Nerves and vessels of the lower limb Flashcards
How many sacral and coccygeal nerves are there?
Sacral: 5
Coccygeal: 1
Which spinal nerves supply each of the following: Neck Upper Limb Trunk Lower Limb Perineum
Neck: C1-C4 Upper Limb: C5-T1 Trunk: T2-L1 Lower Limb: L2-S3 Perineum: S2-C1
Which muscles does the superior gluteal nerve innervate?
Gluteus medius
Gluteus minimus
Tensor fasciae latae
The femoral nerve innervates all the muscles in the anterior compartment of the thigh. Which extra spinal root contributes to the innervation of iliopsoas?
L1
Which nerve roots are responsible for: Inversion Eversion Toe Extension Toe Flexion
Inversion: L4
Eversion: L5, S1
Toe Extension: L5, S1
Toe Flexion: S1, 2
What nerve supplies sensory innervation to most of the posterior of the thigh?
Posterior cutaneous nerve of the thigh
Which two spinal nerve roots are responsible for sensory innervation of most of the posterior side of the lower limb?
S1 + S2
What are autonomous sensory zones?
Regions where you can be confident of the spinal root affected if there is any abnormal sensation in those regions
Which part of the lower limb does the obturator nerve supply sensory innervation to?
Medial compartment of thigh
Which part of the leg does the saphenous nerve provide sensory innervation to?
Medial part of the leg
Which nerve provides sensory innervation to most of the dorsum of the foot?
Superficial peroneal nerve
Where can the common peroneal nerve be damaged easily?
At the neck of the fibula
Describe the position of the posterior tibial artery relative to the medial malleolus.
It is posterior to the medial malleolus
Where can the dorsalis pedis pulse be felt?
Just lateral to the extensor hallucis longus tendon
Where can the posterior tibial artery pulse be felt?
Just posterior to the medial malleolus
What is cut-down and when it is performed?
Where is the incision made in cut-down?
An emergency procedure to gain access to the veins of a patient in shock
2 cm lateral + proximal to the medial malleolus
What is intermittent claudication?
Muscle pain induced by exercise + relieved by rest
Caused by inadequate blood supply to the affected muscles (associated with arterial disease)
What is compartment syndrome?
Ischaemia caused by trauma-induced increased pressure in a confined limb compartment
What is the normal pressure in muscle compartments?
25 mm Hg
What pressure is required to collapse vessels?
50-60 mm Hg
so pulse is still present despite tissue becoming ischaemic
What are the causes of acute and chronic compartment syndrome?
Acute: trauma-associated
Chronic: exercise-induced
What is the treatment of acute compartment syndrome?
Emergency fasciotomy
How do varicose veins form?
Valve dysfunction in the superficial, deep + perforating veins
Results in deep venous return being pushed superficially
Saphenofemoral junction valve is the most important
Can cause lipodermatosclerosis + ulcers
What is a nerve plexus?
A nerve plexus forms when peripheral spinal nerve roots merge + split to produce a network of nerves from which new multi-segmental peripheral nerves emerge.
Describe the path of the common peroneal nerve
Leaves popliteal fossa
Wraps laterally round neck of fibula (susceptible to damage here)
Divides to give superficial + deep peroneal nerves
What is the saphenous nerve the main terminal branch of? What does it supply?
Femoral nerve
Sensory supply to skin on medial leg + foot
What forms the sural nerve?
Communicating branches of tibial + common peroneal nerves
Form cutaneous nerve of lateral leg + foot
Where does the tibial nerve divide?
At ankle
Forms lateral + medial plantar nerves supplying muscles in sole of foot
Describe the composition of the: Femoral nerve Obturator nerve Sciatic nerve Superior Gluteal nerve Inferior Gluteal nerve
F: L2-4 (posterior fibres) O: L2-4 (anterior fibres) S: L4-S3 (anterior + posterior fibres) SGN: L4-S1 IGN: L5-S2
Generally if a muscle is more distal in limb
Its nerve supply is more caudal in spine
Which pairs of spinal nerves are involved in hip flexion and extension?
Flexion: L2 + 3
Extension: L4 + 5
Which pairs of spinal nerves are involved in knee flexion and extension?
Flexion: L5 + S1
Extension: L3 + 4
Which pairs of spinal nerves are involved in ankle flexion and extension?
Dorsiflexion (extension): L4 + 5
Plantarflexion (flexion): S1 + 2
What is the general rule of segmental supply of opposing muscles?
Opposing muscles are innervated by 2 adjacent segments above or below
Describe the segmental and peripheral supply of the posterior thigh
Segmental: S1 + 2 supply most of posterior thigh
Peripheral: Posterior cutaneous nerve supplies posterior thigh (mixed nerves)
What should you remember when considering segmental and peripheral supply?
Peripheral nerves have fibres from more than 1 spinal root
Not all fibres from a spinal root go via a particular peripheral nerve
What would you observe in assessment of a prolapsed intervertebral disc at L5/S1 (a root injury)?
Motor: Loss of eversion
Sensory: Loss of sensation outer border of foot
Reflex: Loss of ankle jerk (S1)
Autonomic: Minimal
What would you observe in assessment of a lesion of common peroneal nerve at fibular neck?
Motor: Foot drop
Sensory: Loss of sensation of dorsum of foot
Reflex: No changes
Autonomic: Minimal
Describe arterial supply of the lower limb
Aorta (splits into internal + external iliac)
External iliac
Femoral (gives off circumflex + deep arteries, passes from anterior to posterior through hiatus of adductor magnus)
Popliteal- trifurcates into:
1 Anterior tibial (becomes dorsalis pedis artery)
2 Posterior tibial (becomes plantar arteries)
3 Common peroneal artery (divides into superficial + deep)
Which artery of the lower limb branches off the internal iliac?
Obturator artery
List the 4 key pulses that can be palpated in the lower limb
Femoral
Popliteal
Posterior tibial
Dorsalis Pedis
Describe the borders of the femoral triangle
Inguinal ligament (superior border) Lateral border of adductor longus Medial border of sartorius
Where are the arteries in relation to the veins in the popliteal fossa?
Arteries are deeper than veins
Where can the femoral artery be palpated?
Midinguinal point (between ASIS + pubic symphysis)
Describe the pathway of the great saphenous vein
Formed from branches of dorsal venous arch of foot which merge anterior + superior to medial malleolus
Travels up medial leg
Skirts slightly behind knee
Up medial thigh, becoming more anterior
Passes through saphenous opening to drain into femoral vein
Describe the pathway of the short saphenous vein
Forms from dorsal venous arch Goes behind lateral malleolus Runs up posterior of leg Pierces fascia over popliteal fossa Drains into popliteal vein
How are deep veins arranged in the lower limb? What is the advantage of this?
Run alongside arteries as venae comitantes- multiple veins with connections between them form networks of smaller veins which accompany arteries
Pulsations of arteries squeeze veins, increasing venous return
Allows blood cooled at extremities to warm on its return to the heart
What has cutdown been superseded by?
Intraosseous administration of fluids
Needle inserted into bone marrow space to infuse fluid
What connects superficial and deep veins in the lower limb? Describe their structure
Perforating veins
Have a valve orientated to only allow flow from superficial to deep
What is DVT?
Deep vein thrombosis= clot lodging in deep veins
Associated with inactivity
If becomes dislodged may result in PE
What is the result of deep veins being sandwiched between calf muscles?
Activity causes contraction of muscles, squeezing the veins + pushing the blood back to the heart = calf pump
How do elastic surgical socks promote vigorous venous return?
Compress superficial veins, forcing blood back via deep return
What can venous grafts be used for? What must be ensured?
Coronary artery bypass grafts
Ensure valves in the vein are orientated in correct direction
