Session 5: Development of the Head & Neck 1 Flashcards
In which week does the development of the head begin?
4th week
What begins growing in the 4th week of embryonic development.
Pharyngeal arches.
Where do the pharyngeal arches form?
In the lateral walls of the embryonic pharynx.
Explain the properties of the pharyngeal arches.
They have a mesenchyme core and ectoderm on its external surface.
On its internal surface they are lined in endoderm.
How many pharyngeal arches form?
Theoretically 6 but only 5 in humans.
Pharyngeal arches 1-4 and then 6.
First arch is the biggest one.
What are the pharyngeal arches associated with?
Cartilage, nerve and artery.
What kind of cartilage does the 1st pharyngeal arch form?
Meckel’s cartilage
What does Meckel’s cartilage give rise to?
Mandible, malleus, and incus bones.
What kind of cartilage does the 2nd pharyngeal arch form?
Reichert’s cartilage - stapes (ear) and also of the upper part of the hyoid bone
What kind of cartilage do the 3rd and 4th pharyngeal arches form?
3rd - Inferior parth of body of hyoid
3rd and 4th - Epiglottis
What kind of cartilage do the 4th and 6th pharyngeal arch form?
Larynx cartilage:
Thyroid cartilage
Arytenoids cartilage
Cricoid cartilage
What arteries do the 1st and 2nd pharyngeal arch form?
None
They disappear
What arteries does the 3rd pharyngeal arch form?
Common, external and internal carotid arteries with their branches.
What arteries does the 4th pharyngeal arch form?
Aortic arch and the brachiocephalic trunk
What arteries does the 6th pharyngeal arch form?
Pulmonary arteries
What nerve does the 1st pharyngeal arch form?
Trigeminal nerve (CN V)
What nerve does the 2nd pharyngeal arch form?
Facial nerve (CN VII)
What nerve does the 3rd pharyngeal arch form?
Glossopharyngeal nerve (CN IX)
What nerve do the 4th and 6th pharyngeal arches form?
Vagus nerve (X)
What muscles does the 1st pharyngeal arch form?
Muscles of mastication
What muscles does the 2nd pharyngeal arch form?
Muscles of facial expression
Stapedius
What muscles does the 3rd pharyngeal arch form?
Stylopharyngeus