Origin
· continuous attachment from lower border of T12 to upper border of L5
· discs above L1-L5 and adjoining parts of bodies
· fibrous arches that span concavities of bodies
· medial ends of transverse processes of L1-L5
Path
· lies in gutter between bodies and transverse processes of lumbar vertebrae
· lumbar plexus embedded in muscle
· covered by psoas fascia
· medial arcuate ligament
· thickening in fascia from body to TP of L1
· gives rise to diaphragm
· sympathetic trunk passes beneath ligament
Nerves
· from lumbar plexus
· in front
· genitofemoral
· lateral border
· iliohypogastric
· ilioinguinal
· LCFN
· femoral
· medial border
· obturator
· lumbosacral trunk
Vessels
· lumbar arteries and sympathetic nerves pass beneath fibrous arches
Insertion
· lesser trochanter
Nerve supply
· L1,2,3 (segmentally)
· present in 2/3 of people
Origin
· T12 and L1
Path
· lies on psoas major
Insertion
· arcuate line
Origin
· TP of L5
· iliolumbar ligament
· adjoining iliac crest
Path
· lies edge to edge with
· psoas medially
· transversus abdominus laterally
· covered by lumbar fascia
· lateral arcuate ligament
· thickening in fascia from TP of L1 to 12th rib
· gives rise to diaphragm
· subcostal NV bundle passes under ligament
Insertion
· TPs of L1-L4
· medial half of 12th rib
Nerve supply
· T12-L3
Origin
· hollow of iliac fossa up to inner lip of iliac crest
· SI jt and anterior SI ligament
Insertion
· lesser trochanter
Nerve supply
· femoral nerve
· covers iliacus
· attached to
· iliac crest
· inguinal ligament
· forms floor to abdominal cavity
· prolonged into femoral sheath
· 3 layers
· anterior
· middle
· posterior
· enclose 2 muscles
· quadratus lumborum
· erector spinae
Anterior
· superior
· 12th rib
· inferior
· front of iliolumbar ligament and iliac crest
· medial
· front of each lumbar TP close to root
· lateral
· blends with middle layer along lateral border of QL
Middle
· superior and inferior
· identical
· medial
· tips of lumbar TPs
· lateral
· blends with anterior and posterior layer
Posterior
· covers all of erector spinae
· reinforced over lumbar region
· fused with aponeurosis of latissimus dorsi
· medial
· spinous processes of T1-S5
· lateral
· angles of all ribs
· blends with middle layer between T12 and sacrum
· transverse tubercles of sacrum and ridge on posterior iliac crest
· T12 - enters abdomen between crura of diaphragm
· L1-L3 - descends on left of bodies
· L4 - bifurcates into common iliac arteries
· L5-sacrum - median sacral artery continues as vestige of aorta
Subcostal artery (T12)
· leaves thoracic aorta above T12
· passes beneath lateral arcuate ligament
· passes in front of QL
· enters plane between TA and IO
Lumbar arteries (L1-4)
· 4 on each side
· one for L1 to L4
· one for L5 represented by iliolumbar artery
· leave abdominal aorta opposite L1-L4
· pass beneath sympathetic trunk and fibrous arches of psoas
· overlaid by IVC on right
· give off posterior and spinal branches
· pass through psoas
· pass behind QL (4th passes in front of QL)
· enter plane between TA and IO
Iliolumbar artery (L5)
· branch of internal iliac artery (posterior division)
· ascends from pelvis in front of lumbosacral trunk
· passes laterally between obturator nerve and psoas
· lumbar branch
· gives posterior and spinal branches (to L5)
· iliac branch
· supplies iliacus
· ends in anastomosis at ASIS
Common iliac artery
· commences to left of midline on body of L4
· thus right is longer than left
· bifurcates in front of SI jt
· into internal and external iliac arteries
· crossed by ureter at bifurcation
Internal iliac artery
· divides into large posterior and small anterior divisions
· branches of posterior division
· iliolumbar
· lateral sacral
· superior gluteal
· branches of anterior division
· obturator
· internal pudendal
· inferior gluteal
· (superior vesical, inferior vesical, middle rectal)
External iliac artery
· runs along pelvic brim on psoas
· gives off 2 branches
· inferior epigastric
· deep circumflex iliac
· passes beneath inguinal ligament
· L5 - commences at confluence of common iliac veins
· L4-L1 - ascends on right of aorta
· T12-T9 - lies on right crus of diaphragm behind liver
· T8 - pierces central tendon of diaphragm
Common iliac veins
· confluence of internal and external iliac veins
· unite on front of L5
· behind right common iliac artery
· receives
· iliolumbar vein
· lateral sacral vein
· median sacral vein (left)
External iliac veins
· enters abdomen on medial side of artery
· runs on pelvic brim behind artery
Internal iliac veins
· see below
Lumbar veins
· 1st and 2nd lumbar veins join azygos system
· 3rd and 4th lumbar veins drain into IVC
· left ones pass behind aorta
· all pass behind sympathetic trunks
· 5th lumbar vein joins iliolumbar vein
· emerge from IV foramina
· enter psoas
· segmentally supply posterior abdominal wall
· psoas and QL
· T12 and L1
· supply anterior abdominal wall
· L2, 3 and 4 (part)
· give anterior and posterior divisions
· reunite to form lumbar plexus
· L4 (part) and L5
· pass as lumbosacral trunk to sacral plexus
Sympathetic trunk
· brings preganglionic fibres from lower thoracic trunk
· enters abdomen by passeing behind medial arcuate ligament
· lies on vertebral bodies
· just touches medial margin of psoas
· relationship to vessels
· left lies along left margin of aorta
· right lies behind IVC
· both lie in front of segmental vessels
· both lie behind common iliac vessels
Lumbar ganglia
· usually 4
· may fuse
· receive input from L1 and L2
· via white rami communicantes
· L1-L5 nerves receive output
· via grey rami communicantes
· formed in psoas
· from anterior rami of L1-L4
· L1 - iliohypogastric and ilioinguinal
· L1,2 - genitofemoral
· L2,3 (posterior) - LFCN
· L2,3,4 (anterior) - obturator
· L2,3,4 (posterior) - femoral
· included for completeness
· passes behind lateral arcuate ligament
· supplies skin of anterior buttock
· L1 divides into anterior and posterior rami
· anterior ramus then divides into primary nerve and collateral
· primary nerve called iliohypogastric
· collateral called ilioinguinal
· emerge from lateral border of psoas
· behind anterior layer of lumbar fascia
· pierce transversus abdominus
· enter NV plane between IO and TA
Iliohypogastric nerve
· gives lateral cutaneous branch
· supplies buttock behind subcostal nerve
· pierces internal and external oblique
· supplies skin of mons pubis
Ilioinguinal nerve
· runs parallel to iliohypogastric
· pierces internal oblique
· enters inguinal ligament
· supplies genitals and medial groin
· formed by posterior divisions of anterior rami of L2 and L3
· may occasionally arise as branch of femoral nerve
· emerges from lateral border of psoas
· below iliolumbar ligament
· passes on surface of iliacus
· deep to iliac fascia
· perforates inguinal ligament (or passes below it)
· 1 cm medial to ASIS
· formed from anterior divisions of anterior rami of L2,3,4
· emerges from medial border of psoas
· passes deep to bifurcation of internal iliac artery
· runs to obturator foramen
· enters obturator canal
· divides into anterior and posterior divisions
Anterior division
· passes over obturator externus
· emerges into thigh
· supplies hip joint
· runs superficial to AB
· deep to AL
· supplies both
· supplies gracilis
· supplies medial thigh
· by branch to subsartorial plexus
Posterior division
· pierces and supplies obturator externus
· runs deep to AB
· runs on AM and supplies its pubic (adductor) part
· supplies knee joint
· formed from posterior divisions of anterior rami of L2,3,4
· emerges from lateral border of psoas
· runs in gutter between psoas and iliacus
· deep to iliac fascia
· gives branches to iliacus
· passes beneath inguinal ligament
· breaks up into branches
· separated into superficial and deep by LCFA
Superficial branches
· nerve to pectineus
· nerve to sartorius
· intermediate FCN
· medial FCN
Deep branches
· nerve to rectus femoris
· supplies hip joint
· nerve to vastus lateralis
· nerve to vastus intermedius
· nerve to vastus medialis
· supplies knee joint
· saphenous nerve
· formed from branches of L1 and L2
· emerges from anterior surface of psoas
· deep to psoas fascia
· divides into genital and femoral branches
Femoral branch
· L1 fibres
· passes in front of femoral artery
· pierces femoral sheath and fascia lata
supplies skin of groin
· formed on front of piriformis muscle
· from lumbosacral trunk and S1-S4
· constituent nerves give off 6 branches
· then divide into anterior and posterior divisions
· each division gives off 3 branches
From behind
· nerve to piriformis
· perforating cutaneous nerve
· posterior femoral cutaneous nerve
From in front
· pelvic splanchnic nerves
· pudendal nerve
· perineal branch of S4
Anterior
· nerve to quadratus femoris (L4,5,S1)
· nerve to obturator internus (L5,S1,2)
· tibial component of sciatic nerve (L4,5,S1,2,3)
Posterior
· superior gluteal nerve (L4,5,S1)
· inferior gluteal nerve (L5,S1,2)
· common peroneal component of sciatic nerve (L4,5,S1,2)
· formed at lower edge of piriformis
· by union of tibial and common peroneal components
· emerges in buttock lying on ischium
· midway between ischial tuberosity and greater trochanter
· nerve relations
· PCFN superficial to it
· nerve to QF deep to it
· passes down in hamstring compartment
· overlaid by long head of biceps
· lies on
· obturator internus and gamelli
· quadratus femoris
· adductor magnus
· divides at upper end of popliteal fossa
Branches in thigh
Tibial division
· motor to hamstrings
· semimembranosus
· semitendinosus
· long head of biceps
· ischial head of adductor magnus
Common peroneal division
· short head of biceps
Divisions
Tibial nerve
· branches
· upper and lower medial and middle genicular nerves
· sural nerve
· nerve to plantaris
· nerves to gastrocnemius
· nerve to soleus
· nerve to popliteus
Common peroneal nerve
· branches
· upper and lower lateral genicular nerves
· recurrent genicular
· peroneal communicating nerve
· lateral cutaneous nerve of calf
· divisions
· superficial peroneal nerve
· deep peroneal nerve