MSK Session 11 Flashcards
What do all of the superficial posterior leg muscles attach to distally?
Calcaneal tendon
What innervates the muscles in the posterior compartment of the leg?
Tibial nerve
What common function do all muscles in the superficial layer of the posterior compartment of the leg share?
Plantarflex ankle
What functions does gastrocnemius have in addition to plantarflexion of the ankle?
Raises heel while walking
Flexes knee
What function additional to plantarflexion of the ankle does soleus have?
Steadies leg on foot
Which muscles are in the deep layer of the posterior leg compartment?
Popliteus
Flexor hallucis longus
Flexor digitorum longus
Tibialis posterior
What is the main action of popliteus?
Weakly flex knee
Unlock knee by rotating femur
Medially rotate unplanted limb
What is the main action of flexor hallucis longus?
Flex all great toe joints
Weak plantarflexion
Support medial longitudinal arch of foot
What is the main action of flexor digitorum longus?
Flex lateral 4 digits
Plantarflexion
Support longitudinal arches of foot
What is the main action of tibialis posterior?
Plantarflex ankle
Invert foot
From which nerve does the tibial nerve originate?
Sciatic
Where can the tibial nerve be located at the ankle?
B/w tendons of FHL and FDL
How does the tibial nerve enter the posterior compartment of the leg?
Passes b/w heads of gastrocnemius
What happens to the tibial nerve at the ankle?
Divides into medial and lateral plantar nerves
What is the sensory distribution of the tibial nerve?
Knee joint
Lateral and posterior part of inferior 1/3 of leg
Lateral foot and heel
Which branch of the popliteal artery supplies the posterior leg and foot?
Posterior tibial
What accompanies the posterior tibial artery in the leg?
Tibial nerve and veins
Describe the path of the posterior tibial artery as it moves through the posterior compartment of the leg.
Posterior to medial malleolus
Runs b/w tendons of FHL and FDL
Divides into medial and lateral plantar arteries deep to flexor retinaculum
What is the largest tibial artery branch called?
Fibular artery
Describe the passage of the fibular artery in the posterior compartment of the leg.
Inferior to popliteus and tendinous soleus arch
Moves medially w/in FHL
What does the fibular artery give rise to?
Nutrient artery of fibula
What have their origin from the anterior and posterior tibial arteries?
Cx fibular artery
Nutrient artery of tibia
What branches off from the anterior and posterior tibial arteries and anastomoses around the knee?
Cx fibular artery
Which is the largest nutrient artery of the body?
Tibial
How are the veins of the posterior leg usually arranged?
As venae comitantes
What is present in all veins of the posterior leg to prevent back flow of blood?
Valves
What do veins in the posterior leg accompany?
All major arteries (so have same names)
Describe the veins through which blood in the posterior compartment of the leg drains.
Superficial –> perforating –> deep
How does calf muscle contraction aid venous return?
Propels blood to heart
Closes lower valve therefore preventing bloodflow away from heart
How is the passage of the great saphenous vein described?
Medial
How is the passage of the small saphenous vein described?
Lateral
Which muscles make up the superficial layer of the posterior compartment of the leg?
Plantaris
Gastrocnemius
Soleus
What is the WHO definition of old age?
> 65 y.o.
Why will 40% of all women >50 y.o. have a fracture?
Osteoporosis
At what rate does bone mineral content decline after the age of 30?
~1% per year
What accelerates bone mineral loss?
Decreased reproductive hormone levels Poor calcium Poor vitamin D Inactivity Endocrine/GI pathologies
What causes a decrease in bone strength as both a material and a structure?
Loss of bone mineral
Changes in architectural structure
What is sarcopenia?
Decrease in muscle mass due to loss of muscle fibres and decreased muscle cross sectional area
What happens with muscle contractility with age?
Decreases
Which neuron fibres are most affected by loss of neuronal innervation?
Alpha-motor (type II fast twitch)
Does the fact that men have a greater muscle mass in proportion to fat than women alter the rate of muscle loss b/w genders?
Nope
How can ageing exacerbate injury to the rotator cuff muscles?
Muscles become marbled w/fat –> tear –> cannot repair due to fat content
What four factors can increase fall risk and combined with bone weakness lead to fracture?
Decreased mobility
MSK-related posture and gait changes
Neuro-related gait and proprioception changes
Environmental hazards
What is type 1 osteoporosis caused by?
Post menopausal loss of oestrogen
What is type 2 osteoporosis caused by?
Old age
Hyperparathyroidism
Hypocalcaemia
What are the risk factors for osteoporosis?
Age Decreased bone mass Caucasian/Asian Previous fragility fracture \+ve FHx Low BMI Lifestyle Early menopause
What is the WHO definition of osteoporosis?
Skeletal disease characterised by decreased bone mass per unit volume
Deterioration of bone micro architecture leading to increased bone fragility and susceptibility to trauma #
How do bisphosphonates prevent bone resorption?
Taken up by osteoclasts
Inhibits mevalonate pathway
Osteoclast loses ruffled border so cannot sit on bone lining
Undergoes apoptosis
What effects do bisphosphonates have on bone turnover, mineralisation and bone volume?
Decreased turnover
Increased mineralisation
Minimal effect on volume
Give some examples of types of bisphosphonates.
Alendronate
Pamidronate
Zoledronate
What do bisphosphonates to do fragility fracture risk?
Decrease by 50%
What is the most important source of blood to the femoral head?
Medial circumflex artery
What will happen to 1 in 3 hip # patients?
Drop one level in mobility
How is an intracapsular hip # fixed?
Hemi/total arthroplasty
How is an extracapsular hip # fixed?
Dynamic hip screw
Intramedullary rod
What is the NICE definition of osteoarthritis?
Disorder of synovial joints w/focal areas of damage to the articular cartilage, remodelling of underlying bone, formation of osteophytes and mild synovitis
What percentage of cartilage loss prevents bone from healing in osteoarthritis?
90%
How does osteoarthritis appear histiologically?
Loss of smoothness
Fibrillation and crevices present
Loss of cartilage means greater proportion of view is subchondral bone
What are the four radiological features associated with osteoarthritis?
Decreased joint space
Sclerosis
Osteophytes
Bone cysts
Where are bone cysts more commonly seen?
Shoulder
How can osteoarthritis be treated?
Weight loss Physiotherapy (improves proprioception) Analgesia Joint injection Arthroscopy Osteotomies Arthrodesis Arthroplasty
What is an osteotomy?
Procedure to cut bone to offset loading which has manifested as bowing of the legs
What is arthrodesis?
Artificial joint ossification
Give some examples of complications associated with osteoarthritis treatments.
Leg length inequality Dislocation Loosening Neurovascular damage Infection DVT (rare but treated prophylactically)
What is the problem with using a metal on metal hip replacement?
Release of metal ions into blood causing large losses of soft tissue
Give some examples of the type of joints that can be used for hip replacement.
Metal on polythene (mainly)
Ceramic
Highly X-linked polyethylene
Metal on metal
Describe the passage of the arteries of the lower limb.
External iliac –> femoral artery (-> deep artery of thigh -> medial and lateral circumflex femoral) –> popliteal artery –> anterior tibial, posterior tibial and fibular
Which arteries support the adductor muscles?
Deep artery of thigh
Obturator artery from internal iliac
Where does the artery to head of femur arise from?
Obturator artery
Is the artery to head of femur important in the blood supply of the adult femoral head?
Nope
How can catheter access to the left side of the heart be achieved?
Femoral artery at mid-inguinal point
Brachial/radial arteries
Where is the mid-inguinal point?
B/w ASIS and pubic tubercle
Why can catheter access to the right side of the heart not use veins in the arms?
Venae comitantes are too small
What venous access is used to access the right side of the heart with a catheter?
Neck
What is the contents of the adductor canal?
Saphenous nerve
Femoral artery
Femoral vein
What are the changes to the path of the femoral artery in the adductor canal?
Crosses to posterior aspect via adductor hiatus
Why is the popliteal artery not easily felt?
Deepest structure in the popliteal fossa
Fascia surrounds fossa
What are the arteries of the posterior knee?
Superior, middle and inferior genicular arteries
Why are anastomoses needed in the anterior knee?
In full flexion the popliteal artery is obstructed so needed for sufficient blood supply
What position would you ask a patient to assume in order to palpate the popliteal pulse?
Prone with knee flexed to relax fascia
Why do you ask the patient to invert the foot when palpating the posterior tibial pulse posterior to the medial malleolus?
Relax flexor retinaculum
How does the anterior tibial artery enter the anterior compartment?
Pierces interosseous membrane
Where can the dorsalis pedis pulse be felt?
Just lateral to EHL tendon
Which artery is bigger, posterior tibial or anterior tibial?
Posterior
What are risk factors for formation of atherosclerotic plaque?
Uncontrolled DM
Hypertension
Dyslipidaemia
Smoking
What are the 8 stages of atheromatous plaque formation?
LDL through vascular endothelium LDL oxidised Cytokines released Monocytes and macrophages migrate Scavenger receptors activated Smooth muscle migration Foam cell formation Cell apoptosis
In which part of the BV wall do atheromatous plaques develop?
Intima
Where are the 5 most common sites for atheromatous plaque formation, starting with the most common?
Abdominal aorta and iliac arteries Proximal coronary arteries Thoracic aorta, femoral and popliteal arteries Internal carotid arteries Vertebral basilar and middle cerebral
Why might you not be able to palpate a dorsalis pedis pulse in a patient?
Arterial occlusion in lower limb
They are one of the ~2% of population with no dorsalis pedis pulse
What should an ankle brachial pressure index show if there is no arterial occlusion?
Similar blood pressures in arm and leg whilst lying down
What imaging methods can be used to assess arterial occlusion?
Doppler ultrasound
Arteriogram
If the radius of an artery decreases by a half, how much will the flow reduce by?
1/16
What are the S/S of peripheral artery disease?
Lack of hair Skin problems Ulcers Improper healing after injury Infection Loss of pulses Cold
What are the Tx for peripheral artery disease?
Antiplatelets
Modify risk factors
Increase exercise to stimulate angiogenesis
What occurs in atherosclerosis to cause acute ischaemia?
Plaque rupture
How would a patient with a popliteal aneurysm present?
Oedema and pain in popliteal fossa with a palpable pulsatile mass
In which two lower leg injuries is the popliteal artery at risk of rupture?
# of distal femur Dislocation of the knee
What is the superficial venous drainage of the lower limb?
Great and small saphenous veins
Describe the course of the great saphenous vein.
Arises from dorsal venous arch of foot Courses anterior to medial malleolus Passes about a hand's breadth medially of the patella Through fascia lata at saphenous opening Drains into femoral vein
What follows the great saphenous vein along its course?
Saphenous nerve
Describe the passage of the small saphenous vein.
Arises from lateral marginal vein of foot
Passes posterior to lateral malleolus
Course up posterior aspect of calf
Drains into popliteal vein in popliteal fossa
What is saphenous cut down?
Incision anterior to medial malleolus to gain access to great saphenous vein
When is saphenous cutdown used?
Emergencies e.g. hypovolaemic shock when veins have collapsed and venepuncture/cannulation is required
What is the pathogenesis of varicose veins?
Valve flaps become incompetent
Stasis of blood in veins
Dilated, tortuous superficial veins
What is the pathogenesis of venous insufficiency?
Valvular incompetence –> dull, aching, tingling legs combined with ulcers and slow healing wounds
What is postphlebitic syndrome a consequence of?
DVT
Chronic deep venous insufficiency
What is the pathogenesis of postphlebitic syndrome?
Damage to venous valves –> lymphedema from high hydrostatic pressure in veins
What do deep veins of the lower limb follow?
Major arteries
