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6. MSK > Lower Limb Nerves > Flashcards

Lower Limb Nerves Flashcards

1
Q

Which spinal nerves form the lumbar plexus?

A

The anterior rami of the lumbar spinal nerves L1, L2, L3, and L4.

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2
Q

How many major peripheral nerves are there of the lumbar plexus and what are they?

A

6: iliohypogastric nerve, ilioinguinal nerve, genitofemoral nerve, lateral cutaneous nerve of the thigh, obturator nerve, and femoral nerve.
Remember: I, I Get Leftovers On Fridays.

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3
Q

What is the anatomical course of the iliohypogastric nerve?

A

First major branch of the lumbar plexus. It runs to the iliac crest, then across the quadratus lumborum muscle of the posterior abdominal wall, where it perforates the transversus abdominis. Finally it divides into its terminal branches.

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4
Q

What are the roots of the iliohypogastric nerve?

A

L1, T12.

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5
Q

What are motor functions of the iliohypogastric nerve?

A

Innervates the internal oblique and transversus abdominis.

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6
Q

What are the sensory functions of the iliohypogastric nerve?

A

Innervates the posterolateral gluteal skin in the pubic region.

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7
Q

What is the anatomical course of the ilioinguinal nerve?

A

From the lumbar plexus. It runs to the iliac crest, then across the quadratus lumborum muscle of the posterior abdominal wall, where it perforates the transversus abdominis. Finally it divides into its terminal branches.

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8
Q

What are the roots of the ilioinguinal nerve?

A

L1.

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9
Q

What are motor functions of the ilioinguinal nerve?

A

Innervates the internal oblique and transversus abdominis.

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10
Q

What are the sensory functions of the ilioinguinal nerve?

A

Innervates the skin on the upper middle thigh. In men, supplies the skin over the root of the penis and anterior scrotum. In females, supples the skin over the mons pubis and labium majus.

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11
Q

What is the anatomical course of the genitofemoral nerve?

A

From the lumbar plexus. Leaves the psoas major muscle and divides into a genital and femoral branch.

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12
Q

What are the roots of the genitofemoral nerve?

A

L1, L2.

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13
Q

What are motor functions of the genitofemoral nerve?

A

Genital branch innervates cremasteric muscle.

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14
Q

What are the sensory functions of the genitofemoral nerve?

A

Genital branch innervates skin of the anterior scrotum in males or mons pubis and labium majus in females. Femoral branch innervates the skin on the upper anterior thigh.

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15
Q

What is the anatomical course of the lateral cutaneous nerve of the thigh?

A

From the lumbar plexus. Purely sensory, it enters thigh at lateral aspect of the inguinal ligament where it provides cutaneous innervation to the skin there.

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16
Q

What are the roots of the lateral cutaneous nerve of the thigh?

A

L2, L3.

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17
Q

What are motor functions of the lateral cutaneous nerve of the thigh?

A

None.

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18
Q

What are the sensory functions of the lateral cutaneous nerve of the thigh?

A

Innervates the anterior and lateral thigh to the level of the knee.

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19
Q

What are the roots of the obturator nerve?

A

L2, L3, L4.

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20
Q

What are motor functions of the obturator nerve?

A

Innervates muscles in the medial compartment of the thigh, except the hamstring part of the adductor magnus.
Adductor longus, adductor brevis, adductor magnus, gracilis, obturator externus.

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21
Q

What are the sensory functions of the obturator nerve?

A

Innervates the skin over the middle part of the medial thigh.

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22
Q

What is lumbosacral plexopathy?

A

Disorder affecting either the lumbar or sacral plexus of nerve.

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23
Q

When is a plexopathy suspected over single nerve damage?

A

When the symptoms can’t be localised to a single nerve.

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24
Q

What is a main cause of lumbosacral plexopathy?

A

Diabetic amyotrophy - high blood sugar levels damage the nerves.
Idiopathic plexopathy, or tumours/ other invasions can compress the plexus with the same effect.

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25
Q

How is lumbosacral plexopathy treated?

A

According to its cause, tumour etc - removed if possible, diabetic or idiopathic - high-dose corticosteroids.

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26
Q

What forms the sacral plexus?

A

The anterior rami of the sacral spinal nerves S1, S2, S3, S4 and also contributions from the lumbar spinal nerves L4, and L5.

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27
Q

How do paired spinal nerves leave the spinal cord?

A

Intervertebal foramina of the vertebral column.

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28
Q

How many major peripheral nerves come from the sacral plexus and what are they?

A

5: superior gluteal nerve, inferior gluteal nerve, sciatic nerve, posterior femoral cutaneous nerve, and pudendal nerve.
Remember: Some Irish Sailor Pester Polly.

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29
Q

What are the two main destinations of the nerves from the sacral plexus?

A

Leave the pelvis from the greater sciatic foramen, enter gluteal region of lower limb and innervate there.
Remain in the pelvis, innervate pelvic muscles, organs and perineum.

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30
Q

What is the anatomical course of the superior gluteal nerve?

A

From the sacral plexus. Leaves the pelvis via the greater sciatic foramen and enters the gluteal region superiorly to the piriformis muscles. Accompanied by the superior gluteal artery and vein for majority of course.

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31
Q

What are the roots of the superior gluteal nerve?

A

L4, L5, S1.

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32
Q

What are the motor functions of the superior gluteal nerve?

A

Innervates the gluteus minimis, gluteus medius, and tensor fascia latae.

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33
Q

What are the sensory functions of the superior gluteal nerve?

A

None.

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34
Q

What is the anatomical course of the inferior gluteal nerve?

A

From the sacral plexus. Leaves the pelvis via the greater sciatic foramen and enters the gluteal region inferiorly to the piriformis muscle. Accompanied by inferior gluteal artery and vein for majority of course.

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35
Q

What are the roots of the inferior gluteal nerve?

A

L5, S1, S2.

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36
Q

What are the motor functions of the inferior gluteal nerve?

A

Innervates gluteus maximus.

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37
Q

What are the sensory functions of the inferior gluteal nerve?

A

None.

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38
Q

What are the roots of the sciatic nerve?

A

L4, L5, S1, S2, S3.

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39
Q

What are the motor functions of the sciatic nerve?

A

Tibial portion - innervates all muscles in posterior compartment of thigh (including hamstring portion of adductor magnus, apart from short head of biceps femoris)., all muscles in the posterior compartment of the leg, and all muscles in the sole of the foot.
Common fibular portion - short head of biceps femoris, all muscles in the anterior and lateral compartments of the leg, and extensor digitorum brevis.

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40
Q

What are the sensory functions of the sciatic nerve?

A

Tibial portion - innervates skin on the posterolateral and medial surfaces of the foot as well as sole of the foot.
Common fibular portion - innervates skin on the anterolateral surface of the leg and dorsal aspect of the foot.

41
Q

What is the anatomical course of the posterior femoral nerve?

A

From the sacral plexus. Leaves the pelvis via the greater sciatic foramen, and enters the gluteal region inferiorly to the piriformis muscle. Descends deep to the gluteus maximus and runs down the back of the thigh to the knee.

42
Q

What are the roots of the posterior femoral nerve?

A

S1, S2, S3.

43
Q

What are the motor functions of the posterior femoral nerve?

A

None.

44
Q

What are the sensory functions of the posterior femoral nerve?

A

Innervates the skin on the posterior surface of the thigh and leg. Also of the perineum.

45
Q

What is the anatomical course of the pudendal nerve?

A

From the sacral plexus. Leaves the pelvis via the greater sciatic foramen and re-enters via the lesser sciatic foramen. It moves anterosuperiorly along the lateral wall of the ischiorectal fossa, and terminates by dividing into several branches.

46
Q

What are the roots of the pudendal nerve?

A

S2, S3, S4.

47
Q

What are the motor functions of the pudendal nerve?

A

Innervates the skeletal muscles in the perineum, the external urethral sphinctor, the external anal sphincter, and levator ani.

48
Q

What are the sensory functions of the pudendal nerve?

A

Innervates the penis and the clitoris and most of the skin of the perineum.

49
Q

What minor branches come from the sacral plexus?

A

Normally nerves directly supplying muscles: nerve to piriformis, nerve to obturator internus, nerve to quadrator femoris.

50
Q

What are the nerve roots of the femoral nerve?

A

L2, L3, L4.

51
Q

What are the motor actions of the femoral nerve?

A

Innervates the anterior thigh muscles that:

  • flex the hip joint, pectineus, iliacus, and sartorius.
  • extend the knee, quadriceps femoris (rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius).
52
Q

What are the sensory actions of the femoral nerve?

A

The first cutaneous branches are the anterior cutaneous branches arising in the femoral triangle, they supply the skin on the anteromedial thigh.
The last cutaneous branch of the femoral nerve is the saphenous nerve which supplies the skin on the medial side of the leg and the foot.

53
Q

What is the anatomical course of the femoral nerve?

A

Comes from the lumbar plexus, largest branch. Descends from the plexus in the abdomen through the psoas major muscle. Then travels through the pelvis to the mid point of the inguinal ligament. It then traverses behind the inguinal ligament to the thigh and splits into an anterior and posterior division. It passes through the femoral triangle lateral to the femoral vessels and gives off articular branches to the hip and knee joints. The terminal cutaneous branch is the saphenous nerve, which continues with the femoral artery and vein, through the adductor canal.

54
Q

In what order, lateral to medial, so the femoral, artery, nerve, and vein lie?

A

NAVY: nerve, artery, vein.

55
Q

When are sephaenous veins stripped?

A

With problematic varicose veins.

56
Q

Why is sephanous vein stripping potentially a problem?

A

The long saphenous vein is accompanied by the saphenous nerve, so it could get damaged in the procedure, leading to pain, parasthesia, or complete loss of snesation to the medial side of the leg.

57
Q

When is femoral nerve block used?

A

In patients requiring lower limb surgery who can’t tolerate a general anaesthetic. Also in peri and post operative analgesia for patients with a fractured neck of femur who can’t tolerate particular analgesias.

58
Q

What is the anatomical course of the obturator nerve?

A

Formed by the anterior divisions of the second, third, and fourth lumbar nerves. Descends through the fibres of the psoas major muscle and emerges from its medial border, running posteriorly to the common iliac arteries and laterally along the pelvic wall to the obturator foramen. Enter thigh through obturator canal and splits into anterior and posterior divisions.
Anterior division descends between the adductor longus and adductor brevis muscles towards the femoral artery - branches off to adductor longus, brevis and gracilis muscles. Pierces fascia lata and becomes the cutaneous branch.
Posterior division descends through obturator externus muscle and passes anteriorly to adductor magnus, supplying it.

59
Q

How can the obturator nerve be damaged?

A

During surgery to the pelvis or abdomen.

60
Q

What are the symptoms of obturator nerve damage?

A

Numbness and apraesthesia on the medial aspect of the thigh and weakness in adduction of the thigh. Or posture and gait problems from loss of adduction.

61
Q

What is obturator nerve block used for?

A

Management of pain after lower limb surgery for chronic hip pain.

62
Q

How is obturator nerve block administered?

A

The anaesthetic is injected inferior to the pubic tubercle and lateral to the tendon of the adductor longus muscle. Performed under ultrasound guidance.

63
Q

What is the anatomical course of the sciatic nerve?

A

Derived from the lumbosacral plexus. Leaves the pelvis via the greater sciatic foramen and emerges inferiorly to the piriformis muscle and descends in an inferolateral direction. It crosses the posterior surface of the superior gemellus, obturator internus, inferior gemellus, and quadratus femoris muscles as it moves through the gluteal region. It then enters the thigh and gives off branches to the hamstring muscles and adductor magnus. It terminates at the apex of the popliteal fossa by bifurcating into the tibial and common fibular nerves.

64
Q

How can the gluteal region be divided into four quadrants?

A

Using 2 lines: one line descends vertically from the highest point on the iliac crest. The other line horizontally passes through the vertical line half way between the highest point on the iliac crest and ischial tuberosity.

65
Q

Where must intramuscular injection in the gluteal region be administered?

A

In the upper lateral quadrants of the gluteal region.

66
Q

What are the nerve roots of the tibial nerve?

A

L4-S3.

67
Q

What is the anatomical course of the tibial nerve?

A

It is a branch of the sciatic nerve that arises at the apex of the popliteal fossa. It travels through the popliteal fossa and gives off branches to muscles in the superficial posterior compartment of the leg. Also branches that contribute to the sural nerve, which innervates the posterolateral aspect of the leg. The tibial nerve continues down the leg, posterior to the tibia and supplies deep muscles of the posterior leg. It passes posteriorly and inferiorly to the medial malleolus through the tarsal tunnel, which is covered by flexor retinaculum. Branches off the tibial nerve supply cutaneous innervation to the heel. It terminates distal to the tarsal tunnel by dividing into sensory branch for the sole of the foot.

68
Q

What are the motor functions of the tibial nerve?

A

Innervates all the muscles in the posterior compartment of the leg:
Deep - popliteus, flexor hallucis longus, flexor digitorum longus, tibialis posterior.
Superficial - plantaris, soleus, gastrocnemius.

69
Q

What is tarsal tunnel syndrome?

A

Condition where the tibial nerve is compressed within the tarsal tunnel.

70
Q

What are the main causes of tarsal tunnel syndrome?

A

Osteoarthritis, rheumatoid arthritis, and post-trauma ankle deformitities.

71
Q

What are the symptoms of tarsal tunnel syndrome?

A

Paresthesia in the ankle and sole of the foot, can radiate up the leg slightly and is aggravated by activity and relieved by rest.

72
Q

What are the sensory functions of the tibial nerve?

A

Branches from the tibial nerve given off in the popliteal fossa combine with branches from the common fibular nerve to form the sural nerve - this innervates the skin of the posterolateral side of the leg and lateral side of the foot. It has three branches:
Medial calcaneal branches - arise within the tarsal tunnel and innervate the skin over the heel.
Medial plantar nerve - innervates plantar surface of the medial three and a half digits and associated sole area.
Lateral plantar nerve - innervates the plantar surface of the lateral one and a half digits, and the associated sole area.

73
Q

What can cause damage to the tibial nerve?

A

Direct trauma, entrapment through narrow space, or compression for a long period of time.

74
Q

What are the effects of tibial nerve damage?

A

Loss of plantar flexion, loss of flexion of the toes and weakened inversion (still some from tibialis anterior).

75
Q

What are the nerve roots of the common fibular nerve?

A

L4-S3.

76
Q

What is the anatomical course of the common fibular nerve?

A

Begins at the apex of the popliteal fossa where the sciatic nerve bifurcates. It follow the medial border of the biceps femoris, running laterally and inferiorly over the gastrocnemius head. It then gives rise to two cutaneous branch which innervate the leg. It wraps around the neck of the fibula to enter the lateral compartment of the leg, and passes between the attachments of the fibularis longus muscle. It terminates by dividing into the superficial fibular and deep fibular nerves.

77
Q

What are the motor functions of the common fibular nerve?

A

Innervates the short head of the biceps femoris. Also its terminal branches innervate other muscles:
Superficial fibular nerve - lateral compartment of the leg, fibularis longus and brevis.
Deep fibular nerve - anterior compartment of leg, tibialis anterior, extensor digitorum longus, and extensory hallucis longus. Also some intrinsic muscles of the foot.

78
Q

What are the sensory functions of the common fibular nerve?

A

Sural communicating nerve - innervates skin of the lower posterolateral leg.
Lateral sural cutaneous nerve - skin of the upper lateral leg.
Superficial fibular nerve - skin of the anterolateral leg and dorsum of the foot.
Deep fibular nerve - skin between first and second toe.

79
Q

What can cause common fibular nerve damage?

A

Fracture of the fibula, or the use of tight plaster cast.

80
Q

What are the symptoms of common fibular nerve damage?

A

Unable to dorsiflex the foot at the ankle joint, so the foot is permanently plantarflexed - footdrop. Characteristic gait from the footdrop.
Lost sensation over the dorsum of the foot, and lateral side of the leg.

81
Q

What are the spinal roots of the superficial fibular nerve?

A

L4-S1.

82
Q

What is the anatomical course of the superficial fibular nerve?

A

It’s a terminal branch of the common fibular nerve, arising at the neck of the fibula. It descends between the fibularis muscles and the lateral side of the extensor digitorum longus to give rise to motor branches. Further down, it’s purely cutaneous and gives sensory innervation to the anterolateral aspect of the lower leg. It pierces the deep crural fascia in the lower third of the leg, and terminates by dividing into the medial and intermedial dorsal cutaneous nerves that enter the foot to innervate its dorsal surface.

83
Q

What are the motor functions of the superficial fibular nerve?

A

Supplies the fibularis longus and brevis (lateral lower leg).

84
Q

What are the sensory functions of the superficial fibular nerve?

A

Skin over the anterolateral leg, and the dorsum of the foot.

85
Q

What are the symptoms of superficial fibular nerve entrapment?

A

Pain, and paresthesia over the lower leg and dorsum of the foot.

86
Q

What can cause superficial fibular nerve entrapment?

A

Ankle sprains, or twisting of the ankle - stretches the nerve. Or in anterior nerve entrapment, the fascia compresses the nerve.

87
Q

How can anterior superficial fibular nerve entrapment be treated?

A

Surgical decompression of the nerve.

88
Q

How can the superficial fibular nerve be damaged?

A

By fracture of the fibula, or a perforating wound to the lateral side of the leg.

89
Q

What are the effects of superficial fibular nerve damage?

A

Loss of eversion and sensation over the majority of the dorsum of the foot and anterolateral aspect of the lower leg.

90
Q

What are the nerve roots of the deep fibular nerve?

A

L4, L5.

91
Q

What is the anatomical course of the deep fibular nerve?

A

Originates from the sciatic nerve, and is a terminal branch of the common fibular nerve. It arises in the superolateral aspect of the leg, between the fibularis longus muscle and the neck of the fibula. It moves into the anterior compartment of the leg and follow the anterior tibial artery. They pass between the tibialis anterior and extensor digitorum longus in the superior portion of the leg and then between the tibialis anterior and extensor hallucis longus in the inferior portion. It crosses the ankle joint and travels deep to the extensor retinaculum, it terminates in the dorsum of the foot into: lateral branch and medial branch.

92
Q

What are the motor functions of the deep fibular nerve?

A

Anterior compartment muscles: tibialis anterior, extensor hallucis longus, extensor digitorum longus, and fibularis tertius.

93
Q

What are the sensory functions of the deep fibular nerve?

A

Innervates the webbed space of skin between the great toe and second toe.

94
Q

What does deep fibular nerve entrapment or compression cause?

A

Paralysis of the muscles in the anterior compartment of the leg, so the patient can’t dorsiflex the foot. This causes foot drop, and difficulty walking, leading to abnormal gait.

95
Q

What is waddling gait?

A

Patient leans excessively onto the normal limb.

96
Q

What is swing-out gait?

A

The patient abducts the abnormal limb.

97
Q

What is high steppage gait?

A

The patient flexes the hip and knee excessively on the abnormal limb so as to clear the dropped foot from the floor.

98
Q

What causes deep fibular nerve compression?

A

Excessive use of anterior leg muscles so compress the nerve in the anterior compartment - pain in anterior leg.
Tight-fitting shoes compress the nerve beneath the extensor retinaculum - pain in dorsum of foot.

6. MSK (30 decks)

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