Flashcards in CFD5- Pharyngeal arches Deck (48)
what are 4 primary germ layers?
-neural crest/ ecto-mesenchyme
Describe the ectoderm.
skin, neural tube, etc this comes from the Epiblast layer
Describe the mesoderm.
forms everything else and is from migratory cells of the epiblast layer
Describe the endoderm.
gut- this comes from the hypoblast
Describe the neural crest/ echo-mesenchyme.
from the ectoderm that migrates into mesoderm to form structures in head and neck
how is neural tube formed?
Describe the formation of feotus.
-sperm fusing with egg
-Embryoblast differentiates into two components – epiblast and hypoblast
amniotic fluid seeping in to form the amniotic cavity –gaps formed so nutrients can get to the cells-this layer of animal cells will form ectoderm and endoderm
-The mesoderm forms and migrates in from the sides and forms a divide between the ectoderm and the endoderm
-The ectoderm migrates into the mesoderm and folds
what day do the arches form?
4th and 5th week
How do the arches change?
Cartilages are made very early and then disappear and replaced by bones
how is the stomatodeum (oral cavity) formed?
gap formed by the disintegration of a layer of cells from the oropharyngeal membrane
what are the arches separated by externally?
what are the arches separated by internally?
what is the only arch not lined by endoderm on the inside?
what lines all the arches on the outside?
what does each arch have?
-endoderm (inside)- except 1st arch
what is the 1st arch called?
what does the first arch form?
what is the mandibular arch made of?
mandibular and maxillary process
Describe the cartilage: meckel's cartilage.
-Primitive support, largely disappears
what does the 1st pharyngeal arch give rise to?
-Body of tongue
-Muscles of mastication:
Temporalis, masseter, pterygoids
Mylohyoid, anterior body of digastric
what nerve innervates the 1st pharyngeal arch?
what is the blood supply of the 1st pharyngeal arch?
maxillary and carotid arteries
Describe treacher-collins syndrome.
-Genetic-can be a simple as a single polymorphism.
-Failure of neural crest cell migration
-Facial Bone hypoplasia:
Mandible and zygoma
Misplacement upper 6s
what does the 2nd arch called?
what does the reicherts cartilage form?
-Lesser horn and superior hyoid body
-styloid process, stylohyoid ligament
what muscles are in the 2nd arch?
facial expression and posterior belly digastric
what other tissues are in the 2nd arch?
thyroid gland and tonsil
what nerve innervates the 2nd arch?
what does the 3rd arch form?
-greater horn of hyoid
-inferior hyoid body
-root of the tongue