1.3.2. The Sacral Plexus Flashcards

1
Q

What is the Sacral Plexus?

A

A network of Nerve Fibers, which supplies the Skin and Musculature of the Pelvis and Lower Limb

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2
Q

Where is the Sacral Plexus located?

A
  1. It is located on the Surface of the Posterior Pelvic Wall

2. Anterior to the Piriformis Muscle

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3
Q

What forms the Sacral Plexus?

A
  1. The Anterior Rami of the of Spinal Nerve S1
  2. The Anterior Rami of the of Spinal Nerve S2
  3. The Anterior Rami of the of Spinal Nerve S3
  4. The Anterior Rami of the of Spinal Nerve S4
    (5. The Anterior Rami of the of Spinal Nerve L4 also contributes)
    (6. The Anterior Rami of the of Spinal Nerve L5 also contributes)
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4
Q

How do the Spinal Nerves leave the Spinal Cord?

A

Via the Intervertebral Foramina of the Vertebral Column

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5
Q

What happens to the Nerves, after they leave the Spinal Cord?

A

They divide into Anterior and Posterior Fibers (or Rami)

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6
Q

What happens to the Anterior Rami of S1-S4?

A

They intertwine (The Sacral Plexus) and divide into several cords

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7
Q
  1. Which Lumbar Roots join the Anterior Rami of S1-S4?

2. What do they combine to form?

A
  1. a) L4
  2. b) L5
  3. Lumbosacral Trunk
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8
Q

Where does the Lumbosacral Trunk travel?

A

Into the Pelvis

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9
Q

What does the Lumbosacral Trunk join?

A

The Sacral Plexus

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10
Q

What do the Cords which leave the Sacral Plexus goes on to form?

A

Major Peripheral Nerves of the Sacral Plexus

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11
Q

What are the Major Peripheral Nerves of the Sacral Plexus?

A
  1. Superior Gluteal Nerve
  2. Inferior Gluteal Nerve
  3. Sciatic Nerve
  4. Posterior Femoral Cutaneous Nerve
  5. Pudendal Nerve
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12
Q

What are the 2 main destinations of the Major Peripheral Nerves of the Sacral Plexus?

A
  1. Leaving the Pelvis to the Gluteal Region

2. Remaining in the Pelvis

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13
Q

Which Major Peripheral Nerves of the Sacral Plexus leave the Pelvis, to the Gluteal Region?

A
  1. Superior Gluteal Nerve
  2. Inferior Gluteal Nerve
  3. Sciatic Nerve
  4. Posterior Femoral Cutaneous Nerve
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14
Q

Which Major Peripheral Nerves of the Sacral Plexus remain in the Pelvis?

A

The Pudendal Nerve

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15
Q

How does the Superior Gluteal Nerve leave the Pelvis?

A

Via the Greater Sciatic Foramen

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16
Q

Where does the Superior Gluteal Nerve enter into the Gluteal Region, in relation to the Piriformis Muscle?

A

Superiorly

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17
Q

What accompanies the Superior Gluteal Nerve as it enters into the Gluteal Region?

A
  1. Superior Gluteal Artery

2. Superior Gluteal Vein

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18
Q

What is the Segmental (or Nerve Root) Value of the Superior Gluteal Nerve?

A
  1. L4
  2. L5
  3. S1
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19
Q

What is the motor function of the Superior Gluteal Nerve?

A
  1. Innervation of the Gluteus Minimus Muscle
  2. Innervation of the Gluteus Medius Muscle
  3. Innervation of the Fascia Lata
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20
Q

What is the sensory function of the Superior Gluteal Nerve?

A

There is none

21
Q

How does the Inferior Gluteal Nerve leave the Pelvis?

A

Via the Greater Sciatic Foramen

22
Q

Where does the Inferior Gluteal Nerve enter into the Gluteal Region, in relation to the Piriformis Muscle?

A

Inferiorly

23
Q

What accompanies the Inferior Gluteal Nerve as it enters into the Gluteal Region?

A
  1. Inferior Gluteal Artery

2. Inferior Gluteal Vein

24
Q

What is the Segmental (or Nerve Root) Value of the Inferior Gluteal Nerve?

A
  1. L5
  2. S1
  3. S2
25
Q

What is the motor function of the Inferior Gluteal Nerve?

A

Innervation of the Gluteus Maximus

26
Q

What is the sensory function of the Inferior Gluteal Nerve?

A

There is none

27
Q

What is the significance of the Sciatic Nerve?

A
  1. It is the longest Nerve in the body

2. It is a thick, flat band - about 2cm

28
Q

What is the Segmental (or Nerve Root) Value of the Sciatic Nerve?

A
  1. L4
  2. L5
  3. S1
  4. S2
  5. S3
29
Q

Where is the Sciatic Nerve derived from?

A

The Lumbosacral Plexus

30
Q

How does the Sciatic Nerve leave the Pelvis?

A

Via the Greater Sciatic Foramen

31
Q

Where does the Sciatic Nerve enter into the Gluteal Region, in relation to the Piriformis Muscle?

A

Inferiorly

32
Q

What direction does the Sciatic Nerve travel, after it enters the Gluteal Region?

A

Inferolaterally

33
Q

What does the Sciatic Nerve cross as it travels through the Gluteal Region?

A
  1. The Posterior Surface of the Superior Gemelli Muscle
  2. The Posterior Surface of the Obturator Externus Muscle
  3. The Posterior Surface of the Inferior Gemelli Muscle
  4. The Posterior Surface of the Quadratus Femoris Muscle
34
Q

Where does the Sciatic Nerve enter into the Thigh, in relation to the Long Head of the Bicep Femoris?

A

Deeply

35
Q

What branches arise off of the Sciatic Nerve within the Posterior Thigh?

A
  1. Branch to the Hamstring Muscle

2. Branch to the Hamstring Part of the Adductor Magnus Muscle

36
Q

Where does the Sciatic Nerve normally terminate?

A

At the Apex of the Popliteal Fossa

37
Q

What happens to the Sciatic Nerve at it terminates?

A

It bifurcates

38
Q

What does the Sciatic Nerve bifurcate into?

A
  1. Tibial Nerve (sometimes known as the Tibial Branch of the Sciatic Nerve)
  2. Common Fibular Nerve (sometimes known as the Common Fibular Branch of the Sciatic Nerve)
    Note - The Sciatic Nerve can be described as these 2 individual Nerve Bundles
39
Q

Where does the Sciatic Nerve terminate in 12% of people?

A

As it leaves the Pelvis

40
Q

Does the Sciatic Nerve provide motor innervation any Muscles in the Gluteal Region?

A

No

41
Q

Where does the Sciatic Nerve directly provide motor innervation for?

A
  1. The Posterior Compartment of the Thigh

2. The Hamstring Part of the Adductor Magnus Muscle

42
Q

What Nerves does the Sciatic Nerve indirectly provide motor innervate via?

A

Via its 2 Terminal Branches:

  1. The Tibial Nerve
  2. The Common Fibular Nerve
43
Q

What does the Tibial Nerve provide motor innervation for?

A
  1. The Muscles of the Posterior Leg

2. Some Intrinsic Muscles of the Foot

44
Q

What does the Common Fibular Nerve provide motor innervation for?

A
  1. Muscles of the Anterior Leg
  2. Muscles of the Lateral Leg
  3. Some Intrinsic Muscles of the Foot
45
Q

What does the Sciatic Nerve provide motor innervation for (in total)?

A
  1. Muscles of the Posterior Compartment of the Thigh
  2. Hamstring Part of the Adductor Magnus Muscle
  3. All of the Muscles in the Leg
  4. All of the Muscles of the Foot
46
Q

Does the Sciatic Nerve provide any direct Cutaneous (sensory) innervation?

A

No

47
Q
  1. Does the Sciatic Nerve provide any indirect Cutaneous (sensory) innervation?
  2. If so, how?
A
  1. Yes
  2. Via its Terminal Branches:
  3. a) The Tibial Nerve
  4. b) The Common Fibular Nerve
48
Q

What does the Tibial Nerve provide Cutaneous (sensory) innervation for?

A
  1. Posterolateral Side of the Leg
  2. Anterolateral Side of the Leg
  3. Plantar Surface (Sole) of the Foot
49
Q

What does the Common Fibular Nerve provide Cutaneous (sensory) innervation for?

A
  1. Lateral Aspect of the Leg

2. Dorsal Surface (Roof) of the Foot