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Year 2 LCRS > Anatomy of the Limbs 8 - Lower Limb Nerves, Arteries and Vessels > Flashcards

Anatomy of the Limbs 8 - Lower Limb Nerves, Arteries and Vessels Flashcards

1
Q

How is nerve function assessed?

A
  • Motor function
  • Sensory function
  • Reflex function
  • Autonomic function
  • Trophic function
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2
Q

Describe the knee jerk. Which spinal nerve is involved?

A
  • Tap
  • Stretch patellar tendon
  • Stimulation of afferent (1a) fibres in quadriceps
  • Passes to spinal cord via posterior nerve root
  • Synapse with alpha motor neurone in the anterior horn of the spinal cord
  • Efferent signal to quadriceps
  • Quadriceps extends the knee joint
  • L3
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3
Q

What supplies the ankle jerk reflex?

A

S1

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4
Q

Describe autonomic segmental supply to the lower limbs.

A
  • Sympathetic via T11-L2 portion of thoraco-lumbar outflow

- No significant parasympathetic outflow to the lower limbs

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5
Q

Where is the lumbosacral plexus derived from?

A
  • Anterior rami of the lumbar and sacral spinal nerves
  • Lumbar plexus L1-4
  • Sacral plexus S1-4 and L4,5
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6
Q

List the branches of the lumbar plexus

A
  • Illiohypogastric and ilio-inguinal nerves (L1)
  • Genitofemoral nerve (L1,2)
  • Lateral cutaneous nerve of the thigh (L2,3)
  • Femoral nerve (L2-4 posterior divisions due to torsion during development)
  • Obturator nerve (L2-4 anterior divisions)
  • Lumbosacral trunk (L4,5 - feeds the sacral plexus)
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7
Q

List the branches of the sacral plexus

A
  • Sciatic nerve (L4,5, S1-3)
  • Nerve to piriformis (S1,2)
  • Posterior cutaneous nerve of the thigh (S1-3)
  • Pelvic splanchnic nerve (S2-4, parasympathetic)
  • Pudendal nerve (S2-4)
  • Nerve to obturator internus (L2, S1,2)
  • Superior gluteal nerve (L4,5, S1)
  • Inferior gluteal nerve (L5, S1,2)
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8
Q

Where is the femoral nerve formed, what does it supply and what is its terminal branch?

A
  • Formed from the lumbar plexus (L2-4 posterior divisions)
  • Supplies the ilio-psoas and anterior thigh muscles
  • Sensory to the front of the thigh
  • Terminal branch is the saphenous nerve, sensory to the medial aspect of the leg
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9
Q

Where is the obturator nerve formed, and what does it supply?

A
  • Formed from the lumbar plexus (L2-4 anterior divisions)
  • Passes through the obturator foramen
  • Supplies the adductor (medial) compartment of the thigh
  • Sensory to the pelvis and medial aspect of the thigh
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10
Q

Where is the sciatic nerve formed, what are its terminal branches and what does it supply?

A
  • Formed from the tibial nerve and common peroneal nerve (L4,5 and S1-3 both posterior and anterior divisions)
  • Passes through the greater sciatic foramen, behind the hip joint and in the posterior compartment of the thigh divides into the tibial and common peroneal nerve
  • Sciatic nerve proper supplies the hamstring muscles in the posterior compartment of the thigh
  • Has some sensory branches to the back of the thigh
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11
Q

Describe the pathway of the common peroneal nerve, what does it supply and what are its terminal branches?

A
  • Passes around the neck of the fibula where it is easily damaged
  • Supplies anterior and lateral compartments of the leg
  • Sensory innervation to anterior and lateral aspects of the leg and the dorsum of the foot
  • Terminal branches are the superficial peroneal nerve and the deep peroneal nerve
  • Important sensory branch: sural nerve
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12
Q

What is supplied by the tibial nerve?

A
  • Posterior compartment of the leg
  • Most of the intrinsic muscles of the foot
  • Sensory to the back of the leg and sole of the foot
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13
Q

List the muscles supplied by the femoral nerve

A
  • Psoas and illiacus
  • Pectineus
  • Sartorius
  • Rectus femoris
  • Vastus medialis
  • Vastus intermedius
  • Vastus lateralis

(anterior compartment of thigh)

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14
Q

List the muscles supplied by the obturator nerve

A
  • Obturator externus
  • Adductor brevis
  • Adductor longus
  • Part of adductor magnus
  • Gracilis

(medial compartment of thigh)

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15
Q

List the muscles supplied by the sciatic nerve

A
  • Biceps femoris
  • Semimembranosus
  • Semitendinosus
  • Part of adductor magnus

(posterior compartment of the thigh)

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16
Q

List the muscles supplied by the common peroneal nerve

A

DEEP PERONEAL NERVE

  • Extensor digitorum longus
  • Extensor hallucis longus
  • Tibialis anterior
  • Peroneus tertius
  • Extensor digitorum brevis

(anterior compartment of leg)

SUPERFICIAL PERONEAL NERVE

  • Peroneus longus
  • Peroneus brevis

(lateral compartment of leg)

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17
Q

List the muscles supplied by the tibial nerve

A
  • Gastrocnemius and soleus
  • Plantaris
  • Popliteus
  • Tibialis posterior
  • Flexor hallucis longus
  • Flexor digitorum brevis
  • Abductor hallucis
  • Flexor hallucis brevis
  • All interossei and lumbricals

(posterior compartment of leg and most intrinsic foot muscles)

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18
Q

When is the femoral nerve injured?

A
  • Superficial in the groin, but rarely damaged except by doctors
  • Most commonly damaged during hip replacements and laparoscopic repair of inguinal nernias
  • Can be damaged during erroneus attempted cannulations of the femoral artery or vein
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19
Q

When is the lateral contaneous nerve of the thigh injured?

A
  • Passes 2cm medial to the ASIS at the level of the inguinal ligament
  • Can be compressed, causing meralgia parasthetica
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20
Q

What is pain in the distribution of the obturator nerve indicative of?

A

Malignant disease of the pelvis - rarely damaged

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21
Q

What is the consequence of injury to the superior gluteal nerve?

A
  • Supplies gluteus medius and minimus

- When damaged, there is trendelenberg gait, where the pelvis lurches during gait

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22
Q

When is the superior gluteal nerve commonly injured?

A
  • Hip replacement

- Nerve lies 5cm proximal to the tip of the greater trochanter. It approaches the hip joint.

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23
Q

What causes injury to the sciatic nerve?

A
  • Hip replacement
  • Common peroneal division is more vulnerable than tibial
  • To avoid damage, IM injections should be given to the upper outer quadrant of the buttock
  • Also damaged in trama (eg. hip dislocations or acetabular fractures) and pelvic disease
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24
Q

When is the common peroneal nerve vulnerable?

A
  • Hip
  • At the level of the fibular neck (where the nerve winds around)
  • Damaged by trauma, knee replacement and external pressure (eg. plasters or during surgical procedure
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25
Q

When is the saphenous nerve damaged?

A
  • Damaged at the medial malleolus (after varicose vein surgery or cut down)
  • At the level of the knee (eg. anterior cruciate ligament surgery)
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26
Q

Describe briefly arterial anatomy of the lower limb

A
  • Aortia to common iliac
  • Common iliac to external and internal iliac
  • External iliac becomes femoral (inguinal ligament)
  • Femoral becomes popliteal (adductor canal)
  • Popliteal trifurcates into posterior tibial artery, peroneal artery and anterior tibial artery
  • Posterior tibial artery enters posterior compartment with the tibialis posterior and passes behind the medial malleolus. In the foot forms medial and lateral plantar arteries
  • Anterior tibial artery passes into the anterior compartment of the leg, and becomes the dorsalis pedis artery
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27
Q

Where is the dorsalis pedis artery palpable?

A

Between the first and second metatarsals, lateral to the extensor hallucis longus

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28
Q

Where is the posterior tibial artery palpable?

A

Behind the medial malleolus

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29
Q

List the branches of the femoral artery in the thigh

A
  • Superficial circumflex iliac artery
  • Superficial epigastric artery
  • Superficial external pudendal artery
  • Deep external pudendal artery
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30
Q

Where is the profunda femoris artery?

A
  • A branch of the femoral artery
  • Arises 4cm distal to the inguinal ligamanet.
  • Major branches of the perforating arteries and the medial and lateral femoral circumflex arteries
31
Q

How do varicose veins occur?

A
  • Perforating veins where blood should flow from the superficial to the deep system
  • Perforating veins and the main saphenous veins have valves
  • If these valves dont exist, it results in varicose veins
32
Q

Where does the long saphenous vein join the femoral vein?

A

Passes through the saphenous opening, 3cm below and lateral to the pubic tubercle (femoral canal)

33
Q

Where are the valves of the long saphenous vein present?

A
  • About 20 valves

- Mainly present below the knee, some above the knee

34
Q

Describe the distribution of the deep and superficial veins

A
  • Deep veins lie in the deep fascia
  • Run alongside the arteries (2 veins for each artery)
  • Have valves to prevent backflow of blood
  • Venae comintantes of the anterior and posterior tibial arteries and the popliteal artery form the popliteal vein. Mainly within muscle.
  • Popliteal vein also recieves the short saphenous vein at the level of the popliteal fossa
  • Femoral vein joined by the profunda femoris veins and the long saphenous vein.
  • Femoral vein then forms the external iliac vein once it passes beneath the inguinal ligamanet
35
Q

When are the femoral artery and vein cannulated?

A
  • For resusitation (vein)

- For cardiac arteriography (artery)

36
Q

When is cut down of the long saphenous vein performed?

A
  • In a shocked patient, venous cannulation may not be easy or possible
  • The long saphenous vein at the ankle, 2cm above and proximal to the tip of the medial malleolus, is a good site for cut down
  • A small incision is made at the ankle, and a venous cannula placed under direct vision into the vein for resuscitation
  • Now, instead intraosseous administration is used (often in the anterior tibia)
37
Q

What is the result of arterial embolism in the popliteal artery?

A
  • The leg may become ischaemic and require amputaton if the lesion is not cleared within a few hours
  • Intermittent claudication (muscle pain in calf during activity)
38
Q

What is intermittent claudication?

A
  • A condition where there is gradual occlusion of arteries within the limb, usually atherosclerotic
  • The muscles supplied distal to the occlusion become deprived of blood on exercise, so there is limited walking distance before pain occurs (mostly calf, can be thigh or buttock)
39
Q

What is compartment syndrome?

A
  • Each compartment in the leg is bound by tight fascia, which only let enclosed muscles swell to a certain degree before resisting further expansion and increasing pressure in the muscle itself
  • If pressure increases too far, the arterial supply and venous return are cut off, resulting in muscle death, loss of movement an contractures
  • Normal pressure is 25mmHg, only need 50-60mmHg to collapse small vessels. The pulse however is still present.
40
Q

What is acute compartment syndrome?

A
  • After trauma to a limb

- Unless fascia is released urgently, the muscle will die with disastrous consequences

41
Q

What is chronic compartment syndrome?

A
  • Occurs in athletes
  • Muscle swells during exercise and causes activity-related pain
  • Elective fasciotomy can relieve the pain in this condition
42
Q

What do most operations for varicose veins involve?

A
  • Tying off the sapheno-femoral junction
43
Q

What are varicose veins?

A
  • Dilated and tortuous superficial veins to to non-functional valves in the perforating vein between the superficial and deep veins
  • Can be painful, causing aching discomfort on standing
  • The increased pressure within superficial venous system can cause skin changes (lipodermatosclerosis or skin thickening) and skin ulcers
44
Q

What is deep venous thrombosis?

A
  • Blood clotting in the deep vains of the lower limb
  • Often silent, may pesent with pain and swelling in the caf or proximal thigh
  • Proximal DVT (thigh) is very dangerous, as there is high risk of propagation to the lungs
  • Associated with immobility, trauma, surgery, malignancy, obesity, pregnancy, oral contraceptive pill
45
Q

What are the two main consequences of DVT?

A
  • Pulmonary embolus (propagate into the pulmonary circulation, can be fatal)
  • May cause increased back pressure in the deep veins, causing venous insufficiency and leg ulcers (post-phlebotic syndrome)
46
Q

What is superficial thrombophelbitis?

A
  • Superficial veins clotting, or becoming inflamed/infected
  • Not as serious as DVT but can be painful
  • Symptomatic treatment (analgesia and rest) rather than anticoagulation
47
Q

How are superifical veins used in elective surgery?

A
  • Used in cardiac and vascular surgery as grafts to replace arteries
  • Arterial by-pass surgery
  • Need to be orientated correctly due to valves
48
Q

Describe organisation of spinal nerves

A 
C1-4 : neck
C5-T1 : upper limb
T2-L1 : trunk
L2-S3 : lower limb
S2-C1 : perineum
49
Q

What is a nerve plexus?

A

A nerve plexus is formed when peripheral spinal nerve roots merge and split to produce a network of nerves from which new multi-segmental (containing fibres from more than one spinal root) peripheral nerves emerge.

50
Q

How is the piriformis used as a landmark?

A
  • Superior gluteal arteries and nerves superior to piriformis
  • Inferior gluteal arteries and nerves inferior to piriformis
  • Sciatic nerve emerges inferior to piriformis
51
Q

What is the sural nerve?

A
  • Formed by branches from the common peroneal nerve and fibular nerve after they divide.
  • Important cutaneous nerve to the lateral leg and foot
52
Q

Describe segmental somatic motor supply to the limbs

A
  • C5-T1 upper limb
  • L2-S3 lower limb
  • Plexi for each limb
  • Anterior divisions are flexor muscles, posterior divisions are extensor muscles
  • Muscles supplied by two adjacent segments
  • Same action on joint = same nerve supply
  • Opposing muscles 1-2 segments above or below
  • More distal in limb = more caudal in spine
53
Q

What are autonomous sensory zones?

A
  • Areas of skin supplied by nerves from only one spinal segment, so loss of sensation will determine the damage of that spinal root
  • L3 upper thigh
  • L4 Knee and thigh
  • S1 posterior lateral region of the leg
  • Obturator nerve supplied the medial thigh
54
Q

Why is peripheral cutaneous supply different to segmental supply?

A

Due to the mixing up of nerve fibres in the lumbosacral plexus

55
Q

Describe cutaneous innervation of the foot

A
  • Dorsal digital nerve dorsal surface between toes 1 and 2
  • Saphenous nerve supplies the medial side
  • Dorsal lateral cutaneous nerve lateral
  • Superficial fibular nerve most of the dorsal surface
  • Common plantar digital nerves lateral side of plantar surface
  • Proper plantar digital nerves and medial plantar nerve the medial foot plantar surface, to 4th half toe
  • Medial calcaneal branch supplies the calcaneus
56
Q

What would be seen in prolapsed intervertebral disc prolapse at L5/S1

A

Motor – loss of eversion
Sensory – loss of sensation outer border of foot
Reflex – loss of ankle jerk (S1)
Autonomic – minimal

57
Q

What would be seen in a lesion of common peroneal nerve at fibular neck?

A

Motor – foot drop
Sensory – dorsum of foot at least
Reflex – none
Autonomic – minimal

58
Q

Describe the pathway of the long saphenous vein

A
  • Anterior to medial malleolus from the dorsal venous arch
  • Medially travels up the leg
  • Just medial to the knee
  • Joins the femoral vein at the saphenous opening
59
Q

Describe the pathway of the short saphenous vein

A
  • Posterior of the leg, from the plantar venous network

- Joins the popliteal vein in the popliteal fossa

60
Q

What are the functions of venous comitantes

A
  • Artery pulse promotes venous flow

- Allow heat exchange between the artery and veins

61
Q

Why can inactivity cause DVT? How can this be avoided?

A
  • One of the ways of returing blood to the heart from the leg is by the calf pump
  • Deep veins are sandwiches between the layers of calf muscles, so when these muscles contract there is more efficient venous return to the heart
  • Surgical socks compress superficial veins to promote more vigorous deep venous return
62
Q

Describe the motor effects of femoral nerve injury

A

Quadriceps paralysis. Weakness of knee, difficulty in climbing up or down the stairs.

63
Q

Describe the sensory effects of femoral nerve injury

A

Sensory loss to anterior & medial thigh, medial side of leg, and medial border of foot (not the big toe)

64
Q

Describe the motor signs of obturator nerve injry

A
  • Paralysis of all adductors (except hamstring part of adductor magnus)
  • “Cross legging” affected
65
Q

Describe the sensory effects of obturator nerve injury

A

Insignificant sensory loss on the medial side of thigh.

66
Q

Describe the motor effects of common peroneal nerve injury

A
  • Foot extensors & evertors paralysed

- Foot in plantar flexed (foot drop) and inverted (tibialis post active)

67
Q

Describe the sensory effecs of damage to the common peroneal nerve

A

Loss in the anterior and lateral side of leg and dorsum of foot

68
Q

Describe the motor effects of tibial nerve injury

A
  • Hamstrings and all muscles of back of leg & sole of foot affected
  • Foot in dorsiflexed and everted position
69
Q

Describe the sensory effects of tibial nerve injury

A

Loss in the sole of the foot

70
Q

Describe the motor effects of sciatic nerve injury

A
  • Hamstrings, and all muscles below the knee are paralysed.

- Foot in plantar flexed position (foot drop) due to its own weight.

71
Q

Describe the sensory effects of sciatic nerve injury

A

Loss below the knee except on a narrow area on the medial side of leg and foot (saphenous nerve area), not the big toe

72
Q

What is sciatica?

A
  • Pain radiating from lower back into buttock, posterior /lateral thigh and into the leg.
  • Caused by herniated lumbar intervertebral disc (L4/L5 or L5/S1) which compresses the L5-S1 component of the sciatic nerve.
  • Pelvic girdle pain during pregnancy is often misdiagnosed as sciatica
73
Q

Compare the effect of damage to the anterior collateral and posterior collateral ligament of the leg

A
  • ACL damage results in limited walking upstairs

- PCL damage results in limited walking downstairs

Year 2 LCRS (128 decks)

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