Embryology VI Flashcards
(90 cards)
What 3 groups of mesoderm fall through the primative streak?
- Laterally Migrating Mesoderm
- Cardiogenic Mesoderm
- Pharyngeal Arch Mesoderm
What are the 3 subgroups of laterally migrating mesoderm?
- Paraxial
- Intermediate
- Lateral Plate Mesoderm
Explain were each of the following migrate after going through the primative streak.
- Laterally Migrating Mesoderm
- Cardiogenic Mesoderm
- Pharyngeal Arch Mesoderm
Laterally Migrating Mesoderm:
Laterally
Cardiogenic Mesoderm:
Most Cranial of all Mesoderms
(to the oropharyngeal membrane)
Pharyngeal Arch Mesoderm:
More caudal then cardiogenic mesoderm (stops short of the oropharyngeal membrane)
What are the 3 components of the pharyngeal apparatus?
- Pharyngeal arches (6)
- Pharyngeal Grooves (4)
* *covers OUTSIDE of the apparatus - Pharyngeal Pouches (4)
* *covers the INSIDE of the apparatus
What embryologic cell types are associated with:
- Pharyngeal Arches
- Pharyngeal Pouches
- Pharyngeal Grooves
Pharyngeal Arches:
Pharyngeal Arch Mesoderm
Pharyngeal Groove (Outer): Ectoderm
Pharyngeal Pouches (inner): Endoderm
T or F: neural crest cells migrate to the pharyngeal arches
True
What 3 components make up each of the pharyngeal arches?
- Arch Cartilage
- Aortic Arch
- Mesoderm the forms head and neck muscles (BE mesoderm)
*Cranial Nerves are also there but they are not derived from the arch
What is arch cartilage?
- what does it give rise to?
- Essential Cells?
- Pre-cartilagenous mesenchyme that gives rise to bone/cartilage/CT
**Migration of Neural Crest = essential to formation
T or F: the cranial nerve associated with each pharyngeal arch is derived from neural crest cells
False, it is derived from neuroectoderm
*Bones/cartilage/CT of pharyngeal arches depends on migration of neural crest cells
What are somites and what are they derived from?
- Mesodermal blocks on each side of the midline
- Mesoderm => Lateral Migrating Mesoderm => Paraxial (somite) Mesoderm
What are the most cranial somites that start to thin out?
- what do they give rise to?
- Occiptal Somites
Give rise to:
- SKELETAL muscles of the tongue
- 7 extraocular muscles
What type of innervation is supplied to occiptal somites and what nerves do this?
- GSE innervation (not BE because these don’t come from the pharyngeal arches)
- CN: 3, 4, 6, 12
Besides occipital somites, what gives rise to the skeletal muscles of the head?
- Pharyngeal Arches (from pharyngeal apparatus)
Nerve associated with each arch?
- V3 (mandibular n.)
- VII
- IX
4/6. X
T or F: 1st and 2nd aortic arches do not form any major systems and the 5th arch never developed anything.
True
What do the R and L sides of the 3rd aortic arch give rise to?
- Major Arterial System of the Neck
- R and L common carotid
- MOST of R and L internal carotid
What is contained in the core of each pharyngeal arch?
- Central Rod of Pre-cartilaginous mesenchyme that gives rise to skeletal structures (bond/cart/CT)
**Developement driven by neural crest cells
Failure of NC cells to migrate to pharyngeal arches leads to defects affecting what general area?
- examples
- Anterior face Development Affected
- Cleft Lip and Cleft Palate both result from this
What is derived from the pharyngeal mesoderm component of each arch?
- Skeletal Muscle
- Aortic Arch Derivatives
**NC cells do skeleton/CT stuff
T or F: each cranial nerve associated with a particular arch is derived from the arch itself.
FALSE, they are derived from neuroectoderm that is only associated with the arch
What bones does Arch 1 give rise to?
- note any cartilaginous intermediates
Anterior Face Bones:
- mandible
- maxilla
- zygomatic bones
Middle Ear Bones (from MECKELs Cartilage):
- Malleus
- Incus
What Muscles are derived from Arch 1?
MAST-MATT
Masication:
- massester
- temporalis
- lateral pterygoid
- medial pterygoid
Matt:
- Mylohyoid
- Anterior Digastric
- Tensor Tympani
- Tensor Veli Palatine
If you have an issue in development of arch 1, what will be the likely results?
- Facial Abnormalities
- Difficulty Chewing
What Bones does the 2nd pharyngeal arch give rise to?
- Cells responsible?
- PARTS HYOID BONE
- styloid process of Temporal bone
- STAPES of Middle Ear
**As always NC cells are responsible for the bony and cartilaginous components