2Nerve plexusesNetworks of successive ventral rami that exchange fibers (crisscross & redistribute)Why would this be protective?Mainly innervate the limbsThoracic ventral rami do not form nerve plexuses
4Lumbar plexus L1-L4 Lies within the psoas major muscle Innervates anterior and medial muscles of thigh through femoral and obturator nerves respectivelyFemoral nerve also innervates skin on anterior thigh (including quads) and medial leg
5Diaphragm and posterior abdominal wall: The psoas major and minor muscles, the quadratus lumborummuscle. The lumbar plexus and its related nerves.5
6LUMBAR PLEXUSSpinal nerves branching from the lumbar region of the cord form the lumbar plexus. Branches of this plexus stimulate muscles of the back, hip and thigh. The plexus also is responsible for sensation in the skin of the thighs, the pubic area and the external genitalia in males and females.
7LUMBOSACRAL SPINAL CORD POSTERIOR VIEW The area within the rectangle shows the lower portion of the spinal cord. The branches leaving the sacral region pass through the sacral foramina forming the sacral plexus.
12Lumbar plexus (be able to label femoral, obturator and saphenous nerves)
13SACRAL PLEXUSSpinal nerves branching from the lumbar (L4 and L5) and sacral (S1, S2, S3 and S4) region of the cord form the sacral plexus. Nerves branching from this plexus innervate the limb and pelvic area. Because the lumbar and sacral plexuses are interconnected, they are sometimes referred to as the lumbosacral plexus.
14Sacral plexusL4-S4Supplies muscles and skin of posterior thigh and almost all of the legMain branch is the large sciatic nerve, which consists of:Tibial nerve – to most of hamstrings, calf and soleCommon fibular nerve – to muscles of anterior and lateral leg and skinOther branches supply pelvic girdle (gluteus muscles) and perineum (pudental nerve)
15Sacral plexus L4 – S4 Superior & inferior gluteal nerves Sciatic nerve To gluteus musclesSciatic nerveTo hamstrings & other posterior thigh & leg musclesPudendal nerveSensory from penis, clitoris, labia minora, anus29 Oct. 2012Spinal-Nerves.ppt15
16Sciatic nerve (roots): L4 L5 S1 S2 S3 Lumbosacral plexusSacral plexus:Sciatic nerve (roots):L4L5S1S2S3*Sciatic nerve is the thickest nerve of body.*It is composed of Common Peroneal andTibial nerves.*Com. Peroneal: composed of dorsal ramiTibial: composed of ventral rami*L4+L5= Lumbosacral trunk3- Lumbosacral trunk4- Sciatic nerve5- common peroneal N.6- tibial N.12- posterior femoral cutaneous nerve13- pudendal nerve14- superior gluteal nerve16
17Sacral plexus (L4-S4) Sciatic nerve (L4-S3) Tibial nerve Motor to muscles of pelvis and lower extremity (gluteal, posterior femoral, lower leg & foot)Sensory from posterior pelvis, posterior thigh, anterior, posterior & lateral legSciatic nerve (L4-S3)Tibial nerveCommon peroneal (fibular) nerve
19SCIATIC NERVEThe sciatic nerve (astrerisk) is formed from spinal nerves arising from the lumbar (L4 and L5) and sacral (S1, S2 and S3) regions of the spinal cord. It passes into the thigh and lower leg supplying innervation of sensation and movement for the entire lower limb. When giving a gluteal intramuscular injection, it is important to inject into the gluteus medius muscle to avoid damage to this large nerve.
20Sacral Plexus Sciatic Superior gluteal nerve Motor: Branches into: HamstringBranches into:Tibial nerveCutaneousPosterior leg and sole of footMotorPosterior leg, footCommon fibular (peroneal) nerveAnterior and lateral leg, dorsum footLateral compartment, tibialis anterior, toe extensorsSuperior gluteal nerveGluteus medius and minimus, tensor fasciae latae
23The only one of the three that travel below the knee is the sciatic nerve. The sciatic nerve branches into two nerve:1. tibial nerve2. common peroneal nervea. Superficial peroneal nerveb. Deep peroneal nerve
24Anterior compartment- Extensors of the kneeFemoral NervelateralmedialfemurMedial compartment-Adductors of the kneeObturator NervePosterior compartment-Flexors of the kneeSciatic Nerve
25Motor Branches of the Femoral Nerve L2 L3 L4 Rectus femoris iliopsoas pectineussartoriusVastus lateralisVastus medialisVastus intermedius
26Motor Branches of the Obturator Nerve Adductor brevis Adductor longus gracilisAdductus magnus
27Motor Branches of the Sciatic Nerve Hamstrings Common peroneal nerve SemitendinosisBiceps femorissemimembranosusHamstringsCommon peroneal nerveTibial nerveDeep peroneal nerveSuperficial peroneal nerveAnterior compartment of legGastrocnemius and posterior compartment of the leg and footLateral compartment of leg
28Sacral plexus nerves:(Be able to label sciatic, tibial and common fibular nerves)
30Dermatomes (innervation of skin) (area of skin innervated by the cutaneous branches from a single spinal nerve is called a dermatome)Reveal sites ofdamage to spinalnerves or spinal cordDermatomes (innervation of skin)