Human Systems And Embryology Flashcards
What are the features of an infant skull?
Eyes are large, ears are low set
Forehead upright and bulbous: face appears broad
Nasal region is vertically shallow with nasal floor close to inferior orbital rim
What are the 3 ways an infant skull can grow?
At sutures or periosteal lined contact areas
In cartilage
By surface deposition
Where in the skull does growth appear at sutures/periosteal lined contact areas?
Between the flat bones of the cranial vault and between the bones of the cranium and maxillary
Where in the skull does growth occur at cartilage?
Synchondroses between the bones forming the base of the skull
In the mandibular condyle and in the cartilage of the nasal septum
Where in the skull does growth occur by surface deposition?
Over the surfaces of the cranial and facial bones
Beneath the covering periosteum
How does the cranial vault grow?
The cranium expands in response to the growing brain (until 6-7 years)
After neural growth ceases, the forehead continues to expand due to enlarging air sinuses
How does the cranial base grow?
Synchondroses
At what age is the lateral growth of the cranial base completed by?
3 years
At what age does the sphenoethmoidal Synchondroses fuse?
6-7 years
At what age does growth cease at the sphenoid-occipital Synchondroses and what age does it fuse?
12-15 years
20 years
What direction does the maxilla grow?
Downward and forward
Where does maxillary growth occur?
At sutures between maxilla and skull
Where does surface deposition occur in maxillary growth?
Posteriorly
Where does surface resorption occur in maxillary growth?
Anteriorly and inferiorly
What direction does the mandible grow in?
Downwards and forwards
Where does mandibular growth occur?
Condylar cartilage
Where does surface resorption occur in mandibular growth?
Anteriorly and lingually
Where does surface deposition occur in mandibular growth?
Posteriorly and laterally
When do the mandible and maxilla grow in width in males and females?
Before pubertal growth spurt: 9-10 years
When do the mandible and maxilla grow in length in males and females?
Throughout puberty:
Males- 18 years
Females- 14-15 years
When does vertical growth of the mandible and maxilla end in males and females?
Males: 20s
Females: 17-18
What are the 4 predictors of pubertal growth spurt?
Chronological age
Secondary sexual characteristics
Hand-wrist radiographs
Cervical vertebral maturation (CVM)
What is CVM 1-6?
CS1/2; growth approaching
CS3; peak growth in 1 years
CS4; peak growth past
CS5/6; peak growth ended
What do forward growth rotations lead to?
A short face
What do downwards and backwards growth rotations lead to?
A long face
In a lat cephalogram what do the following mean?
S
N
A
B
ANS
PNS
Pog
M
Go
Po
Or
Ba
S; Sella
N; Nasion
A; A point
B; B point
ANS; Anterior Nasal Spine
PNS; Posterior Nasal Spine
Pog; Pogonion
M; Mentón
Go; Gonion
Po; Ponion
Or; Orbital
Ba; Basion
In a lat cephalogram what do the following mean?
S
N
A
B
ANS
PNS
Pog
M
Go
Po
Or
Ba
S; Sella
N; Nasion
A; A point
B; B point
ANS; Anterior Nasal Spine
PNS; Posterior Nasal Spine
Pog; Pogonion
M; Mentón
Go; Gonion
Po; Ponion
Or; Orbital
Ba; Basion
When is full masticatory function developed?
2 years
What is the language development stage at 1 year?
Understands 20 words/simple phrases
Uses 2-3 words
What is the language development stage at 2 years?
Understands simple commands/ questions
Uses 100 words
What is the language development stage at 3 years?
Understands prepositions, object function, simple conversation
Uses 4 word sentences
What is the language development stage at 4 years?
Understands colours, numbers, tenses
Uses long grammatical sentences
What is the periodontium?
Tissues that surround and support the teeth
What is the role of the periodontium?
Retain teeth in sockets
Resist masticatory loads
Defensive barrier
What does cementum do?
Covers root dentine
Provides attachment for some periodontal fibres
In what ways is cementum similar to bone?
Collagen matrix
Lamellar arrangement
What are the two types of cementum?
Cellular and Acellular
What is cementum laid down by?
Cementocytes
What are the features of cellular cementum?
Contains cementocytes
Secondary formed
Found on apical root and furcation regions
What are the features of acellular cementum?
No cells within
Adjacent to dentine
Primary formed
What is the alternative classification of cementum?
Acellular Extrinsic Fibre Cementum
Cellular Intrinsic Fibre Cementum
What are the features of acellular extrinsic fibre cementum?
Contain’s Sharpey’s fibres
Cervical 2/3 root
What are the features of cellular intrinsic fibre cementum?
No Sharpeys fibres
Contains collagen fibres
No role in tooth attachment
What are the features of alveolar bone?
Similar to bone
Cortical plate forms inner lining of tooth socket
Provides attachment (Sharpey’s fibres)
Penetrated by nutrient canals (Volksmann)
Inner cancellous bone containing marrow
What is the role of the periodontal ligament?
Attaches tooth to jaw
Transmits biting forces to alveolar bone
Organised connective tissue
0.2mm thick
What does the periodontal ligament contain?
Cells
Extracellular matrix
Fibres
Nerves
Blood vessels
What cells are found in the periodontal ligament?
Fibroblasts
Cementoblasts
Osteoclasts
Cementoclasts
Epithelial cells
Defence cells
What does the ECM in the periodontal ligament contain?
Hyaluronate GAGs
Glycoproteins (fibronectin)
Proteoglycans (proteodermatan sulfate, chondroitin/dermatan SO4 hybrid)
What fibres are found in the periodontal ligament?
True
Gingival
What do true fibres do?
Connect tooth to bone at/apical to alveolar crest
What do gingival fibres do?
Fibres found above the alveolar crest
What nerves are found in the periodontal ligament?
Sensory: mechanoreceptors (Ab and Af)
Nociception: (Af and C)
Autonomic: blood vessel control
What blood vessels are found in the periodontal ligament?
Inferior and superior alveolar arteries
Lingual and palatine arteries
What is the role of collagen in the pdl?
Principal fibres
Support tooth
Bear load
What is oxytalan?
Found in the pdl
Role unknown
What are the Alveolo-dental fibres?
Alveolar crest
Horizontal
Oblique
Apical
Interradicular (multi-rooted)
What are the interdental fibres?
Transeptal
What are the gingival fibres?
Dento-gingival
Alveolo-gingival
Dental-periosteal
Circular
What does the junctional epithelium contain?
Basal lamina
Hemidesmosomes
Lamina propria
What is the interdental col?
Dekeratinised tissue between teeth
What are the stages of feeding?
Ingestion
Stage 1 transport
Mastication
Stage 2 transport
Swallowing
What is ingestion? (feeding)
Movement of food from external to internal environment
Accomplished by biting and oral seal
What is stage 1 transport? (feeding)
Food is gathered on the tip of the tongue and transported posteriorly to the posterior teeth
What is mastication? (feeding)
Bolus is broken down by mechanical mastication with posterior teeth and chemical means via saliva
What is stage 2 transport in solids? (feeding)
Bolus is propelled into the oropharynx via the squeeze back mechanism
Solids move through through fauces to pharyngeal surface of tongue
What is swallowing? (feeding)
Epiglottis covers trachea, respiration pauses as food enters the oesophagus
What is stage 2 transport in liquids? (feeding)
Bolus is propelled into the oropharynx via the squeeze back mechanism
Oral seal holds liquids at the pillar of fauces
What are the features of peritubular (intratubulat) dentine?
Highly mineralised
No collagenous fibres
What are the features of intertubular dentine?
Less mineralised
Collagenous
What is dentine?
Hydroxyapatite crystals in a collagenous scaffold
What are tomes fibres?
Cytoplasmic process of odontoblasts
What is the difference between coronal dentine and dentine near to the root?
Coronal dentine is more permeable
What is the hydrodynamic theory?
Pain transmission through fluid movement through dentinal tubules activates mechanoreceptors
What is the difference between infected and affected dentine?
Infected is contaminated
Affected is softened/demineralised
What are the stages in the formation of enamel and dentine?
Cells of the dental papilla adjacent to the IEE differentiate into odontoblasts
Odontoblasts secrete dentine matrix which is later mineralised
Predentine formation causes cells of the IEE to elongate and differentiate into ameloblasts
Ameloblasts secrete enamel matrix (30% min)
Organic component removed and mineralisation occurs
What is the lung covered by?
Pleura
What are the contents of the pulp?
Cells
Nerves
Blood vessels
Vital tissue
What cells does the pulp contain?
Odontoblasts
What nerves does the pulp contain?
Plexus of Raschkow: alpha fibres, C fibres
What is the role of vital tissue in pulp?
Responds to stimuli
Regenerative potential
What are the functions of pulp?
Nutritive
Sensory
Protective
Formative
What are the sensory functions of pulp?
Temperature
Pressure
Pain
What are the protective functions of pulp?
Tertiary dentine formation
What are the formative functions of pulp?
Secondary dentine formation
What are the causes of pulpal injuries?
Caries
Dentine dehydration
Restorations (materials/etch)
Toothier
Orthodontic treatment
Cutting odontoblast processes
Direct injury
Cavity/crown prep
Radiation therapy
Periodontal pathology
Trauma
What happens to dentine tubules as they approach the pulp?
Increase in number and diameter
What are the features of alpha fibres in the pulp?
Myelinated
Sharp pain
Stimulated by EPT
What are the features of C fibres in the pulp?
Unmyelinated
Dull, aching pain
Stimulated by increased pulpal blood flow and increased pulpal pressure
