Branchial apparatus (arches, clefts, pouches) Flashcards
Aortic arch derivatives
1-6
develop into arterial system
1st aortic arch
part of maxillary artery (branch of external carotid)
1st arch is MAXimal
2nd aortic arch
stapedial artery and hyoid artery
second=stapedial
3rd aortic arch
common carotid artery and proximal part of internal carotid
C is 3rd letter of alphabet
4th aortic arch
left - aortic arch
right- proximal part of right subclavian artery
4th arch = 4 limbs
5th aortic arch
degenerates
6th aortic arch
proximal part of pulmonary arteries and (on left only) ductus arteriosus
nerve that gets caught in aortic arches
recurrent laryngeal nerve
right- loops under right subclavian (4th arch)
left - loops under aortic arch, distal to ductus arteriosus
branchial clefts
derived from ectoderm
aka branchial grooves
branchial arches
derived from mesoderm (muscle, arteries) and neural crest (bones and cartilage
branchial pouches
derived from endoderm
order of branchial apparatus
CAP covers outside to inside
branchial clefts - ectoderm
branchial arches - mesoderm
branchial pouches - endoderm
1st cleft
external auditory meatus
2nd-4th clefts
temporary cervical sinuses
obliterated by proliferation of 2nd arch mesenchyme
persistent 2nd-4th clefts
persistent cervical sinus
branchial cleft cyst within lateral neck, doesn’t move
versus thyroglossal cysts - midline and moves with swallowing
branchial 1st arch
M+T+chew
CARTILAGE - meckel cartilage: mandible, malleus, incus, spheno-mandibular ligament
MUSCLE - muscles of mastication (temporalis, massester, lateral and medial pterygoids), mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini
NERVES - CN V2 and V3
branchial 2nd arch
S+smile
CARTILAGE - reichert cartilage: stapes, styloid process, lesser horn of hyoid, stylohyoid ligament
MUSCLE - muscles of facial expression, stapedius, stylohyoid, platysma, posterior belly of digastric
NERVES - CN VII (facial expression)
branchial 3rd arch
pharynx+ swallow stylishly
CARTILAGE - greater horn of hyoid
MUSCLE - stylopharyngeus (innervated by glossopharyngeal nerve)
NERVES - CN IX
branchial 4+6th arch
cricothyroid+ larynx+ simply swallow + speak
CARTILAGE - thyroid, cricoid, arytenoids, corniculate, cuneiform
MUSCLE - 4th: most pharyngeal constrictors, cricothyroid, levator veli palatini; 6th: all intrinsic muscles of larynx except cricothyroid
NERVES - 4th: CN X (superior laryngeal branch); 6th: CN X (recurrent laryngeal branch)
Treacher Collins syndrome
1st arch neural crest fails to migrate -> mandibular hypoplasia, facial abnormalities
Congential pharyngocutaneous fistula
persistence of cleft (2nd/3rd) and pouch -> fistula between tonsilar area and lateral neck
posterior third tongue make up
arches 3 and 4
branchial 5th arch
no major developmental contributions
branchial 1st pouch
develops into middle ear cavity, eustachian tube, mastoid air cells
contributes to endoderm lined structures of ear
branchial 2nd pouch
develops into epithelial lining of palatine tonsil
branchial 3rd pouch
dorsal wings - develop into inferior parathyroids
ventral wings - develop into thymus
3rd pouch contributes to 3 structures
branchial 4th pouch
dorsal wings - develop into superior parathyroids
mnemonic for branchial pouches
ears, tonsils, bottom to top
1) ear
2) tonsils
3) dorsal bottom for inferior parathyroids
3) ventral (to=thymus)
4) top=superior parathyroids)
