Development Of The Face And Palate Flashcards
What are the main prominences that form the face and palate?
The main prominences are the frontonasal prominence (FNP), maxillary prominences, mandibular prominences, medial nasal prominences (MNPs), and lateral nasal prominences (LNPs).
What does the frontonasal prominence (FNP) form?
The FNP forms the forehead and the dorsum and apex of the nose.
What structures are derived from the first pharyngeal arch?
Cranial nerve: Maxillary and mandibular divisions of the trigeminal nerve (CN V).
Artery: Maxillary artery.
Muscles: Muscles of mastication (e.g., temporalis, masseter), mylohyoid, anterior belly of digastric, tensor tympani, and tensor veli palatini.
Skeleton: Maxilla, mandible, incus, malleus, and zygomatic bone.
What structures are derived from the second pharyngeal arch?
Cranial nerve: Facial nerve (CN VII).
Artery: Stapedial artery.
Muscles: Muscles of facial expression (e.g., orbicularis oculi, orbicularis oris), stapedius, posterior belly of digastric, and stylohyoid.
Skeleton: Stapes, styloid process, and upper part of the hyoid bone.
What is the role of neural crest cells (NCC) in head development?
Neural crest cells contribute to the formation of connective and skeletal tissues of the head, including the skull.
: What is the stomodeum, and what is its significance in facial development?
The stomodeum is the primitive mouth, an external depression of surface ectoderm. It is the central structure around which the face develops, and its floor is initially formed by the oropharyngeal membrane.
How does the nose develop during embryogenesis?
The nose develops from five facial prominences:
Frontonasal prominence: Forms the bridge of the nose.
Medial nasal prominences: Form the crest and tip of the nose.
Lateral nasal prominences: Form the sides (alae) of the nose.
What is the philtrum, and how is it formed?
The philtrum is the vertical groove in the middle of the upper lip. It is formed by the fusion of the medial nasal prominences.
What are the primary and secondary palates, and how do they form?
Primary palate: Forms from the medial nasal prominences and gives rise to the anterior part of the palate, including the four maxillary incisors.
Secondary palate: Forms from horizontal shelves of the maxillary prominences that grow towards the midline and fuse with each other, the nasal septum, and the primary palate.
What causes cleft lip and cleft palate?
Cleft lip and cleft palate result from the failure or incomplete fusion of the medial nasal prominences with the maxillary prominences (for cleft lip) or the palatal shelves (for cleft palate).
What is Kabuki syndrome, and what are its main features?
Kabuki syndrome is a rare genetic disorder characterized by:
Dysmorphic face: Unusual eyes, large and low ears, depressed nasal tip, arched eyebrows, cleft lip and palate.
Mental retardation, postnatal growth retardation, skeletal abnormalities, and multisystem disorders.
What are the facial features of Fetal Alcohol Syndrome (FAS)?
Microcephaly (small head circumference).
Short palpebral fissures (small eye openings).
Epicanthal folds (skin folds at the inner corner of the eyes).
Flat midface, low nasal bridge, indistinct philtrum, and thin upper lip.
What is Treacher Collins syndrome, and what are its typical features?
Treacher Collins syndrome is a type of first arch syndrome characterized by:
Downward slanting palpebral fissures.
Small lower jaw (micrognathia).
Malformed or absent ears.
How does the tongue develop embryologically?
The tongue develops from three lingual swellings:
Two lateral swellings and one median swelling (tuberculum impar) from the first pharyngeal arch (forms the anterior 2/3 of the tongue).
Copula from the second, third, and part of the fourth pharyngeal arches (forms the posterior 1/3 of the tongue).
Epiglottis from the fourth pharyngeal arch.
What is the sensory innervation of the anterior 2/3 and posterior 1/3 of the tongue?
Anterior 2/3: General sensory by the lingual branch of the trigeminal nerve (CN V), taste by the facial nerve (CN VII).
Posterior 1/3: General sensory and taste by the glossopharyngeal nerve (CN IX).
What is ankyloglossia (tongue-tie)?
Ankyloglossia is a condition where the frenulum (the tissue under the tongue) is too short or tight, restricting tongue movement. It results from incomplete degeneration of tissue under the tongue during development.
What is choanal atresia, and what causes it?
Choanal atresia is a congenital condition where the oronasal membrane fails to break down, leading to blockage between the nasal cavity and the pharynx.
What is the significance of the incisive foramen in palate development?
The incisive foramen is the landmark that separates the primary palate (anterior) from the secondary palate (posterior).
What is the oropharyngeal membrane, and when does it break down?
The oropharyngeal membrane forms the floor of the stomodeum (primitive mouth) and separates it from the pharynx. It breaks down by the end of the 4th week, allowing communication between the stomodeum and the pharynx.
What is the terminal sulcus, and what does it separate?
The terminal sulcus is a V-shaped groove that separates the anterior 2/3 of the tongue (derived from the first pharyngeal arch) from the posterior 1/3 (derived from the third pharyngeal arch).
What is the foramen cecum, and what is its significance?
The foramen cecum is a small pit located at the junction of the anterior and posterior parts of the tongue. It marks the origin of the thyroid gland during development.
What is the motor innervation of the tongue muscles?
The muscles of the tongue are innervated by the hypoglossal nerve (CN XII).
What is Pierre Robin syndrome, and what are its features?
Pierre Robin syndrome is marked by:
Micrognathia (very small lower jaw).
Glossoptosis (tongue falling back).
Cleft soft palate.
What is the labiogingival lamina, and what does it form?
The labiogingival lamina is an ectodermal ingrowth that separates the lips from the gums. Its degeneration forms the labial frenulum.
What is macroglossia, and what conditions is it associated with?
Macroglossia is an abnormally large tongue, often associated with genetic syndromes like Down syndrome.
