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Anatomy of lumbosacral plexus (by Murtaza Syed)
This document provides an overview of the anatomy of the lumbosacral plexus, which is formed from the combination of the lumbar and sacral plexuses. It describes the roots, branches, divisions, and terminal branches that form the various nerves. These include the femoral, obturator, superior gluteal, inferior gluteal, and sciatic nerves. It also outlines the motor and sensory distributions of the nerves of the lumbosacral plexus to the lower limbs and related structures.
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Introduces the topic by outlining spinal cord anatomy and components of the lumbar and sacral plexuses.
Details the lumbar and sacral enlargements, conus medullaris, and cauda equina in the spinal cord.
Describes the lumbosacral plexus, its combined structure of lumbar and sacral plexus, and key components.
Explains root, branches, divisions, and terminal branches (R-B-D-T) of lumbar plexus with a focus on major nerves.
Details the formation and function of the femoral nerve and its sensory branches like the saphenous nerve.
Explains formation of the sacral plexus and its terminal branches, including gluteal and sciatic nerves.
Describes the pathway of the sciatic nerve and its division into common peroneal and tibial nerves.
Provides mnemonics for identifying the key terminal branches of the sacral plexus for better understanding.
Explains the cutaneous branches from nerves supplying sensory innervation to the posterior and lateral aspects of the legs.
Lists various nerves, their origins, and the muscles or areas they supply, providing a comprehensive overview of innervations.
Concludes the discussion with acknowledgment of key references and thanks for the audience's patience.
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Similar to Anatomy of lumbosacral plexus (by Murtaza Syed)
Anatomy of lumbosacral plexus (by Murtaza Syed)
- 1. AANNAATTOOMMYY OOFF LLUUMMBBOO--SSAACCRRAALLPPLLEEXXUUSS By: Syed Irshad Murtaza Technologist. Neurophysiology Dept. AKUH Karachi. 12-08-2014 L.S Plexus by IM
- 2. OOuuttlliinnee • Spinalcord. • Lumbar plexus anatomy • Sacral plexus anatomy • Components of lumbosacral plexus • Key for the L.S Plexus • Key to draw L.S Plexus. • Terminal Branches of L.S plexus. • Motor and Sensory Distribution. • Questions. • References L.S Plexus by IM
- 3. SSppiinnaall ccoorrdd •Lumbar and sacral enlargement. .. The sites where the nerves serving the lower limbs, emerge. • Conus Medullaris: • The terminal portion of the spinal cord • Cauda equina: • The collection of nerve roots at eh inferior end of the vertebral canal. • Spinal cord ends at the level of L2 vertebrae (adults). • Spinal nerves 31 pairs L.S Plexus by IM
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- 6. LLuummbboossaaccrraall pplleexxuuss Lumbosacralplexus is basically combination of two plexus, Lumbar Plexus & Sacral Plexus. 1.LUMBAR PLEXUS: The lumbar plexus is formed by the ventral rami of first four lumber nerve roots (L1, L2, L3 (major) & part of L4). In 50% of cases it receives a contribution from the ventral rami of last thoracic root (T12). It lies within the substance of the posterior part of psoas major muscle, anterior to the transverse processes of the lumbar vertebrae. The branches emerge to both lateral and medial sided of psoas major muscles. L.S Plexus by IM
- 7. • "iliopsoas" arereferred to as the "dorsal hip muscles“ or "inner hip muscles. L.S Plexus by IM
- 8. Components ooff lluummbboossaaccrraallpplleexxuuss • Components of the lumbosacral plexus are as, • 1. Lumbar plexus L1, L2, L3, L4 • 2. Lumbosacral Trunk L4, L5 • The above roots contribute in lumbar and sacral plexus both. • 3. Sacral Plexus S1, S2, S3, S4 • Smaller branches of the lumber plexus innervate the posterior abdominal wall and psoas muscles (psoas major, iliacus). • Main branches innervate the anterior thigh and their relative muscles. • Key to remember. • Root →Branches→Divisions→Terminal Branches • (RBDT) L.S Plexus by IM
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- 12. RRBBDDTT • Root:these are constituted by the anterior primary rami of L1, L2, L3, L4 (T12). • Branches: L1 root gives an upper and lower branch • L2 Root gives and upper and lower branch • L3 does not give any branch • L4 gives an upper and lower branch • Division: Lower branch of L2, upper branch of L4 and ventral rami of L3 nerve roots divide into small anterior and large posterior division. • From L2 and L3 each gives two and L4 one posterior divisions, with single anterior division from all branches (L2, L3, L4). • Lower branch of L4 and L5 unite to form lumbosacral trunk L.S Plexus by IM
- 13. Terminal BBrraanncchheess ooffLLuummbbaarr PPlleexxuuss • L1 unites with a small branch from T12 and splits into an upper and lower branches. • The upper larger branch divides into two: • iliohypogastric (T12, L1) and ilioinguinal nerves (L1). • The lower smaller branch of L1 unites with a branch from L2 to form the genitofemoral nerve. • The remainders of L2, L3 and L4 divide into ventral and dorsal branches. Ventral (Anterior) divisions of L2, L3, L4 unite to form obturator nerve. • The dorsal (posterior) divisions of L2 and L3 divide into small and larger parts. Smaller parts of dorsal divisions of L2 and L3 unite to form the lateral femoral cutaneous nerve. • Larger parts of dorsal divisions of L2 and L3 unite with L4 to form femoral nerve. L.S Plexus by IM
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- 15. FFEEMMOORRAALL NNEERRVVEE •It is formed by the dorsal or posterior division of the anterior rami of L2,L3, & L4 roots. • The femoral nerve is the largest branch of the lumbar plexus. It mainly supplies the extensors muscles of the knee (quadriceps) (VL, VI, VM, RF). • The Saphenous Nerve is a purely sensory nerve which the largest and longest cutaneous branch of the femoral nerve. • Lateral femoral cutaneous nerve of the thigh The lateral femoral cutaneous nerve of the thigh emerges from the lateral border of psoas major which is formed by the posterior divisions of L2 and L3. . It gives cutaneous supply to the lateral part of the L.S Plexus by IM
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- 17. • KEY: •Roots • ↓ • Branches • ↓ • Divisions • ↓ • Terminal branches. • R-B-D-T • IIGOLF L.S Plexus by IM
- 18. Sensory Distribution ofthe Lower Limb L.S Plexus by. IM. 12-08-2014 18
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- 20. Lumbosacral Trunk &sacral plexus. • The sacral plexus is formed by the lumbosacral trunk (L4 ,L5 ), & ventral rami of S1, S2, S3, S4 . • Contribution of the fourth sacral ventral rami is partial & the remainder of the last (S5 ) joins the coccygeal plexus. • Key to remember sacral plexus: • Root Divisions Terminal Branches (R.D.T/B) • Roots: These are constituted by the anterior primary rami of L4 , L5, S1, S2, S3, & S4 • Divisions: The lower branch of L4 ventral rami & ventral rami of L5 , S1 & S2 give anterior and posterior divisions. While S3 forms & shares only anterior division . • Terminal Branches: These anterior and posterior divisions unite to form the terminal nerve branches. L.S Plexus by IM
- 21. TTeerrmmiinnaall BBrraanncchheess •The posterior division of L4 ,L5 & S1 joins to form Superior Gluteal Nerve . • The posterior divisions of L5,S1 & S2 unites to form the Inferior Gluteal Nerve. • The posterior divisions of L4 ,L5 ,S1 & S2 joins to form Common fibular or Peroneal Nerve. It’s the about one-half the size of the tibial nerve. • The anterior divisions of L4 ,L5 ,S1,S2 & S3 unites to form Poterior Tibial Nerve. • The anterior divisions of S2,S3& S4 unites to form Pudendal Nerve. • So both these nerves i.e. Tibial and peroneal run in a single covering of sheath and called as Sciatic Nerve (L4 ,L5,S1,S2 &S3) . Which is the largest nerve of the body. • L.S Plexus by IM
- 22. SScciiaattiicc NNeerrvvee •Sciatic Nerve descends along the back of the thigh and through the middle of the popliteal fossa, to the lower part of the Popliteus muscle. It divides just 5cm above the politial fossa into Common Peroneal & Tibial nerves to supply their relative muscles. L.S Plexus by IM
- 23. KKeeyy ttoo DDrraawwssaaccrraall PPlleexxuuss 111221 Anterior 2332 Posterior • SIPPP • S. Superior Glutal Nerve (L4, L4, S1) Posterior • I. Inferior Glutal Nerve (L5, S1, S2) Posterior • P. Peroneal (common fibular) Nerve (L4,L5,S1,S2) Posterior • P. Posterior Tibial Nerve (L4,L5,S1,S2,S3 )Anterior • P. Pudendal Nerve. (S2, S3, S4) Anterior
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- 26. Sensory DDiissttrriibbuuttiioonn ttootthhee LLeeggss:: • Superficial Peroneal: it’s the cutaneous branch from the common peroneal nerve which supplies to the anterio-lateral aspect of leg upto dorsum of the foot. • Sural nerve formed by the junction of the medial sural cutaneous (it is the sensory branch of tibial nerve) with the peroneal anastomotic branch (its branch of lateral sural cutaneous nerve), passes downward near the lateral margin of the tendo-calcaneous, lying close to the small saphenous vein, to the interval between the lateral malleolus and the calcaneous. • It supplies to the posterio-lateral aspect of the leg upto lateral malleolus. L.S Plexus by IM
- 27. Nerve Name OriginSupplies Iliohypogastric T12,L1 Motor supply to internal oblique, transverses muscles, sensation over lower anterior abdominal wall Ilioinguinal L1 Sensation over anterior pubis (mons) and anterior scrotum or labia Genitofemoral L1, L2 Genital branch: motor supply to cremastor muscle, sensation to anterior scrotum; femoral branch: sensation to anterior thigh Femoral L2, L3, L4 Motor supply to extensors of the knee, sensation to anterior thigh Obturator L2, L3, L4 Motor supply to adductors of the thigh, sensation to medial thigh Lumbosacral trunk L4, L5 Joins the sacral nerves to form the lumbosacral plexus that supplies motor and sensory innervations to the lower extremities Posterior femoral cutaneous S2, S3 Sensation to perineum, posterior scrotum, and posterior thigh Pudendal S2, S3, S4 Motor to levator ani, muscles of the urogenital diaphragm, anal and striated urethral sphincter, sensation to the perineum, scrotum, and penis L.S Plexus by IM
- 28. Nerve Name OriginSupplies Nerve to quadratus femoris 12/08/2014 L4,L5,S1 quadratus femoris, inferior gemellus Superior gluteal L4,L5,S1 gluteus medius & minimus, tensor fasciae latae Inferior gluatel L5,S1,S2 Gluteus maximus Nerve to obturator internus L5,S1,S2 obturator internus, superior gemellus sciatic sacral plexus (ventral primary rami of L4-L5, S1- S3) (via its tibial & common peroneal branches) semitendinosus, semimembranosus, biceps femoris, part of adductor magnus, muscles of leg & foot skin of leg & foot (excluding medial side of leg & foot) L.S Plexus by IM
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- 32. RReeffeerreenncceess • Electromyographyand neuromuscular disorders • By David C. Preston • Snell's Clinical Anatomy 9th Edi • By Richard S. Snell • Electrodiagnosis in Diseases of Nerve and Muscle: Principles and Practice • By Jun Kimura • http://en.wikipedia.org/wiki/Sural_nerve • http://en.wikipedia.org/wiki/Quadriceps_femoris_muscle TThhaannkkss ffoorr tthhee ppaattiieennccee L.S Plexus by IM