growth patterns/timings of head and neck, clinical relevance Flashcards
bones in human head
28 bones
- 8 cranial
- 14 facial
- 6 auditory
- 1 hyoid
head to body ratio proportions
- 1:4 @ birth (large proportion at birth due to the growth of the brain)
- 1:8 adults
when do sutures fuse
7 yeras
what type of growth are surtures
secondary
- repsonding to the brain growing
early fusuon of sutures
craniosynotosis syndromes - crouzon - apert - pfeiffer
development of the lower 2/3 face
- downward and downward growth of maxilla and mandible
- elongation of nose
what is found at the base of the skul
cranial base synchrondroses
crainial base synchondroses
spheno ethmoidal
spheno occuipital
spehno ethmpidal
anterior cranial base
follows neurla growth pattern
neural growth pattern
rapid growth early on which then slows, follows growth pattner of briain
spheno occipital
posterior cranial base
somatic growth pattern (much later on)
what is it when synchondroses dont grow
achrondroplasia (dwafism)
achrondroplasia
- short stature
- large head as a proportion
- prominent forehead (frontal bossing)
- small midface
- flattened nasal bridge
what is responsible for achrondroplasia
- changes in the genes
how does the maxilla grow
downwards and forwards through growth in the cranial base
- new bone added to both sides of sutures
- possible secondary growth site following soft tissue growth
sycondroses growth site type
primary
- growht of the cartilage is the driving force pushing the face downwards and forwards
why does the maxialla grow width ways
due to mid palatal suture
fuses around puberty
- areas of new bone addition and resportion
maxilla bone shaping
floor of nose resorbs
bone added to floor of mouth
appears to move more downwards than forwards
- surface remoddeling occurs in opposite direction to bone translation
reshaping of face as bone moves downwards and forwards
how can orthodontics be used to influence growth of mx
push apart suture to grow the middle of the suture
md growth
grows in height and length
role of conyde in md growth
get longer and remodels
growth in length by cartilage replacement in the condyle
unsure if 1/2 growth site
condylar cartilage
resembles epiphyseal plate cartilage of long bones
- proliferative cell can differentiate into chrondroblasts
appositional, not proliferative
not organised into parallel colums
remodelling involved in md formation
resoprtion from the anterior surface
deposition on the posteiror surface
remodeling of the glenoid fossa
growht in height continutes throughout life, lenght ceaces in teens
rotation upon growing in md
- remodelling of surfaces of the mandible masks the rotation (masked by surface apposition and resorption)
- due to differential growth in anterior and posterior face heights
- internal rotation in core of mandible relative to the cranial base (forwards and upwards)
- seen by superimposing serial radiographs with implants
greater growth in one side of the condyl can lead to
facial asymmetry
mx rotation
small but variable rotation
mean 3 degrees anterior, but can be backwards
when is soft tissue growth most rapid
around puberty
attemtpted mechancisms that control head and face growth
1) Remodelling theory
2) sutural theory
3) cartilaginous theory
4) functional matrix theory
5) part counterpart principle
6) servo system theory
non proven
when should you fit functional applicances
when puberty growth occurs
how can you predict when puberty growth will occue
Can use hand wrist radiographs
- ulnar sesamoid graph ossifies at start of pubertal growth spurt
Cervical spine maturation
- undertaken on lateral cephalometric radiograph
