Lumbar and Sacral Plexus Flashcards
lower extremity receives innervation from
the ventral rami of spinal n.
the ventral rami of spinal n. are organized into
the lumbar and sacral plexuses (“lumbosacral plexus”)
where do the lumbar and sacral plexuses emerge from?
the lumbar enlargement of the spinal cord
what is the lumbar plexus comprised of?
the ventral rami of L1-L4
what is the sacral plexus comprised of?
ventral rami of L4-S4
what are the lumbar and sacral plexuses connected by?
the distal portion of the lumbar plexus
what is the distal portion of the lumbar plexus?
the lumbosacral trunk
what is the lumbosacral trunk?
L4 and L5
Cauda equina
L2-S5, most of the lumbar and sacral plexuses make up this
the peripheral nerves that originate from the lumbar and sacral plexuses course along
the inner abdominal and pelvic walls, and down to the lower extremity
the peripheral nerves carry
general sensory information from the body wall and lower limb, as well as somatomotor to muscles in these regions
gluteal region nerves
superior and inferior gluteal nerves and nerves to small rotators of the hip joint
thigh nerves
lateral femoral cutaneous, femoral, obturator and sciatic nerves
leg nerves
sciatic nerve- common fibular and tibial nerves
ankle and foot nerves
sciatic nerve- common fibular and tibial nerves
cutaneous innervation to the thigh includes which nerves?
lateral femoral cutaneous n., posterior femoral cutaneous n., genitofemoral n. (groin), ilioinguinal n. (groin)
innervation of the thigh’s deep structures includes which nerves?
anterior compartment: femoral n.
medial compartment: obturator n.
posterior compartment: sciatic n.
cutaneous innervation of the leg includes which nerves?
saphenous n. (terminal femoral branch), lateral sural cutaneous n., sural n.
innervation of the leg’s deep structures includes which nerves?
sciatic n.: anterior and lateral compartments: common fibular n. (deep and superficial branch)
posterior compartment: tibial n.
innervation of the foot includes which nerves?
medial and lateral plantar nn., from tibial n.
what is a dermatome?
an area of cutaneous innervation on the skin that can be traced back to a single spinal nerve
what are the dermatomes of the lower extremity?
spinal nerve roots L1-S5, includes the groin and gluteal region
cutaneous nerves of the peripheral nerves of the lumbar and sacral plexuses, and/or branches of these peripheral nerves distribute…
over the limb in a different pattern, since nerves typically carry axons from more than one spinal nerve
what are myotomes?
the segmental innervation of muscle groups, they tend to correspond to movements
myotomes ______, such that…
overlap, such that a given movement will involve more than one myotome, also because motor fibers from more than one spinal nerve segment
what are the 2 deep tendon reflexes and what spinal cord segments/tendons do they correspond with?
quadriceps (knee jerk): L3/L4, patellar tendon, tests function of the femoral nerve and spinal cord segments L3-L4, absence is called Westphal’s sign
calcaneal (ankle jerk): S1/S2, achilles tendon
what are the major nerves of the lumbar and sacral plexuses?
femoral obturator sciatic (fibular division= common fibular, tibial division= tibial) lateral femoral cutaneous posterior femoral cutaneous
femoral n. roots
L2-L4
obturator n. roots
L2-L4
Sciatic n. roots
L4-S3, F: L4-S2, T: L4-S3
lateral femoral cutaneous n. roots
L2-L3
posterior femoral cutaneous n. roots
S1-S3
Iliohypogastric n.
provides sensory innervation to the lateral gluteal region and motor innervation to abdominal musculature (L1)
Iliolinguinal n.
provides sensory innervation to the superior medial thigh and regions of the perineum, as well as motor innervation to abdominal musculature (L1)
Genitofemoral n.
provides sensation to the superior thigh region (femoral portion) and the perineum (genital portion) (L1 and L2)
Lateral femoral cutaneous n.
provides innervation to the skin of the lateral thigh region (L2 and L3)
Femoral n.
the nerve of the anterior compartment of the thigh (L2, L3, L4)
Obturator n.
the nerve of the medial compartment of the thigh (L1-L4), provides cutaneous innervation of the medial region of the thigh
Lumbosacral trunk
unites the lumbar plexus with the sacral plexus
femoral nerve (which innervates the _____ compartment of the ____) innervates muscles that do
anterior, thigh, flexion of hip, extension of knee
obturator nerve (which innervates the ____ compartment of the ____) innervates muscles that do
medial, thigh, adduction of thigh, some extension of hip
femoral nerve branches into nerves that innervate
iliacus, sartorius, rectus femoris, vastus lateralis, vastus medialis, vastus intermedius, pectineus
obturator nerve branches into nerves that innervate
pectineus, adductor brevis, adductor longus, gracilis, adductor magnus, obturator externis
the sacral plexus is made of which nerves?
superior and inferior gluteal nerves, nerve to piriformis, sciatic nerve (common fibular and tibial divisions), posterior femoral cutaneous nerve, pudendal nerve
superior and inferior gluteal nerves
provide motor to the three gluteal muscles
nerve to piriformis
provide motor innervation to the small rotators of the hip
sciatic nerve provides innervation to
to the posterior thigh and leg
posterior femoral cutaneous nerve
innervates the skin of the posterior thigh
pudendal nerve
sensation to the perineum
sciatic nerve is composed of nerves _____ and innervates
L4 and L4, lumbosacral trunk, hamstring muscles in the thigh, which function to flex the knee; and branches into the tibial nerve (for plantar flexion of the foot and toes, inversion of foot, posterior leg) and the common fibular nerve (for dorsiflexion of foot and toe extension, foot eversion, anterior and lateral leg)
