510-03 Craniofacial Embryology Flashcards
As neurulation proceeds through the third week of development, the embryo elongates and folds in which two directions?
cephalocaudally (head + tail) and laterally (see figure 2-9 on slide 4)
As the head and neck begin to form during the 4th-5th weeks of development, the embryonic ____ develops a series of external arches, clefts, and internal pouches that contain tissues that will develop into important nerves, blood vessels, bones, cartilage and other organs of the head and neck.
pharynx
(T/F) Each pharyngeal cleft develops its own artery, nerve, muscle, and skeletal elements of the head and neck
False, each pharyngeal ARCH develops its own artery, nerve, muscle, and skeletal elements of the head and neck
pharyngeal arches consist of bars of mesenchymal tissue separated by internal pharyngeal ____ and external pharyngeal ___.
pouches, clefts
Pharyngeal pouches are lined by which germ layer?
endoderm
Which structure gives rise to the middle ear cavity, eustachian tube, palatine tonsil, parathyroid glands, thymus and ultimobranchial bodies? (pharyngeal arches/ pouches/ clefts)
pharyngeal pouches
Which pharyngeal cleft gives rise to the external auditory meatus?
the first cleft
What structure does the first pharyngeal cleft give rise to?
external auditory meatus
What structure is formed by the tracheo-bronchial diverticulum?
the lungs
Outgrowths of the pharynx form ____ that will form structures in the head and neck
pouches
What are 3 diffusible signaling molecules that help guide neural crest cell migration?
1) sonic hedgehog (Shh)
2) bone morphogenic proteins (Bmp)
3) fibroblast growth factors (Fgf)
Development of head and neck tissues depend on migration of what kind of cells into the pharyngeal arches?
neural crest cells
Migrating neural crest cells express genes that regulate differentiation of developing head and neck tissues by establishing gradients that are regulated by expression of ___ genes.
Hox genes
Which arch develops into the mandible and maxilla?
first
Which arch contains Meckel’s cartilage?
first
Which ossicles are made due to Meckel’s cartilage?
Incus and malleus
Which arch contains Reichert’s cartilage?
second
What ossicle is made due to Reichert’s cartilage?
stapes
The ____ that will eventually become the opening of the oral cavity is initially closed by a buccopharyngeal membrane in a 24 day embryo.
stomodeum
The stomodeum that will eventually become the opening of the oral cavity is initially closed by a ______ membrane in a 24 day embryo.
buccopharyngeal
What cellular process do the nasal placodes rely on in order to form into nostrils?
apoptosis
Of the 6 pharyngeal arches, which ones produce significant body structures?
1-4
What does the 6th pharyngeal arch contribute to?
laryngeal cartilage
The cartilages of the first and second pharyngeal arches are derived from ______. The cartilages of the 3rd-6th arches are derived from ____.
neural crest cells, mesoderm
(T/F) the cartilages of the 3rd-6th pharyngeal arches are derived from neural crest cells
FALSE
Which arch contains thyroid cartilage?
4
Which arch contains cricoid cartilage?
6
Which arch forms into the temporal bone?
1
Which arch forms into the hyoid bone?
3
What is the process in which maxillary bones develop, where bone progressively replaces the embryonic connective tissue?
intramembranous ossification
What are the 2 types of ossification?
intramembranous and endochondral
The membranous bone of the developing mandible grows completely around the ___ ____ nerve and forms the ____ ___ that will contain the nerve.
inferior alveolar nerve, mandibular canal
The ramus develops from a rapid spread of ossification away from Meckel’s cartilage at a point marked by the ___ in an adult mandible
lingula
The perichondrium of Meckel’s cartilage becomes the _____ ligament
sphenomandibular
The ___ cartilage develops as an independent piece of cartilage that fuses with the mandibular condyle. The ____ cartilage is a transient growth cartilage that disappears long before birth.
condylar, coronoid
Most of the condylar cartilage is replaced by bone through ____ ossification
endochondral
Mutations in the TCOF1 gene are responsible for most cases of treacher collins syndrome. The product of this gene is a protein called ___ , which is necessary for preventing apoptosis and maintaining proliferation in neural crest cells.
treacle
Epibranchial placodes are specialized regions of surface ectoderm that invaginate to contribute to the formation of the sensory ganglia for which cranial nerves?
5, 7, 9, 10
What are specialized regions of surface ectoderm that invaginate to contribute to the formation of the sensory ganglia for cranial nerves 5,7,9 and 10?
epibranchial placodes
Which cranial nerve will supply tissues from the first arch, including muscles of mastication?
5 (trigeminal)
Which cranial nerve will innervate the muscles of facial expression?
7 (facial)
Which 2 cranial nerves will innervate muscles involved in swallowing?
9 (glossopharyngeal) + 10 (vagus)
What is the fate of pharyngeal clefts 2,3 and 4?
They fuse to temporarily form a cervical sinus that eventually disappears
What is derived from the first pharyngeal pouch?
tympanic membrane + eustachian canal
What is derived from the second pharyngeal pouch?
palatine tonsils + tonsillar fossa
What is derived from the third pharyngeal canal?
inferior parathyroid gland + thymus
What is derived from the fourth pharyngeal canal?
superior parathyroid gland + ultimobranchial body (Parafollicular/C cells)
What forms if the cervical sinus from clefts 2, 3, and 4 is not completely obliterated? Where?
lateral cervical cysts. On the lateral side next to the sternocleidomastoid muscle
The thyroid gland originates from a midsagittal invagination of the pharyngeal epithelium at the ____ ____. This forms the ___ duct which closes after the thyroid tissue migrates to the trachea below the larynx.
foramen cecum, thyroglossal duct
What kind of cyst occurs due to remnants of oral ectoderm tissue along the migration pathway from the foramen cecum towards the larynx and trachea?
thyroglossal cyst
the human face develops of the growth of what 5 prominences? What structures does each one form?
1) frontonasal - forehead, bridge of nose, medial and lateral nasal prominences
2) maxillary - cheeks, lateral portion of upper lip
3) medial nasal- philtrum of upper lip, crest, and tip of nose
4) lateral nasal- alae of nose
5) mandibular - lower lip
(T/F) all facial prominences are paired except for the frontonasal prominence
true
Is cleft lip more common in males or females?
males
Is isolated cleft palate related to maternal age?
no
Does cleft palate occur more oftern in males or females?
females
Partial unilateral and bilateral clefting of the lip results from the failure of which prominences to fuse?
How about clefts involving the hard and soft palate?
- maxillary and medial nasal
- palatal shelves
1) the body of the tongue develops from which arch?
2) the root of the tongue develops from which arch?
3) The epiglottis develops from which arch?
1) 1
2) 3
3) 4
The body of the tongue develops from the ___ ___ swellings and the ___ ___ of the 1st arch growing together.
lateral lingual swellings, tuberculum impar
The root of the tongue develops from the ___ of the 3rd arch
copula
What is it called when the tip of the tongue is divided longitudinally due to a disturbance in the developmental process?
bifid tongue
What is ankyloglossia of the tongue?
tongue-tie, decreases mobility of the tongue
