Craniofacial dev final

robbypowell's version from 2015-04-27 16:48

Pharyngeal Arch Development

Question Answer
What is Gastulation?Formation of the 3 layers: Endo- Meso- & Ectoderm (from the 2 layered that existed prior to gastrulation)
Where does the embryologic disc fold? How?in the midline of the NEURAL PLATE, which folds DORSALLY
Which embryologic disc fold gives rise to the head?Neural Crest cells, from the roof of the neural tube
Why are horizontal sections of the head of the developing embryo actually coronal sections?because we are curled up while developing, so that "chin" would be against "chest"... head is tilted forward
What is Neurulation?The convergence of the NEURAL PLATE, DORSALLY to form the NEURAL TUBE
What makes up the neural plate? What does it form?A thickening of ECTODERM tissue, it folds to form the NEURAL TUBE
What forms the neural crest? What happens to these cells?the crest of the Neural Tube transitions from epithelial to MESENCHYMAL tissue, and is now the Neural Crest
What is the stomatodeum? Where is it found? What separates it from the GI tract?Stomatodeum is primordial opening to the GI tract, it is separated (until the 26th day) by the Buccopharyngeal Membrane, aka the Oropharyngeal membrane
When do the four main pharyngeal arches appear?Beginning of 4th week
How do the pharyngeal arches grow? What do they eventually separate?They grow from dorsal surface VENTRALLY, eventually separate GI tract from external environment
What is the composition of the pharyngeal arches on the lateral surface, inside, and mesial surface? Which arch is the exception?general rule: Ectoderm outside, Mesenchyme inside process, Endoderm internal lining... 1st arch is exception, which has ectodermal internal lining
What are the three components of each pharyngeal arch?Pouch, body, Groove/cleft
What is the difference between a pharyngeal pouch, groove/cleft, and arch?POUCH is normally ENDOdermal in origin, Groove/Cleft normally Ectodermal in origin, Arch normally MESENCHYMAL
What is the truncus arterioles?initial vascular components of the pharyngeal arches, they connect to a single descending aortii
Neurulation is the convergence of the ____ ____ dorsally, to form the ____ ____.Neural PLATE converges to form NEURAL TUBE
On what day does the Oropharyngeal (Buccopharyngeal) membrane rupture?26th day
What is the fate of the Anterior part of Mickel’s cartilage?disappear (some say incorporated into mandible... not true)
What is the fate of the Intermediate part of Mickel’s cartilage?spheno-mandibular ligament
What is the fate of the Posterior part of Mickel’s cartilage?Malleus & Incus bones
What is Pinto’s ligament?ligament that may or may not exist, related to 1st pharyngeal arch, believed to connect TMJ to middle ear
What forms the first TMJ of the embryo?Mickel's cartilage
What is true Eagle’s Syndrome?Ossification of styloid process along Stylo-hyoid ligament connecting to lesser horn of Hyoid bone
What is the carotid body?Ballooning of Carotid at division into Internal and External
What is the only intrinsic muscle of the larynx not supplied by the Recurrent Laryngeal branch of the vagus nerve? What is it supplied by?Cricothyroid muscle, External Laryngeal Nerve (of Vagus)
What is the fate of the fifth arch?Disappears (gives rise to nothing)
The 1st pharyngeal arch splits into the ____ and ___ prominencesMaxillary & Mandibular
During the ___ or ____ week, Meckel's cartilage begins to appear4th or 5th
Mandible and TMJ form laterally to Meckel’s cartilage during the ___ week10th
Does V1 (Opthalmic branch) supply derivatives of the 1st Phar Arch?NO (V2 & V3, not V1)
What is the nature of all the derivatives of the pharyngeal pouches?endodermal in origin (except for maybe 1st?)
What separates pharyngeal pouches from pharyngeal clefts?pharyngeal membranes
What are the derivatives of the 1st Phar Pouch?tubotympanic recess, eustachian tube, mastoid air cells
What are the derivatives of the 2nd Phar pouch?tonsillar fossa
what are the derivatives of the 3rd Phar pouch?(dorsal part) INFERIOR parathyroid glands, (ventral part) thymus
what are the derivatives of the 4th Phar pouch?Superior parathyroid glands & Parafollicular cells of thyroid
What is a fistula?
Question Answer
What forms the outer ear? Ear drum (tympanic membrane)?outer ear formed by First Pharyngeal Cleft/Groove; Tympanic Membrane by First Pharyngeal Membrane
What is a pre-auricular pit/sinus?Residual Sinus of First Pharyngeal Cleft failure to completely disappear
Why is a pre-auricular pit/sinus difficult to operate on surgically?Facial Nerve runs through it
Why does a branchial vestige/fistula/cleft form?failure to obliterate cleft or groove. SECOND is most common
A branchial vestige cleft/fistula/sinus under the border of the mandible is usually from the ____ phar groove1st
A branchial vestige cleft/fistula/sinus under the Sternocleidomastoid muscle is usually from the ____ phar groove2nd
What is first arch syndrome? What is the main clue to diagnose it?Failure of migration of neural crest cells; main clues include wide mouth ((ichi the killer) & deformed auricle of ear
What is Treacher Collins syndrome? What is it caused by?90% have mutation in TCOF1 gene, (although etiology unknown)
What is Pierre Robin Syndrome? What are two possible causes?Chromosomal anomaly at 2, 11, or 17; Trapping of Mandible under Sternum
36. When does the dental lamina form? Where does it form? What is it made of?
Question Answer
What process is the origin of the PREMAXILLA?Medial Nasal Process (not maxillary process)
The mandible is formed by _____ ossificationINTRAMEMBRANEOUS (not from mickel's cartilage)
the meeting of Maxillary + Medial Nasal Process is called the ...Bucco-nasal Groove
the meeting of Maxillary + Lateral Nasal process is called the ...Naso-lacrimal Groove
This syndrome is commonly associated with a mutation in TCOF1 geneTreacher Collins Syndrome
Symmetric hypoplasia of the facial bones, especially the mandible and zygoma. Dental agenesis or malformationTreacher Collins Syndrome
Syndrome where Severe micrognathia and posterior retraction of the tongue --> Airway obstruction and cleft palatePierre Robins Syndrome
On what day are Jaw processes are fused?38th day
In week ____ dental laminae appear6th week
Dental Lamina is an invagination of _____ into ____EPITHELIUM into ECTOMESENCHYME

What are the derivatives of the following branches of the truncus arteriosus

Question Answer
1st and 2ndMid Meningeal Artery & other branches of internal and external carotid
3rdInternal & common Carotid
Right 4th Subclavian & Brachicephalic artery
Left 4thArch of Aorta
6thPulmonary Arteries


Cranial Development

Question Answer
the ___ is the LEAST variable and most tightly controlled part of the developing skullCHONDROCRANIUM (CN's are coming in here, can't have growth affect)
viscerocranium refers to the bones of what?THE FACE (mandibular and maxillary bones and all that jazz that is not skull base or skull vault)
chondrocranium is also referred to as the ___ ___Skull Base
desmocranium is also referred to as the ___ ____Skull Vault
by age ___ the neurocranium is 95% of its maximum size10 yo
When you are born, the neurocranium is ___ of its maximum size25%
Cortex develops its hardwiring completely, by what pointend of first year
what is the "skull vault"?Desmocranium
How does the desmocranium develop?membraneous ossification
What are the 2 layers of the Desmocranium?Endomeninx & Ectomeninx
What does the endomeninx give rise to?pia mater and arachnoid mater
what does the ectomeninx give rise to?dura mater and calvarial bone
what is the regulator of suture growth of skull bones?Dura mater (derived of ectomeninx)
The SKULL VAULT is formed via ___ ossification and referred to as the ____-ocraniumINTRA-MEMBRANEOUS; DESMO-cranium
The SKULL BASE is formed via ___ ossification and referred to as the ____-ocraniumEndochondral; CHONDRO-CRANIUM
Viscerocranium is formed from _____ ossificationINTRA-MEMBRANEOUS
What are 3 components of Skull development?Desmocranium, Chondrocranium & Viscerocranium
What 2 components makeup the NEUROCRANIUMDesmocranium (vault) & Chondrocranium (base)
Of the 3 components of the skull, which is the first to develop?Chondrocranium (base of skull)
Of the 3 components of the skull, which are tightly controlled by genetic factors and which by epigenetic/environmental factors?Chondro- by genetic, Desmo- & Viscero- by epigenetic/environmental factors
Of the 3 components of the skull, which is the most consistent over the course of development across individuals? (aka less variable in development)Chondro-cranium
When a pediatrician refers to the cranium of a developing child to assess their development, they tend to look at this component of the skull, because it is the least variable and therefore best indicator of true developmentChondro-cranium, base of skull
Of the 3 components of the skull, what is the MOST VARIABLE in its development?The VISCEROCRANIUM (bones of face)
What are the 3 important factors that drive development of the skull in order?1. BRAIN (drives development of neurocranium) 2. Accommodation of AIRWAY (nasal septum drives maxillary growth) 3. Mastication (drives mandibular growth into adulthood)
By the age of ___ the neurocranium is 95% of its maximum size10 yo
The developing brain is initially surrounded by a membraneous capsule derived from the ___ ___ or the ___ ___PARAXIAL MESODERM or NEURAL CREST (some bones are derived from each)
The outer layer of the membraneous capsule that initially encloses the developing brain is called theECTO-meninx
The inner layer of the membraneous capsule that initially encloses the developing brain is called theENDO-meninx
During development of the Desmocranium, what is the "regulator of suture growth" and WHY?Dura Mater is regulator of suture growth, because it is part of the same layer as the CALVARIAL BONE (that layer being the ECTO-meninx)
This layer is often referred to as the ENDO-CRANIUM or ENDOSTEUM of Cranial bonesDura Mater
The radiation of bone growth from from ossification centers are referred to asSPICULES
What bones & portions of bone are derived from Paraxial Mesoderm?Parietal bone, Petrous portion of Temporal Bone, Occipital bone
What bones & portions of bone are derived from Neural Crest?Frontal bone, Zygomatic bone, Nasal bone, Lacrimal Bone, Sphenoid bone, Squamos portion of Temporal bone, Mandible, Maxilla, Hyoid Bone
What adult cranial bone has portions derived from BOTH Paraxial Mesoderm & Neural Crest?Temporal Bone (Squamos from Neural Crest) (Petrous from Paraxial Mesoderm)
Of the 3 components of the cranium, which component is exclusively derived from neural crest?Viscerocranium (face)
What are membraneous gaps where some sutures interact, that allow expansion of cranial cavity to accommodate growth of brain?Fontanels**
What are the 6 fontanels?Bregma (anterior fontanelle), Lambda (posterior fontanelle), Rt & Lt Pterion (sphenoid fontanel), Rt & Lt Asterion (mastoid fontanel)
What the heck are SYNDESMOTIC ARTICULATIONS?SUTURES, articulations between flat bones
Mesenchyme overlying developing desmocranium islands of bone becomes ____, while the mesenchyme between becomes ____ ____Periosteum, Syndesmotic Articulations (aka sutures)
What is the name of the suture between the two developing portions of FRONTAL bone?METOPIC
METOPIC suture separates what two islands of developing bone?Rt & Lt parts of FRONTAL bone
____ forces of the developing brain keep the developing sutures open during desmocranial developmentTENSION FORCES
The idea that the growth of the brain determines the shape and growth of the neurocranium is support for developing neurocranium as a ___ ___FUNCTIONAL MATRIX (FUNCTION determines FORM)
As long as the brain is expanding, mechanisms work to _____ bone growth at suturesINHIBIT
Craniostenosis is caused by what?PREMATURE FUSION of cranial sutures
The idea that the content is shaping the container is expressed in what theory of cranial development?FUNCTIONAL MATRIX THEORY
If the brain growth determines the growth and development of the skull... and the brain would grow outward uniformly in all directions if left to its own devices... why isn't the skull spherical?DURA MATER plays a role in controlling direction of brain growth (part of functional matrix theory)
What are the 4 important (listed on slide) sutures of the developing Desmocranium?Frontal (or Metopic), Sagittal, Lambdoidal, & Coronal
Functional Matrix theory holds up when applied to growth of the _____ but NOT the ____Neurocranium (desmo especially), but NOT Viscerocranium (face: maxilla, mandible, orbits, nasopharynx etc.)
_____ growth causes expansion of the NeurocraniumBRAIN GROWTH
The ___ ___ MOLDS the expanding brain, hence non-spherical brainDURA MATER
____ ____ is an important indicator of brain development during the first 24 months or 2 years of lifeHead Circumference
Head Circumference is an important indicator of brain development during what period?first 2 years
When the cranium develops an Inner Cortical plate and an Outer cortical plate, this referred to as ____DIPLOE
At what age is the feature of DIPLOE developed?4 yo
Inner cortical plate responds to ____ forces while Outer cortical plate responds to ____ forcesInner, BRAIN; Outer, Muscle
From birth to adulthood... the brain size multiplies from ___cc to ___cc400cc (birth) to 1400cc (adulthood)
During the first 6 months of life, pediatricians closely watch infant's ____ to assess developmentWEIGHT
During the first 2 years of life, pediatricians closely watch infant's ____ _____ to assess developmentHEAD CIRCUMFERENCE

ratio of neurocranium to viscerocranium at different ages

Question Answer
At birth8:1 (neuro:viscero)
2nd year6:1 (neuro:viscero)
5th year4:1 (neuro:viscero)
Adult2:1 or 2.5:1 (neuro:viscero)

Growth of Neurocranium to max size (what % is neurocranium of its max size at these ages?)

Question Answer
At birth neurocranium is ___% of its max size25%
6 months old neurocranium is ___% of its max size50%
2 yo neurocranium is ___% of its max size75%
10 yo neurocranium is ___% of its max size95%
10 yo the VISCEROCRANIUM is ___% of its max size65%
After birth... the Neurocranium grows __to__ times to reach maximum size, while the Viscerocranium grows __to__ times to reach its maximum sizeNeuro, 4-5 times; Viscero, 8-10 times