Pharyngeal Apparatus Development Flashcards
Where are pharyngeal grooves or clefts?
-external and covered by ectoderm
What are pharyngeal arches?
- 6 bilateral ridges form in cranial to caudal sequence
- neural crest cell migration
- support lateral walls of pharynx
- forms the face, nasal cavities, mouth, larynx, pharynx and neck
Where are pharyngeal pouches?
- internal and lined by endoderm
- 4 are well define with the 5th being rudimentary or absent
What are pharyngeal membranes?
- separating the grooves from the pouches
- ectodermal/endodermal double-layered membrane
- resemble fish at this stage
What is the stomodeum?
-slight external depression indicating location of future mouth
What is the oropharyngeal membrane?
bilaminar membrane separating stomodeum from pharynx
- external surface covered by ectoderm - internal surface lined by endoderm - ruptures and opens passage into forgut
What forms the core of pharyngeal arches?
mesenchyme
What is the mesenchyme in pharyngeal arches formed by and what does it therein form?
- formed by neural crest cells
- forms all CT and smooth mm
- mm derived from somites
What covers the surfaces of pharyngeal arches?
ectoderm = external surface endoderm = internal surface
What does each pharyngeal arch contain?
- cartilaginous rod = skeletal structures
- mm component = somites
- sensory/motor nn. = neuroectoderm
- pharyngeal arch a. = truncus arteriosus
What does pharyngeal arch 1 (Mandibular arch) give rise to?
- malleus & incus - dorsal part
- sphenomandibular ligament and ant ligament of malleus - perichondrium of middle portion
- mandibular prominence - forms mandible - forms by intramembranous ossification
- maxillary prominence forms maxilla, zygomatic and temporal bone
- maxiallary prominence
What does pharyngeal arch 2 (Hyoid arch) give rise to?
- stapes and styloid process of temporal bone - from dorsal part
- stylohyoid ligament - from perichondrium of middle portion of cartilage
- lesser cornu and superior body of hyoid - from ventral portion of cartilage
What does pharyngeal arch 3 give rise to?
-greater cornu and inferior body of hyoid
What does pharyngeal arch 4&6 give rise to?
- fuse to form laryngeal cartilages
- thyroid, cricoid, arytenoids, corniculate, cuneiform
- EXCEPTION: epiglottis
- forms from hypopharyngeal eminence on floor of pharynx
What does pharyngeal arch 5 form?
Rudimentary = no structures!
What are the corresponding nerves for pharyngeal arch 1?
V2(maxillary) and V3(mandibular) of CNV (trigeminal)
What mm do the nerves that correspond to pharyngeal arch 1 innervate?
-mm of mastication, mylohyoid, ant belly of digastric, tensor tympani, tensor veli palatini
What are the corresponding n to pharyngeal arch 2?
CNVII (facial)
What mm are innervated by the nerves of pharyngeal arch 2?
mm of facial expression, stapedius, post belly of digastric, stylohyoid.
What is the corresponding n to pharyngeal arch 3?
CNIX (glossopharyngeal)
What mm do the nerves of pharyngeal arch 3 innervate?
stylopharyngeus
What is the corresponding n to pharyngeal arch 4?
CNX (vagus)
What mm do the n that correspond to pharyngeal arch 4 innervate?
-pharyngeal constrictors, cricothyroid, levator veli palatini
What is the corresponding n of pharyngeal arch 6?
CNX (vagus)