Flashcards in Development of the Pharyngeal Arches Deck (68)
What gives rise to the oral plate?
stomadeum- ends at the pharynx. Surrounded by the 1st pharyngeal arch and is surrounded by ectoderm. (ectoderm also present anterior of the tonsillar fossa)
What are the arches made of externally, at the core and internally?
What do each of the arches consist of?
- aortic arch
- cranial nerve
What are each of the arches separated by?
- pharyngeal cleft on the outside
- pharyngeal pouch on the inside
(together they make the pharyngeal membrane)
Blood and nerve supply of the first pharyngeal arch?
blood- 1st aortic arch
nerve- mandibular and maxillary of trigeminal (CNV)
Blood and nerve supply of the 2nd pharyngeal arch?
blood- 2nd aortic arch
nerve- facial (CNVII)
Blood and nerve supply of the 3rd pharyngeal arch?
blood- 3rd aortic arch
nerve- glossoopharyngeal (CNIX)
Blood and nerve supply of the 4th pharyngeal arch?
blood- 4th aortic arch
nerve- vagus (CNX)
What do the neural crest cells make?
- bones of the face and skull
- hyoid cartilage from 2nd arch
- cartilage, bone, dentin, tendon, dermis, sensory neurons and glandular stroma
What are the 3 segments of the early brain?
forebrain, midbrain and hindbrain surrounded by somatomeres.
What is the role of HOX genes?
aid in cephalocaudal development and helps the neural crest cells migrate from different regions of the brain to the pharyngeal arches.
**HOX genes are NOT expressed anterior to rhombomere 3
What is the stomadeum bounded by?
posteriorly-buccopharyngeal membrane aka oral plate
- surrounded by the 1st arch and ectoderm
What is found anterior of the tonsillar fossa?
What are the 4 prominences that the 1st arch develops into?
- 2 maxillary prominences
- 2 mandibular prominences
What does the 1st pharyngeal cleft develop into?
external auditory meatus
What gives rise to the external ear?
1st and 2nd pharyngeal arches
What is the cervical sinus?
the 2nd arch grows downward and covers the 3rd 4th and 6th arches forming the cervical sinus
What is the fate of the ectoderm of the 1st arch?
- skin over maxilla, mandible, around the ear and external auditory meatus.
- salivary glands
- enamel around the teeth
- epithelium of buccal cavity
- epithelium of anterior portion of the tongue
Fate of ectoderm of the 2nd arch?
-skin around ear and part of external auditory meatus
- epithelium behind the ear
Fate of ectoderm of the 3rd and 4th arches?
epithelium around the ear
What does the 1st pharyngeal pouch give rise to?
middle ear cavity and auditory tube (tympanic membrane, tympanic cavity, mastoid antrum, eustacian tube)
What does the 2nd pharyngeal pouch give rise to?
endoderm and mesoderm give rise to lymphatic tissue (tonsils) and palatine tonsillar fossa
What does the 3rd pharyngeal pouch give rise to?
- Endoderm gives rise to the thymus which migrates downward into the superior mediastinum (week 4-7)
- Inferior parathyroids (week 5)
What does the 4th pharyngeal pouch give rise to?
- superior parathyroids at week 5-7
- ultimobranchial body
What does the thyroid develop from?
Endoderm. Develops as a diverticulum of the foramen secum that is located between the 1st and 3rd arch or between the tuberculum impar and the hypobranchial eminence.
Where does the diverticulum migrate to in the development of the thyroid? And where is the diverticulum from?
Endoderm of the pharynx forms the diverticulum that moves downward in front of the pharynx and as this happens there is a thyroglossal duct that appears and can persist into adulthood on occasion.
What is the thyroglossal duct?
A narrow duct that allows the pharynx to stay in contact with the thyroid.
Where do the parafollicular cells develop from?
From the 4th and 5th pouch (ultimobranchial body)
What is the pharynx?
first part of the foregut and is surrounded by the pharyngeal arches