Lumbar and sacral plexuses
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Lumbar and sacral plexuses
Nerve 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
Lumbar plexusL1-L4Lies within the psoas major muscleInnervates anterior and medial muscles of thigh through femoral and obturator nerves respectivelyFemoral nerve also innervates skin on anterior thigh (including quads) and medial leg
Diaphragm and posterior abdominal wall:The psoas major and minor muscles, the quadratus lumborum muscle. The lumbar plexus and its related nerves.
LUMBAR 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.
LUMBOSACRAL SPINAL CORD POSTERIOR VIEWThe 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.
29 Oct. 2012Spinal-Nerves.ppt*Lumbar plexusL1 L4 (+ L5)Ilioinguinal nervemostly sensory from skin of thigh & genitalsGenitofemoral nervemostly sensory from scrotum, labia majora, ant. ThighFemoral Nerveto quadriceps, sartorius
Lumbar plexus (T12- L4):
1- Obturator nerve (L2-L3-L4) 2- Femoral nerve (L2-L3-L4)3- Lumbosacral trunk (L4-L5)7- subcostal nerve (T12)8- iliohypogastric N. (T12-L1)9- ilioinguinal N. (L1)10- genitofamoral N. (L1-L2) 11- lateral cutaneous N. of the thigh (L2-L3)
Lumbar PlexusFemoral nerveCutaneous branchesThigh, leg, foot (e.g. saphenous nerve)Motor branchesAnterior thigh muscles (e.g. quadriceps, sartorius, iliopsoas)Obturator nerveSensorySkin medial thigh; hip, knee jointsMotorAdductor musclesLateral femoral cutaneousSensorySkin lateral thighGenitofemoral SensorySkin scrotum, labia major, anterior thighMotorCremaster muscle
Lumbar plexus(be able to label femoral, obturator and saphenous nerves)
SACRAL 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.
Sacral 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)
29 Oct. 2012Spinal-Nerves.ppt*Sacral plexusL4 S4Superior & inferior gluteal nervesTo gluteus musclesSciatic nerveTo hamstrings & other posterior thigh & leg musclesPudendal nerveSensory from penis, clitoris, labia minora, anus
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 rami Tibial: composed of ventral rami
*L4+L5= Lumbosacral trunk
3- Lumbosacral trunk4- Sciatic nerve5- common peroneal N.6- tibial N.12- posterior femoral cutaneous nerve13- pudendal nerve14- superior gluteal nerve
Sacral plexus (L4-S4) Sciatic nerve (L4-S3) Tibial nerve Common peroneal (fibular) nerveMotor to muscles of pelvis and lower extremity (gluteal, posterior femoral, lower leg & foot)Sensory from posterior pelvis, posterior thigh, anterior, posterior & lateral leg
SCIATIC 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.
Sacral PlexusSciaticMotor:Hamstring Branches into:Tibial nerveCutaneousPosterior leg and sole of footMotorPosterior leg, footCommon fibular (peroneal) nerveCutaneousAnterior and lateral leg, dorsum footMotorLateral compartment, tibialis anterior, toe extensorsSuperior gluteal nerveMotorGluteus medius and minimus, tensor fasciae latae
Sacral Plexus (continued)Inferior gluteal nerveMotorGluteus maximusPosterior femoral cutaneous nerveSensoryInferior buttocks, posterior thigh, popliteal fossaPudendal nerveSensoryExternal genitalia, anusMotorMuscles of perineum
The only one of the three that travel below the knee is the sciatic nerve.The sciatic nerve branches into two nerve: 1. tibial nerve 2. common peroneal nerve a. Superficial peroneal nerve b. Deep peroneal nerve
femurmediallateralAnterior compartment-Extensors of the kneeFemoral NerveMedial compartment-Adductors of the kneeObturator NervePosterior compartment-Flexors of the kneeSciatic Nerve
L2L3L4iliopsoasRectus femorispectineusVastus medialisVastus intermediussartoriusVastus lateralisMotor Branches of the Femoral Nerve
Adductus magnusgracilisAdductor longusAdductor brevisMotor Branches of the Obturator Nerve
L4L5S1S2S3SemitendinosisBiceps femorissemimembranosusHamstringsGastrocnemius and posterior compartment of the leg and footTibial nerveCommon peroneal nerveDeep peroneal nerveAnterior compartment of legLateral compartment of legSuperficial peroneal nerveMotor Branches of the Sciatic Nerve
Sacral plexus nerves:
(Be able to label sciatic, tibial and common fibular nerves)
Diaphragm? Phrenic nerve C3-5
Arm and forearm extensors? Radial nerveMedial hand? Ulnar nerveLateral palm? Median nerve
Quad? Femoral nerve
Footdrop? Common fibular/peroneal nerve (branch of Sciatic nerve)Cervical plexus C1-5
Brachial plexus C5-T1
Lumbar plexus L1-4
Sacral plexus L4-S4Nerve plexuses (very) simplified.
Dermatomes (innervation of skin) Dermatomes
(area of skin innervated by the cutaneous branches from a single spinal nerve is called a dermatome)
Reveal sites of damage to spinalnerves or spinal cord