pharyngeal apparatus Flashcards
pharyngeal apparatus
pharyngeal clefts
pharyngeal arches
pharyngeal pouches
pharyngeal clefts
external invagination of ectoderm
4
pharyngeal arches
core of mesenchyme (neural crest and paraxial mesoderm)
neural crest gives rise to CT components, paraxial mesoderm to mm
each arch own CN and blood supply
6 arches, by 5th regresses
pharyngeal pouches
internal evagination of pharyngeal endoderm
4
arch 1 skeletal derivatives
viscerocramium (malleus, incus)
CT of face
arch 1 mm derivatives
mm of mastication ant belly of diagastric mylohyoid tensor tympani tensor veli palatini
Nerve of arch 1
V3
Oropharyngeal membrane
from 2 processes of arch 1
outer layer of ectoderm and inner layer of endoderm
ruptures by day 26 to allow for communication btwn oral cavity and pharynx
arch 2 skeletal derivatives
stapes, styloid process of temporal bone
stylohyoid lig, lesser horn and sup portion of body of hyoid
arch 2 mm derivatives
mm of facial expression
stylohyoid
posterior belly of diagastric
stapedius
nerve of arch 2
VII
arch 3 skeletal derivatives
greater horn and inferior portion of body of hyoid bone
arch 3 mm derivatives
stylopharyngeus
n of arch 3
glossopharygeal IX
arch 4 skeletal derivatives
forms all laryngeal cartilages
arch 4 of mm derivatives
cricothyroid
arch 4 n
X
arch 6 skeletal derivatives
w/4th arch form all laryngeal cartilages
arch 6 mm derivatives
laryngeal mm except cricothyroid
skeletal m of esophagus
nerve of arch 6
X and recurrent laryngeal n
pouch 1
contributes to formation of middle ear and auditory tube
pouch 2
forms stroma of palatine tonsil
tonsillar fossa
pouch 3
dorsal portion- inf parathyroid glands
ventral portion- thymus
pouch 4
dorsal portion- sup parathyroid glands
ventral portion- ultimobrachial body
first cleft
formation of external ear
clefts 2-4
get buried by arch 2
remnants form cervical sinus which is later obliterated
thyroid development
derived froom median endodernal thickening of pharyngeal floor
connected to tongue by thyroglossal duct until wk 7
superior opening of thyroglossal duct becomes foramen cecum
50% of ppl of pyramidal lobe, remnant of distal thyroglossal duct
parafollicular C cells derived froom ultimobrachial body of 4th pouch
tongue development
1st pharyngeal arch form the body (ant 2/3) GSA from V
3rd arch forms root (post 1/3) GVA from glossopharyngeal
4th arch forms epiglottic region of tongue GVA from X
mm derived from paraxial mesoderm of occiptial somites
lateral cervical cysts
form when cervical sinus fails to degenerate
found along ant border of SCM
Branchial fistulas
when 2nd arch fails to overgrow 3rd and 4th arches
cervical sinus retains connection w/surface (external fistula)
rarely the lateral cervical cyst can open into pharynx (internal fistula)
neural crest defects
treacher collins syndrome
robin sequence
DiGeorge anomaly
DiGeorge syndrome
deletion of long arm chrom 22 cardiac abnormalities craniofacial defects thymic hypoplasia parathyroid dysfunction -> hypocalcemic
