innervation of lower limbs Flashcards
The lumbar plexus is composed of…
The ventral rami of L1-L4
The subcostal nerve arises from…
T12
The “superior” divisions of L1 give rise to…
The iliohypogastric + ilioinguinal nerves
The genitofemoral nerve is formed by…
The “inferior” division of L1 and the “superior” division of L2
The obturator nerve arises from…
The anterior divisions of L2, L3 and L4
The femoral nerve arises from …
The posterior divisions of L2, L3 and L4
The “posterior” posterior divisions of L2 and L3 give rise to a nerve. Name it
Lateral femoral cutaneous nerve
The obturator nerve runs … to the psoas major
First posterior and then medial
As the obturator nerve descends, it enters into…
The lesser pelvis
Once it’s in the lesser pelvis, the obturator nerve branches into…
Anterior + posterior branches
The anterior branch of the obturator nerve innervates…
The adductor longus + brevis, gracilis
Which muscles “cover” the anterior branch of the obturator nerve?
Adductor longus + pectineus (anteriorly)
Obturator externus + adductor brevis (posteriorly)
The posterior branch of the obturator nerve innervates 2 adductors. Name them
Obturator externus + adductor magnus
Name the muscle that is pierced by the posterior branch of the obturator nerve as it descends towards the medial portion of the thigh
Obturator externus
Describe the position of the femoral nerve with regards to the psoas major as it descends
It originates posterior to it, more laterally than the obturator nerve + then descends in the groove between the psoas and iliacus to the femoral triangle
Describe the alignment of the vessels and nerves in the femoral triangle
VAN from medial to lateral
BUT: then the femoral artery + saphenous nerve cross medially
in the end, the vein + artery are on top of each other & the saphenous nerve is medial
Name the muscles that are innervated by the motor branches of the femoral nerve
Sartorius, pectineus + quadriceps
The saphenous nerve arises from…
The most medial fibres of the femoral nerve
Explain the trajectory of the saphenous nerve from thigh to knee
It runs obliquely and crosses over the femoral artery towards the adductor hiatus. Once it reaches the vastoadductor septum, it lays completely anterior + medial to both vessels. Also anterior to the adductor magnus.
It then becomes more superficial (already at the level of the leg) and runs between the sartorius and gracilis.
It branches into the infrapatellar branch (goes anterior)
Describe the trajectory of the saphenous nerve from knee to foot
It descends medially, pretty straight, alongside the greater saphenous vein. At the level of the ankle, it passes anterior to the medial malleolus + the dorsum of the foot
The lumbosacral plexus is formed by the rami of…
L4, L5, S1-S5
What is the name of the “structure” formed by L4 and L5?
Lumbosacral trunk
The common fibular nerve arises from…
The dorsal division of the lumbosacral
plexus
The tibial nerve arises from…
The ventral division of the lumbosacral plexus
Name the nerve that innervates the gemellus superior + obturator internus
Nerve to obturator internus
Name the nerve that innervates the gemellus inferior + quadratus femoris
Nerve to quadratus femoris
