Questions and Answers
What is the direction of projection of the lateral palatine processes in the beginning?
During which weeks do the lateral palatine processes elongate and ascend to a horizontal position above the tongue?
What develops in the anterior part of the palate?
What is the source of the intrinsic muscles of the tongue?
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What nerve supplies the posterior 1/3rd of the tongue?
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What is the origin of the musculature of the tongue?
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What forms the anterior 2/3 of the tongue?
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During which week does the fusion with the nasal septum begin?
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What is the source of the paired mandibular prominences during facial development?
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What forms as a result of the elevations of the nasal pits?
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How many facial primordia appear around the stomodeum?
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What is the source of the paired maxillary prominences during facial development?
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What do the maxillary prominences form?
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When do nasal placodes sink below to form nasal pits?
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What is the fate of the nasal placodes?
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What do the mandibular prominences form?
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At what stage is the embryo when the fronto-nasal process and pharyngeal arches are present?
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What do the medial nasal prominences fuse to form?
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What is the number of branchial arches involved in facial development?
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What gives rise to the philtrum of lip?
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How long does the development of palate take?
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What is the critical period for the development of palate?
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What does the primary palate represent in the adult hard palate?
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When does the development of the primary palate begin?
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Study Notes
Development of Face and Palate
- Face develops from structures around the stomodeum (4th week)
- Structures involved: fronto-nasal process, 1st pharyngeal (mandibular) arch of each side, maxillary process, and mandibular process
Formation of Mandibular and Maxillary Processes
- Single fronto-nasal prominence ventral to the forebrain
- Paired maxillary prominences develop from the cranial part of the 1st branchial arch
- Paired mandibular prominences develop from the caudal part of the 1st branchial arch
- Five facial primordia appear as prominences around the stomodeum
Further Development of Face
- Formation of nasal placodes and lens placodes (4th week)
- Nasal placodes sink below to form nasal pits (5th week)
- Elevations of the nasal pits form the medial and lateral nasal processes
- Nasal placodes are primordia of the nose and nasal cavities
Derivatives of Facial Components
- Fronto-nasal prominence forms the forehead, bridge of the nose, frontal and nasal bones
- Maxillary prominences form the upper cheek regions, most of the upper lip, maxilla, zygomatic bone, and secondary palate
- Mandibular prominences fuse and form the chin, lower lip, lower cheek regions, and mandible
- Lateral nasal prominences form the alae of the nose
- Medial nasal prominences fuse and form the intermaxillary segment
Development of Palate
- Medial nasal swellings enlarge, grow medially, and merge with each other in the midline to form the intermaxillary segment
- Intermaxillary segment gives rise to the philtrum of lip, premaxillary part of the maxilla, primary palate, and palatogenesis
- Palatogenesis begins at the end of the 5th week and gets completed by the end of the 12th week
- The most critical period for the development of palate is from the end of 6th week to the beginning of 9th week
- The palate develops from two primordia: primary palate and secondary palate
Primary Palate
- Begins to develop early in the 6th week
- Develops from the deep part of the intermaxillary segment as a median palatine process
- Lies behind the premaxillary part of the maxilla
- Fuses with the developing secondary palate
- Represents only a small part lying anterior to the incisive fossa of the adult hard palate
Secondary Palate
- Is the primordia of hard and soft palate posterior to the incisive fossa
- Begins to develop early in the 6th week
- Develops from the lateral palatine processes, which grow medially and fuse in the median plane
Development of Tongue
- Formation of tongue: median and lateral tongue buds arise from the floor of the 1st pharyngeal arch and grow rostrally
- Formation of tongue: fusion of tuberculum impar, two lingual swellings, and caudal medial swelling (hypobranchial eminence)
- Anterior 2/3 of the tongue is formed by fusion of median and lateral tongue buds
- Posterior 1/3 of the tongue is supplied by glossopharyngeal nerve (nerve of 3rd arch)
- Musculature of tongue is derived from occipital myotomes, explaining nerve supply by hypoglossal nerve, nerve of these myotomes
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Description
Learn about the formation of the face and palate during embryonic development, including the structures involved and the processes that shape them.
