Chapter 17: Head and neck Flashcards
occur when the second pharyngeal arch fails to grow caudally over the third and fourth arches, leaving remnants of the second, third, and fourth clefts in contact with the surface by a narrow canal
Branchial fistulas
Such a fistula, found on the lateral aspect of the neck directly ____ to the ____, usually provides drainage for a _____
anterior - sternocleidomastoid muscle - lateral cervical cyst
____ are rare; they occur when the cervical sinus is connected to the lumen of the pharynx by a small canal, which usually opens in the tonsillar region
Internal branchial fistulas
____ are essential for formation of much of the craniofacial region
Neural crest cells
Because neural crest cells also contribute to the _____, which septate the outflow tract of the heart into pulmonary and aortic channels, many infants with craniofacial defects also have cardiac abnormalities, including persistent truncus arteriosus, tetralogy of Fallot, and transposition of the great vessels
conotruncal endocardial cshions
______ is a rare autosomal dominant disorder occurring in 1/50,000 live births with 60% of cases arising as new mutations
Treacher Collins syndrome [mandibulofacial dysostosis]
____ is common as are external ear defects accompanied by atresia of the auditory canals and abnormalities of the middle ear ossicles, such that bilateral conductive hearing loss is often present
Cleft palate
The product of this gene is a nucleolar protein called ____ that appears to be necessary for preventing apoptosis and maintaining proliferation in neural crest cells but not for regulating their migration, which occurs normally
treacle
In _____, the tongue is
not freed from the floor of the mouth. Normally, extensive cell degeneration occurs, and the frenulum is the only tissue that anchors the tongue to the floor of the mouth. In the most common form of ankyloglossia, the frenulum extends to the tip of the tongue
ankyloglossia [tongue-tie]
_____ may occur independently or in association with other syndromes and malformations. Like Treacher Collins syndrome, it alters first-arch structures, with development of the mandible most severely affected. Infants usually have a triad of micrognathia, cleft palate, and glossoptosis [posteriorly placed tongue]
Robin sequence
_____ includes a number of craniofacial abnormalities that usually involve the maxillary, temporal, and zygomatic bones, which are small and flat
Hemifacial microsomia [oculoauriculovertebral spectrum or Goldenhar syndrome]
_____ is the most common deletion syndrome in humans and has several presentations, including DiGeorge locardiofacial syndrome, Shprintzen syndrome, conotruncal anomaly face syndrome, and congenital thymic aplasia and hypoplasia.
22q11.2 Deletion syndrome
Cleft lip and cleft palate are common defects that result in abnormal facial appearance and difficulties with speech. The ____ is considered the dividing landmark between ___ and ____ deformities.
incisive foramen - anterior and posterior
Sometimes, a thyroglossal cyst is connected to the outside by a fistulous canal, a _____. Such a fistula usually arises secondarily after rupture of a cyst but may be present at birth.
thyroglossal fistula
A ____ may lie at any point along the migratory pathway of the thyroid gland but is always near or in the ____ of the neck.
thyroglossal cyst - midline
Those anterior to the incisive foramen include _____, _____, and ___ between the primaryand secondarypalates
lateral cleft lip, cleft upperjaw, and cleft
_____ may be found anywhere along the path of descent of the thyroid gland. It is commonly found in the base of the tongue, just behind the foramen cecum, and is subject to the same diseases as the thyroid gland itself
Aberrant thyroid tissue
Those that lie posterior to the incisive foramen include ____ and ____
cleft [secondary] palate and cleft uvula
____ is the most common syndrome associated with cleft lip with or without cleft palate. The syndrome is inherited as an autosomal dominant and is due to mutations in _____ [IRF6; 1p32—41] that is expressed in the medial [fusing] edge of the palatal shelves.
Van der Woude syndrome - INTERFERON REGULATORY FACTOR 6
_____ are produced by failure of the maxillary prominence to merge with its corresponding lateral nasal prominence along the line of the nasolacrimal groove
Oblique facial clefts
_____, a rare abnormality, is caused by incomplete merging of the two medial nasal prominences in the midline
Median [midline] cleft lip
Infants with midline clefts are often _____ and may have brain abnormalities that include varying degrees of loss of midline structures
cognitively impaired
Loss of midline tissue may be so extensive that the lateral ventricles fuse [______. These defects are induced very early in development, at the beginning of neurulation [_____] when the midline of the forebrain is being established
holoprosencephaly] - days 19 to 21
The frequency of isolated ____ is lower than that of cleft lip [1/1,500 births], occurs more often in females [55%] than in males. In females, the palatal shelves fuse approximately 1 week later than in males, which may be related to why isolated cleft palate occurs more frequently in females than in males.
cleft palate
Most cases of cleft lip with or without cleft palate are multifactorial. These conditions are usually classified as
[l] cleft lip with or without cleft palate
[2] cleft palate are thought to be etiologically and pathogenetically distinct
Causes of cleft lip with or without cleft palate are not well defined. Some cases are syndromic and associated with certain syndromes and genes. Others are nonsyndromic but associated with some of the same genes that cause syndromes, such as ____ and ____.
IRF6 [van der Woude syndrome] and MSX1
____ have erupted by the time of birth. Usually, they involve the mandibular incisors, which may be abnormally formed and have little enamel
Natal teeth
Teeth may be abnormal in number, shape, and size. They may be discolored by foreign substances, such as ____, or be deficient in enamel, a condition often caused by _____.
tetracyclines - vitamin D deficiency [rickets]
