Face, Mouth Pharynx Development Flashcards
Which structures are involved in the development of the face (mouth and nasal cavity)
Frontonasal prominence
Medial and lateral nasal processes
Mandibular arch 1
Maxillary prominence
Where does the face originate?
Neural crest cells
How are the base bones of the skull developed?
Endochondral ossification
How are the face bones developed?
Intramembranous ossification
What does the medial nasal prominence and mandibular prominence form when they fuse?
Nasal septum and the primary pallate
The development of the nasal and oral cavities?
- Oronasal membrane separates the oral and nasal cavities
- Breakdown of the oronasal membrane –> temporary confluence of both cavities
- Formation of the primary palate
- Formation of the secondary palate
Nasolacrimal Duct
Lateral nasal process and maxillary prominence fusion line
Ectoderm thickens and forms ND
What does the frontal prominence form?
Frontal bone
Forehead area
What does the lateral nasal prominence form?
Nasal & lacrimal bones
Sides and alae of nose
What does the medial nasal prominence form?
Vomer and incisive bones
Medial part of the upper lip and gingiva, nasal septum
What does the Mandibular prominence form?
Mandible
Lower lip, gingiva and cheeks
What does the maxillary prominence form?
Maxillae, palatine, petryoid, zygomatic and squamous parts of temporal bones
Upper lip, gingiva and cheeks
How are salivary glands formed?
Epithelium: ectoderm and endoderm
CT: mesenchyme of brachial arch 1
How is the pituitary gland formed?
Oral ectoderm (Rathke’s pouch) and diencephalon
How is the 2 lateral swellings of the tongue developed?
Mandibular arch 1
How is the medium tuberculum impar of the tongue developed?
Tubercle arch 1 &2
How is the copula and body of the tongue developed?
C: Arches 3 & 4
B: Lateral and medial swelling (ectoderm)
How is the root, muscle and CT of the tongue developed?
R: copula (endoderm)
M: Occipital somites
CT: brachial mesenchyme
How is the tongue innervated?
Body: Arch 1= trigeminal
Root: Arches 3 & 4 = glossopharyngeal and vagus
Muscles: Hypoglossal
How are the taste buds innervated?
Special sensory (from arch 2) by facial n.
How is the enamel of the tooth developed?
Ectoderm –> inner enamel epithelium –> ameloblasts
How is the dentin of the tooth developed?
Neural crest –> pulp cavity –> ondontoblasts
How is the pulp cavity of the tooth developed?
Mesenchyme
How is the cementum of the tooth developed?
Mesenchyme –> dental sac –> cementocyte
How is periodontal and alveolar bone of the tooth developed?
Mesenchyme –> dental sac –> fibroblasts/ osteocytes (cementocyte)
How is Arch 4 & 6, laryngeal and pharyngeal muscles innervated?
Vagus nerve
How are mastication muscles innervated?
Trigeminal nerve
What is the only muscle what glossopharyngeal nerve innervates?
Stylopharyngeus muscle
What does each (6) pharyngeal arch consist of?
Mesenchymal core
Endoderm pouch
Ectodermal clefts
What does cleft 1 of the pharyngeal cleft develop into?
Dorsal part is the external auditory meatus
Outer epithelium of the eardrum
What happens to the rest of the pharyngeal clefts?
Cleft 2 mesenchyme overgrows 3 & 4 and merges with the epicardial ridge in the neck
Merge and form a cervical sinus (disappears with development)
If persists: cyst, sinus or fistula on lateral side of the neck
What does the pharyngeal pouch 1 develop into?
Dorsal: auditory tube, tympanic cavity (guttural pouch)
What does pouch 2 develop into?
Dorsal: Crypt of palatine tonsil
Ventral: none
What does pouch 3 develop into?
Dorsal: External parathyroid
Ventral: reticular cells of thymus
What does pouch 4 develop into?
Dorsal: internal parathyroid (non in pig)
How does the thyroid gland develop?
From endoderm of the floor of the pharynx between pouch 1 & 2 –> then goes to first 2 tracheal ring
Cleft lip
Rare in domestic animals
Lack of fusion of medial nasal prominences with each other or with maxillary prominences
Which animals is cleft lip normal in?
Sheep
intermediate in dogs
Cleft palate?
Defect in the incisive bone due to the failure of medial nasal prominences to fuse
Failure of palatine processes of maxilla to fuse
Facial cleft
Extends for the nasal cavity to medial canthus of the eye
Caused by failure of maxillary prominence to fuse with lateral nasal prominence
Atresia of the nasolacrimal duct
Failure of epithelial cells between maxillary and lateral nasal prominences to canalize
Results in overflow of lacrimal glands secretion
Agnathia (absent) and bracnygnathia (subnormal) inferior or superior
Mal-development of lower of upper jaw, respectively
