Growth and Development Flashcards
Where is the growth site of the mandible?
Mandibular Condyle / condylar cartilage
What is osteogenesis?
Process of bone formation is called osteogenesis ?
Types of Osteogenesis ?
- Endochondral
- Intramembranous
- Both
What is Endochondral bone formation?
The bone formation is preceded by formation of cartilaginous model - which is replaced by bone.
Examples of Endochondral bone formation?
Ethmoid
Hyoid
Incus
Stapes
what is Intramembranous bone formation?
In intramembranous ossification - the bone is formed by secretion of bone matrix directly within the connective tissues, without any intermediate formation of cartilage.
Examples of Intramembranous bone formation?
Maxilla
Nasal Bones
Parietals
Zygoma
Vomer
Lacrimal
Zygomatic
Examples of bone where both intramembranous and endochondral ossification is seen in - ?
Occipital
Temporal
Sphenoid bones
Scammon’s Growth curve classifies body tissues into 4 types - each of these tissues grow at different times and rates - what are they ?
- Lymphoid Tissue
- Neural Tissue
- General or Visceral Tissue (muscles and bones)
- Genital tissues
Lymphoid Tissue from Scammon’s growth curve -
proliferates rapidly in late childhood and reaches 200% adult size. This is an adaptation to protect children from infections.
By the age of 18 years - lymphoid tissue undergoes involution to reach adult size
Neural Tissue from Scammon’s growth curve -
Grows very rapidly and reaches maximum size by 6-7 years of age.
Very little growth of neural tissue occurs after 6-7 years.
General or visceral tissue (muscles, bones) from Scammon’s growth curve -
Exhibits an S shaped curve with rapid growth up to 2-3 years followed by a slow phase of growth between 3-10 years
After 10 years - a rapid phase of growth occurs terminating by the 18th-20th years
Genital tissues from Scammon’s growth curve -
Shows negligible growth until puberty.
Grows rapidly at pubertal age and reaches adult size after which growth ceases.
Name the Theories of Growth
- sutural theory
- cartilaginous theory
- functional matrix theory
- servo system theory of growth (cybernatics)
- Multifactorial theory
- Genetic Theory
- Neurotropism
Servo system theory of growth was given by - ?
Petrovic and Chartier
Cartilaginous theory of growth was given by - ?
Scott
Sutural theory of growth was given by -?
Sicher
Functional matrix theory of growth was given by -
Melvin Moss
Multifactorial theory of growth was given by - ?
Vam Limborgh
How many bones are there in an infant skull as compared to an adult ?
At birth infant skull is composed of 45 bones which are reduced to 22 in adults
Greatest amount of cranial growth occurs by - ?
Birth to 5 years
At birth which structure is nearest the size it will eventually attain in adulthood
Cranium
What are epigenetic factors ?
Epigenetic factors are present outside the skull and manifests their influence in indirect way by intermediary action on associated structures
eg. Eyes, Brain
Genetic Theory - statement
Growth is controlled by genetic influence and is preplanned
Sicher’s Sutural Theory - statement
Growth in the sutures is responsible for craniofacial growth
Van Limborgh’s theory - multifactorial theory - statement
Combines existing theory and states that - growth is under control of intrinsic genetic, epigenetic, and environmental factors.
Scott’s cartilaginous theory of growth - statement
Cartilaginous part of the skull and primary centers of growth with sutures being only secondary in nature.
According to scott - the nasal septal cartilage is the pacemaker for growth of entire naso-maxillary complex.
Moss’s functional matrix theory of growth - statement
The growth of skeletal components largely depends on functional matrices or non-skeletal tissues
The important synchondroses, the growth sites of cranial base, found in cranial base are -
- Spheno-occipital synchondrosis
- Spheno-ethmoid synchondrosis
- Inter- sphenoidal synchondrosis
- Intra-occipital synchondrosis
Spheno-occipital synchondrosis
- Principle growth cartilage of the cranial base during childhood.
- It is cartilaginous junction between sphenoid and the occipital bone.
- The direction of growth of the spheno-occipital synchondrosis upwards and forwards.
- It closes at an average age of 18 years - ie early adult stage.
Spheno-ethmoid synchondrosis
It is a cartilaginous band between the sphenoid and the ethmoid bones.
It ossifies by 5-25 years of age
Inter- sphenoidal synchondrosis
It is a cartilaginous band between the 2 parts of the sphenoid and ethmoid bones.
It ossifies at birth
Intra-occipital synchondrosis
Ossifies by the age of 3-5 years
Remnants of Meckel’s Cartilage
AIMS
A - anterior ligament of malleus
I - Incus; Malleus
M - Mental Ossicles / mandibular symphysis
S - Sphenomandibular Ligament
What is the dental arch form ultimately determined by ?
Balance between facial an intraoral musculature
Growth of oral structures is mainly influenced by factors that are -
Hereditary - influenced by environment
Growth Spurts
- Just before birth
- Infantile or childhood growth spurts - upto 3 years of age
- Mixed dentition growth spurts / juvenile growth spurts - boys - 8-11 years , Girls - 7-9 years
- Pre-pubertal growth spurts / adolescent growth spurts - boys 14-16, Girls - 11-13
Duration of adolescence in boys is -
5 years
Mandibular condyles grow by which mechanism?
Endochondral bone formation
All other areas of the mandible-formed& grow by direct surface aposition
Maximum increase in height of children is seen at -
1st year
Maturation of oral function - a gradient
Maturation of oral function can be characterised in general as following a gradient from anterior to posterior.
At birth, the lips are relatively mature and capable of vigorous suckling activity, whereas more posterior structures are quiet immature.
as time passes, greater activity by the posterior parts of tongue and more complex motions of the pharyngeal structures are acquired.
5 principal stages in craniofacial development
- Germ layer formation and initial organisation of craniofacial structures
- Neural tube formation and initial formation of the oropharynx
- Origins, migrations and interactions of cell populations, especially neural crest cells
- Formation of organ systems, especially the pharyngeal arches and the primary and secondary palates
- Lineal differentiation of tissues (skeletal, muscular, and nervous elements)
Related Syndromes of each Stage of Craniofacial Development
- Germ layer formation and initial organisation of craniofacial structures - Fetal Alcohol Syndrome
- Neural tube formation and initial formation of the oropharynx - Anencephaly
- Origins, migrations and interactions of cell populations, especially neural crest cells - Hemifacial Microsomia, Mandibulo Facial dysostosis (treacher Collin Syndrome), limb Abnormalities
- Formation of organ systems, especially the pharyngeal arches and the primary and secondary palates - Cleft lip and/or palate, Cleft other facial structures, Cleft palate.
- Lineal differentiation of tissues (skeletal, muscular, and nervous elements) - Achondroplasia, synostosis syndromes
Hemifacial Microsomia occurs during?
Migration of neural crest cells
After the age of 6, the increase in size of the mandible occurs distal of 1st molars-why?
The mandible grows in length by resorption at the anterior border and deposition at the posterior border of ramus. This provides the required space for the developing and erupting permanent teeth.
What is vital staining ?
An experimental method of measuring growth. The method consists of injecting dyes that stain the mineralising tissues.These dyes get deposited in the bones and teeth of the animals - which can be histologically studied.
Who introduced vital staining ?
John Hunter
What are the agents for vital staining ?
- Alizarin
- Tetracycline
- Technicium isotope
Period of adolescent growth in boys is -
5 years
The pharyngeal structure established in early age and remain constant throughout life is -?
Depth of nasopharynx
- the depth of nasopharynx is established during the first 2 years of life and this dimension remains constant thereafter.
Absence of sesamoid bone in girl of age about normal range of puberty is said to have - ___________
Delay in reaching puberty
Importance of sesamoid bone
The sesamoid is a small nodular bone most often present embedded in tendons in the region of the thumb.
Calcification of sesamoid bone is one of the important features of pubertal growth spurt, which is earlier in females than in males.
Absence of sesamoid bone indicates delay in reaching puberty.
How many stages of cervical vertebrae growth are present in assessment of age ?
6 stages -
stage 1
stage 2
stage 3
stage 4
stage 5
stage 6
Stage 1 of cervical vertebrae growth
Peak of growth will start not earlier than 2 years after this stage.
c2,c3,c4 - lower borders are flat
Stage 2 of cervical vertebrae growth
Peak of growth will start 1 year after this stage
c2 - lower borders will show concavity
Stage 3 of cervical vertebrae growth
Peak of growth starts with in a year from the diagnosis of this stage
c2,c3 lower borders show concavity
Stage 4 of cervical vertebrae growth
Peak of growth occurred a year or two before this stage
c2,c3,c4 - lower borders show concavities
Stage 5 of cervical vertebrae growth
Peak of growth ended one year before this stage
c2,c3,c4 - show concavity at the lower borders
Stage 6 of cervical vertebrae growth
Peak of growth ended at least 2 years before this stage
c2,c3,c4 - concavities at lower borders are marked
