Block 4 Embryo Flashcards
pharyngeal apparatus consists of
pharyngeal arches, pouches, clefts (grooves), and membranes
each pharyngeal arch consists of
mesoderm (differentiates into muscles and arteries)
neural crest cells (differentiate into bone and connective tissue)
List the cranial nerves associated w/ each pharyngeal arch
1: CN V (trigeminal)
2: CN VII (facial)
3: CN IX (glossopharyngeal)
4: CN X (superior laryngeal)
5: CN X (recurrent laryngeal)
List the pharyngeal arches
1,2,3,4, and 6 (5 regresses)
List the pharyngeal pouches and what they’re made of
1,2,3,4
evaginations of endoderm that line the foregut
List the pharyngeal clefts/grooves and what they’re made of
1,2,3,4
invaginations of ectoderm located b/w each pharyngeal arch
List the pharyngeal membranes & what they’re made of
1,2,3,4
consists of ectoderm, intervening mesoderm and neural crest, and endoderm located between each arch
Fate of pharyngeal cleft/groove 1
develops into the external auditory meatus
Describe development of the thyroid gland
in the midline of the floor of the pharynx, endodermal lining of the foregut forms the thyroid diverticulum
the thyroid diverticulum migrates caudally, passing ventral to the hyoid bone and laryngeal cartilages. during this migration, the thyroid remains connected to the tongue by the thyroglossal duct, which is later obliterated
List arch 1 derivatives
mesoderm: muscles of mastication, mylohyoid, anterior belly of digastric, tensor veli palatini, tensor tympani
neural crest: maxilla, mandible, incus, malleus, zygomatic bone, squamous temporal bone, palatine bone, vomer, sphenomandibular ligament
CN V (trigeminal nerve)
List arch 2 derivatives
mesoderm: muscles of facial expression, posterior belly of digastric, stylohyoid, stapedius
neural crest: stapes, styloid process, stylohyoid ligament, lesser horn and upper body of hyoid bone
CN VII (facial N)
List arch 3 derivatives
mesoderm: stylopharyngeus, common carotid arteries, internal carotid arteries
neural crest: greater horn ad lower body of hyoid bone
List arch 4 derivatives
mesoderm: muscles of soft palate (except tensor veli palatini), muscles of pharynx (except stylopharyngeus), cricothyroid, cricopharyngeus, laryngeal cartilages, right subclavian artery, arch of aorta neural crest: none CN X (superior laryngeal)
List arch 6 derivatives
mesoderm: intrinsic muscles of larynx (except cricothyroid), upper muscles of esophagus, laryngeal cartilages, pulmonary arteries, ductus arteriosus neural crest: none CN X (recurrent laryngeal nerve)
Pouch 2 develops into
epithelial lining of palatine tonsil crypts
Pouch 3 develops into
inferior parathyroid gland, thymus
Pouch 4 develops into
superior parathyroid gland