Musculoskeletal System Flashcards
What is a fracture?
Dissolution of bony continuity with/without displacement of fragments.
State 5 types of soft tissue damage which may accompany a fracture.
Torn vessels
Bruised muscles
Laceration of skin
Injured internal organs
Contused nerves.
State 4 forces which cause a fraction to occur.
Torsion
Bending
Compression
Shear
Why may a fraction occur?
Force is applied which exceeds the bone strength and elasticity
State the 3 causes of fracture
Indirect Trauma
Direct Trauma
Pathological
What is Indirect Trauma
Force transmitted in a specific fashion where there is a predictable outcome.
What is direct trauma
Force applied resulting in an unpredictable outcome e.g. RTA or a fall
What is a pathological fracture?
When the animal has an underlying bony or systematic disease which causes abnormal bone.
What are 3 ways a fracture may be classified?
Open/Closed
Complete/Incomplete
Shape of fracture
Which fracture shapes are classed as complete?
Simple Transverse
Simple Oblique
Simple Spiral
Comminuted
Avulsion
Segmented
Compression
Which fracture shapes are classed as incomplete?
Greenstick
Fissure
What force results in a greenstick fracture?
Bending
Is a fissure fracture a result of indirect or direct trauma?
Direct
What force results in transverse fracture?
Bending
What force results in oblique fracture?
Bending or Axial Compression
What force results in spiral fracture?
Override or Rotation
What causes communated fractures?
High energy trauma (direct)
Why may an avulsion fracture occur?
Muscular contraction that is stronger than the forces holding the bone together occurs e.g. a fall or pull.
What steps would you take when dealing with an open fracture?
KY Jelly
Clip the fur
Lavage
Sterile wound dressing
Doughnut bandage (relieves pressure)
State 5 principles of fracture repair
Restore bone continuity
Restore bone length
Restore functional shape of bone
Maintain freely moveable joints
Maintain normal soft tissue function
What are the 4 steps to take to ensure fracture repair
Sufficient reconstruction of normal form
Immobilisation of fragments until healing
Mobilisation of joints to prevent joint stiffness and muscle atrophy
Rehabilitation
What is a closed reduction of a fracture?
Realignment of bones without surgery with use of a splint or dressing support.
What is an open reduction of a fracture?
Surgical fixation where internal fixation is needed
What are the 3 requirements of a fracture so it can heal
Reduction of space between fragments
Immobilisation in correct alignment until clinical union
Preservation of blood supply
What is primary healing?
Direct healing where there is little to no space at fracture sites after applying internal fixation. Little or no bridging callus visible on radiographs.
What is secondary healing?
Healing via production of callus which relies on stability and viable biological tissue. (Casts and splints)
What are the four stages of bone healing?
Inflammation
Proliferative
Maturation
Remodelling
What occurs at the inflammatory stage?
Haemorrhage for 6-8 hours until haematoma forms
Vasodilation to reduce blood flow
Oedema forms
Oestocytes deprived of nutrition and die
Ends of fracture sites turn nectrotic and die
Inflammatory cells migrate to area and phagocytosis removes nectrotic tissue.
What occurs at the proliferative stage?
Haematoma is organised and stem cells invade
Granulation tissue and cartilage forms where haematoma was
Blood vessels grow down peristeum and medulla
Soft callus formed and appears 4-5 days post fracture (not seen on xray until 10-12 days post fracture)
What happens at maturation phase?
Hard callus is formed by fibrous tissue, cartilage and immature bone
High proportion of osteocytes
When callus envelopes bone ends- stability
Fibrous tissue replaced by cartilage and bone and clinical union occurs at 12-16 weeks.
What is the remodelling phase?
Initial soft callus and extra bone removed by scavenger cells
Woven bone replaced with stronger lamellar bone
Stress on bone means e+ on convex surface (osteoclastic activity) and e- on concave (osteoblastic activity)
What are 3 problems that can occur during fracture repair
Non Union (surgical intervention),
Delayed Union,
Malunion (abnormal alignment)
What negative effect could internal fixations have on an animal?
Atrophy, joint stiffness, tissue adhesion to fixture, movement of fixture
State 4 factors which may influence the rate of healing
Age, Damage to soft tissue (more likely to become infected due to reduced blood supply), Osteomyelitis (inflammation) and systemic illness
Which fracture heals faster oblique or transverse?
Oblique due to the larger surface area to promote tissue regrowth.
State 5 main functions of the skeleton
Support for soft cells and tissues
Attachments for muscles
Protection of delicate organs
Haemopoeisis- maturation of blood cells
Reservoir/Storage for minerals-calcium
What does arthritis mean?
Joint Inflammation
What are the two reasons an animal may have osteoarthritis?
Secondary complication of an existing disease (hip dysplasia) or normal aging process.
What are the clinical signs of osteoarthritis?
Swelling, Heat, lameness, systemic illness, muscle wastage, stiffness after rest/when moving, loss of ROM, crepitus
What is the pathophysiology of osteoarthritis?
Loading ability of joint is hindered
Chondrocytes are damaged and secrete enzymes that break down collagen
No new collagen is being synthesised and NO2 is released
Cartilage breaks down and inflammation is supported- decreasing viscosity of synovial fluid
Bone becomes sclerotic
What are 5 risk factors of osteoarthritis?
1)working
2)athletic
3)obesity
4)collagen disorders
5)trauma
What is the pathophysiology of a cruciate rupture?
Sudden rotation of the stifle causes cruciates to wind around each other
CrCl wound tight rubbing against femoral condyle
Hyperextension causes ligament rupture
What are the clinical signs of a crucitate rupture?
Lameness, toe touching, joint efflusion
What is an osteoblast?
A cell that synthesises new bone
What is an osteoclast?
A cell that remodels and breaks down bone
What is an osteocyte?
A cell formed from osteoblasts which help with the turnover of the bony matrix.
What is the shaft of the bone called?
Diaphysis
What is the end of the bone called?
Epiphysis
What is the growth plate on the bone called?
Epiphyseal plate
What is the name for formation of bone?
Endochondral Ossification
What is the first stage of endochondral ossification?
Hyaline cartilage dehydrates, dies and calcifies in the centre of diaphysis.
What is the second stage of Endochondral Ossification?
Blood vessels bring osteoblasts and a collar of bone is formed around the diaphysis which supports the calcifying cartilage.
What is the third stage of Endrochondral Ossification?
Blood vessels penetrate the collar and proliferate allows osteoblasts to enter which secrete new bone- leaved red gelatinous marrow.
What is the fourth stage of Endrochondral Ossification?
Secondary centres of ossification begin at epiphysis, cartilage between epiphysis and diaphysis is known as epiphyseal plate.
What is dyschondroplasia?
Abnormal/ underdeveloped formation of limb, trunk or head bones
What are the signs of dyschondroplasia?
Short legs, disproportionation, short vertebrae and short thick limb bones.
What are the signs of osteochondrodysplsia?
Short stumpy legs, folded ears and curly tail (scottish fold breed)
Why are epihyphyseal plate (growth plate) fractures common?
Not as strong as bone so likely to experience trauma where damaged cells would no longer be able to function normally.
Clinical signs of growthplate fractures?
None weight baring, swelling, pain and angulation in distal part of leg.
What is a type 1 Salter-Harris fracture?
Fracture in only the growth plate
What is a type 2 Salter-Harris Fracture?
Fracture in growth plate and metaphysis
What is a type 3 Salter-Harris fracture?
Fracture in growth plate and epiphysis
What is a type 4 Salter-Harris fracture?
Fracture in all 3 elements (metaphysis, growth plate and epiphysis)
What is a type 5 Salter-Harris Fracture?
Crush injury of growth plate
What is Carpal Valgus (queen ann legs) caused by?
premature closing of distal ulnar growth plate
State 4 nutritional reasons an animal may have abnormal bone formation
1)Low calcium-interruption of blood supply to bone
2)High phosphorous -decreases calcium absorption
3) Vitamin D deficiency- no calcification of growth plate
4)Zinc deficient-impaired growth and skeletal development
What is hip dysplasia?
Poor fitment between femoral head and acetabulum which interferes with normal devlopment
What are the clinical signs of hip dysplasia?
Obsesity, abnormal gait, swaying gait, lameness, pain, crepitus in hips, exercise intolerance
What are the three types of muscle tissue?
1)Skeletal
2)Cardiac
3)Smooth
Which muscle tissue are described as ‘striated’?
Skeletal and Cardiac
Which muscle tissue is described as non-striated?
Smooth
Which muscle tissue are involuntary?
Cardiac and Smooth
Which muscle tissue is voluntary?
Skeletal
Which muscle tissue has multiple nuclei?
Skeletal
Which muscle tissue has intercalated discs?
Cardiac
What are the three layers of skeletal muscle?
Epimycium (outer layer)
perimycium (blood vessels and nerves)
endomycium (surrounds muscle fibres)
What is the muscle cell membrane called?
Sarcolemma
What is the cytoplasm of a mucle cell called?
Sarcoplasm
What is the endoplasmic reticulum of a muscle cell called?
Sarcoplasmic reticulum
What are the 2 proteins that make up myofilaments called?
Actin and Myosin
What is the band that covers both actin and myosin?
A band
What is the Z line?
The end of the sarcomere.
What is an I band?
The actin filaments only
What is the M band?
Myosin only
Where is calcium stored in a muscle?
Sarcoplasmic reticulum
What is the name of the neurotransmitter that passes across the neuromuscular junction?
Acetylcholine
What is the sliding filament theory?
Calcium ions bind to troponin, moving the tropomyosin. This exposes the binding sites so myosin head binds to actin and contracts, breaking down ATP in the process which releases energy.
When might a cow experience low calcium levels?
At the end of pregnancy-> foetal calcification
Start of lactation and Colostrum production
Why would a cow experience milk fever?
Demand for calcium ions increases larger than the amount of calcium in bone- calcium is taken from plasma. No impuses across neuromuscular junction means that muscles arent stimulated and cow becomes paralysed.
Why is an older cow more susceptible to milk fever?
Bone turnover is slower
Readily available bone mineral is reduced
Less able to cope with huge demands of calcium at parturition
What are clinical signs of milk fever in dogs?
Panting, restlessness, collapse, seizures, facial pruritis, muscle tremours
