Pharyngeal Arches Flashcards
When does the head and neck start to develop?
Week 4
What forms the structure of the head and neck?
Pharyngeal arches
How do the pharyngeal arches form?
Growth of mesenchymal tissue in cranial region forms arches separated by clefts
What separates the arches on the internal surface?
Pharyngeal pouches
What separates the arches on the external surface?
Pharyngeal clefts
What makes up the internal surface?
Endoderm
What makes up the external surface?
Ectoderm
How many pharyngeal clefts are there initially?
4
What happens to the clefts?
1st cleft becomes external auditory meatus
2nd, 3rd, 4th are obliterated by 2nd pharyngeal arch
How many pharyngeal arches are there initially?
6
Which pharyngeal arch regresses?
5th
What makes up each arch?
Cranial nerve
Muscular component
Skeletal/cartilaginous supporting element
Vascular component
How is the 1st arch split?
Maxillary prominence (dorsal portion)
Mandibular prominence (ventral portion)
What does the maxillary prominence form?
Maxilla
Zygomatic bone
Part of temporal bone
What cartilage is associated with the maxillary prominence?
Maxillary cartilage
What does the maxillary cartilage give rise to?
Incus
What does the mandibular prominence form?
Mandible
What cartilage is associated with the mandibular prominence?
Meckel’s cartilage
What does Meckel’s cartilage give rise to?
Malleus
Sphenomandibular ligament
What is the artery of the 1st arch?
Maxillary artery
What cranial nerve is associated with the 1st arch?
CN V - trigeminal
What muscles are formed by the 1st arch?
Muscles of mastication
Mylohyid
Anterior belly of digastric
Tensor tympani
What are the arteries of the 2nd arch?
Stapedial artery
Hyoid artery
What is the cartilage component of the 2nd arch?
Reichart’s cartilage
What does Reichart’s cartilage give rise to?
Stapes
Styloid process
Stylohyoid ligament
Part of hyoid bone
What cranial nerve is associated with the 2nd arch?
CN VII - facial
What muscles are formed by the 2nd arch?
Muscles of facial expression Stapedius Stylohyoid Platysma Posterior belly of digastric
What is the artery of the 3rd arch?
Common carotid
What does the cartilage of the 3rd arch give rise to?
Part of hyoid
What cranial nerve is associated with the 3rd arch?
CN IX - glossopharyngeal
What muscle is formed by the 3rd arch?
Stylopharyngeus
What are the arteries of the 4th arch?
Right = proximal subclavian
Left = aortic arch
What does the cartilage of the 4th arch give rise to?
Laryngeal cartilages
- thyroid
- corniculate
- cuneiform
What cranial nerve is associated with the 4th arch?
Superior laryngeal branch of CN X - vagus
What muscles are formed by the 4th arch?
Pharyngeal constrictors
Levator palatini
Cricothyroid
What are the arteries of the 6th arch?
Right - proximal pulmonary arteries
Left - ductus arteriosus
What cranial nerve is associated the 6th arch?
Recurrent laryngeal branch of CN X - vagus
How many pharyngeal pouches are there?
5 - only 4 give rise to adult structures
What is formed from the 1st pouch?
Eustachian tube
Middle ear cavity
What is formed from the 2nd pouch?
Lining of the palatine tonsils
What is formed from the 3rd pouch?
Dorsal - inferior parathyroid glands
Ventral - thymus
What is formed from the 4th pouch?
Dorsal - superior parathyroid glands
