3.1.2 Branchial Arches Flashcards
What fraction of birth abnormalties involve craniofacial defects?
1/3
What are branchial pouches?
Endodermal outpocketings
Describe the ebryonic orgin of the tongue
Top 2/3 of tongue: 1st
Posterior 1/3 of tongue: 3rd
Most posterior: 4th-6th
What CN are associated with the pharygeal arches: 1, 2, 3, 4-6?
1st arch: CN V
2nd arch: CN VII
3rd arch: CN IX
4-6 arches: CN X
How many branchial/pharyngeal arches are there?
4-6
What comprises branchial arches?
mesenchymal core (mesoderm and neural crest) in b/t clefts and pounches
Where do the pharyngeal arches sit in relation to the pharyngeal clefts/pouches?
The pharyngeal arches sit rostral to their respective clefts/pouches. Thus, the first pharyngeal arch sits rostral to the first cleft/pouch.
Age of development? What is covered?
How is the general sensation of the tongue distributed?
Anterior 2/3: CN V3
Posterior 1/3: CN IX
Extreme Posterior: CN X
Epiglottis: CN X
How is taste distributed throughout the tongue?
Anterior 2/3: CN VII
Posterior 1/3: CN IX
Epiglottis: CN X
What are the muscle derivatives of the pharyngeal arches?
First arch: muscles of mastication/ anterior belly of digastric
2nd arch: muscles of facial expression/posterior belly of digastric
3rd: stylopharyngeus
4th: pharyngeal and laryngeal
Fill in this chart.
Which aortic arches orginate from the pharyngeal arches? What is the adult derivative of those arches?
1st and 2nd: degenerate
3rd in 3rd: internal carotid
4th in 4th: subclavian on R, portion of arch of aorta on L
6th in 6th: pulmonary arteries (ductus arteriosus)
What is being covered? Where will it be found along the neck?
Pharyngeal cyst; laterally
What is the innervation of the branchial arches?
1st branchial arch: CN V
2nd branchial arch: CN VII
3rd branchial arch: CN IX
4th branchial arch: CN X
Age of development? What is covered?
Cervical sinus
What two structures play an important role in the mirgration of the thyroid?
Top: Foramen cecum
Bottom: Thyroglossal duct
What is the intrinsic motor innervation of the tongue?
Intrinsic musculature: CN XII (Hypoglossal)
Palatoglossus: CN X (pharyngeal plexus)
What are the 4 possible consituents of a branchial arch?
Artery (aortic arch), nerve (cranial nerve), muscle (mesoderm-derivative), cartilage (neural crest derivative)
C
What age of development? ID the parts
What are branchial clefts?
Ectodermal ingrowths
Know the cartilages
Age of development? What is covered?
Neural crest cells migrate into the ultimobranchial body which forms from the ventral part of the 4th pouch or the 5th pouch (if it forms in humans). The C cells of the thyroid are therefore derived from neural crest cells. Please note the vertical transposition of the parathyroids developing from the 3rd and 4th pouches.
Note: They are vertically transposed during embryogenesis. This is significant in function-preserving parathyroidectomy, because both the superior and the inferior parathyroids are supplied by the inferior thyroid artery. If the surgeon is to leave a single functional parathyroid for the patient, he/she must preserve the appropriate blood supply.
Neural crest cells migrate into the ultimobranchial body which forms from the ventral part of the 4th pouch or the 5th pouch (if it forms in humans). The C cells of the thyroid are therefore derived from neural crest cells. Please note the vertical transposition of the parathyroids developing from the 3rd and 4th pouches.
Note: They are vertically transposed during embryogenesis. This is significant in function-preserving parathyroidectomy, because both the superior and the inferior parathyroids are supplied by the inferior thyroid artery. If the surgeon is to leave a single functional parathyroid for the patient, he/she must preserve the appropriate blood supply.
What are these images of?
Branchial (pharyngeal) fistula
Where in the neck?
Top: Lateral
Bottom: Midline
Fill in this chart
How old is this embryo?
28 days
