Embryology 4 - The Oropharyngeal Apparatus Flashcards
A core of mesenchyme covered externally by ectoderm and internally by endoderm
Pharyngeal Arch
What is the mesenchyme derived from in teh third week?
Mesoderm
During the fourth week, most of the mesenchyme is derived from _______ cells that migrate into the ________
Neural crest cells; pharyngeal arches
When the neural crest cells migrate into the arches, what does their differentiation into mesenchyme produce?
Maxillary and mandibular prominences
Components of a pharyngeal arch?
- Artery
- Cartilaginous rod
- Muscular component
- Sensory and motor nerves
Where does a pharyngeal arch artery arise from?
Truncus arteriosus from primordial heart
What does the pharyngeal arch cartilaginous rod form?
The skeleton of the arch
What does the muscular component of the pharyngeal arch differentiate into?
Muscles of the head and neck
Where are the sensory and motor nerves of the pharyngeal arches derived from?
Neuroectoderm of the primordial brain
The pharyngeal arches are the main formative elements of what structures?
- face
- nasal cavities
- mouth
- pharynx
- larynx
- neck
During the fifth week, what happens to the second pharyngeal arch? What is produced?
- Second pharyngeal arch enlarges and overgrows the third and fourth
- Forms the cervical sinus
What happens by the end of the seventh week?
Second and fourth arches disappear - gives head and neck smooth contour
What does the primordial pharynx join when it widens cranially and caudally?
- Cranially = stomodeum
- Caudally = esophagus
The pharyngeal endoderm lines the internal aspects of the pharyngeal arches and passes into the diverticula = ________
Pharyngeal pouches
How many pairs of pharyngeal pouches are there?
4 (the 5th is rudimentary or absent)
What separates the pharyngeal pouches from the pharyngeal grooves? How many layers?
Pharyngeal membrane = 2 layers (no mesoderm)
Where are the pharyngeal grooves located?
On the outside of the embryo
The first pharyngeal arch separates into what two prominences?
Maxillary and mandibular
What does the maxillary prominence give rise to?
Maxilla, zygomatic bone, part of vomer
What does the mandibular prominence give rise to?
Mandible (and also forms the temporal bone)
What do the second and third pharyngeal arches form?
The hyoid bone
The first and second pharyngeal cartilages give rise to what?
Ossicles of middle ear and styloid process of temp bone
The fourth and sixth pharyngeal arches give rise to what?
Laryngeal cartilage
The third and fourth pharyngeal arches give rise to what?
The epiglottis
