tongue, thyroid and face Flashcards
what are pharyngeal arches
protrusions of mesenchyme at head end separated by pharyngeal clefts
become visible at -5 weeks
what is a rhombomere
a divided segment of the developing neural tube within the hindbrain region in the area that eventually becomes the rhombencephalon
what is the role of neural crest cells in developing pharyngeal arches
neural crest migration from the diencephalon, mesencephalon and rhombomeres of the hindbrain
• Transcription factors determine expression patterns into the pharyngeal arches
under control of endodermal signals
• Crest cells give rise to neurons supplying pharyngeal arches and
guide axons toward the CNS
• Arch mesoderm structures are derived from neural crest, lateral plate and paraxial mesoderm
what is the first arch nerve
trigeminal, three divisions
what is the 2nd arch nerve
facial
what is the third arch nerve
glossopharyngeal
what is the 4th and 6th arch nerve
vagus
4- superior laryngeal
6- recurrent laryngeal
what does the cartilage of the 1st arch become
mandible and middle ear, malleus and incus (neural crest)
what does the cartilage of the 2nd arch become
lesser horn of hyoid, styloid ligament and styloid, stapes
neural crest
what does the cartilage of the 3rd arch become
greater horn of hyoid
neural crest
what does the cartilage of the 4th and 6th arch become
thyroid and cricoid
lateral plate mesoderm
what is the terminal sulcus made from
junction between 1st and 3rd arch mesenchyme
what part of the tongue is made from the 1st arch
body
what is the sensation supply of the anterior 2/3rds of the tongue
trigeminal (first arch)
what is the sensation supply of the posterior third of the tongue
glossopharyngeal (3rd arch)
what is the innervation of the epiglottis
4th arch- vagus, superior laryngeal
what is the taste supply of the tongue
facial, glossopharyngeal, vagus
what is the solitary nucleus
a series of purely sensory nuclei (clusters of nerve cell bodies) forming a vertical column of grey matter embeddedd in the medulla oblongata.
functions: taste, sensory from the ear, carotid and aortic body,
general visceral afferent pathway via vagus and glossopharyngeal nerves
where does the thyroid originate
foramen caecum, caudal to the tuberculum impar
where does the thyroid migrate to by week 7
anterior to hyoid and thyroid cartilages
what is the thyroglossal duct
connects thyroid with tongue
what can cause thyroid dysgenesis
mutations in transcription factors PAX8 and TITF1
what do follicular cells in the thyroid secrete
triiodothyronine and thyroxine
what do parafollicular cells produce
calcitonin
derived from the fourth pouch
what is a thyroglossal cyst
remnant of thyroglossal duct
moves upwards on tongue protrusion
usually associated with the hyoid bone
what is the stomodeum
a depression between the brain and pericardium in an embryo and is the precursor of the mouth and pituritary gland
what structures are formed by the intermaxillary segment
philtrum, incisors, primary palate
what does the palatine shelf form from
maxillary process
what factors increase the likelihood of cleft lip/palate
Environmental
• Maternal age
• Medications antiepileptic agents or corticosteroids,
• Smoking
• Alcohol consumption during pregnancy
• Maternal illness was suggested to elevate the chance of CL/P
• Maternal diabetes
• Lack of dietary folic acid
Genetic
• Aberrant gene variants are inherited from mother or father
• Inheritance is variable, often not strictly Mendelian probably because of environmental factors
may be syndromic- treacher collins/ van de woude
what are the effects of CL/CP
difficulty feeding, hearing and ear problems, speech problems, dental abnormalities, social and psychological
