nerves of the lower limb: lumbar plexus Flashcards
- what rami of which nerve roots are involved in the lumbar and sacral plexuses?
- what do the lumbar and sacral plexuses supply?
- what are the two largest nerves from these plexuses?
- Lumbar and sacral (lumbosacral) plexuses (ventral rami of L1 – S4)
- Supply the lower limbs, parts of the abdominal wall, pelvis and perineum
- The largest nerves from these plexuses entering the thigh are the femoral nerve (L2-4) and the sciatic nerve (L4-S3)
which muscle is the lumbar plexus formed within? and where does it lie?
what function of the branches does it have?
what nerve roots supply the lumbar plexus?
- The lumbar plexus is formed within thepsoas major muscle and anterior to the transverse processes of the lumbar vertebrae.
- Has motor and sensory branches
- L1-L4
femoral nerve:
1. what structure does the femoral nerve descend behind?
- where does the femoral nerve pass through?
- what branches does the femoral nerve give off?
- what nerve roots supply the femoral nerve?
- Descends behind the inguinal ligament
- Passes through the femoral triangle in the thigh.
- Gives off muscular, anterior cutaneous femoral and saphenous branches
- L2-L4
femoral nerve:
1. what is the sensory innervation of the femoral nerve?
- what is the motor innervation of the femoral nerve?
Sensory innervation:
- Hip joint
- Knee joint
- Skin on the anterior surface of the thigh (by the anterior cutaneous femoral branch)
- Skin of the medial leg and foot (by the saphenous nerve)
Motor innervation
- Iliacus
- Muscles in the anterior compartment of the thigh:
1. Quadriceps femoris
2. Sartorius
3. Pectineus
saphenous nerve:
1. what is characteristic about this branch of the femoral nerve?
- what structure does it enter?
- when does it become superficial?
- what structure does it accompany?
- what does it supply?
- it is the largest and terminal cutaneous branch of the femoral nerve
- it enters the adductor canal with femoral vessels
- it pierces the medial wall of the adductor canal and becomes superficial
- it accompanies the greater saphenous vein in the leg
- Supplies the skin on the medial surface of the knee, anteromedial surface of leg and medial malleolus
obturator nerve:
1. where does the obturator nerve travel?
- where does it pass through and enter?
- what is its sensory innervation?
- what is it’s motor innervation?
- it travels anteriorly on lateral pelvic wall towards obturator canal, deep to ovaries in females
- it passes through obturator canal and enters the medial aspect of the thigh
- Sensory innervation
- Hip joint
- Upper half of medial thigh
- Knee joint - Motor innervation
- Obturator externus
- Muscles in the medial compartment of the thigh - Adductor magnus*
- Adductor longus
- Adductor brevis
- Gracilis
sacral plexus:
what rami of which nerve roots form the sacral plexus?
on which structure is it located?
it is formed by anterior rami of L4 and L5 (the lumbosacral trunk) + S1-4
it is located on the surface of the posterior pelvic wall, deep to the piriformis muscle
gluteal nerves: superior + inferior
superior
1. what nerve roots supply the superior gluteal nerve?
2. where does it exit the pelvis?
3. what two muscles does it run between?
4. what 3 muscles does it supply?
inferior
1. what nerve roots supply the inferior gluteal nerve?
2. where does it exit the pelvis?
3. what does it innervate?
- L4-S1
- it exits the pelvis through the suprapiriform space
- it runs laterally between the gluteus medius and gluteus minimus
- it supplies the gluteus media, gluteus minimus and tensor gluteus maximus
- L5-S2
- it exits the pelvis through the infrapiriform space
- it innervates the gluteus maximus
sciatic nerve:
1. what nerve roots supply the sciatic nerve?
- how does it enter the gluteal region?
- where does it descend to?
- where should intragluteal injections be performed?
- L4-S3
- it enters the gluteal region through the infrapiriform space
- it descends deep to gluteus maximus, midway between the ischial tuberosity and the greater trochanter, behind the hip joint
- intragluteal injections should only be performed in the superolateral quadrant of the buttock, away from the majority of neurovascular structures
sciatic nerve:
1. where does the sciatic nerve usually give off its terminal branch?
- what are the two branches of the sciatic nerve?
- what is the sensory innervation of the sciatic nerve?
- what is the motor innervation of the sciatic nerve?
- The sciatic nerve usually gives off its terminal branches at the apex of the popliteal fossa but in some cases can branch near the piriformis (12%)
- Tibial nerve and common fibular [peroneal] nerve
- Sensory innervation:
- Hip joint - Motor innervation
- Muscles in the posterior compartment of thigh- Hamstring muscles
- Adductor magnus (in addition to the obturator nerve)
- Hamstring muscles
what nerves are within the anterior compartment of the leg?
what nerves are within the lateral compartment of the leg?
what nerves are within the posterior compartment of the leg?
- the anterior compartment is deep fibular nerve territory; innervating the dorsiflexors of the foot
- the lateral compartment is superficial fibular nerve territory innervating the evertors of the foot
- the posterior compartment is innervated by the tibial nerve innervating the plantar flexors of the foot and toes
tibial nerve:
1. what nerve roots supply the tibial nerve?
- where does the tibial nerve descend?
- what branch does it give off?
- what structure does it pass into?
- what nerves does it divide into?
- L4-S3
- it descends in the popliteal fossa, postero-lateral to the popliteal vessels
- it gives off medial sural cutaneous branch (sensory)
- it passes into the sole behind medial malleolus, deep to the flexor retinaculum
- it divides into the Medial and Lateral plantar nerves
tibial nerve:
what is the sensory innervation of the tibial nerve?
what is the motor innervation of the tibial nerve?
Sensory innervation
- Ankle joint
- Skin of the heel
Motor innervation
- Hamstring muscles except short head of biceps femoris
Plantaris
- Popliteus
- Muscles in the superficial posterior compartment of the leg
1. Gastrocnemius
2. Soleus
- Muscles in the deep posterior compartment
1. Tibialis posterior
2. Flexor hallucis longus
3. Flexor digitorum longus
plantar nerves: medial and lateral planter nerves
medial plantar nerve
1. what 4 muscles does the medial plantar nerve innervate?
2. what is the sensory supply to?
lateral plantar nerve
1. what muscles does the lateral plantar nerve innervate?
2. what is the sensory supply to?
Medial plantar nerve
1. Supplies Abductor hallucis, Flexor hallucis brevis, Flexor digitorum brevis, Lumbrical 1
- Sensory supply to anterior two-thirds of the sole and adjacent surfaces of the medial 3.5 toes
Lateral plantar nerve
1. Supplies all other plantar muscles
2. Sensory supply to skin on the lateral side of the anterior two-thirds of the sole and the adjacent plantar surfaces of the lateral 1.5 digits
Plantar digital nerves
common fibular (peroneal) nerve
1. what nerve roots supply the common fibular nerve?
- what is the key characteristic of this branch of the sciatic nerve?
- where does it descend?
- what branch does it give off?
- what nerves does it divide into?
- what muscle does it supply?
- L4-S2
- it is the smallest terminal branch
- it descends laterally in the popliteal fossa and winds around the neck of the fibular
- it gives off the lateral cutaneous sural branch
- it divides into its terminal branches:
- superficial fibial (peroneal) nerve
- deep fibular (peroneal) nerve - it supplies the short head of the biceps femoris
