Week 8: Craniofacial Embryology Flashcards
when do head and neck develop and from what?
weeks 4-8; from pharyngeal or branchial apparatus
3 components of pharyngeal apparatus
- arches, clefts, and pouches
* 5 pairs of arches forms starting on day 22
pharyngeal clefts are made from what germ layer?
ectoderm
pharyngeal pouches are made from what germ layer?
endoderm
structure of each pharyngeal arch
outer ectoderm, inner endoderm, and core of mesenchyme -> mesoderm and neural crest
The neural crest portion of the pharyngeal arches form
cartilage, CT, and an arch-associated nerve
The mesoderm portion of the pharyngeal arches form
skeletal muscle and an artery
2 components of 1st pharyngeal arch
- maxillary process
* mandibular process
Maxillary process of 1st arch forms
maxilla and zygomatic bones
mandibular process of 1st arch forms
mandible and Meckel’s cartilage
what does Meckel’s cartilage become?
the incus and malleus of the middle ear
muscle derived from the 1st arch
- muscles of mastication (temporalis, masseter, and pterygoids)
- anterior digastric
- mylohyoid
- tensor tympani
- anterior 2/3 of the tongue
cranial nerve associated with 1st arch
trigeminal nerve (CN V), specifically the maxillary and mandibular divisions
1st pharyngeal arch artery gives rise to
a portion of the maxillary artery
2nd pharyngeal arch forms what skeletal structures
- Reichart’s cartilage -> stapes of middle ear
- styloid process of temporal bone
- lesser cornu (horn) and upper body of hyoid bone
muscle derived from 2nd arch
- muscles of facial expression
- stapedius
- stylohyoid
- posterior belly of digastric muscle
nerve associated with 2nd arch
facial nerve (CN VII)
Artery of the 2nd arch form
- 2 embryonic arteries: stapedial and hyoid
* hyoid develops into a small branch of the internal carotid
3rd pharyngeal arch forms
greater cornu and lower body of hyoid bone
muscles derived from 3rd arch
stylopharyngeus muscle
nerve associated with 3rd arch
glossopharyngeal nerve (CN IX)
artery of the 3rd arch
common carotid and proximal part of the internal carotid on each side
4th and 6th pharyngeal arches form
they fuse to form laryngeal cartilages: •thyroid •cricoid •aryntenoid •corniculate •cuneiform
muscle derived from 4th and 6th arches
laryngeal muscles