Embryology Flashcards
What is the pharyngeal apparatus consist of?
Clefts = Pharyngeal groove = ectoderm Arches = mesoderm Pouches = endoderm
What is another name for the pharyngeal apparatus?
brachial
means gill
What does each arch have?
own nerve, vasuclar, muscular
Why is the 5th signicant?
rudimentary
disappears
no 5th arch, cleft, pouch
What happens with the 4th and 6th arch?
incorporated into 4th
What is the derivative of the arches and pouches?
Ear, tonsils, bottom to, top
1 = tympanic (middle ear cavity) + auditory (eustacian) tube
2= palatine tonsils + tonsilar fossa
3= inferior parathyroid gland + thymus
4= superior parathyroid gland + ultimobranchial body (parafollicular C cells of thyroid gland)
What is the fate of the clefts?
1st = external auditory meatus
2, 3, 4 = obliterated by overgrowth of the 2nd and 4th arch to form cervical sinus
How many arches are there at the 4th week?
4 arches
What happens if 2,3,4 clefts persist?
branchial cyst or fistula along anterior border of sternocleidomastoid
Fistual= has secretion inside and drains to outer border of SCM
What is the only membrane that persists?
1st = tympanic membrane
What do kids do at the golden arches?
Chew (1st) = 5 Smile (2nd) = 7 Stylish (3rd) = 9 Swallow (4th) Speak (6th) 10
What are the derivatives of the 1st arch?
Arch: mandibular
Nerve: V2 maxillary and V3 mandibular
Muscles: mstication (temp, mass, med lat ptery, mylohyoid, ant belly digastric, tensor palatine, tensory tympani
Sig skeletal: Meckel’s cartilae, malleus, incus
What are the derivatives of the 2nd arch?
Arch: hyoid
Nerve: VII facial
Muscles: facial expression (buccinator, auricularis, frontalis, playsma, orbicularis oris, orbicularis oculi), post belly digastric, stylohyoid, stapedius
Sig skeletal: stapes, styloid process, stylohyoid ligment
What are the dervicates of the 3rd arch?
Arch:
Nerve: IX glossopharyngeal
Muscles: stylopharyngeus
Sig skeletal: body of hyoid bone
What are the dervitives of the 4-6 arch?
Arch:
Nerve: X vagus = superior laryngeal and recurrent laryngeal
Muscles: cricothyroid, levator palatine, onstrictuors of pharynx, instrinsic mucles of larynx
Sig skeletal: thryoid
What is the path of IX glossopharyngeous?
1 innervates Stylopharngeous
2 goes into tonsilar fossa to supply palatine tonsil
3. taste of posterior 1/3 of tongue
What does all msucles of palate except one?
X
except tensor palatine = 5
What does superior parathyriod’s parafollicular c cells make?
calcitonin- role in calcium metabolism
Where does the thyroid develop from?
growth from floor of primordial pharynx between 1st and 2nd pouches
at foramen cecum of tongue
decends to larynx
What drags the thyroid down?
thryoglossal duct
Where does parathyroid gland relocate?
inferior down, superior up
thymus drags to center of chest
What are the parafollicular cells from?
mainly from 4th pair of pharyngeal pouches
What happens if the thyroid gland does not descend completely from tongue?
ectopic thyroid gland
What happens if thyroglossal duct persists?
thyroglossal duct cysts
located at midline of neck under mandible near hyoid bone
How does the oral part (anterior 2/3) of the tongue develop?
from fusion of 2 lateral lingual swellings and median tongue bud
sensory by V and taste by 7
How does the pharyneal part (post 1/3) of the tongue deveop?
from copula (hypobranchial eminence)
IX
Where do the muscles of the tongue arise?
from migration of occipital myotomes
What is anklyoglossia?
tongue tie
cant protrude tongue, cant articulate letters
What is lingual thyroid?
extopic thyroid
interrupted thyroid duct so extra tissue
What are the 3 prominences of the face development?
1 frontonasal
2 maxillary
3 mandibular
Which prominance is unpaired?
frontonasal