Lumbosacral plexus Flashcards
(27 cards)
What are the roots of the iliohypogastric nerve?
T12, L1
What is the trajectory of the iliohypogastric nerve?
emerges from upper lateral border of psoas major
crosses obliquely behind lower pole of kidney + in front of quadratus lumborum
runs to iliac crest across quadratus lumborum muscle of posterior abdominal wall
perforates transversus abdominis
divides into its terminal branches.
What are the motor functions of the iliohypogastric nerve?
Innervates internal oblique + transversus abdominis.
What is the sensory function of the iliohypogastric nerve?
Innervates pubic region
What is the root of the ilioinguinal nerve?
L1
What is the trajectory of the ilioinguinal nerve?
follows same anatomical course as larger iliohypogastric nerve->passes obliquely across quadratum lumborum
enters tranversus abdominis near anterior end of iliac crest (there can be easily pierced to perform local anaesthesia to the inguinal canal)
After innervating muscles of anterior abdominal wall
innervates upper middle thigh + suprapubic skin.
What are the motor functions of the ilioinguinal nerve?
Innervates internal oblique + transversus abdominis.
What is the sensory function of the ilioinguinal nerve?
Innervates skin on upper middle thigh.
- In males: also supplies skin over root of penis + anterior scrotum.
- In females: supplies skin over mons pubis + labia majora.
What are the roots of the genitofemoral nerve?
L1, L2
What is the trajectory of the genitofemoral nerve?
descends under peritoneum on psoas major
crosses obliquely behind ureter
Above inguinal ligament quickly divides into genital branch + femoral branch.
What are the sensory functions of the genitofemoral nerve?
innervates skin of anterior scrotum (in males) or skin over mons pubis + labia majora (in females).
Femoral branch innervates skin on upper anterior thigh.
What is a specificity of the lateral femorsl cutaneous nerve?
- purely sensory function.
What are the roots of the lateral femoral cutaneous nerve?
L2, L3
WHat is the trajectory of the lateral femoral cutaneous nerve?
emerges lateral to psoasenters thigh under lateral aspect of inguinal ligament
providing cutaneous innervation to the skin there
supplies parietal peritoneum in iliac fossa
then passes under inguinal ligament
over Sartorius muscle into thigh
divides into two branches: anterior + posterior branches
What is Meralgia paresthetica?
tingling, numbness and burning pain in your outer thigh due to obesity, pregnancy causing compression of lateral femoral cutaneous nerve.
What is the sensory function of the lateral femoral cutaneous nerve?
Innervates anterior + lateral thigh.
What are the roots of the femoral nerve?
L2, L3, L4
What is the trajectory of the femoral nerve?
descends through psoas major
emerges low on its lateral border
in this proximal portion innervates iliacus
descends from the lumbar plexus in iliac fossa through psoas major muscle
then travels through pelvis to approximately mid-point of inguinal ligament
traverses behind the inguinal ligament
supplies branches to iliacus + pectineus muscles before entering thigh
passes through femoral triangle lateral to femoral vessels (enclosed within femoral sheath)
gives off articular branches to hip + knee joints by traversing behind inguinal ligament + spliting into anterior + posterior division.
What is the anterior division of the femoral nerve?
o Medial cutaneous nerve of thigh: supplies skin of medial side of thigh
o Intermediate cutaneous nerve of thigh: supplies skin as far as knee + ending in peripatellar plexus (anterior cutaneous branches)
o Nerve to sartorius
What is the posterior division of the femoral nerve?
o Saphenous nerve : terminal cutaneous branch of femoral nerve
continues with femoral artery + vein, through adductor canal
descends lateral to femoral artery
At the distal end of canal: leaves artery
emerges through aponeurotic covering with saphenous branch of descending genicular artery.
Great saphenous vein frequently runs intimately along saphenous nerve (in leg region)
o Muscular branches
What are the sensory functions of the femoral nerve?
o 1st cutaneous branches of femoral nerve are anterior cutaneous branches (medial + intermediate cutaneous branches) that arise in femoral triangle (anterior division) –> supply skin on anteromedial thigh.
o last cutaneous branch of femoral nerve: saphenous nerve (posterior division) –> supplies skin on medial side of leg + foot.
What are the motor functions of the femoral nerve?
o supplies some of muscles of anterior thigh:
o Hip Flexors
Pectineus: adducts + flexes thigh, assists with medial rotation of thigh.
Iliacus: acts with psoas major + psoas minor (iliopsoas) to flex thigh at hip joint + stabilize joint.
Sartorius: flexes, abducts, laterally rotates thigh at hip joint. Flexes leg at knee joint.
o Knee Extensors
Quadriceps femoris (rectus femoris, vastus lateralis, vastus intermedius): extend leg at knee joint. Rectus femoris also steadies hip joint + assists iliopsoas in flexing thigh.
What are the roots of the obturator nerve?
L2, L3, L4
What is the trajectory of the obturator nerve?
descends through fibres of psoas major muscle
emerges from its medial border
runs posteriorly to common iliac arteries + laterally along pelvic wall to obturator foramen
then enters thigh through obturator canal
splits into anterior + posterior divisions.
