Craniofacial Bone Complex and Joints Flashcards
Human Skeleton
About 270 bones at birth Reduced to 206 by Adulthood
Axial Bones
Skull: _____ bones plus _____ associated bones
Torso: 52 bones
Appendicular bones
Upper extremities: 64 bones Lower extremities:62 bones
22
9
The Skull
_____: The region of the skull that encases the brain
_____:
The region of the skull that makes up the bones of the face
neurocranium
vicerocranium
Neurocranium
Cranial _____:
The portion of the skull that overlies the brain; It is formed by _____ ossification
Cranial _____:
The portion which underlies the brain; It is formed through _____ ossification (_____)
vault intramembranous base endochondral chondrocranium
Membranous bones of the skull:
Membranous bones making up the calvarium of the skull are each derived from the _____ ossification center.
how membranous bones develop
week _____: bony spicules, ossification centers grow outward and then they meet; the area where they meet never really _____ > develops into the cranial _____
occipital, parietal, frontal, maxilla, mandible, nasal bone
primary
6-7
ossifies
sutures
Development of Cranial base: Chondrocranium
Cartilaginous precursors of the cranial base, several small cartilages form a central stem and other cartilages outline paired lateral structures, begin to appear at about _____ weeks of development in the mesoderm or ectomesenchyme separating the brain above from the rest.
The chondrocranium is fully fused and differentiated by the end of the _____ month of pregnancy, or _____ weeks since the initiation of cartilage formation.
Mineralization of the chondrocranium takes place at various centres of
ossification that appear in the cartilages of the cranial base
7
second
2
Alveolar process of maxilla
alveolar process - teeth are embedded; different from the rest of bone, develops in a different _____; present only when teeth are present, when no teeth > it _____ and _____
manner
regresses
disappears
Prenatal Growth and Development of Maxilla:
- Maxilla forms within the maxillary _____ extending ventrally from the _____ arch
- _____ ossification
- Ossification starts in _____ week
- _____ development
mandibular arch is the _____ brachial arch > has a maxillary process that extends and forms the upper face; ossification begins here
brachial arch is _____ (maxilla is derived from neural crest)
prominences mandibular intramembranous 7th palatal
first
neural crest
Postnatal Growth and Development :
Two Basic Modes of Growth Movements
- Remodeling:
Deposition and resorption of bone
(a) _____
(b) _____ - Displacement:
Growth movements which cause separation of the different bones
(a) _____
(b) Cranial base _____
cortical drift
relocation
sutural growth
synchondrosis
Postnatal Growth and Development
intramembranous > bone is added on the surface, only grows by _____ growth
as you go from immature to mature bone; you must ____ (cortical drift/relocation)
appositional
remodel
Remodeling and Relocation vs. Cortical Drift
EXPLAIN ME
YES
Remodeling of Palate
ü Bone ____ on oral side
ü Bone ____ on nasal side
deposition
resorption
know that the maxilla (maxillary tuberosity, alveolar processes) grows via a ____ process
remodeling
Mandible
mandibular notch, when condyle is absorbed in arthritis, you will see changes in the mandibular ____
notch
Mandible: Prenatal Growth & Development
- ____ week in uterine
- ____ & ____ ossification
6th
intramembranous
endochondral
Body:
The mandible is ossified in the fibrous membrane covering the outer surfaces of ____ (6th wk)
meckel’s cartilage forms the original ____, but never turns into the mandible; serves strictly as the ____ structure; formed by ____ ossification
meckel’s cartilages
temple
positioning
intramembranous
Ramus:
The condylar cartilage - Carrot shaped cartilage appears (____ wk) in the region of the condyle and occupies most of the developing ramus. Converts to bone by ____ ossification (____ wk), forming condyle head and neck.
Coronoid process - A small strip of cartilage appears along the anterior border of the coronoid process. It is invaded by the surrounding membrane bone and undergo absorption (____ wk).
condylar cartilage is maintained until ____; cartilage in coronoid process ____
10th
endochondral
14th
10-14th
puberty
regresses
Alveolar Bone
It starts when the deciduous tooth germs reach the early ____ stage. The bone of the mandible begins to grow on each side of the tooth germ.
The alveolar processes grow at a rapid rate during the periods of ____.
bell
tooth eruption
Mandible: Postnatal Growth & Development
Main Growth Sites:
ü Secondary Cartilage (____ Cartilage)
ü ____ Ridge
ü The Ramus
ü Lingual ____
condylar
alveolar
tuberosity
- Condylar Cartilage:
• ____ cartilage
• Functions as ____ cartilage and ____ site (which is why it is formed by both intra/endo ossification).
• Adoptive response to mechanical ____ and development
• Growth of condylar cartilage helps in:
- Increase in ____ of the mandibular ramus
- Increase in the overall ____ of the mandible
- Increase of the inter condylar distance (____) - Growth with the alveolar process:
• Due to the increase in the space between the upper and lower jaws a space created between the opposing teeth to erupt. This means that bone deposition contributes to the growth of the body of the mandible in ____.
secondary articular growth stress height length width
height
- Ramus:
Periosteal bone apposition and resorption (bone remodeling) help in mandible growth. The results depend on the place of bone remodeling. Growth can occur in ____, ____ and ____
Move posteriorly by bone deposition on ____ border and resorption on ____ border. The anterior part of the ramus becomes the ____
height
length
width
posterior
anterior
corpus
Width
Completed before ____ growth spurt at around age ____
Length
Continues through puberty
- Girls: ____ years
- Boys: ____ years
Height
Continues into ____ after the growth spurt
large mandible > jaw surgery > you want it to be passed the time of length completion (girls for 16, boys closer for 20)
height growth until adulthood becomes a problem for placing dental implant in teenagers (18 y.o.); the dental implant will still behind, nowadays implants are placed much later on (girls 20, boys even later)
adolescent
12
14-15
18-19
adult
Jaw Alignment
Class I = ____
Class II = ____
Class III = ____
class III > if overgrown mandible, postpone surgery because mandible continues to grow until later in life (bc has it’s own growth potential)
balanced jaw relationship
underdeveloped mandible
overgrown mandible/underdeveloped maxilla
JOINTS in the SKULL • \_\_\_\_ • Sutures • \_\_\_\_ • Gomphosis
TMJ is not identical to other synovial joints in the body; synovial joints in the skull are ____
not unique joint structure in skull > synchondroses/sutures (____ and ____ are unique in skull)
synchondroses
synovial joint
unique
synovial joints
gomphosis
Synchondrosis
- A union between two bones by the formation of either ____ cartilage or ____ cartilage
- Usually ____ and exists during the growing phase until the intervening cartilage becomes progressively ____ and ultimately becomes obliterated and converted into bone before adult life
hyaline
fibro
temporary
thinner
Midline Synchondroses of Cranial Base
Important ____ for the skull
Spheno-ethmoid Synchondrosis closes at ____
Intersphenoid Synchondrosis ossifies at ____
Spheno-occipital synchondro closes between age ____
intersphenoid synchondrosis very little ____ contribution
orthodontists love the ____ synchondrosis; cannot manipulate cartilage
growth center
age 6
birth
13-15
post-natal
spheno-occipital
Epiphyseal growth plate of long bones:
Resting/Proliferating/Hypertrophic
Synchondrosis
Hypertrophic/Prolif/Resting
/Prolif/Hypertrophic
REWATCH ME
HALLO
Cranial Base Synchondroses are Important “Growth Center”
Ex vivo explant experiment showed that spehnoid-occipital synchondrosis can enlarge independently without ____ factors.
Cranial base synchondroses are regarded as important growth centers of the craniofacial skeleton, particularly the ____ synchondrosis because of its late ossification and important contribution to post-natal cranial base growth
has intrinsic potential to how much it grows; ____ programmed
Timing of Closure:
• Spheno-ethmoid S: ____ yrs
• Interspenoidal S: at ____
• Spheno-occipital S: ____ yrs
extrinsic spheno-occipital 6 birth 13-15
Abnormal Development of the Cranial Base:
- ____ (Apert, Crouzon, Pfeiffer)
- Down’s syndrome
- ____ syndrome
- Klinefelter syndrome
- ____ syndrome
- Achondroplasia
Premature growth arrest of the cranial base leads to midface ____ and reduced midfacial ____
syndromic craniosynostosis turner william's retrusion height
Premature Closure of the Cranial Base - ____ distraction osteogenesis
Lefort II
Temporomandibular Joint (TMJ)
- The only movable ____ in the head that connects the mandible to the rest of the skull
- One of the most used joints in the body
- Biting force, ____ lbs/in2
synovial joint
600-1000
TMJ movement
only when open a half inch = ____ movement
when you open more; the disc and the joint slides forward; ____ movement > exerts a lot of stress to the joint; which is protected by the ____
roll
translational
articular disc
TMJ movement
when closed; disc sits right on top; when you open the disc moves with the condyle; protects the condyle, the tip of condyle is thin articular cartilage so it requires protection
when abnormal; disc is ____ displaced; ____ stage, the condyle moves so the disc gets placed back on top of the condyle
or it can be totally ____ so the disc does not return to the top of the condyle; when this continues > ____
treatment > remove the disc, or pull the disc back over top of the condyle
Osteoarthritis
• Surface ____
• Perforation of ____
• Fibrous ____
anteriorally
early
locked
osteoarthritis
erosion
disc
adhesion
Joint Lubricants in TMJ:  • \_\_\_\_ • \_\_\_\_ • Surface Active Phospholipids
Lack of lubrication > increased ____ > adhesion, displacement, ____, distortion of the articular disc > degenerative arthritic change
lubricin
hyaluronate (HA)
friction
hypertropy
The effect of loss of Lubricin function in PRG4 knock out mouse TMJ
Lubricin has ____ and ____ activities
PRG4 makes ____; when KO the gene, the disc becomes ____, and the increase of protein deposit on the ____ chamber, and the disc changes its properties
after 3 months, ____ of the surface and ____ of the disc
anti-adhesion
anti-cell growth
lubricin
thick
upper
erosion
adhesion
HA-deficient TMJ in
Has2f/f;Aggrecan CreERT2
Has2f is the enzyme that makes ____, when KO the join starts to change in appearance, the cartilage looks VERY ____
really ____ cells on top of the cartilage, cracking of the cartilage surface, it is clearly an arthritic joint
proves that we need enough lubricant for proper TMJ function
hyaluronate (HA)
different
proliferating
TMJ Disorder (TMD): • A group of conditions that cause pain in the jaw joint and muscles, noises (clicking or crepitus) and restricted jaw movement. • 10-30 million people/year in US, (F:M = \_\_\_\_) Causes: - Trauma - Rheumatoid arthritis - Psycosocial – stress - Parafunctional activities, \_\_\_\_ - \_\_\_\_ factor - Systemic joint \_\_\_\_ - Unknown
2:1
bruxism
occlusal
laxity (flexible joint)
TMJ and Facial Development
Abnormal facial development is observed in patients with
• Trauma to TMJ
• Developmental malformation of the ____
• ____
Juvenile idiopathic rheumatoid arthritis:
• ____ in age between 0-15 yrs; this number is actually under-estimated, in reality it is much higher
• Reports on TMJ involvement in JIA varies between 40-70%
• TMJ erosion is often associated with ____
• ____ joint in JIA
• Early ____ is necessary to prevent severe damage to
the TMJ and its consequences.
mandibular condyle
juvenile idiopathic rheumatoid arthritis (JIA)
1-1000
no pain
under-diagnosed
detection
TMJ and Facial Development
- ____
- Limited mouth opening
- ____ dysfunction
- Occlusal cant/Facial asymmetry
- ____
- Breathing problem: ____
micrognathia (mandible)
jaw muscle
open bite
obstructive sleep apnea (OSA)
Missing/smaller condyle? Suggestive of ____
arthritic TMJ
