Lecture 6: Embryology of Pharyngeal Apparatus Flashcards
What does a pharyngeal apparatus consist of?
- Pharyngeal Arches
- Pharyngeal Pouches (internal structure - endoderm)
- Pharyngeal Grooves/Clefts (ectoderm)
What is the embryological origin of phayngreal arches?
Neural Crest Cells
What pharyngeal arch do the primordial jaws arise from?
1st Pharyngeal Arch
Neural Crest Cell
What germ layer(s) contribue to the core of a pharyngeal arch?
What germ layer(s) externally cover the pharyngeal arch?
- *Core:** Mesoderm and Mesenchyme (migratory NCC)
- *Cover:** Ectoderm and Endoderm
What is the function of pharyngeal arches?
- Support lateral walls of primordial pharynx
- Give rise to prominences of tissue that contribue to craniofacial development
What germ layer plays an essential role in regulation the development of arches?
Pharyngeal Endoderm
What germ layer gives rise to facial muscles?
Paraxial Mesoderm
What germ layer gives rise to endothelium?
Lateral Plate Mesoderm
What germ layer gives rise to extraocular muscles?
Prechordal Plate Mesoderm
What structures will a typical pharyngeal arch contain?
- Cartilagenous Rod: skeletal elemnts
- Muscular Component: Paraxial and Prechordal derived
- Cranial Nerves: sensory and/or motor components
- Artery: from truncus arteriosus
What pharyngeal arch does Meckel’s cartilage arise from?
Pharyngeal Arch 1
What does the dorsal part of Meckel’s cartilage form?
What germ layer do these structures arise from?
Malleus and Incus bones
Neural Crest Cells
What does the perichondrium of Meckel’s cartilage form?
Anterior ligament of Malleus bone
Sphenomandibular Ligament
What does the ventral side of Meckel’s cartilage give rise to?
Primordium of mandible (transient structure)
Proper mandible will form laterally to it while Meckel’s cartilage disintegrates
What is the cartilage of Pharyngeal Arch 2?
Riechert’s cartilage
What does the dorsal part of Riechert’s cartilage form?
Stapes
Styloid Process of the Temporal Bone
What arises from the ventral end of Riechert’s cartilage?
Lesser cornu/horn of Hyoid bone
What arises from the perichondrium of the Riechert’s cartilage?
Stylohyoid L.
What does the 3rd Pharnygeal cartilage give rise to?
Greater horn/cornu of hyoid bone
What does the hypopharyngeal eminence give rise to?
What PAs does it arise from?
Body of hyoid bone
Arises from Pharyngeal Arches 3 and 4: floor of embryonic pharanyx
What pharyngeal arches do the laryngeal cartilages come from?
Pharyngeal Arches 4 and 6