8. Tendon and Ligament Flashcards
CONNECTIVE TISSUES are VITAL to FUNCTIONING of the…
JOINTS
there are 6 MAJOR TYPES of of connective tissues:
- LOOSE connective tissue
- FIBROUS connective tissue
- BONE
- ADIPOSE TISSUE
- CARTILAGE
-BLOOD
what does TENDON do
LINK MUSCLE to BONE
- transmits FORCE for MOVEMENT
Not all tendons are required to perform the same functional role
there are
ENERGY-STORING TENDONS & POSITIONAL TENDONS
what is the ROLE of a LIGAMENT
LINKS BONE to BONE
- ASSISTS in STABILISATION of JOINT
- PREVENTS EXCESSIVE MOTION
- RESTRICTS MOVEMENT
also ABSORBS SHOCK
(high tensile strength)
what is it called when a TENDON is TORN/OVERSTRETCHED
STRAIN
what is it called when a LIGAMENT is TORN/OVERSTRETCHED
SPRAIN
(ACL commonly injured)
how is COLLAGEN in TENDONS/LIGAMENTS HIGHLY ORGANISED
collagen molecule
-> COLLAGEN FIBRILS
-> COLLAGEN FIBRES
-> COLLAGEN FASCICLE
in TENDONS/LIGAMENTS what can you find around the collagen FASCICLES (2)
EPITENON / EPILIGAMENT
- loose connective tissue surrounding fascicles
INTERFASCICULAR MATRIX
how are FIBROBLASTS arranges in LIGAMENT
DISPERSED in LIGAMENT MATRIX and OUTER VASCULAR EPITENON layer
TENDON VS LIGAMENT
TENDON:
(links?
elastic?
how are fibres arranged?
cells?
ECM composition)
BONE TO MUSCLE
NON-ELASTIC and TOUGH
collagen fibres as COMPACT, PARALLEL bundles
TENOCYTE cells
ECM: TYPE 1 COLLAGEN
PROTEOGLYCANS
ELASTIN
TENDON VS LIGAMENT
LIGAMENT:
(links?
elastic?
how are fibres arranged?
cells?
ECM composition)
BONE TO BONE
ELASTIC and STRONG
CROSS-CONNECTING, COMPACT collagen bundles
(non-parallel)
LIGAMENTOCYTE cells
ECM: TYPE 1 COLLAGEN
PROTEOGLYCANS
ELASTIN
ECM in both TENDONS and LIGAMENTS consists of
TYPE 1 COLLAGEN
PROTEOGLYCANS
ELASTIN
how does the ECM COMPOSITION in LIGAMENTS DIFFER to in TENDONS
- MORE PROTEOGLYCAN
- MORE ELASTIN
- mixed cell morphology
- MORE CARTILAGINOUS PROTEINS
eg. TYPE II COLLAGEN, AGGRECAN - LESS COMPACT
TENDONS DEVELOPMENT can be Organised into 3 AREAS
- HEAD tendons
- AXIAL tendons
- LIMB tendons
all originate from different things in embryology
where do AXIAL TENDONS ORIGINATE from
SOMITES
where do HEAD TENDONS ORIGINATE from
NEURAL CREST CELLS
where do LIMB TENDONS ORIGINATE from
LIMB LATERAL PLATE
how does MUSCLE DEPENDENCY VARY in DIFFERENT TENDONS:
HEAD AND LIMB TENDONS:
- tendons INITIATE development INDEPENDENTLY
- FUTHER DEVELOPMENT REQUIRES A MUSCLE
how does MUSCLE DEPENDENCY VARY in DIFFERENT TENDONS:
AXIAL TENDONS:
INITIATION REQUIRES A MUSCLE
what is SCX in TENDON&LIGAMENT DEVELOPMENT
and how is the expression
the EARLIEST KNOWN MARKER of tendon/ligament DEVELOPMENT
REGULATES downstream TENDON-RELATED GENES during development
- EXPRESSION DECREASES after BIRTH
what do Egr1 and Mkx do in TENDON DEVELOPMENT
And how is the expression
SUPPORT DIFFERENTIATION
( from MESENCHYMAL CELLS to TENOCYTES to TENDON)
EXPRESSION PERSISTS THROUGHOUT POSTNATAL MATURATION
- important for tissue maintenance in adult life
how are FORCES APPLIED in TENDONS VS in LIGAMENTS
TENDONS: UNIAXIAL
acts in only 1 DIRECTION
LIGAMENT: forces may be applied in a number of directions depending on the range of motion of the associated joint
TENDONS and LIGAMENTS are…
(behaviour)
VISCOELASTIC
- VISCOUS and ELASTIC BEHAVIOUR
(the material to some extent both behaves like a liquid and a solid material, and that it has a time-dependent strain)
how is VISCOELASTICITY REPRESENTED
in a STRESS AND STRAIN CURVE
In a STRESS & STRAIN CURVE
what happens BEYOND 2% STRAIN
CRIMPLED FIBRES are STRAIGHTENED
In a STRESS & STRAIN CURVE
what happens LESS THAN 4% STRAIN
Tendon/Ligament RETURNS TO ORIGINAL LENGTH when unloaded
In a STRESS & STRAIN CURVE
what happens BETWEEN 4%-8%
COLLAGEN FIBRES begin to SLIDE PAST EACH OTHER
as CROSS LINKS start to FAIL
- MICROSCOPIC FAILURE
(PARTIAL RUPTURE)
In a STRESS & STRAIN CURVE
what happens ABOVE 8% STRAIN
MACROSCOPIC FAILURE
(visible)
VISCOUS is..
TIME-DEPENDENT
3 MAJOR CHARACTERISTICS of VISCOELASTIC PROPERTIES of tendons:
- STRESS RELAXTION
time-dependent DECREASE in load
ability to REDUCE STRESS over time - CREEP
time-dependent DEFORMATION under constant LOAD
ability to increase elongation strain - HYSTERESIS
UNLOADING and LOADING CURVES are DIFFERENT- can measure by difference in curves
difference represents amount of ENERGY RELEASED in loading/unloading
tendons and ligaments are … responsive, meaning
MECHANO-RESPONSIVE
can ADAPT to altered MECHANICAL LOADING
Tendons & ligaments are LARGELY MADE UP OF..
COLLAGEN
how many different types of COLLAGEN
At least 28
what is COLLAGEN MADE UP OF / STRUCTURE
AMINO ACIDS
Wound to form TRIPLE HELIX - 3 POLYPEPTIDE CHAINS
which are ALLIGNED in ELONGATED FIBRILS (there are also non-fibrillar collagens)
AMINO ACID repeats in COLLAGEN
GLYCINE (Gly)
PROLINE (X)
HYDROXY PROLINE / HYDROXY LYSINE (Y)
where is TYPE I COLLAGEN FOUND
BONE
SKIN
TENDONS/LIGAMENTS
Swhere is TYPE II COLLAGEN FOUND
CARTILAGE
where is TYPE III COLLAGEN FOUND
EXTENSIBLE CONNECTIVE TISSUE
- SKIN
- LUNG
- VASCULAR SYSTEM
IMPORTANT ROLES of COLLAGEN
- Principle SOURCE of TENSILE STRENGTH
- MAINTAINING TISSUE STRUCTURE and FUNCTION
- Cell ADHESION
- CHEMOTAXIS
- Cell MIGRATION
- TISSUE REMODELLING during GROWTH
- WOUND HEALING
ALLIGNMENTS of COLLAGEN in
tendon/ligament:
annulus fibrosus:
meniscus:
tendon/ligament:
UNIDIRECTIONAL (1 direction)
annulus fibrosus:
INTRA-LAMELLAR (x)
meniscus:
INTERSPERSED
example of a COLLAGEN ABNORMALITIES (3)
SCURVY
OSTEOGENESIS IMPERFECTA
EHLERS DANOS SYNDROME
COLLAGEN ABNORMALITY: SCURVY
what is the CAUSE of SCURVY, and what are the effects
- LACK OF VITAMIN C
- vitamin C required as a CO-FACTOR in COLLAGEN SYNTHESIS (hydroxylation)
- FRAGILE CAPILLARIES, abnormal BLEEDING, BRUISING, internal HAEMORRHAGING
- TEETH LOOSEN, BONES BREAK EASILY
COLLAGEN ABNORMALITY: OSTEOGENESIS IMPERFECTA
CAUSE? EFFECT?
problem with CONNECTIVE TISSUE due to LACK OF TYPE I COLLAGEN
due to MUTATION in TYPE I COLLAGEN
- mainly affect BONES (break easily)
- JOINT HYPERMOBILITY,
SKIN HYPERLAXITY (can be stretched),
BLUE SCLERA (white part of the eye (sclera) has a blue, gray or purplish tint),
DENTINOGENESIS IMPERFECTA (disorder of tooth development)
COLLAGEN ABNORMALITY: EHLERS DANOS SYNDROME
CAUSE? EFFECT?
- group of disorders that effect CONNECTIVE TISSUE
due to MUTATIONS in TYPE 5 COLLAGEN
- JOINT HYPERMOBILITY, SKIN FRAGILITY (&stretchy)
what do PROTEOGLYCANS do (3)
- Contribute to the FIBRIL and FIBRE STRUCTURAL INTEGRITY
- Interact with collagen fibres to YIELD VISCOELASTIC PROPERTIES
- Role in COLLAGEN FIBRILOGENESIS and ORGANISATION
when are PROTEOGLYCANS INCREASED
In INJURY
(tissue swelling)
what results from LACK of PROTEOGLYCANS (ABSENCE of BIOGLYCAN and FIBROMODULIN)
leads to…
leads to..
ALTERED COLLAGEN FIBRILS in the tendons
-> JOINT INSTABILITY
-> ABNORMAL GAIT, ECTOPIC OSSIFICATION, OSTEOARTHRITIS
3 CRITICAL ROLES of ELASTIC FIBRES
- important MECHANICAL PROPERTIES in tissue elastic RECOIL and RESILIENCE
- REGULATION of CELL FUNCTION
- REGULATION of ACTIVITY of the GROWTH FACTOR TGF-BETA FAMILY
what were found to be localised between collagen FASCICLES
FIBRILLIN-1 and FIBRILLIN-2
(Elastin mainly at IFM region and co-localised with fibrillin 1and 2)
in human tendon what has FIBRILLIN-1 been associated with
TYPE 6 COLLAGEN
INCREASE in TEAR SIZE (INJURY) links to INCREASE In… (2)
- TYPE 6 COLLAGEN
- FIBRILLIN-1
what is the name of the DISORDER of the CONNECTIVE TISSUE that is caused by MUTATION in the FIBRILLIN-1 (FNBN1) GENE
& its effects
MARFAN SYNDROME
- Tall and Thin with long arms, legs, fingers and toes
- Flexible joints and scoliosis
- Abnormalities of the heart and the aorta
