Chapter 3 Flashcards
The oropharynx is composed of…
primitive oral cavity and the area of foregut called the pharynx
The oral pit first appears when?
4th week of development
The pharyngeal arches are so termed because?
they bend around the sides of the pharynx as bars of tissue
Within the pharynx grooves called _______ separate each arch
Pharyngeal pouches
What does the second hyoid arch form?
facial muscles vessels and hyoid bone
The outer surface of each arch is covered with?
ectoderm
What will the ectoderm become?
Epithelial lining of oral cavity
What does the first pharyngeal groove deepen to become?
external auditory canal leading to the middle ear
True or False
After the 5th week no other pharyngeal grooves are seen externally, as the tissues of the 2nd and 5th arch grow over the other arches/grooves to make contact with each other.
True
What does the second pharyngeal pouch become?
palatine tonsils
What does the third pharyngeal pouch become?
inferior parathyroids/thymus
What does the fourth pharyngeal pouch become?
superior parathyroids
What does the fifth pharyngeal pouch become?
ultimobranchial body (gives rise to the parafollicular cells of thyroid which produce hormone calcitonin)
What do the parafollicular cells of the thyroid produce?
Produce hormone calcitonin
The palatine tonsils function in the development of ______
lymphocytes (important for immunology)
What do the parathyroid glands regulate?
Calcium
What does the thymus produce?
t-cells (destroy invading microbes)
What does the ultimobranchial fuse with to contribute to parafollicular cells?
Thyroid
When do the first and second aortic arch begin to develop?
4th week and disappear in the 5th week (third arch vessel takes over the facial area of the first two)
What do the third arch vessels become?
common carotid arteries (supply face, neck and brain)
What do the fourth arch vessels become?
dorsal aorta (supplies blood to remainder of body)
What do the vessels of the sixth arch supply
supply lungs with pulmonary circulation
After seven weeks the circulation to the face and neck shifts from the internal carotid artery to ___________
the external carotid (internal carotid continues to supply the growing brain)
What do the initial skeleton of the pharyngeal arches develop as?
cartilaginous bars
Which three bilateral cartilages later transform into bone and function as the middle ear/hearing bone?
malleous
stapes
incus
What is the initial TMJ during the first 20 weeks?
contact point of malleous and incus is the articulation of the lower jaw for the first 20 weeks
What is the rod shaped cartilage of the 2nd/hyoid arch known as?
Reichert cartilage
What arises from the second arch?
stapes, styloid process, lesser horn, and upper body of the hyoid
What does the third arch form?
the greater horn/lower part of hyoid body
The fourth arch contributes to hyoid cartilage which then supports what?
thyroid gland
What does the 6th arch cartilage form?
laryngeal cartilage
What does meckl’s cartilage become?
mandible
True or False
The cartilage articulations exist between the ethmoid and sphenoid and occipital bones in the midline during the period of cranial facial growth
True (ethmosphenoid, sphenooccipital articulations)
What are sutures?
Fibrous joints in which opposing surfaces are closely united
