nerves of lower limb Flashcards
where is the lumbar plexus
within the substance of psoas major muscle
two plexuses of the lower limb
sacral and lumbar
which ventral rami form the lumbar plexus
L1-4
what are the 3 divisions emerging from the lateral surfae of the lumbar plexus as they emerge from psoas
- iliohypogastric and ilioinguinal nerves (ilioinguinal is like a branch of iliohypogastric) - lateral cutaneous nerve of thigh - femoral nerve
which ventral rami contribute to the iliohypogastric and ilioinguinal nerves
L1
what is the sensory innervation of the ilioinguinal and iliohypogastric nerves
cutaneous supply of the skin over the inguinal region and the front of the scrotum
what is the motor innervation of the iliohypogastric and ilioinguinal nerves
- the lowermost fibres of internal oblique and transversus abddominus
which ventral rami contribute to the lateral cutaneous nerve of thigh
L2 and L3
what is the sensory innervation of the lateral cutaneous nerve of thigh
supplies the skin of the lateral part of the thigh
route of the lateral cutaneous nerve of thigh
emerge from the lateral border of psoas major and onto iliacus –> beneath the inguinal ligament and into the anterior compartment of the thigh
which ventral rami contribute to the femoral nerve
L2,3,4
onto what surface does the femoral nerve go onto of the thigh
the anterior compartment
which nerve of the lumbar plexus emerges from the anterior surface of psoas
genitofemoral nerve
which ventral rami contribute to the genitofemoral nerve
L1,2
what does the femoral branch of the genitofemoral nerve supply
sensory supply to the area of skin immediately beneath the middle of the inguinal ligament
what does the genital branch of the genitofemoral nerve supply
the sensory supply to the spermatic cord
which nerve of the lumbar plexus emerges from the medial border of psoas
obturator
which ventral rami contribute to the obturator nerve
L2,3,4
what are all the nerves of the lumbar plexus
iliohypogastric and ilioinguinal nerves lateral cutaneous nerve of thigh femoral nerve genitofemoral nerve obturator nerve
which nerves contribute to the sacral plexus
S1-4 (and also what is left of L4 and L5)
where is the sacral plexus
formed on the surface of piriformis on the posterior wall of the pelvis
what is the motor innervation of the femoral nerve
to quads, sartorius and pectineus (muscles of the anterior thigh)
what is the sensory innervation of femoral nerve
- anteromedial thigh (via anterior cutaneous branches) - medial side of knee, leg and ankle (saphenus nerve)
what other innervation, other than sensory and motor, does the femoral nerve do
articular branches to hip and knee
what is the positioning of the femoral nerve as it passes beneath the inguinal ligament and into the anterior compartment of the thigh
it is lateral to vascular structures, OUTSIDE the femoral sheath
where abouts does the femoral nerve branch into its terminal branches
about 2.5cm below the inguinal ligament
which group of muscles does the obturator nerve supply
the adductor muscles (medial)
describe the route of the obturator nerve
emerges from medial border of psoas –> drops onto lateral wall of pelvis –> through obturator canal –> medial compartment of thigh
which muscles specifically does the obturator nerve supply
adductor longus and brevis - via anterior division adductor magnus and gracilis - via posterior division and pectineus
where is the sensory innervation of the obturator nerve
sensory to inferomedial thigh (just above the medial side of knee)
what other supply does the obturator nerve do apart from sensory and motor
articular branches to hip
which two branches of the sacral plexus contribute to the innervation of the leg
posterior cutaneous nerve of thigh sciatic nerve
what is the supply of the posterior cutaneous nerve of thigh
sensory supply over the back of the thigh
what are the two “components” of the sciatic nerve
tibial nerve common fibular nerve
what is the route of the sciatic nerve through the leg
exits pelvis via greater sciatic foramen –> emerges beneath piriformis, onto the posterior of the hip joint –> descends in the posterior thigh under biceps femoris and on obturator internus and gemeli –> divides into terminal branches at the apex of the popliteal fossa
which type of hip dislocation can take out the sciatic nerve
posterior
what is the motor innervation of the sciatic nerve
to the hamstrings (via the tibial component of sciatic nerve - apart from SHOB)
what articular branches does the sciatic nerve give
articular branches to hip
which rami contribute to the tibial nerve
L4-5, S1-3
the tibial nerve is the nerve of which compartment of the leg
the posterior compartment (calf - flexors)
what is the route of the tibial nerve
continues the vertical descent of sciatic nerve through the popliteal fossa behind the knee joint –> beneath fibrous arch of Soleus –> descends between the superficial and deep muscles of the calf on tibialis posterior –> posterior to medial malleolus –> sole of foot –> divides into medial and lateral plantar nerves
what is the motor innervation of the tibial nerve
the to posterior muscles of the leg
what is the sensory innervation of the tibial nerve
posterior leg and lateral side of foot - sural nerve sole of foot - medial calcaneal, medial and lateral plantar nerves
which part of the sole of the foot is supplied by the saphenous nerve
very medial part
what is the route of the common fibular nerve
remains next to (medially) biceps femoris –> superficial to lateral head of gastrocnemius on route –> winds around the neck of fibula –> into substance of fibularis longus –> divides into terminal branches (deep and superficial fibular nerves)
if you take out the common fibular nerve what is the sign
“Foot drop”
what is the motor innervation of the common fibular nerve
nothing
what is the sensory innervation of the common fibular nerve
- sensory to upper lateral leg via sural cutaneous nerve - gives communicating branch to sural nerve (from tibial nerve)
which nerve roots contribute to the common fibular nerve
L4-5, S1-2 (no S3)
the common fibular nerve is the nerve of which compartment
the anterior compartment of the leg (extensors)
two divisions of the common fibular nerve
deep and superficial fibular nerves
route of the deep fibular nerve
begins in substance of fibularis longus –> descends deep to EDL, anterior to interosseous membrane –> beneath extensor retinaculum -> dorsum of the foot –> between toe cleft of 1st and 2nd toes
motor innervation of deep fibular nerve
anterior compartment of the leg - tibialis anterior, EDL, EHL extensor digitorum brevis (on dorsum of the foot)
what is the sensory innervation of the deep fibular nerve
sensory to the skin between the 1st and 2nd toes
what is the motor innervation of the superficial fibular nerve
lateral compartment of the leg - fibularis longus and brevis
what is the sensory innervation of the superficial fibular nerve
lower lateral leg and dorsum of the foot (sparing the first web space)
explain the innervation of the muscles in the gluteal region
superior gluteal nerve - supplies gluteus minimus and medius inferior gluteal nerve supplies gluteus maximus
which nerves innervate the anterior, medial and posterior compartments of the thigh
anterior - femoral medial - obturator posterior - sciatic nerve
how do you get a dermatomal or myotomal disruption to the lower limb
disruption of the nerves at the root level
what are the roots of the superior and inferior gluteal nerves
superior - L5,5,S1 - emerges above piriformis inferior - L5, S1,2 - emerges below piriformis
