510-3 Flashcards
When do the head and neck begin to form in the embryo?
4 to 5 weeks
What are the three main components of the embryonic pharynx?
1)ARCHES 2)POUCHES(inside=endoderm) 3)CLEFTS(outside=ectoderm)
What are 3 signaling molecules that help guide Neural Crest Cells to the pharyngeal arches?
1)Shh (Sonic hedge hog) 2)Bmp (Bone morphogenic proteins) 3)Fgf(fibroblast growth factors)
How are regional growth factor gradients regulated in the embryo (2 ways)? What are the overall genes expressed?
Temporally & Spatially by expression of Hox genes
What comprises a pharyngeal arch? What does each pharyngeal arch develop into?
Mesenchymal tissue. They each develop into its own artery, nerve, muscle, and skeletal element of the head and neck.
What do the pharyngeal clefts give rise to?
outer ear canal (external auditory meatus), doesn’t do too much
What is a branchial?
BRAIN-Key-Al, what develops into gills in fish/amphibians
What is the vitelline duct?
VIT-EL-IN=yoke
What does DHNC stand for in the 5wk embryo?
Dorsal Hollow Nerve Chord-continuance of the developing brain
What does FP stand for in the 5 wk embryo?
Frontal Prominence-developing brain
FOUNDATIONAL: Does cartilage form into bone?
NO. :)
What are the three MAIN developments from the 1st pharyngeal arch?
1)Mandible 2)Maxilla 3)MECKEL’s Cartilage
What structure in the 24day embryo will eventually become the opening of the oral cavity?
Stomodeum “STO-MO-DE-UM” another name for the buccopharyngeal membrane.
What is the named cartilage of the 1st pharyngeal arch? If you get this wrong, you deserve death. Which ear ossicles?
MECKEL’s cartilage (the mandible) “MECK-EL’s” The INCUS and the MALLEUS
What is the named cartilage of the 2nd arch? Which ear ossicle?
Reichert’s cartilage (hyoid/ear bones) “RY-Kurt’s” the STAPES
What are the 5 main bones derived from the 1st arch cartilage?
1)Maxilla 2)Mandible (Meckel’s) 3)Temporal 4)Malleus 5)Incus
What does the maxilla develop from?
a mesenchymal condensation in the 1st arch
What is the process of the development of the maxilla?
I.O. ==INTRAMEMBRANOUS OSSIFICATION-bone progressively replaces the embryonic connective tissue
How can mid face deficiency develop?
Injury to the suture or failure of the cranial base to lengthen behind the nasomaxilla (MAX grows OUT and DOWN from the skull
What are the two methods of the formation of the mandibular bone? Which portions specifically?
Intermembranous Ossification (majority) NEURAL REGION and endochondrial ossification ARTICULAR REGION
What are the main nerves of concern for a dentist? What anatomical landmark are their embryological origins?
The main nerves of concern are V-Trigeminal,VII-Facial,IX-Glossopharyngeal,X-Vagus. They are EPIBRANCHIAL PLACODES.
Which arch and muscles are innervated by V?
V-Trigeminal: 1st Pharyngeal Arch (BOTH Max and Mand processes). Innervates Muscles of Mastication
Which arch and muscles are innervated by VII?
VII-Facial: 2nd Pharyngeal Arch. Muscles of Facial Expression
Which arch and muscles are innervated by IX?
IX-Glossopharyngeal: 3rd Pharyngeal Arch. Muscles of Swallow Reflex
Which arch(es) and muscles are innervated by X?
X-Vagus:Arches 4-6. Muscles of Swallow Reflex
What does the first pharyngeal CLEFT yield?
The 1st pharyngeal cleft gives rise to the external auditory meatus. Clefts 2,3,4 fuse to temporarily form a cervical sinus that will disappear.
Which pouch is involved with the formation of the thyroid gland? Which specific cells does it give rise to in the thyroid?
The ULTIMOBRANCHIAL body of the 4th pouch. Gives rise to parafollicular or C-Cells that secrete calcitonin.
What do the endodermal layer and ectodermal layers form in the 1st POUCH and CLEFT respectively come together to form?
The tympanic membrane!
Name four derivatives of the 1st pharyngeal Pouch
1)Tympanic Membrane 2)Tympanic Cavity 3)Mastoid Antrum 4)Auditory(Eustachian) Tubes
Name the derivative(s) of Pharyngeal Pouch Number TWO
TONSILS: Palatine Tonsils
Name the two derivatives of the 3rd Pharyngeal Pouch
INFERIOR Parathyroid Glands, Thymus
Name the two derivatives of the 4th Pharyngeal Pouch
Superior Parathyroid Glands, Ultimobranchial Bodies
Which anatomical landmark did the Thyroid originate?
The foramen cecum
Which duct is formed from invaginated pharyngeal epithelium?
Thyroglossal duct. (((Thyroid + Tongue)))
Which cells produce the metabolic hormones of the thyroid T3 and T4?
follicular cells
Where is the most common thyroglossal cyst located?
By the adam’s apple
What is the most common cause of a lateral cervical cyst?
if the cervical sinus from the 2nd, 3rd, 4th pharyngeal CLEFTS are not completely obliterated
What are the 5 elevated prominences of the embryo that develop the face?
1)Frontonasal 2)Maxillary 3)Medial Nasal 4)Lateral Nasal 5)Mandibular
What structure invaginates to form nasal pits?
Nasal Placodes
Compare the mandibular and maxillary process development. Which one starts connected? Which one fuses?
Mandible begins connected and the initial groove goes away. Maxilla begins separate and merges.
Which two main facial prominences combine to make the INTERMAXILLARY segment?
1) Maxillary prominence 2) Medial Nasal Prominence
When the maxillary prominence and the medial nasal prominences join what 3 structures arise?
1) Philtrum 2)the 4 incisor portion of the maxilla 3)TRIangular primary palate
What does the MAIN portion of the maxillary palate develop from?
The palatine shelves. End result=secondary plate
At what junction is the incisive foramen?
The junction between the PRIMARY palate and the palatal shelves.
What is the dividing landmark between the anterior and posterior cleft deformities?
The incisive foramen
Most common: cleft lip or cleft palate?
Cleft lip (male dominated)
Which two pharyngeal arches does the tongue develop from?
1st (tuburculum impar)and 3rd (copula-root of tongue)
Which arch yields the epiglottis?
4th
What is the common name for Ankyloglossia?
Tongue-tie:from not enough apoptosis
