Craniofacial development Flashcards
What are the pharyngeal arches?
Outpouchings on left and right side of the pharynx
How are pharyngeal arches separated on the ectoderm?
by the pharyngeal clefts - external
How are pharyngeal arches separated on the endoderm?
by the pharyngeal pouches (internal)
How are the pharyngeal arches named?
I, II, III, IV, VI - arch V does not develop
What does each pharyngeal arch contain?
- cartialge
- artery
- mesoderm (for muscle)
- specific cranial nerve
- skeletal component derived from ectomesenchyme
Which cranial nerve innervates pharyngeal arch I?
trigeminal nerve - CNV
Which cranial nerve innervates pharyngeal arch II?
facial nerve - CNVII
Which cranial nerve innervates pharyngeal arch III?
Glossopharyngeal nerve -CNIX
Which cranial nerve innervates pharyngeal arch IV?
vagus nerve (CNX)
Which cranial nerve innervates pharyngeal arch VI?
vagus nerve (CNX)
What muscles are formed from pharyngeal arch I?
- muscles of mastication (temporalis, masseter)
- myelohyoid for swallowing and speaking
- muscle stabilising the hyoid bone while swallowing (anterior belly of digastric muscle)
- tensor veli platini
What muscles are formed from pharyngeal arch II?
- muscles of facial expression
- stylohyoid
- posterior belly of digastric muscle (stabilises hyoid bone)
- stapedius
What muscles are formed from pharyngeal arch III?
Stylopharyngeus (stabilises pharynx in swallow)
What muscles are formed from pharyngeal arch IV?
- pharyngeal constrictors
- soft palate
- levator veli palatini (elevates soft palate in swallow)
What muscles are formed from pharyngeal arch VI?
Intrinsic muscles of larynx - move vocal cords to produce speech sounds
What are the skeletal derivatives of pharyngeal arch I?
- Meckel’s cartilage
- ear cartilage
- malleus
- incus
What are the skeletal derivatives of pharyngeal arch II?
- stapes
- styloid process
- part of hyoid bone
What are the skeletal derivatives of pharyngeal arch III?
hyoid bone
What are the skeletal derivatives of pharyngeal arch IV?
- laryngeal arches
- epiglottis
What does the first pharyngeal cleft form?
External ear
What happens to the pharyngeal clefts?
I - grows into outer ear
All others grow over