Lecture 18- Lumbrosacral plexus Flashcards
muscles lining the posterior abdominal wall (4)
psoas major
iliacus
quadratus lumborum
psoas minor- missing in 40% of population
loose areolar connective tissue that lines the posterior abdominal wall muscles and the entire internal surface of the abdominal wall
endoabdominal (or transversalis) fascia
endoabdominal (or transversalis) fascia is continuous with the ________ in the pelvis and is usually invested with fat.
endopelvic fascia
where does the lumbar plexus form from?
anterior primary rami of L1-L4
T12 also contributes to the lumbar plexus
roots that send white rami communicates to the sympathetic trunk
T12-L2
where do the grey rami communicates enter?
all 5 roots, T12-L4
the lumbar plexus forms within what muscle?
psoas major
the lumbar plexus emerges where from the psoas major?
lateral, anterior, and medial borders
Nerve that emerges from T12
subcostal nerve
Nerves that emerge from L1
iliohypogastric nerve and Ilioinguinal nerve
nerve that emerges from L1-L2
genitofemoral nerve
nerve that emerges from L2-L3
lateral femoral cutaneous nerve
nerves that emerge from L2-L4
femoral nerve, obturator nerve
In about 9% of cases, this nerve exists
accessory obturator nerve
What is the sacral plexus formed by?
- lumbosacral trunk
- ventral primary rami of S1-3 and part of S4
Where does the sacral plexus lie?
anteriorly to the piriformis muscle on the posterior pelvic wall
What is the sacral plexus covered by?
endopelvic fascia
2 division of sacral plexus
anterior and posterior
nerves in posterior division of sacral plexus
- superior gluteal nerve
- inferior gluteal nerve
- sciatic nerve (also anterior)
- posterior femoral cutaneous nerve
- perforating cutaneous nerve
- nerve to piriformis muscle
nerves in anterior division of sacral plexus
- sciatic nerve (also posterior)
- nerve to quadratus femoris and gemellus inferior
- nerve to obturator internus and gemellus superior
- posterior femoral cutaneous nerve
- pudenal nerve
- pelvic splanchnic nerves
- sacral nerve
- nerve to levator ani
superior gluteal nerve
- posterior division
- L4-5, S1
- innervates gluteus medius, gluteus minimus, and tensor fascia lata
inferior gluteal nerve
- posterior division
- L5, S1-2
- innervates gluteus maximus
sciatic nerve
- posterior and anterior divisions
- L4-S3
- innervates hamstring and muscles of leg and foot
- supplies sensory to skin on lateral aspect of leg and foot
What nerves does the sciatic nerve split into?
- tibial nerve: L4-S3
- common peroneal nerve: L4-S2
nerve to quadratus femoris and gemellus inferior
- anterior division
- L4-S1
- innervates quadratus femori and gemellus inferior
nerve to obturator internus and gemellus superior
- anterior division
- L5-S2
- innervates obturator internus and gemellus superior
posterior femoral cutaneous nerve
- anterior: S2-3
- posterior: S1-2
- sensory to thigh
perforating cutaneous nerve
- posterior division
- S2-3
- sensory to medial aspect of buttocks
pudenal nerve
- anterior division
- S2-S4
- innervates muscles of the perineum
- provides sensory to lower half of anal canal, perianal skin, and genitalia in both sexes
pelvic splanchnic nerves
- anterior division
- S2-perineal branch of S4
nerve to levator ani
- anterior division
- S3-S4
iliohypogastric nerve
- L1
- to gluteal and hypogastric skin
- to external and internal abdominal oblique muscles and transversus abdominis
ilioinguinal nerve
- L1
- to skin of groin and scrotum/labia majorum
- to external and internal abdominal oblique muscles and transversus abdominis
genitofemoral nerve
- L1-2
- to skin of mons pubis, labia majorum/scrotum
- to skin of femoral triangle, cremaster muscle
lateral femoral cutaneous nerve
- L2-3
- supplies sensory to skin on anterolateral thigh
femoral nerve
- L2-4
- to anterior surface of thigh and medial aspect of leg and foot
- to skin on medial side of leg and foot via saphenous branch
- innervates iliacus, pectineus, sartorius, quadriceps femoris
- to articular capsule of hip and knee joints
obturator nerve
- L2-4
- to medial surfaces of thigh and articular capsule of hip and knee joints
- innervates gracilis, adductor brevis, adductor longus, adductor magnus, obturator externus
- sometimes innervates pectineus via accessory obturator nerve (L3-4)
