A&P 2.12 sacral plexus

Question 1

Sacral plexus

Answer 1

Sciatic nerve - main branch and largest nerve in the body

Pelvis and posterior LE entirely innervated by the branches of the sacral plexus
From ventral rami L4-S4
Composed of tibial and common fibulas nerve wrapped together in a single fascial sheath
Innervates posterior thigh and lateral leg

Question 2

Sciatic nerve

splits at and becomes

Answer 2

SPLITS AT KNEE TO BECOME TIBIAL (medial - posterior) AND COMMON FIBULAR NERVES

Question 3

Peroneal nerve

Answer 3

Common FIBULAR nerve

Question 4

lumbosacrial plexus

Answer 4

Lumbar and sacral plexus are often considered together

Question 5

Sciatica

Answer 5

Pain along the course of the sciatic nerve (from buttock down posterior and or lateral LE)
Or may be referred from trigger points (most of the time this is at least a component of the pain)

Question 6

Sciatica may result from

Answer 6

A true neuralgia of the sciatic nerve by

Or trigger points located in the gluteus minimums or piriformis

Question 7

True neuralgia

2 main causes

Answer 7

Pressure on roots of L5

entrapment of sciatic nerve by pisiform muscle

Question 8

Pressure on roots of L5 by:

Answer 8

Herniated disc
Osteroarthritis on the lumbosacrial spine
Pressure from the uterus during Px
An improperly administered gluteal intramuscular injection

Question 9

Trigger points

Answer 9

Trigger points located in the gluteus minimums or piriformis

• cause a pseudo-sciatica where there is no real disturbance to the nerve
  At least partially involved in the vast majority of sciatica cases

Question 10

Nuclei versus ganglia chart

Answer 10

CNS (axons - tracts - white) (cell body- nuclei - grey)

PNS (axons- nerves - white). ( cell bodies - ganglia - grey)

Question 11

ONLY GANGLIA IN CNS IS THE

Answer 11

ONLY GANGLIA IN CNS IS THE BASAL GANGLIA

Question 12

Herpes zoster

name & cause

Answer 12

Shingles
Caused by a VIRUS - chicken pox/varicella virus
Lies dormant in the dorsal root ganglia (meeting point for all the sensory neurons in each dermatome
If you had chicken pox, you can get shingles

Question 13

Herpes zoster

Affects

Answer 13

Affects - the dendrites at the end of sensory neurons along a specific dermatome, blisters break out at nerve endings. Blisters unilaterally.

Question 14

Herpes zoster

triggers

Answer 14

Triggers - stress, weakened immune system, chemotherapy

Question 15

Herpes zoster

Symptoms

Answer 15

Symptoms: pain is present before outbreak, for the 2-3 weeks during outbreak, and can last for months after the lesions have healed.

Question 16

Shingles

Meaning

Answer 16

Latin for belt or girdle

Describing the distribution of blisters around chest or abdomen along a single dermatomal line

Question 17

Herpes zoster

Treatments

Answer 17

Treatment - anti-viral prescriptions, and will also help stave off Post Herpetic Neuralgia (painful after effects), steroids, antidepressants, anti convulsion, and topical agents

Question 18

Post Herpetic neuralgia

Answer 18

Pain is the most common complication of shingles. The pain ranges from tenderness, burning, or throbbing to pain is stabbing, shooting or sharp. It can last for months to years

Question 19

Nerve fiber repair

Answer 19

Mature neurons are typically thought to be incapable of cell division and cannot be replaced. Only option for healing due to damage or disease is repair of those already present.

Question 20

Nerves can be repaired if

Answer 20

Damage is not too extensive
Cell body and cell membrane (neurilemma) remain intact
Scarring has not occurred

Question 20

Stages of nerve repair

PNS ONLY

4 stages

Answer 20

Injury resulting in a nerve cut
WALLERIAN DEGENERATION
Remaining NEURILEMMA tunnel from the point of injury to the effector
Neuron’s connection with effector is reestablished

Question 21

Stages of nerve repair

PNS ONLY

Stage 1

Answer 21

Injury resulting in a nerve cut

Immediately after injury, DISTAL portion of axon degenerates, along with its myelin sheath (WALLERIAN DEGENERATION)

Remaining NEURILEMMA tunnel from the point of injury to the effector: new Schwann cells grow within a tunnel maintaining a pathway for axon regrowrh. Several growing axon sprouts appear. When one of these growing fibers reaches the tunnel, it increases its growth rate. The other sprouts eventually disappear (approximately 1mm per day)

Neuron’s connection with effector is reestablished

Question 22

Stages of nerve repair

PNS ONLY

Stage 2

Answer 22

Immediately after injury, DISTAL portion of axon degenerates, along with its myelin sheath (WALLERIAN DEGENERATION)

Question 23

CNS VERSUS PNS repair

Answer 23

Repair in CNS is not as successful in the PNS.
Oligodendrocytes and astrocytes have an inhibiting effect on fiber growthalso the way oligodendrocytes form the myelin sheaths is different.

Question 24

Stages of nerve repair

PNS ONLY

Stage 3

Answer 24

Remaining NEURILEMMA tunnel from the point of injury to the effector: new Schwann cells grow within a tunnel maintaining a pathway for axon regrowrh. Several growing axon sprouts appear. When one of these growing fibers reaches the tunnel, it increases its growth rate. The other sprouts eventually disappear (approximately 1mm per day)

Question 25

Stages of nerve repair

PNS ONLY

Stage 4

Answer 25

Neuron’s connection with effector is reestablished

Question 26

WALLERIAN DEGENERATION

Answer 26

DISTAL portion of axon degenerates, along with its myelin sheath

Question 27

Glial cells are capable of

Answer 27

Cell division

Question 28

Quadratus lumborum

A, I, O

Answer 28

Unilateral: ipsilateral flexion, lateral pelvic tilt (to same side)
Bilateral: extension of the spine, fix the ribs during inhalation

O- proximal attachment: 12th rib (internal margin), TP of L1-L4

I- distal attachment: iliac crest (internal lip)