivisions
Clefts - derived from ectoderm (also called branchial grooves)
Arches - derived from mesoderm (muscles, arteries) and neural crest (bones, cartilage)
Pouches - derived from endoderm
1st Branchial Cleft
Develops into external auditory meatus
2-4th clefts
Temporary cervical sinuses, obliterated by proliferation of 2nd arch mesenchyme
Persistent Cervical Sinus vs. Thyroglossal Duct Cyst
Branchial cleft cyst in lateral neck that doesn’t move when swallowing. Thyroglossal duct cyst is medial and does move
1st Arch Structures, Nerve, Abnormality
Lotsa Ms and Ts: Meckel cartilage, Mandible, Malleus and incus, sphenoMandibular ligament
Muscles of Mastication, Mylohyoid, anterior belly of digastric, Tensor Tympani, Tensori veli palatini
Innervated by CN V2 and V3 (Maxillary and Mandibular)
Treacher Collins Syndrome - facial abnormalities
2nd Arch Structures, Nerve, Abnormality
Lotsa S’s
Reichert cartilage, Stapes, Styloid process, leSSer horn of hyoid, Stylohyoid ligament
Muscles of facial expression, Stapedius, Stylohyoid, platySma, posterior belly of digastric
Innervated by CN VII (facial expression/Smile)
Congenital pharyngocutaneous fistula
3rd Arch Structures, Nerve
Pharyngeal:
Cartilage: greater horn of hyoid
StyloPHARYNGEUS
Innervated by CN IX (glossoPHARYNGEAL)
4th-6th Arches Structures, Nerves
Cricothyroid and larynx:
Cartilages: Thyroid, cricoid, arytenoids, corniculate, cuneiform
4th arch: most pharyngeal constrictors, cricothyroid, levator veli palatini
6th arch: all intrinsic muscles of larynx except cricothyroid
4th arch: CN X (superior laryngeal branch) (swallow)
6th arch: CN X (recurrent larygneal branch) (speak)
1st Pouch Derivatives
Middle ear cavity/eustachian tube/mastoid air cells
2nd Pouch Derivatives
Epithelial lining of palatine tonsil
3rd Pouch Derivatives
Dorsal wings - develop into INFERIOR parathyroids
Ventral wings - develop into thymus
4th Pourch Derivatives
Dorswal wings - develop into SUPERIOR parathyroids
