Pharyngeal Apparatus
Consists of 4
- Pharyngeal
- Arches
- Pouches
- Grooves
- Membranes
Beining of pharyngeal arch development
- Begin as neural crest cells migrate to heand and neck region from posterior/dorsal neural tube
*
Rapid proliferation of mesenchyme begin to form prominences then 4 more steps
- Stomadeum forms into the embryo laying ectoderm throughout oral cavity
- Most of oral cavity will come from ectoderm (peridontum, enamel)
- Stomadeum and pharynx are seperated by buccopharyngeal membrane
- Buccopharyngeal membrane ruptures opening to oropharynx
1st pharyngeal arch develops 2
- The mandibular arch, 1st arch develops
- Maxillary and mandibular prominences
- Plays major role in facial development
2nd pharyngeal arch contributes to
The hyoid arch contributes to formation of hyoid bone
Arches are what encased in what
Each arch has
Arches are mesenchyme encased in external ectoderm and internal endoderm
Ea contains
Nerve artery cartilage muscle
the 5 arches form which CN
- 1–> Trigeminal 5
- 2–> Facial nerve 7
- 3–> Glossopharyngeal 12
- 4–> Vagus 10
- 5–> Vagus 10, arch will degenerate
arches and arteries they form
- 1–> maxillary artery
- 2–> Stapedial artery then corticotypanic art
- 3–> carotid artery
- 4–> part of aorta and right subclavian
- 5–> pulmonary artery
Derivatives are formations originating from
- Clefts/grooves –> external ectoderm
- Pouches –> internal endoderm
Clefts 1, 2, 3, 4 form
- cleft 1
- forms external auditory meatus
- Pharyngeal arch 2
- rapid mesenchyme proliferation grows over remaining clefts
- Clefts 2-4
- form cervical sinus that resorbs
Pharyngeal pouches 1-4 form
- pouch 1
- Pharyngotympanic tune
- Pouch 2
- Palatine tonsil
- Pouch 3
- Inferior parathyroid gland and thyus
- Pouch 4
- Superior parathyroid gland and ultimo branchial body
Thyroid development and migration
- Primitive thyroiod forms at midline of pharynx just below tuberculum impar
- Thyroid migrates through foramen cecum to below circoid
- Migration forms thyroglossal duct
- Can form thyroglossal duct cyst on MIDLINE
Oral part of tongue development
Develps from fusion of lateral lingual swellings and median tongue bud (tuberculum impar) from arch 1
Pharyngeal part of tongue development
- From Copula/hypobranchial eminence
- Muscles of tongue arise from occipital somites
Development of skull
Neurocranium and Viscercranium**
- Neuro cranium-encases brain
- Membraneous neurocranium (flat bones)
- Cartilaginous neurocranium (Chondocranium-base of skull)
- These 2 are partly from Neural crest cells and partly somitomeres (mesoderm)
- Vescerocranium face
- Entirely Neural crest cells
Chranioschisis
Craniosynotosis
- Cranioschisis
- cranial vault fails to form
- Craniosynotosis
- Premature closure of suures
Nasla and oral cavity form from
- Nasal olfactory placode
- Nose
- Stomadeum
- oral cavity
- Pharyngeal arch 1
- Max and mand prominences
Nasal cavity progression
- Nasal pit (ectodermal invagination)
- Nasal sac (ectoderm)
- Nares
What seperates oral and nasal cavities
Oronasal mebrane, perpendicular to buccopharyngeal membrane
Sinuses develop from
From outgrowths of nasal cavity called diverticulums
What 2 segments form the palate
Primary palate/ pre-maxilla
Secondary palate
Primary palate formation
- Median nasal processses fuse to form
- Intermaxillary segment
- Median palatine process
- Intermaxillary segment
Secondary palate includes
Begins from what process to then form what
- Includes hard and soft palate
- Maxillary processes form
- Lateral palatal process
- fuse ant to post
During secondary palate formation what outgrowths appear
Nasal septum
2 palatine shelves
