Head and Neck Development + Imaging w/ Headaches! Flashcards
Where are the 3 major growth areas of the head?
The skull base
Face
Cranial vault (calvarium)
What process enlarges the bones during development?
Endochondral ossification
Where are the fontanelles of the head located?
Anterior
Anterolateral/sphenoidal (each side)
Posterolateral/mastoid (each side)
Posterior
What are the flat paired bones of the skull formed from and by?
Formed from somatic mesoderm by intramembranous ossification.
What is unique about the TMJ/temporomandibular joint?
It is the only true synovial joint of the head. It has a fibrocartilage disc.
How many arches does a fetus have and what are the numbers?
1,2,3,4,6
Humans lack a 5th pharyngeal arch.
Name the CN that goes to each pharyngeal arch.
1 - V3
2 - VII
3 - IX
4 - X
6 - recurrent of X
Based on what you know regarding the arches, what muscles do they innervate?
1 is V3, so muscles of mastication.
2 is VII, so muscles of facial expression.
3 and 4 are IX and X, so muscles of the pharynx and palate.
6 is recurrent of X, so most of the phonation (laryngeal) muscles.
Describe the difference between a pharyngeal pouch and cleft.
A cleft is lateral, while pouches are medial.
What do the first pharyngeal pouches become?
Auditory tubes
What do the second pharyngeal pouches become?
Palatine tonsils
What do the third pharyngeal pouches become?
Inferior parathyroid and thymus.
What do the fourth pharyngeal pouches become?
Superior parathyroid and ultimobranchial body
What does the first pharyngeal cleft become?
External auditory meatus
What is unique about the third pharyngeal pouch?
During development, it sinks below the fourth pouch, which is why it contains the inferior parathyroid gland and the thymus.
What is malformation of the external ears commonly indicative of?
1st and 2nd arch development issues.
What is the significance of the cervical sinus in development and what do defects with it cause?
The cervical sinus needs to destroy itself during development. If not, it can form branchial cysts/fistulae.
You can have an external or internal branchial fistula/sinus, which appears as a hole in the neck or drains into the palatine tonsil.
Branchial cysts are self-isolated and fluid-filled. They do not open to skin or the pharynx.
Describe the path the thyroid gland descends down during development.
It leave the foramen cecum, going under the tongue and anteriorly, going under the hyoid anteriorly and descending in front of all the cartilages.
What is the abnormality we learned regarding thyroid development?
Thyroglossal duct cysts, where the thyroid tissue gets stuck as the gland moves down. Looks like a giant adam’s apple that is superior to where it should be.
At what week in development does a fetus look like a muppet?
3.5 weeks
At what week in development does a fetus look like an alien lizard?
5 weeks
Describe the underlying developmental issue in unilateral cleft lip and the two kinds.
Unilateral failure of the medial nasal prominence to fuse with the maxillary prominence.
Incomplete appears with an intact nose and a lip deformity unilaterally.
Complete appears with the unilateral lip fused to the nose.
What is the key developmental difference in unilateral cleft lip and oblique facial clefts?
Oblique facial clefts involve both the lateral and medial nasal prominences failing to fuse with the maxillary prominence, not just the medial.
Describe the underlying developmental issue in bilateral cleft lip and the two kinds.
Bilateral cleft lip is the same as unilateral but with both medial nasal prominences failing to fuse to the maxillary prominences. It has both incomplete and complete.
