Lumbosacral plexus

it's Origin, Motor and Sensory innervation.

1. Abdul Mohsin Presented To Sir Idrees Semester II KIHST Lumbosacral plexus

2. Lumbar Spinal nerves  Lumbar plexus Sacral spinal nerves  Sacral plexus Together form the Lumbosacral plexus Lumbar plexus is the upper portion. Sacral plexus is the lower portion. Lumbosacral Plexus 3

3. Lumbar plexus Larger part of  lumbosacral plexus It is formed by first four lumbar nerves (L1-L4)and  subcostal nerve (T12) V entral rami of the L4 pass communicating with L5 to form  lumbosacral trunk . lumbar plexus pass in front of the hip joint. It provides motor and sensory contributions to the anterior and medial compartment of leg as well as abdominal wall and the pelvis areas . 4

4. Runs posterior to the P soas major   lateral border. Anterior to Quadratus Lumborum . it pierces the  T ransversus abdominis  to run above the  iliac crest. It gives motor branches to these muscles.(discuss above ) S ensory branch to the skin of the lateral hip . anterior cutaneous branch  H ypogastric region iliohypogastric Nerve (T12,L1 ) 5

5. Ilioinguinal nerve L1 Follows a course slightly inferior to iliohypogastric nerve , With it may Anastomose , and is distributed to the skin of the upper medial part of the thigh and the root of the penis and scrotum ( mons pubis and labia majora ) 6

6. Genitofemoral nerve (L1,L2) Emerges from the anterior surfaces of the psoas muscles , runs obliquely downward on the surface of this muscle and divides into the external spermatic nerve , which supplies the cresmastric muscle and the skin of the scrotum or labia and the lumboinguinal nerve, which supplies the skin of the middle upper part of the thigh. 7

7. Lateral femoral cutaneous nerve (L2,L3) Passes obliquely across the iliacus muscle and under Inguinal ligament to divide into several rami distributed to the skin of the anterolateral side of the thigh. 8

8. Femoral Nerve (L2-L4) Largest branch of the lumbar plexus. Arise from the posterior division of the plexus which derived from L2,L3,L4. Emerges from the lateral border of the psoas muscle just above the inguinal ligament where it divides into terminal branches. Motor branch above the inguinal ligament supply the iliopsoas . Motor branches in the thigh supply the Sartorius, pectineus and quadriceps femoris muscles. Sensory branches include anterior femoral cutaneous branches to the anterior and medial surface of the thigh and the saphenous nerve to the medial side if the leg and foot. 9

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10. Obturator Nerve (L2-L4) Arise from the anterior division of L2,L3,L4. Emerges from the medial border of the psoas muscle near the brim of the pelvis. passes on the lateral side of the Hypogastric vessels and Ureter and descends through the obturator canal in the upper part of the obturator foramen to the medial side of the thigh. 11

11. In the canal the obturator nerve splits into anterior and posterior branch . Motor rami from the posterior branch supply the obturator externus and adductor magnus muscles. Motor rami from the anterior branch supply the adductor longus , adductor brevis and gracilis muscles. Sensory rami from the anterior branch of the nerve supply the hip joint and a small area of skin on the medial internal part of the thigh . 12

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13. Sacral plexus Roots Anterior rami of L4-L5 and S1-S4. Each of the 5 roots splits inti an anterior and posterior divisions The upper 4 posterior divisions (L4,L5 and S1,S2) join to form the common peroneal nerve. All 5 of the anterior divisions (L4,L5 and S1,S2,S3) join to form the Tibial nerve. The peroneal and tibial nerves are fused as the sciatic nerve. 14

14. Pudendal nerve (S2-S4) Roots anterior division of S2,S3 and S4 . Main nerve of perineum. Carry sensation from external genitalia ( both sex ) as well give motor innervation to various pelvic floor muscles. 15

15. Sciatic Nerve Sciatic nerve is the largest nerve in the body . It consists of 2 separate nerves in one sheath ; Common peroneal Tibial Nerve The common peroneal nerve is formed by the upper 4 posterior divisions of the sacral plexus. The Tibial nerve is formed from all 5 anterior divisions of the sacral plexus. 16

16. The N erve leaves the pelvis through the greater Sciatic foramen and terminates in the thigh by dividing into the T ibial and Common peroneal nerves . Branches in the thigh supply the Hamstring muscles ; Rami from the Tibial trunk pass to the Semitendinosus and S emimembranous muscles , the long head of the biceps , and the adductor magnus muscles ; and a Ramus from the Common peroneal trunk supplies the short head of the biceps. 17

17. Common peroneal nerve ( L 4,L5and S 1,S2) Formed by the fusion of the upper 4 posterior divisions of the sacral plexus ( L4-S2 ) upper part of the popliteal space , where the common peroneal nerve begins its independent course . Sensory branches  Superior and inferior articular branches to the knee joint and the lateral sural cutaneous nerve , which joins the medial sural Cutaneous nerve (from the Tibial nerve ) to form the sural nerve Supplying the skin of the lower dorsal aspect of the leg . The lateral malleolus and lateral side of the foot and fifth (5) toe . 18

18. Further divide into superficial and deep peroneal nerves. A ccompanies with the anterior T ibial recurrent artery supplying the Tibiofibular and knee joint a small branch to tibialis anterior muscle . The superficial peroneal nerve descends along the intermuscular septum to supply muscular branches to the lateral of the leg , and terminal cutaneous branches to the Dorsum of the foot , part of Big toe, and 2 nd and 5 th toes up to the 2 nd phalanges. 19

19. The Deep peroneal (anterior T ibial ) nerve descends in the anterior compartment of the leg. Muscular branches extend to the T ibialis anterior, Extensor digitorum longus , Extensor hallucis longus and Peroneus tertius muscles. Articular filaments supply the inferior tibiofibular and ankle joint. Terminal branches extend to the skin of the adjacent sides of the first 2 toes and the Extensor digitorum brevis muscles and Adjacent joints. 20

20. Tibial Nerve (L4,L5 and S1,S2,S3 ) Roots ; Anterior divisions of L4,L5 and S1-S3. The Tibial nerve is the largest component of the Sciatic nerve in the thigh. It courses to the dorsomedial aspect of ankle, from which point its terminal branches, the Medial and Lateral planter nerves, continue into the foot. 21

21. Motor branches extend to the Gastrocnemius, plantaris , soleus, popliteus, Tibialis posterior, flexor digitorum longus pedis , and flexor halluces longus muscles. Sensory branches The medial sural cutaneous nerve , joins the lateral sural nerve to form the sural nerve , which is the skin of the dorsolateral part of the leg and the lateral side of the foot . 22

22. There are 2 terminal branches. M edial planter nerve M otor branches to the flexor digitorum brevis, adductor halluces, flexor halluces brevis, and 1 st Lumbrical muscles . S ensory branches to the medial side of the sole, the planter surface of the medial 3 and half toes . 23

23. lateral plantar nerve M otor branches to all the small muscles of the sole except those innervated by the medial plantar nerve . Sensory branches to the lateral 1 st and half Toes . 24