development of pharyngeal arches Flashcards
pharyngeal arches consist of a core of mesenchyme which is made of ____
mesoderm and NCCs
pharyngeal arches are covered by ____ externally and ____ internally
ectoderm
endoderm
pharyngeal arches are separated by ____ externally and ____ internally
pharyngeal clefts/grooves
pharyngeal pouches
where groove and pouch touch
pharyngeal membrane
what is crucial for proper facial development?
1st arch separates found on either side of oropharyngeal membrane
allows future pharynx and foregut to communicate with amniotic cavity once oropharyngeal membrane breaks down
stomodeum
components of pharyngeal arches
artery
cartilaginous rod
muscular component
nerve
from truncus arteriosus of heart
artery
supports the arch and is involved in formation of arch derived skeletal elements
cartilaginous rod
forms many muscles of head and neck
muscular component
each arch is associated with one ____ that supplies skin, mucosa, and muscles associated with the arch
cranial nerve
arches contributions
face
nasal cavities
mouth
larynx
pharynx
neck
1st arch cartilage derivatives
palatoquadrate bar (maxillary swelling): incus and alisphenoid
Meckel’s cartilage (mandibular swelling): proximal: malleus, anterior ligament of malleus and sphenomandibular ligament
distal: mandible
2nd arch cartilage derivatives
reichert’s cartilage: stapes, styloid process, stylohyoid ligament, lesser cornua and body of hyoid bone
3rd arch cartilage derivatives
greater cornua and part of body of hyoid bone
4th and 6th arch cartilage derivatives
laryngeal cartilages
1st arch artery derivative
maxillary artery
2nd arch artery derivative
stapedial artery
3rd arch artery derivative
common carotid artery and proximal internal carotid artery
4th arch artery derivative
R: proximal right subclavian artery
L: arch of aorta
6th arch artery derivative
L: proximal left pulmonary artery and ductus arteriosus
R: proximal right pulmonary artery
1st arch muscle derivatives
muscles of mastication: temporalis, pterygoids and masseter
tensor tympani
tensor veli palatini
mylohyoid
anterior belly of digastric
2nd arch muscle derivatives
muscles of facial expression
posterior belly of digastric
stylohyoid
stapedius
3rd arch muscle derivative
stylopharyngeus
4th and 6th arch muscles derivatives
pharyngeal constrictors
levator palatini
cricothyroid
laryngeal muscles
1st arch nerve
trigeminal CN V
2nd arch nerve
facial CN VII
3rd arch nerve
glossopharyngeal CN IX
4th and 6th arch nerve
vagus CN X
1st pharyngeal cleft derivative
external acoustic meatus
external layer of tympanic membrane
how is the cervical sinus created?
remaining grooves are obliterated by overgrowth of 2nd pharyngeal groove
1st pharyngeal pouch derivatives
tubotympanic recess
tympanic cavity
mastoid antrum
internal surface of tympanic membrane
pharyngotympanic tube
2nd pharyngeal pouch derivatives
tonsillar sinus (fossa)
tonsillar crypts
3rd pharyngeal pouch derivatives
dorsal: inferior parathyroid gland
ventral: thymus
4th pharyngeal pouch derivatives
superior parathyroid gland
ultimobranchial body
describe the development of the tongue
begins as median swelling on floor of primordial pharynx rostral to foramen cecum
two distal tongue buds rapidly increase in size, fuse and overgrow median tongue bud creating anterior 2/3 tongue
copula from fusion of ventromedial parts of 2nd arches forms caudal to foramen cecum
hypopharyngeal eminence from ventromedial parts of 3rd and 4th arches overgrows copula forming posterior 1/3 of tongue
where are most of the tongue muscles derived from?
occipital somites
firs endocrine gland to develop
thyroid
describe the development of the thyroid
forms from median endodermal thickening of floor of primordial pharynx
becomes an out-pocketing (thyroid primordium)
where is the orientation of the thyroid when it descends into the neck?
ventral to hyoid and laryngeal cartilages
proximal opening of thyroglossal duct persists as small pit
foramen cecum
thyroid gland is connected to tongue via ____
thyroglossal duct
form anywhere along the course of the thyroglossal duct
thyroglossal duct cyst
where can a thyroglossal cyst form?
in tongue or anterior to neck just inferior to hyoid bone
opens in median plane anterior to laryngeal cartilages
thyroglossal duct sinus