Exam 3: Sacral Nerves, Sacral Plexus, Coccygeal Plexus Flashcards

1
Q

How many pairs of sacral spinal nerves are there?

A

5 pairs

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2
Q

Where do the sacral nerves descend inside and what do they help form?

A

descend inside the dura and form much of the cauda equina

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3
Q

How does each sacral nerve divide?

A

into an anterior primary ramus and a posterior primary ramus

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4
Q

What rami travel through the posterior sacral foramina?

A

posterior primary rami of S1-S4

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5
Q

Where does the S5 posterior ramus travel through?

A

the sacral hiatus

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6
Q

Describe the size of the posterior primary rami of the sacral nerves?

A

they decrease in size from superior to inferior

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7
Q

What rami of sacral nerves will divide?

A

the posterior primary rami of S1-S3 divide into medial and lateral branches

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8
Q

What do the medial branches and lateral branches of the posterior primary rami of S1-S3 supply?

A

Medial–> adjacent multifidi (motor)

Lateral–> combine with branches from L5 and S4 to supply skin over buttocks

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9
Q

What does the lateral branch of the posterior primary rami of S1-S3 combine with to supply?

A

combine with branches from L5 and S4 to supply skin over buttocks

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10
Q

What do the posterior primary rami of S4 and S5 do?

A

unit with coccygeal posterior rami to supply the skin over the coccyx

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11
Q

Where do the anterior primary rami of S1-S4 travel through? What about the anterior primary rami of S5?

A

the four anterior sacral foramina

S5 through sacral hiatus

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12
Q

What rami are traveling through the sacral hiatus?

A

posterior primary rami and the anterior primary rami of S5

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13
Q

What plexus do the anterior primary rami of sacral nerves contribute to?

A
Sacral plexus (S1-S4)
Coccygeal plexus (S4,S5)
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14
Q

What other part of the nervous system do the Sacral Spinal nerves have communication with? What part of the sacral nerves communicates with it?

A

the sympathetic trunk

anterior primary ramus of each sacral nerve will receive POSTganglionic sympathetic fibers via a gray ramus communicans

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15
Q

How may sacral sympathetic ganglia are there?

A

usually 3-4

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16
Q

What forms the Sacral Plexus?

A

anterior primary rami of L4, L5, S1, S2, S3…and part of S4

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17
Q

The contribution of L4 and L5 to the sacral plexus is via what?

A

via the lumbosacral trunk

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18
Q

What nerve fibers are in the lumosacral trunk?

A

L4 and L5

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19
Q

On top of what muscle does the Sacral Plexus form?

A

on the anterior surface of the piriformis muscle

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20
Q

What do the nerve roots that supply the sacral plexus divide into and when do they do this?

A

anterior and posterior divisions shortly after exiting their IVF/sacral foramen

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21
Q

What are all the branches off the anterior division of the sacral plexus?

A
  1. Nerve to the quadratus femoris and gemellus inferior (L4,L5,S1)
  2. Nerve to the obturator internus and gemellus superior (L5,S1,S2)
  3. Pudendal Nerve ( S2,S3,S4)
  4. ind. Muscular branches to levator ani and coccygeus muscles (S4)

–contribute to posterior cutaneous nerve of the thigh (S2,S3) and Sciatic Nerve via the Tibial Nerve (L4-S3)

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22
Q

What nerve fibers does the Nerve to the quadratus femoris and gemellus inferior contain? How does it leave the pelvis? What actions do these muscles contribute to?

A

L4, L5, S1 nerves of anterior division

leaves via Greater Sciatic Foramen

contribute to lateral rotation and adduction of the thigh

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23
Q

What fibers does the Nerve to the obturator internus and gemellus superior carry? How do they leave the pelvis and give off the branches to the muscles?

A

L5, S1, S2 nerves of anterior division

via Greater Sciatic Foramen –> gives branch to gemellus superior, then–> RE-ENTERS pelvis via Lesser Sciatic Foramen to supply obturator internus

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24
Q

What action do the muscles of Nerve to the obturator internus and gemellus superior contribute to?

A

lateral rotation and abduction of the thigh

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25
Q

What nerve fibers does the Pudendal nerve contain? How does it leave the pelvis and can you describe its path?

A

S2, S3, S4 of anterior division

via Greater Sciatic Foramen–> arches around ischial spine–> and into perineum via Lesser Sciatic Foramen –> then travels in Pudendal Canal (inf. to pubic symphysis to dorsal side of penis/clitoris)

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26
Q

After the Pudendal Nerve arches around the ischial spine and into perinuem via the Lesser Sciatic Foramen, where does it travel next?

A

through the Pudendal Canal, inferior to the pubic symphysis to reach the dorsal side of the penis (males) or clitoris (females)

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27
Q

What are the branches that come off the Pudendal Canal in the Pudendal Canal?

A
  1. Inferior Rectal Nerves ( S and M)
  2. Perineal Nerve (divides into Deep-motor and Superficial-sensory branches)
  3. Dorsal nerve of the penis (males) or clitrois (females) (S and M)–is terminal branch of pudendal nerve
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28
Q

What does the Inferior Rectal Nerves supply?

A

(branch of Pudendal Nerve)
Sensory–> skin around anus and inf. 2/3 of anal canal
Motor–> external anal sphincter (anal wink ;)

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29
Q

What does the Perineal Nerve do?

A

(branch of Pudendal nerve) will divide into Deep motor branch and superficial sensory branch

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30
Q

What does the deep branch of the Perineal Nerve supply?

A

Motor:

  1. External anal sphincter
  2. Bulbosponsiosus
  3. Ischiocavernosus
  4. Superficial transverse perineus
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31
Q

What does the superficial branch of the Perineal Nerve supply?

A

Sensory:

  • Males–> posterior scrotum, urethral mucosa, and bulb of penis
  • Females–> labium majus, external urethral orifice, and vestibule
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32
Q

What is the terminal branch of the Pudendal nerve? What type of fibers does it carry?

A

Dorsal Nerve of the Penis (males) or Dorsal Nerve of the Clitoris (females)
- motor and sensory

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33
Q

What does the Dorsal Nerve of the Penis/Clitoris supply?

A
(terminal branch of Pudendal Nerve)
Motor:
- Deep transverse perineus
- Urethral sphincter muscles 
Sensory:
- Males--> corpus cavernosum, glans penis, and skin covering penis
- Females--> corpus cavernosum, clitoris
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34
Q

What do the individual Muscular Branches off the sacral plexus contain fibers from and what do they supply?

A

fibers from S4
Supply Muscles:
- levator ani
- coccygeus

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35
Q

We splanchnic nerves come off the sacral plexus and what do they supply?

A

Pelvic Splanchnic nerves; fibers from S2, S3, and S4)

36
Q

What are all the branches off the posterior division of the sacral plexus?

A
  1. Nerve to the Piriformis (S1, S2)
    2, Superior Gluteal Nerve (L4, L5, S1)
  2. Inferior Gluteal Nerve (L5, S1, S2)
  3. Perforating Cutaneous Nerve ( S2, S3)

–contributes to Posterior Cutaneous Nerve of the Thigh (S1, S2) and Sciatic Nerve via Common Fibular Nerve (L4-S2)

37
Q

What nerve fibers does the Nerve to the Piriformis Muscle contain?

A

(branch of posterior division)

S1 and S2

38
Q

What fibers does the Superior Gluteal Nerve contain and how does it leave the pelvis? What does it divide into?

A

(branch of posterior divison)
L4, L5, and S1

via Greater Sciatic Foramen, SUPERIOR to piriformis and splits into—> superior and inferior branches

39
Q

What do the superior branches of the Superior Gluteal Nerve supply? What do the Inferior branches supply?

A

Superior –> gluteus medius and minimus

Inferior–> gluteus medius and minimus AND tensor fascia lata

40
Q

What fibers does the Inferior Gluteal Nerve contain? How does it leave the pelvis? What does it supply?

A

(branch of posterior division)
L5, S1, and S2

via Greater Sciatic Foramen, INFERIOR to piriformis

supplies gluteus maximus

41
Q

What is the Perforating Cutaneous Nerve named for and what fibers does it contain? What does it supply? Are there any anomalies?

A

named b/c it travels THROUGH the sacrotuberous ligament

sensory–> lower medial aspect of buttocks

(may instead be formed by branch off pudendal nerve OR be absent)

42
Q

What two nerves of the sacral plexus are formed by BOTH anterior and posterior divisions?

A
  1. Posterior Cutaneous nerve of the Thigh ( Ant. S2, S3 and Post. S1, S2)
  2. Sciatic Nerve (Tibial Nerve–Ant. L4-S3; and Common Fibular Nerve–Post. L4-S2)
43
Q

How does the Posterior Cutaneous Nerve of the Thigh leave the pelvis? Describe its path and what is ultimately communicates with.

A

via the Greater Sciatic Foramen–> descends through the posterior thigh and inferior to the leg–> ultimately communicates with Sural Nerve

44
Q

What does the Posterior Cutaneous Nerve of the Thigh Supply?

A

(Ant. Div. S2,S3 and Post Div. S1, S2)

skin on posterior and medial thigh

45
Q

What is the largest nerve in the human body?

A

Sciatic nerve; ~ 2 cm in diameter

spinal cord is also ~2 cm–WOW

46
Q

What makes up the Sciatic Nerve?

A

Tibial Nerve from Ant. Div. (L4-S3)

Common Fibular Nerve From Post. Div. (L4-S2)

47
Q

How does the Sciatic Nerve leave the Pelvis?

A

both parts w/in a common sheath, through the Greater Sciatic Foramen, BELOW the piriformis muscle

48
Q

How does the Sciatic Nerve travel after exiting the pelvis via the Greater Sciatic Nerve below the piriformis muscle?

A

continues inferiorly on POSTERIOR aspect of adductor magnus and ~ 2/3 way to the knee is splits into its Common Fibular Nerve and Tibial Nerve components

(point at which nerve divides is quite variable)

49
Q

What fibers it the Common Fibular Nerve Composed of? Is it more laterally located or medially located?

A

L4-S2 of post. div.; more laterally located

50
Q

What branches are given off from the Common Fibular Nerve in the thigh before it separates from the Tibial Nerve fibers?

A

branch to one muscle–> Biceps Femoris (short head)

51
Q

Once the Common Fibular Nerve separates from the Tibial nerve, what path does it take?

A

goes around lateral aspect of fibula and on reach the antero-lateral aspect of the leg it gives off an articular branch to the knee joint

52
Q

What are the branches that the Common Fibular Nerve gives off?

A
  • while still with Tibial nerve fibers–> branch to Biceps femoris (short head)
  • articular branch to knee joint

Lateral Aspect of Popliteal Fossa:

  • Lateral Sural Cutaneous Nerve
  • Fibular Communicating Branch

Divides into:

  • Superficial Fibular Nerve
  • Deep Fibular Nerve
53
Q

What branches does the Common Fibular Nerve give off on the lateral aspect of the popliteal fossa? What do they supply?

A
  1. Lateral Sural Cutaneous Nerve–> skin on lateral aspect of leg
  2. Fibular Communicating Branch –> combines with Medial Sural Cutaneous Nerve (from Tibial Nerve) and forms Sural Nerve
54
Q

What form the Sural Nerve?

A
  1. Fibular Communicating Branch off the Common Fibular Nerve
    and the
  2. Medial Sural Cutaneous Nerve from the Tibial Nerve
55
Q

After the Common Fibular Nerve gives off its two branches on the lateral aspect of the popliteal fossa, when what does it do?

A

Divides into the Superficial Fibular Nerve and the Deep Fibular Nerve (both have S and M)

56
Q

How does the Superficial Fibular Nerve travel?

A

(off Common Fibular Nerve)

  • -travels inferior b/w fibularis longus and fibula –> down to dorsum of the foot and supplies two muscles–> then splits into:
    • Medial Dorsal Cutaneous Nerve
    • Intermediate Dorsal Cutaneous Nerve
57
Q

What muscles does the Superficial Fibular Nerve supply? What action do they do?

A
  1. Fibularis Longus
  2. Fibularis Brevis
    (lateral compartment of leg)

action: eversion (and some plantar flexion b/c tendons go post. to lateral malleolus)

58
Q

What are the Medial Dorssal Cutaneous Nerve and the Intermediate Dorsal Cutaneous Nerve branches of? What do they supply?

A

splits from the Superficial Fibular Nerve (branch of Common fibular nerve)
Supply: skin over dorsum of foot, EXCEPT skin b/w first two digits

59
Q

Describe the path of the Deep Fibular Nerve.

A

(branch from Common Fibular Nerve)
runs inferiorly along tibialis anterior –> reaches dorsum of foot–> supplies extensor muscles of foot and toes and sensory to skin b/w first two digits

60
Q

What nerve supplies the skin b/w the first two digits of the toes?

A

Deep Fibular Nerve

61
Q

What muscles does the Deep Fibular Nerve supply?

A
(branch off Common Fibular Nerve)
Found in ant. compartment:
1. Tibialis Anterior
2. Extensor Digitorum longus
3. Extensor hallucis longus
4. Fibularis tertius
~action = dorsal flexion
-----------------------------
On dorsum of foot:
5. Extensor digitorum brevis
6. Extensor halluces brevis
62
Q

What sensory supply does the the terminal branch of the Deep Fibular Nerve have?

A

sensory to skin b/w first two toes

63
Q

If someone has a Steppage Gait for Foot Drop, what nerve are we thinking is involved?

A

Deep Fibular Nerve

cannot dorsiflex the foot (cannot raise their toe up) and will come down on toe first b/c must lift leg up higher so avoid tripping

64
Q

What fibers make up the Tibial Nerve? Is it more laterally or medially located?

A

L4-S3, more medially located and is considerably larger than the common fibular nerve

65
Q

While the Tibial Nerve is still combined with the Common Fibular Nerve, what muscles does it supply?

A
  1. Biceps Femoris (long head)
  2. Semitendinosus
  3. Semimembranosus
  4. Adductor magnus
66
Q

When the Tibial Nerve is in the popliteal fossa, what branches does it give off?

A
  1. articular branches to knee joint
  2. Muscular branches to 4 muscles
  3. Popliteal Branch–> Interosseous nerve of the leg
  4. Medial Sural Cutaneous Nerve (so form Sural Nerve)
67
Q

What muschles do the branches of the Tibial nerve given off in the popliteal fossa supply?

A
  1. Popliteus
  2. Gastrocnemius (both heads)
  3. Soleus
  4. Plantaris
68
Q

What does the popliteal branch of the tibial nerve give rise to?

A

travels inferior to give rise to Interosseous Nerve of the Leg

69
Q

What is the path of the Interosseous Nerve of the Leg? What does it supply?

A

(branch of popliteal branch of tibial nerve)
continues inferior along posterior surface of interosseous membrane
Sensory info from:
- tibial periosteum
- ankle
- tibiofibular joints

70
Q

Once the Tibial Nerve is in the leg, what branches does it give rise to?

A
  1. Muscular branches (supply 3 muscles)

2. Medial Calcaneal Branches (sensory)

71
Q

What do the muscular branches that arise from the Tibial Nerve in the leg supply?

A
  1. Flexor digitorum longus
  2. Flexor hallucis longus
  3. Tibialis posterior
72
Q

What does the Medial Calcaneal branches supply?

A

(branch of tibial nerve in the leg)

- skin over medial heel

73
Q

After giving off its branches in the leg, what does the Tibial Nerve do next?

A

travels around MEDIAL malleolus to plantar surface of foot and divides into two terminal branches:

  1. medial plantar nerve
  2. lateral plantar nerve
74
Q

What are the two terminal branches of the Tibial Nerve?

A
  1. Medial Plantar Nerve (M and S)

2. Lateral Plantar Nerve (M and S)

75
Q

What does the Medial Planter Nerve send motor fibers to? What action do theses muscles contribute to?

A
  1. Abductor hallucis
  2. Flexor digitorum brevis
  3. Flexor hallucis brevis

~~ plantar flexion and inversion
(deep posterior compartment)

76
Q

What muscles does the Medial Plantar Nerve supply?

A
  1. Abductor hallucis
  2. Flexor digitorum brevis
  3. Flexor hallucis brevis
77
Q

What will the Medial Plantar Nerve divide into? What do these branches supply?

A

Common Plantar digital nerves
Motor: to 1st lumbrical
Sensory: via Proper Plantar Digital Nerves to skin b/w toes

78
Q

What does the Lateral Plantar Nerve do?

A
(a terminal branch of Tibial nerve)
motor and sensory
Divides into:
- Superficial Branch (sensory)
- Deep Branch (motor)
79
Q

What does the Superficial Branch of the Lateral Plantar Nerve supply?

A

skin around 5th digit

80
Q

What does the Deep Branch of the Lateral Plantar Nerve supply?

A

(terminal branch of Tibial nerve)

  1. Adductor hallucis
  2. Flexor digiti minimi brevis
  3. Abductor digiti minimi
  4. Quadratus plantae
  5. Lateral Lumbricals (3)
  6. Interossei muscles
81
Q

What nerve can we test by having the patient flex their toes against your resistance or have them stand on their tippy toes?

A

Tibial Nerve–>

82
Q

What can we have the patient do to test the sciatic nerve?

A

Tibial Nerve–> stand on tippy toes/flex toes

Common Fibular Nerve –> take steps on heels

Superficial Fibular Nerve–> have them evert vs resistance

83
Q

What nerve is involved in hammer toes? Describe what is occur at the joints.

A

Tibial Nerve

  • DIP –> hyperextended
  • IP –> hyperflexed
  • PIP –> hyperextended
84
Q

What would “claw foot” be associated with?

A

tibial nerve (but tough to identify, but similar to claw hand)

85
Q

What forms the Coccygeal Plexus?

A

anterior rami of S4, S5, and Co1 nerves

86
Q

The nerves of the coccygeal plexus combine and form what? What type of information does it carry?

A

gives rise to anococcygeal nerves
– carries sensory info from skin adjacent to the coccyx and anus

(anal winking ;)