msk extra Flashcards
What are the nerve roots of the sciatic nerve?
L4-S3
What cell lineage are osteoclasts derived from?
Haematopoietic Stem Cells
What type of growth does the skeleton undergo?
Appositional Growth
diff between ligament and tendon
tendons connect muscle to bone
higher collagen 1
little elastin
organised fibres
muscles of rotator cuff
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
what provides bone stiffness
mineral
brachial plexus roots
C5 - T1
cytokine expressed by osteoblasts that stimulates osteoclast action, and hence bone resorption
RANK-L
What bones are formed by intramembranous ossification?
flat bones of the skull, the clavicles and most of the cranial bones.
What does Endochondral ossification form
remainder of the axial skeleton and the appendicular skeleton.
what nerve affected by a mid shaft humerus fracture
radial nerve - causing wrist drop, as it innervates triceps brachii and the extensor muscles in the forearm
innervation of biceps brachii
musculocutaneous nerve (C5-C7)
root of axillary nerve
C5 and C6
root radial nerve
C5 - T1
root of ulnar nerve
C8 - T1
root of median nerve
C6 - T1
sensory distribution of the median nerve?
Palmar surface of the lateral side of the hand. Palmar surface of the lateral 3½ digits. The skin over the dorsum of the distal phalanges of the lateral 3½ digits.
radial nerve sensory nerve distribution
dorsal surface of the lateral side of the hand. Skin over the dorsum of the lateral 3½ digits as far as the distal interphalangeal joint.
Ulnar nerve sensory nerve distribution
palmar and dorsal surface of the medial side of the hand and the medial 1½ digits.
which muscles travel through the carpal tunnel?
flexor digitorium superficialis, flexor digitorum longus, flexor pollicis longus and median nerve
osteoblast function
secretes osteoid that gets mineralised and builds bone
lachman’s test function
test for acl damage
types of joints
hinge, pivot, plane, ball and socket, condyloid, saddle
muscle spindle function
sense how much a muscle is stretched
effect of intrascapular Neck of Femur Fracture
leg is shortened and internally rotated
two foot slide tackle to the lateral aspect of rob’s knee was appropriate punishment. Rob sustained an unhappy triad injury, classically what injuries are involved in this triad?
Medial collateral ligament, medial meniscus, PCL
flexor digitorum profundus function
flexes the metacarpophalangeal (MCP) and distal interphalangeal (DIP) joints of the medial 4 fingers.
what type of joint is the knee
synovial hinge joint
What does a patients’ FRAX score measure?
10-year probability of experiencing a major osteoporotic fracture
What range of results from her DEXA scan would be indicative of osteopenia?
Between -1 and -2.5
osteoprotegrin function
However in the presence of OPG, Rank-ligand binds to OPG, so
blocks RANK-RANK formation- inhibits osteoclast activity preventing excessive bone resorption
e.g of suture,gomphoses and syndesmoses
suture = junctions between skull bones
gomphoses =Peg and socket joints e.g. teeth
syndesmoses = connected by membranes E.g. between radius and ulnar
what is bone matrix made up of
Bone matrix is made from mineral- calcium hydroxyapatite and
collagen protein.
where do osteblasts and osteocytes originate from
osteoblasts = mesenchymal stem cells
osteocytes =Mesenchymal stem cell, derived from osteoblasts
what is released in bone resorption
calcium and phosphate
what regulates osteoblasts
cytokines and growth factors
endochondral ossification
- in utero mesenchymal stem cells become chondroblasts
- chondroblasts secrete ECM and becomne trapped becoming chondrocytes, perichondrium forms around cartilage
- chondrocytes hypertrophy and burst - releasing contents that trigger calcification
- calcification forms small cavities for osteoblasts to move into
- osteoblasts deposit new bone into the diaphysis forming bone collar
- bone collar prevents nutrients from diffusing into cartilage leading to chondrocyte death
- there are increased cavities and osteogenesis continues, forming the primary ossification centre in shaft. Cartilage forms above and below
- after birth the secondary ossification centre develops from osteogenic cells in the end
intramembranous ossification
1.condensation of mesenchymal cells into a flat sheet - forms straight into bone
2. osteoblast precursos form on surface and differentiate into mature active osteoblasts
3. osteoid formation traps osteoblasts in new trabecular bone matrix - osteocytes > mineralisation
4. compact bone develops above and blood vessels enter trabecular bone
types of fracture
transverse
oblique
spiral
comminuted
segmental
avulsed
impacted
torus
greenstick
3 stages of fracture healing
inflammation (0-7 days)
repair (2-3 weeks)
remodelling (months to years)
haematoma formation
Blood vessels in the broken bone tear and haemorrhage
* This results in clotted blood (haematoma) at the break site
* The severed blood vessels are sealed by the clotting process
* Bone cells deprived of nutrients begin to die à osteocytes
fibrocartilaginous callus formation
Within days capillaries grow into the haematoma
* Phagocytic cells begin to clear away the dead cells
* Fibroblasts and osteoblasts enter and begin to reform bone
* Fibroblasts produce collagen fibres that connect the broken bone
ends, while osteoblasts start to form spongy bone
* The repair tissue between broken ends (the fibrocartilaginous
callus) is formed of both hyaline and fibrocartilage
* Some bone spicules may appear at this point
types of fracture fixation
Slings
* Casts and splints
* Extra-medullary devices à plates and screws
* Intra-medullary devices à nails
* External fixation
what is osteoperosis
Bones become brittle and fragile from a loss of tissue and reduced
mineralisation due to increased resorption rates compared to formation (dexa scan below -2.5)
osteomalacia
Softening of the bones that happens when mineralisation doesn’t happen
properly – deficiency in vit. D or calcium
bone remodelling process
Activation - Pre-osteoclasts are attracted to the remodelling sites, activated by RANK ligand produced by osteoblasts Pre-osteoclasts fuse to form multinucleated osteoclasts
Resorption - Osteoclasts dig out a cavity (resorption pit) in spongy bone or burrow a tunnel in compact bone by releasing acids and cathepsin K Calcium can be released into the blood for use in various body functions Osteoclasts disappear
Reversal - Mesenchymal stem cells appear along the burrow or pit They then proliferate and differentiate into pre-osteoblasts
Formation - Then mature into osteoblasts at the surface of the burrow or pit And release osteoid at the site, forming a new soft non-mineralised matrix The new matrix is then mineralised with calcium and phosphorus
Quiescence - The site, with resting lining cells, remains dormant until the next
cycle. Osteoprotegerin mops up any RANK ligands to prevent
segond fracture
small flake of bone pulled of lateral tibia
FGF-23 function
Decreases phosphate
* Decreases 1-alpha hydroxylation of vitamin D which overall
decreases its affects including gut absorption of phosphate
* Decreases expression of Na+ transporter in the renal tubules
which overall increases renal excretion of phosphate
* Cannot work without klotho
Which nerve innervates the triceps brachii?
radial nerve
what nerve supplies the muscles that abduct the arm
the axillary nerve supplies the deltoid muscle which is a major abductor of the arm
what catalyses purines to xanthanine to uric acide
purine oxidase
what do pyrimidines breakdown into
C02 and NH3
effects of high uric acid breakdown
kidney stones and gout crystals
Allopurinol function
blocks action of xanthanine oxidase
Woven bones def
having a disorganised structure, made
quickly in development and is temporary?
muscles of thenar eminence.
OAF; Opponens pollicis (1), Abductor pollicis brevis (1), Flexor pollicis brevis (1)
root of common peroneal
L5
Where does gastrocnemius originate and insert on the posterior aspect of the lower
leg?
Origin - Condyles of the femur (accept medial/lateral) (1)
Insertion - Calcaneus
Trendelenburg sign is produced by observing a positive unilateral pelvic drop. What nerve is affected by this?
superior gluteal
what does superior gluteal nerve innervate
Gluteus medius and gluteus minimus
what does Musculocutaneous nerve innervate
Biceps brachii (must say ‘brachii’) (1)
- Coracobrachialis (1)
- Brachialis
Which levels of the spinal cord
are responsible for the ankle jerk reflex?
s1/2
