Lumbar and lumbosacral plexus

Question 1

*The entire lower limb is supplied by which 2 somatic nerve plexi?

Answer 1

1) Lumbar plexus (ventral rami of L1-L4)

2) Lumbosacral plexus (ventral rami of L4 and L5 joining the ventral rami from S1-S4)

Question 2

*What does the lumbar plexus innervate?

Answer 2

Lumbar plexus (ventral rami of L1-L4) innervates – skin and muscles of the lower abdominal wall

• • skin covering the root of the penis and anterior scrotum and the skin over the mons pubis and anterior portion of the labia majora
• • skin and muscles in the anterior and medial compartments of the thigh
• • skin of the lateral thigh
• • skin of the medial side of the leg.

Question 3

*What does the lumbosacral plexus innervate?

Answer 3

lumbosacral plexus (ventral rami of L4 and L5 joining the ventral rami from S1 to S4) innervates

• • the skin and muscles of the gluteal region
• • the skin and muscles of the perineum
• • the skin and muscles of the posterior thigh
• • the skin and muscles of the anterior, lateral, and posterior leg and the muscles of the medial leg
• • the skin and muscles in the foot.

Question 4

*Which plexus innervates the foot muscles?

Answer 4

lumbosacral (ventral rami of L4 and L5 joining the ventral rami of S1 to S4)

Question 5

*Which plexus innervates the glute muscles?

Answer 5

lumbosacral (ventral rami of L4-L5 joining with S1-S4)

Question 6

*Which plexus innervates the skin of the medial side of the leg?

Answer 6

lumbar plexus (ventral rami of L1-L4)

Question 7

*Which plexus innervates the muscles of the anterior thigh?

Answer 7

lumbar plexus (ventral rami of L1-L4)

Question 8

*Which plexus innervates the muscles of the medial thigh?

Answer 8

lumbar plexus (ventral rami of L1-L4)

Question 9

*Which plexus innervates the skin of the anterior thigh?

Answer 9

lumbar plexus (ventral rami of L1-L4)

Question 10

*Which plexus innervates the skin of the medial thigh?

Answer 10

lumbar plexus (ventral rami of L1-L4)

Question 11

*Which plexus innervates the skin of the gluteal region?

Answer 11

lumbosacral plexus (L4-L5 and S1-S4)

Question 12

*Which plexus innervates the foot skin?

Answer 12

lumbosacral plexus (L4-L5 and S1-S4)

Question 13

*Which plexus innervates the muscles of the posterior thigh?

Answer 13

lumbosacral plexus (L4-L5 and S1-S4)

Question 14

*Which plexus innervates the skin of the posterior thigh?

Answer 14

lumbosacral plexus (L4-L5 and S1-S4)

Question 15

*Which plexus innervates most of the leg muscles and leg skin?

Answer 15

lumbosacral plexus (L4-L5 and S1-S4)

Question 16

*What do the clunial nerves do?

Answer 16

provide cutaneous innervation to the skin of the gluteal region.

Question 17

*What are the different groups of clunial nerves?

Answer 17

1) Superior clunial nerves (dorsal rami of L2, L3)
2) Middle clunial nerves (dorsal rami of S2, S3, S4)
3) Inferior clunial nerves (branches from posterior cutaneous nerve of the thigh– ventral rami of S2, S3)

Question 18

*What are the superior clunial nerves and what do they supply?

Answer 18

derived from dorsal rami of L2, L3, L4. Supply the skin over the central and superior portion of this region.

Question 19

*What are the middle clunial nerves and what do they supply?

Answer 19

derived from dorsal rami of S2, S3, and S4. Supply medial portion of the buttock.

Question 20

*What are the inferior clunial nerves and what do they supply?

Answer 20

branches from posterior femoral cutaneous nerve of the thigh (which is a branch from the ventral rami of the sacral plexus). Inferior clunial nerves (S2 and S3) supply skin covering inferior portion of the buttock.

Question 21

*Each paravertebral ganglion in the lumbar and sacral portion of the sympathetic chain is connected to a lumbar or sacral ventral ramus via?

Answer 21

grey ramus

Question 22

*The lumbar and lumosacral plexi are what? What are they responsible for?

Answer 22

The lumbar and lumbosacral plexi are somatic nerve plexi responsible for supplying cutaneous sensaton from the skin and motor innervation to the muscles of the entire lower limb.

Question 23

*What is responsible for the cremaster reflex? What is the cremaster reflex used for?

Answer 23

The L1 spinal nerve (the genital branch of the genitofemoral nerve off of the lumbar plexus) is responsible for the cremaster reflex. This reflex is used to determine integrity of the L1 spinal nerve. The cremaster muscle should contract (causing the testicles to retract lightly) if the L1 dermatome is stimulated (either by rubbing the skin of the anterior scrotum or upper thigh).

Question 24

*Which is the largest nerve plexus in the body?

Answer 24

lumbosacral or sacral plexus

Question 25

*preganglionic sympathetic neurons are found only as far inferior as the ___ region of the spinal cord? Axons from these neurons enter the sympathetic chain via ____?

Answer 25

Preganglionic sympathetic neurons are found only as far inferior as the L2 region of the spinal cord. Axons from these neurons enter the sympathetic chain via a white ramus that connects the first 2 lumbar ventral rami with the first 2 lumbar paravertebral ganglia.

Question 26

*The first two lumbar paravertebral ganglia are attached to the first 2 lumbar ventral rami via ____?

Answer 26

both a white and grey ramus

Question 27

*Any paravertebral ganglion below ____ is attached to the corresponding ventral ramus by ____?

Answer 27

Any paravertebral ganglion below the 2nd lumbar paravertebral ganglion is attached to the corresponding ventral ramus by a grey ramus only.

Question 28

*How do preganglionic sympathetic axons reach the lower lumbar and sacral ganglia?

Answer 28

Those preganglionic neurons in the lower thoracic and upper lumbar regions of the spinal cord can descend down the chain before forming a synapse, in addition to synapsing in the ganglion in which they enter the sympathetic chain.

Question 29

*A contribution from ___ may join ___ in the lumbar plexus.

Answer 29

A contribution from T12 ventral ramus may join L1 ventral ramus in the lumbar plexus.

Question 30

*The L1 ventral ramus splits into…?

Answer 30

1) iliohypogastric nerve

2) ilioinguinal nerve

Question 31

*What does the iliohypogastric nerve do and where is it derived?

Answer 31

Derived from L1, the iliohypogastric nerve supplies the muscles forming the lower portion of the abdominal wall (lower internal abdominal oblique). it is also sensory to the region of skin covering the abdominal wall over the pubic bone, just superior to the inguinal ligament.

Question 32

*What does the ilioinguinal nerve do?

Answer 32

Derived from L1, the ilioinguinal nerve supplies the muscles forming the lower portion of the abdominal wall (lower internal abdominal oblique). It is also sensory to the region of skin covering the root of the penis and anterior scrotum in the male and the mons pubis and anterior labia in the female.

Question 33

*What does the genitofemoral nerve do?

Answer 33

Derived from L1 and L2, the genitofemoral nerve is divided into two branches:

1) The femoral branch supplies the skin of he upper thigh, just below the inguinal ligament.
2) The genital branch in males goes through the inguinal canal to innervate the cremaster muscle.

Question 34

*What does the lateral femoral cutaneous branch do?

Answer 34

Derived from L2 and L3 of the lumbar plexus, the lateral femoral cutaneous branch supplies the skin over the lateral thigh. The nerve becomes cutaneous as it passes under the lateral portion of the inguinal ligament.

Question 35

*What is meralgia peristatica?

Answer 35

Meralgia Peristatica is a condition that leads to a burning sensation over the lateral thigh. This condition is caused by the entrapment of the lateral femoral cutaneous nerve (L2, L3) between the inguinal ligament and the ASIS. This compression can be caused by wearing tight hip-hugger pants.

Question 36

*What is the femoral nerve?

Answer 36

Derived from L2, L3, and L4, the femoral nerve supplies motor innervation to the muscles of the anterior compartment of the thigh (quadriceps femoris and sartortius) and cutaneous sensation from the anterior and medal thigh and medial leg. The medial leg cutaneous innervation is supplied by the saphenous branch.

Question 37

*What is the obturator nerve?

Answer 37

Derived from L2, L3, and L4, the obturator nerve supplies cutaneous innervation to a smakk region along the medial thigh near the knee and motor innervation to the obturator externus and adductors of the hip.

Question 38

*What are the branches of the lumbar plexus?

Answer 38

1) Iliohypogastric (L1)
2) ilioinguinal (L1)
3) genitofemoral (L1, L2)– genital and femoral branches
4) lateral femoral cutaneous (L2, L3)
5) femoral (L2, L3, L4)– branches to psoas and saphenous
6) Obturator (L2, L3, L4)

Question 39

*Which of the clunial nerves comes from ventral rami?

Answer 39

Inferior clunial nerve (off of the posterior femoral cutaneous nerve of the sacral plexus)

Question 40

*what nerve is responsible for inversion of the foot?

Answer 40

L4

Question 41

*what nerve is responsible for eversion of the foot?

Answer 41

S1

Question 42

*What nerve is responsible for extension of the knee?

Answer 42

L2 and L3

Question 43

*What nerve is responsible for hip flexion?

Answer 43

L1 and L2

Question 44

*What nerve is responsible for ankle plantar flexion?

Answer 44

S1

Question 45

*What nerve is responsible for ankle dorsiflexion?

Answer 45

L5

Question 46

*The ventral rami of what nerves join to form the lumbosacral trunk of the sacral plexus?

Answer 46

L4 and L5

Question 47

*The lumbosacral trunk is joined by the ventral rami of which nerves as it descends into the pelvis?

Answer 47

S1-S4, which enter through the ventral sacral foramina

Question 48

*The branches from the lumbosacral plexus enter the ____ either above for below the ____ muscle.

Answer 48

The branches from the lumbosacral plexus enter the gluteal region either above or below the piriformis muscle.

Question 49

What are the branches of the sacral plexus?

Answer 49

1) Superior gluteal nerve (L4, L5, S1)
2) inferior gluteal nerve (L5, S1, S2)
3) nerve to piriformis (L5, S1)
4) nerve to quadratus femoris and inferior gemellus (L4, L5, S1)
5) nerve to obturator internus and superior gemellus (L5, S1)
6) Posterior cutaneous nerve of the thigh (S1, S2, S3)
7) Pudendal nerve (S2, S3, S4)
8) Sciatic (Tibial– S2, S3, S4 and Common fibular division (L4, L5, S1, S2)

Question 50

*What is the difference between peripheral nerve lesion and radiculopathy and spinal cord lesion?

Answer 50

1) A peripheral nerve lesion results in loss of function of muscle and atrophy because a peripheral nerve lesion will have more than one spinal segment associated with it and thus several associated dermatomes (e.g. femoral L2-L4).
2) A radiculopathy is associated with one dermatomy (eg L5). This will cause weakness of muscle and sensation loss restricted to one area.
3) a spinal cord lesion causes widespread muscle paralysis and loss of sensation below the site of the lesion.

Question 51

*What is a common cause of a radiculopathy?

Answer 51

Herniated disc

Question 52

***Radiculopathy of root L1 and L2 is associated with which dermatome and myotome?

Answer 52

dermatome = lower abdomen and upper thigh.

myotome = hip flexion.

Question 53

***Radiculopathy of root L2 and L3 is associated with which dermatome and myotome?

Answer 53

dermatome: anterior and medial thigh
myotome: hip adduction and knee extension

Question 54

***Radiculopathy of root L4 is associated with which dermatome and myotome?

Answer 54

Dermatome: medial leg

myotome: inversion and supination of tarsal joints

Question 55

***Radiculopathy of root L5 is associated with which dermatome and myotome?

Answer 55

Dermatome: dorsum of foot.

myotome: hip abductors and dorsiflexion of ankle

Question 56

***Radiculopathy of root S1 is associated with which dermatome and myotome?

Answer 56

dermatome: lateral and posterior leg
myotome: ankle plantar flexion. eversion and pronation of tarsal joints.

Question 57

A herniated disc is usually a ____ injury wherein the nucleus bulges in a ______ direction. This is because the worn out annulus cannot contain the nucleus.

Answer 57

A herniated disc is usually a flexion injury wherein the nucleus bulges in a posterior lateral direction, blocking the intervertebral foramen and pressing on the spinal nerves. This is because the worn out annulus can not contain the nucleus.

Question 58

What are three types of disc herniation?

Answer 58

1) Soft disc herniation. This is when the nucleus pulposus breaks through the annulus fibrosus. This commonly affects lumbar spine. This is because the elasticity and water content of the discs decrease with age in the nucleus pulposus, leaving 3-50 year old persons most susceptible.
2) hard disc herniation
3) combination of soft and hard disc herniation

Question 59

What are the types of low back pain?

Answer 59

1) acute (6-12 weeks)

2) chronic (lasts more than 12 weeks; recurrent)

Question 60

What are causes of low back pain?

Answer 60

1) lumbosacral strain (muscle tear),
2) sumbosacral sprain (tearing of ligaments),
3) herniated discs,
4) referred pain from visceral organs, metastases

Question 61

What are the symptoms of low back pain?

Answer 61

localized, radiating

Question 62

Lumbosacral radiculopathy usually affects ___ and may involve ____

Answer 62

lumbosacral radiculopathy usually affects cauda equina and may involve more than one root

Question 63

lumbosacral spinal nerves exit ____ corresponding vertebrae

Answer 63

lumbosacral spinal nerves exit below corresponding vertebrae

Question 64

*Disc L1,2 is associated with which spinal nerve, providing sensory and motor/function to…?

Answer 64

Disc L1, 2 is associated with spinal nerve L2, providing sensory to the mid-thigh and motor to the iliopsoas (hip flexion)

Question 65

*Disc L2, L3 is associated with which spinal nerve, providing sensory and motor/function to?

Answer 65

Disc L2,3 is associated with spinal nerve L3, providing sesnory to the lower thigh and motor to quadriceps (knee extension) and adductors (hip adduction)

Question 66

*Disc L3, L4 is associated with which spinal nerves, providing sensory and motor/function to?

Answer 66

Disc L3, L4 is associated with spinal nerve L4, providing sensory to the medial leg and motor to the tibalis anterior and posterior (foot inversion)

Question 67

*Disc L4,L5 is associated with which spinal nerves, providing sensory and motor/function to?

Answer 67

Disc L4,L5 is associated with spinal nerve L5, providing sensory to the dorsum of the foot and motor to the anterior crural muscles (ankle dorsiflexion) and gluteus medius and minimus (hip abduction)

Question 68

*Disc L5, S1 is associated with which spinal nerves, providing sensory and motor/function to?

Answer 68

Disc L5, S1 is associated with spinal nerve S1, providing sensory to the lateral leg and foot, and motor to the triceps surae (ankle plantar flexion)

Question 69

*Squat tests?

Answer 69

quadriceps (L3)

Question 70

*Heel walk tests?

Answer 70

L5– dorsiflexion (anterior crural muscles)

Question 71

***Trendelenburg tests?

Answer 71

L5– hip abductors (gluteus medius and minimus)

Question 72

*Toe walk tests?

Answer 72

S1– plantarflexion (triceps surae) and gastrocnemius and soleus

Question 73

*During the straight leg raise test, if a patient experiences sciatic pain when the straight leg is at an angle of between ___ and ____ degrees, the test is positive and a ____ is likely to be the cause of the pain.

Answer 73

During the straight leg raise test, if a patient experiences sciatic pain when the straight leg is at an angle of between 30 and 70 degrees, the test is positive and a L5, S1 herniated disc is likely to be the cause of the pain.

Question 74

*Approximately 90% of herniated discs occur at the ____ and ___ level, causing pain in the ___ or ____ nerve that radiates down the ____ nerve.

Answer 74

Approximately 90% of herniated discs occur at the L4-L5 and L5-S1 level, causing pain the the L5 or S1 nerve that radiates down the sciatic nerve.

Question 75

How is a spinal cord lesion classified?

Answer 75

By the segments of cord that still function. For example, a C5 lesion means that all segments up to and including C5 are still functioning, and an L3 lesion means that all segments up to and including L3 are functioning.

Question 76

If a person has a T10 spinal cord lesion would they be a paraplegic?

Answer 76

yes

Question 77

The sacral paravertebral ganglia are connected to the ventral rami forming the sacral plexus by only a ____.

Answer 77

The sacral paravertebral ganglia are connected to the ventral rami forming the sacral plexus by only a grey ramus.

Question 78

*The superior gluteal nerve is supplied by which roots and innervates what? The superior gluteal nerve enters the pelvis ____ the _____ muscle in company of _____?

Answer 78

The superior gluteal nerve of the sacral plexus is supplied by L4, L5, and S1. The superior gluteal nerve innervates the muscles attached from the outer portion of the body of the ilium, including the tensor fascia lata, gluteus medius and minimus. The superior gluteal nerve enters the pelvis above the piriformis muscle in company of the superior gluteal artery and vein.

Question 79

*The inferior gluteal nerve is supplied by which roots and innervates what? The inferior gluteal nerve enters the pelvis ____ the ____ muscle in company of ____?

Answer 79

The inferior gluteal nerve is supplied by L5, S1, and S2 and innervates the gluteus maximus. The inferior gluteal nerve enters the pelvis below the piriformis muscle in company of the inferior gluteal artery and vein.

Question 80

*The nerve to obturator internus is supplied by which roots and innervates what? The nerve to obturator internus exits the pelvis ____ to the ____ muscle.

Answer 80

The nerve to obturator internus is supplied by L5, S1, and S2 and innervates the obturator internus and superior gemellus muscles. The nerve to obturator internus exits the pelvis inferior to the piriformis muscle.

Question 81

*The nerve to the quadratus femoris is supplied by which roots and innervates what?

Answer 81

The nerve to the quadratus femoris is supplied by L4, L5, and S1. It innervates the quadratus femoris and the inferior gemellus muscle as well as the hip joint.

Question 82

*The pudendal nerve is supplied by which roots and innervates what? The pudendal nerve exits the pelvis ___ the ____ muscle in the company of ____?

Answer 82

The pudendal nerve is supplied by S2, S3, S4 and supplies the muscles associated with the external genitalia and sphincters of the anus and urethra. The pudendal nerve exits the pelvis below the piriformis muscle in the company of the pudendal artery and vein.

Question 83

*The sciatic nerve is supplied by which roots and innervates what before diving into _____? The sciatic nerve exits the pelvis ____ the ____ muscle.

Answer 83

The sciatic nerve is supplied by L4, L5, S1, S2, S3, and S4. The sciatic nerve innervates the hamstring muscles in the posterior portion of the thigh before dividing into its terminal branches, the tibial and common fibular (peroneal) nerves. The sciatic nerve exits the pelvis below the piriformis muscle.

Question 84

• The posterior femoral cutaneous nerve is supplied by which roots and innervates what?

Answer 84

The posterior femoral cutaneous nerve is supplied by S1, S2, and S3. The posterior femoral cutaneous nerve supplies the skin of the posterior thigh and popliteal region.

Question 85

***A 21 year old female runner comes to your practice and complains that she has a hard time abducting her right hip. She also has a hard time coming out of the blocks when she is starting a 100 meter sprint. When she stands on her right leg with her left foot off the ground, you notice that her left iliac crest falls and on the right the crest rises. What muscles are involved with these symptoms? Do you think that there is a nerve involved? Do the symptoms suggest a nerve lesion or raciculopathy?

Answer 85

1

Question 86

***A fifty five year old PT who was a good athlete when he was younger decides to lift a very heavy object by himself. The next day he wakes up with pain in his
back and radiating pain down the posterior of his thigh and leg. He has tingling sensation on the lateral and plantar surface of his foot. He has weak plantarflexion and has problems when asked to toe walk. His can abduct his hip but hip extension is somewhat weaker. Is this a nerve or nerve root problem? What are the differences? What nerve runs down the posterior of the thigh and leg? Do the dermatomes involve suggest a nerve lesion or does the distribution suggest a single dermatome? What does the toe walking test indicate? Can there be localized pain and radiating pain?

Answer 86

1

Question 87

The developing strength of what muscle is responsible for the development of the lordotic curvature in the lumbar region?

Answer 87

iliopsoas

Question 88

What about the lumbar region of the spine promotes mobility?

Answer 88

large vertebral bodies

Question 89

Pain radiating along the back of the thigh and down the leg to the foot is indicative of ____?

Answer 89

nerve root impingement.

Question 90

Radiculopathy can result from…?

Answer 90

intervertebral disc herniation, spinal stenosis, arthritis involving the intervertebral foramen

Question 91

Any examination of low back pain should first try to rule out _____?

Answer 91

internal organ pain radiating to the low back region. Urinary system pain, pain with the reproductive system, or lower digestive system pain can all radiate back to the low back region.

Question 92

lumbosacral strain usually involves which muscles?

Answer 92

true back muscles like the erector spinae.

Question 93

lumbosacral sprains usually involve injury to…?

Answer 93

ligaments.

Question 94

Which back ligaments are often injured?

Answer 94

posterior longitudinal, supraspinous, and ligamentum flavum. Flexion has a greater range of motion than extension. During flexion, the posterior longitudinal ligament, supraspinous ligament, and ligamentum flavum are required to help stabilize the lumbosacral spine. Thus, these are the most often injured

Question 95

What is the most common cause of radiating back pain?

Answer 95

Radiculopathy due to herniated intervertebral disc

Question 96

What movement puts most stress on intervertebral discs?

Answer 96

flexion coupled with lateral flexion, especially during lifting heavy objects.

Question 97

Which regions of the vertebral column are affected most by herniated discs?

Answer 97

The C5-T1 region of the cervical spine and the L4-S1 region of the lumbar spine (the regions in which the largest amount of flexion takes place).

Question 98

A herniation of the intervertebral disc between the C4 and C5 vertebrae will compress the ____ spinal nerve?

Answer 98

C5

Question 99

A herniation between C6 and C7 vertebrae will affect the ___ spinal nerve?

Answer 99

C7

Question 100

What is a classic sign of radiculopathy?

Answer 100

radiating pain

Question 101

*If deep knee bends are difficult to perform then herniation affects which roots?

Answer 101

L2 and L3 (quadriceps femoris)

Question 102

*If heel walk is difficult to perform then herniation affects which root?

Answer 102

L5 (anterior crural muscles– dorsiflexion)

Question 103

*If toe walk is difficult to perform then herniation affects which root?

Answer 103

S1 (ankle plantar flexion– triceps surae)

Question 104

Spinal cord lesion at C2 would result in?

Answer 104

quadriplegia and person cannot breath unassisted. There would be no sensation below upper region of the neck. They would have no motor reflexes.

Question 105

spinal cord lesion at C6 would result in?

Answer 105

shoulder function, elbow flexion, wrist extension intact. No lower limb function. The neck, posterior lateral arm, and radial forearm would be unaffected. They would have biceps and brachioradialis reflexes.

Question 106

spinal cord lesion in thoracic region would result in?

Answer 106

complete use of neck nad upper limb, but there would be lower limb paraplegia. The neck and upper limb would be intact, but there would be lower limb anesthesia. Depending upon the level injured there may or may not be sensation to the thorax and abdomen. Reflexes would include brachioradialis, biceps, and triceps.

Question 107

spinal cord lesion in L2 would result in?

Answer 107

hip flexion and some adduction possible. Portion of anterior and medial thigh intact. No sensation in remainder of limb. No lower limb reflexes and incontinence.

Question 108

spinal cord lesion in L4 would result in?

Answer 108

hip flexion, adduction, and knee flexion normal. anterior, medial thigh, medial leg and foot normal. patellar reflex possible and incontinence.

Question 109

spinal cord lesion in S1 would result in?

Answer 109

hip, knee, and ankle dorsiflexors normal. Ankle plantar flexors and intrinsic muscles of the foot are weak. Lack of sensation in perineum but most of lower limb would lack sensation. Motor reflexes include patellar and achilles. Incontinence