10 - Head and Neck Development 2 Flashcards
What are the growth centers of the face? What do they surround?
Frontonasal prominence, maxillary prominence, and the mandibular prominence.
They surround the stomadeum, the primordial mouth.
What is the difference between fusion and merging?
Fusion: two free structures come together, oppose each other, and the epithelium between them degenerates and the underlying mesenchyme comes together.
Merging: accumulation of mesenchyme underneath adjacent prominences.
Where are the lateral and medial nasal prominences located? What do these surround?
Within the frontonasal prominence.
Surrounds the nasal placode, which becomes the floor of the nasal pit.
What forms the nasolacrimal duct?
The maxillary prominence fusing with the lateral nasal prominence and frontonasal prominence.
What do the medial nasal prominences form?
The intermaxillary segment:
- middle part of the upper lip
- incisor bridge of the maxilla
- primary palate
The fusion of the maxillary prominence and the medial nasal prominence completes the formation of what?
The upper lip.
As a result of the fusion of the maxillary prominence and the medial nasal prominence, the primitive nasal cavity is now isolated from what?
The oral cavity and the nasopharynx.
The maxillary prominence merges with the mandibular prominence to form what?
The cheek and narrows the opening of the mouth.
The lower jaw is now complete.
How does is the communication between the nasal cavity and the pharynx established?
The lateral and medial prominences expand and form a nasal pit.
The oronasal membrane between the nasal cavity and the oral cavity will stretch out and rupture, causing a communication between the nasal cavity and the developing nasopharynx called the choana.
When the choana are formed, what structure is now present?
The soft palate, a boney shelf that separates the oral and nasal cavity.
What is choanal atresia?
The absence of the nasal choanae (a hole not forming).
What type of atresia can cause respiratory distress in newborn infants?
Bilateral choanal atresia, because newborns are obligate nasal breathers.
What is responsible for the depth and height of the nasal cavity and kepts the orbit separated at a proper distance
Ethmoid bone.
Describe the growth of the mid-face that occurs during weeks 5-9?
Constant and lateral.
Arch 1 grows faster than the others. Facial muscles (arch 2) grow over those derived from arch 1.
Eyes move toward the midline and ears move superio-dorsally.
What important switch happens between week 7 and 8?
The switch of blood supply from the stapedial artery to the external carotid artery.