Lumbar and lumbosacral plexus

• Epineurium

  A tough fibrous sheath that encloses all the fascicles to form the nerve

  
• Perineurium

  A coarse connective tissue wrapping that binds groups of axons into bundles called fascicles
• Endoneurium

  A delicate layer of loose connective tissue that also encloses the fibers associated schwann cells
• Nerve Axons

  • Constitute only a small fraction of the nerves bulk. Balance consist of myelin, protective tissue wrappings, blood vessels, and lymphatic vessels

  
• Motor unit

  A motoneuron and all of its associated muscle fibers. Their activity represents the final output of the CNS
• Vascular supply to the peripheral nerve

  • Exogenous (located on loose connective tissues around nerves and epineurium, composed of small arteries and veins from neighbouring tissue space and muscular blood vessels)
  • Endogenous
• Major nerves formed by the lumbar plexus

  • 2 nerves arise from 1 root (L1): iliohypogastric and ilioinguinal
  • 2 nerves arise from 2 roots: genitofemoral from anterior division of L1 and L2; lateral femoral cutaneous from posterior divisions of L2 and L3
  • 2 nerves arise from 3 roots: femoral from posterior divisions of L2, L3 and L4; obturator nerve from anterior divisions of L2, L3, and L4
  • Femoral nerve gives rise to the saphenous nerve

  
• Pneumonic = I (TWICE) Got Lost On Freeways
• Cutaneous

  Supplying the skin
• Femoral nerve

  1. Course = down front of thigh

  2. Originates from L2 – L4

  3. Passes through Psoas major; traverses laterally then runs sandwiched between iliacus and psoas major (iliacus below, psoas above (supplies both muscles)

  4. Enters the thigh through the femoral triangle (lateral to crotch both sides – made up of inguinal ligament, sartorius, and adductor longus) inferior to the inguinal ligament (groin) (sartorius, adductor longus and inguinal ligament)

  5. Lies lateral to the femoral artery (vein, artery nerve moving from medial to lateral)

  6. Divides into an anterior and a posterior division

  
• Anterior division of femoral nerve

  • Four terminal branches – Motor to pectineus and sartorius
  • Sensory – medial cutaneous nerve of the thigh and intermediate cutaneous nerve

  
• Posterior division of femoral nerve

  • One sensory and four motor branches
  • The sensory branch becomes the saphenous
  • Motor branches supply rectus femoris, vastus medialis, lateralis and intermedius

  
• Saphenous nerve


  1. Originates from L2 to L4 nerve roots in the lumbar plexus

  2. Enters the femoral triangle, a hollow, wedge-shaped area between the upper thigh and groin

  3. Runs down the front of the thigh between the psoas major and hip flexor muscles

  4. Travels alongside the femoral artery

  5. Splits into two nerves, anterior and posterior division, beneath the inguinal ligament

  6. The posterior division becomes the saphenous nerve at the adductor canal

  7. Provides sensations to the knee, lower leg, ankle and foot

  
• Femoral triangle

  • Males (more likely) get hernias at the inguinal ligament
  • Femoral artery nerve and vein are in the femoral triangle
  • Acronym for contents of femoral triangle = NAVEL: nerve, artery, vein, empty space, lymph nodes
  • If lymph nodes are inflamed, there will be a little lump over the inguinal ligament
  • Empty space allows veins and lymph vessels to distend to accommodate different levels of flow

  
• Adductor canal

  Musculofascial canal situated in medial side of thigh. Commences at inferior angle of femoral triangle at intersection of adductor longus and sartorius. Canal is triangular in cross-section and contains anterior, posterior, and medial walls

  
• Saphenous nerve

  1. Travels all the way down the medial leg

  2. A branch of the posterior division of the femoral nerve

  3. The sensory branch becomes the saphenous nerve when it passes through the adductor canal

  4. Travels along the medial aspect of the tibia for about half its length

  5. At that point it divides into two branches- one more posterior (ends at ankle), second more anterior – which continues along the medial aspect of the foot to terminate at the hallux

  
• Common peroneal nerve

  • Common = further down its going to split into 2
  • A continuation of the sciatica nerve
  • Lateral branch of the sciatic nerve (L4 to S2)
  • Passes along the upper lateral side of the popliteal fossa to the posterior part of the head of the fibula
  • Passes around the neck of the fibula where it divides into the superficial and deep peroneal nerves
  • Broken fibula causes damage to peroneal nerve
  • Supplies the knee joint and the superior tibiofibular joints
  • Lateral cutaneous nerve supplies the posterolateral side of the 2/3rds of the leg

  
• Deep peroneal nerve

  • A continuation of the common peroneal nerve
  • Comes more medial
  • Arises from the common peroneal nerve
  • Given off from around the neck of the fibula
  • Passes inferomedially onto the anterior surface of the IO membrane
  • At the ankle joint it lies deep to the extensor retinaculum and tendon of EHL
  • Crosses the dorsum of the foot and divides into medial and lateral branches, the medial passes to the cleft between the great and 2nd toe and supplies the skin on the adjacent sides as far as the DIP joint
  • The lateral supplies EDB and the small joints of the foot
  • Supplies EDL, EHL, Peroneus T, Tibialis A
  • Supplies the inferior tibiofibular joint and the ankle joint

  
• Femoral nerve

  1. Passes through Psoas major; traverses laterally then runs sandwiched between iliacus and psoas major (iliacus below, psoas above (supplies both muscles)

  2. Enters the thigh through the femoral triangle inferior to the inguinal ligament (sartorius, adductor longus and inguinal ligament)

  3. It lies lateral to the femoral artery (vein, artery nerve moving from medial to lateral)

  4. Divides into an anterior and a posterior division

  5. Anterior division – four terminal branches – Motor to pectineus and sartorius

  6. Sensory – medial cutaneous nerve of the thigh and intermediate cutaneous nerve

  7. Posterior division – one sensory and four motor branches

  8. The sensory branch becomes the saphenous

  9. Motor branches supply rectus femoris, vastus medialis, lateralis and intermedius

  
• Lateral plantar nerve

  • Continuation of tibial nerve
  • Similar to the ulnar nerve in the hand
  • Given off from the tibial nerve
  • Passes anterolaterally towards the base of the 5th MT and divides into superficial and deep branches
  • Supplies all the interossei, FDMB, Abductor DM, Adductor H, lateral 3 lumbricals
  • Supplies the tarsal and tarsometatarsal joints
  • Supplies the lateral side of the sole and 5th toe, 4th and 5th toes and nailbeds and the dorsum of the distal phalanx

  
• Medial plantar nerve

  • Continuation of tibial nerve
  • Given off from the tibial nerve
  • Similar to the medial nerve in the hand
  • Passes deep to abductor halluces
  • At the base of the MT the nerve passes transversely across the foot giving cutaneous branches to the medial and plantar side of the sole, the great toe and the sides of the 2nd/3rd/4th toes including the dorsal surface of the distal phalanx and nail beds
  • Supplies Abductor Hallucis, FDB, FHB and the 1ST Lumbrical
  • Supplies the tarsal and tarsometatarsal joints

  
• Saphenous nerve

  1. A branch of the posterior division of the femoral nerve

  2. The sensory branch becomes the saphenous nerve when it passes through the adductor canal (begins where the medial border of the sartorius muscle crosses the medial border of the adductor longus muscle)

  3. Travels along the medial aspect of the tibia for about half its length

  4. At that point it divides into two branches- one more posterior (ends at ankle), second more anterior – which continues along the medial aspect of the foot to terminate at the hallux

  
• Sciatic nerve

  • Formed by the posterior divisions of L4 to S3
  • Leaves the pelvis through the greater sciatic foramen passing deep to biceps femoris
  • ~ 2/3rds of the way down the back of the thigh it divides into its terminal branches the common peroneal and tibial nerves (surface marked by a line drawn from the midpoint between the ischial tuberosity and the greater trochanter)
  • Supplies the knee joint, semitendinosus, semimembranosus, biceps femoris and adductor magnus

  
• Sciatic nerve branches

  • Tibial Nerve (as continuation of Sciatic Nerve)
  • Sural Nerve (as a branch of Tibial Nerve)
  • Medial Plantar Nerve (as continuation of Tibial Nerve)
  • Lateral Plantar Nerve (as continuation of Tibial Nerve)
  • Common Peroneal Nerve (as continuation of Sciatica Nerve)
  • Superficial Peroneal Nerve (as continuation of the Common Peroneal Nerve)
  • Deep Peroneal Nerve (as continuation of the Common Peroneal Nerve)

  
• Superficial peroneal nerve

  • A continuation of the common peroneal nerve
  • Arises from the common peroneal nerve
  • Given off from around the neck of the fibula
  • Descends vertically between EDL and PL to the fibula
  • ~half way down the leg it divides into its terminal branches the medial and intermediate dorsal cutaneous nerves passing over the anterolateral aspect ankle joint and into the foot
  • Supplies PL and PB
  • Supplies the anterolateral aspect of the leg and around the lateral malleolus
  • The medial dorsal supplies the medial and dorsal aspect of the foot and great toe/2nd and 3rd toes
  • The intermediate supplies the dorsum of the foot and the 3rd 4th 5th toes

  
• Sural nerve

  • A branch of tibial nerve
  • Given off from the tibial nerve
  • Descends between the 2 heads of gastrocnemius, passes behind the later malleolus and runs along the lateral border side of the foot
  • Supplies the posterior and lateral sides of the lower 1/3rd leg and the lateral border of the foot and 5th toe

  
• Tibial nerve

  • A continuation of the sciatic nerve
  • Medial branch of the sciatic nerve (L4 to S3)
  • Passes through the popliteal fossa, then descends inferiorly and medially to pass behind the medial malleolus deep to the flexor retinaculum
  • As it enters the plantar aspect of the foot it divides into medial and lateral plantar nerves
  • Supplies gastrocnemius, soleus, plantaris, popliteus, tibialis posterior, FDL, FHL and gives off the sural nerve
  • Supplies the knee joint, the superior tibiofibular joint and the ankle joint