\n![\"\"](\"https:\/\/meddists.com\/wp-content\/uploads\/2020\/01\/Screenshot_10-600x379.png\")
<\/a>Figure 1. <\/strong>The lumbosacral plexus<\/figcaption><\/figure>\n<\/div>\n\n\nParts and origin<\/h4>\n<\/span>\n\n\n
![\"\"](\"https:\/\/meddists.com\/wp-content\/uploads\/2020\/01\/Screenshot_10.png\")
<\/a>Parts and origin<\/h4>\n<\/span>\n\n\nAs its name suggests, the lumbosacral plexus consists of two parts \u2014 the lumbar plexus, and the sacral plexus.<\/p>\n\n\n\n
- Lumbar plexus<\/strong>: L1-L3 (with contributions from the lower part of T12, and the upper part of T4).<\/li>
- Sacral plexus<\/strong>: L4-S4<\/li><\/ul>\n\n\n<\/span>\n
Lumbar plexus<\/h4>\n<\/span>\n\n\nAs it forms, it merges with the origin of the psoas major muscle and then branches out to four parts:<\/p>\n\n\n\n
- Under the kidneys (iliohypogastric<\/strong> and ilioinguinal nerves<\/strong>)
- Both nerves rise from the L1 spinal nerve and enter between the abdominal muscles.<\/li>
- The iliohypogastric nerve passes between and innervates the transversus abdominis and internal oblique muscles, with terminal branches innervating the abdominal skin.<\/li>
- The ilioinguinal nerve passes between the abdominal muscles to blend with the spermatic cord, passing through the inguinal canal, innervating the skin of the scrotum and the medial surface of the thigh.<\/li><\/ul><\/li>
- Lateral to the psoas major muscle (lateral femoral cutaneous nerve <\/strong>and femoral nerve<\/strong>)
- The lateral femoral cutaneous nerve arises from L2-L3, runs on the surface of the quadratus lumborum muscle, passing in the lacuna musculonervosa of the subinguinal hiatus, and emerges below the inguinal ligament, innervating the skin of the lateral thigh.<\/li>
- The femoral nerve is one of the major nerves from the lumbar plexus, arising from L2-L4 it runs lateral to the iliopsoas muscle, and similarly to the lateral femoral cutaneous nerve, it passes in the lacuna musculonervosa, entering the femoral triangle of the thigh, laterally to the femoral artery.
- It innervates all of the anterior muscles of the thigh, the iliacus and pectineus muscles, the skin of the anterior thigh and knee, and the medial ankle and foot.<\/li><\/ul><\/li><\/ul><\/li>
- Piercing the psoas major muscle (genitofemoral nerve<\/strong>)
- The genitofemoral nerve arises from L1-L2 and divides into the genital and femoral branches.<\/li>
- The genital branch passes to the inguinal canal within the spermatic cord, innervating the cremaster muscle and the scrotum.<\/li>
- The femoral branch passes through the lacuna vasorum of the subinguinal hiatus, innervating a small portion of the skin of the medial upper thigh.<\/li><\/ul><\/li>
- Medial to the psoas major muscle (obturator nerve<\/strong>)
- The obturator nerve arises from L2-L4, passing on the lateral wall of the pelvis, entering through the obturator canal together with the obturator artery, to innervate the obturator externus muscle, the adductor muscles of the thigh (except adductor magnus), and the skin of the medial and upper thigh.<\/li><\/ul><\/li><\/ul>\n\n\n<\/span>\n
Sacral plexus<\/h4>\n<\/span>\n\n\nFormed by the lumbosacral trunk (L4 and L5) and the anterior rami of S1 to S4, the plexus forms in front of the piriformis muscle:<\/p>\n\n\n\n
- Sciatic nerve<\/strong>
- Arises from L4-S3 and is the largest nerve of the body.<\/li>
- It forms on the anterior surface of the piriformis muscle and leaves the pelvic cavity through the greater sciatic foramen, inferior to the piriformis.<\/li>
- As it passes through the gluteal region into the thigh, it divides into the common peroneal and tibial nerves.<\/li>
- It innervates muscles in the posterior compartment of the thigh, in the leg and foot, carrying sensory fibers from the skin of the foot and lateral leg.<\/li><\/ul><\/li>
- Pudendal nerve<\/strong>
- The pudendal nerve arises from the ventral divisions of S2-S4.<\/li>
- It enters the gluteal region by leaving the pelvic cavity through the greater sciatic foramen, inferior to the piriformis muscle.<\/li>
- It courses into the perineum by immediately passing around the sacrospinous ligament, where this joins the ischial spine, and through the lesser sciatic foramen.<\/li>
- It innervates the skin and skeletal muscles of the perineum.<\/li><\/ul><\/li>
- Superior gluteal nerve<\/strong>
- The superior gluteal nerve arises from the dorsal divisions of L4-S1, it leaves the pelvic cavity through the greater sciatic foramen, superior to the piriformis muscle, innervating the gluteus medius, gluteus minimus, and tensor of fascia lata muscles.<\/li><\/ul><\/li>
- Inferior gluteal nerve<\/strong>
- The inferior gluteal nerve arises from the dorsal divisions of L5-S2, it leaves the pelvic cavity through the greater sciatic foramen, inferior to the piriformis muscle, innervating the gluteus maximus.<\/li><\/ul><\/li>
- The\u00a0nerve to the obturator internus<\/strong>
- The nerve to obturator internus arises from the ventral divisions of L5-S2, leaving the pelvic cavity through the greater sciatic foramen, inferior to the piriformis muscle. It enters into the perineum similarly to the pudendal nerve.<\/li><\/ul><\/li>
- The\u00a0nerve to the quadratus femoris and inferior gemellus muscles<\/strong>, and the\u00a0posterior femoral cutaneous nerve<\/strong>
- Arise from\u00a0 L4-S1 (nerve to quadratus femoris and inferior gemellus muscles) and S1 and S3 (posterior femoral cutaneous nerve)<\/li>
- Leave the pelvic cavity through the greater sciatic foramen, inferior to the piriformis muscle, coursing to muscles (the muscular branch) and skin (the cutaneous branch) in the lower limb.<\/li>
- The posterior femoral cutaneous nerve innervates the skin of the posterior surface of the thigh.<\/li><\/ul><\/li>
- Other nerves include the\u00a0perforating cutaneous nerve<\/strong>, which leaves the pelvic cavity by penetrating directly through the sacrotuberous ligament, innervating the skin over the inferior aspect of the buttocks, and the\u00a0nerve to the piriformis<\/strong>\u00a0and several small nerves to the levator ani and coccygeus muscles, which do not leave the pelvic cavity.<\/li><\/ul>\n\n\n<\/span>\n
Attributes<\/h4>\n<\/span>\n\n\n- Figure 1. OpenStax,\u00a0CC BY-SA 4.0<\/a><\/li><\/ul>\n<\/span>
Lumbar plexus<\/h4>\n<\/span>\n\n\nAs it forms, it merges with the origin of the psoas major muscle and then branches out to four parts:<\/p>\n\n\n\n
- Under the kidneys (iliohypogastric<\/strong> and ilioinguinal nerves<\/strong>)
- Both nerves rise from the L1 spinal nerve and enter between the abdominal muscles.<\/li>
- The iliohypogastric nerve passes between and innervates the transversus abdominis and internal oblique muscles, with terminal branches innervating the abdominal skin.<\/li>
- The ilioinguinal nerve passes between the abdominal muscles to blend with the spermatic cord, passing through the inguinal canal, innervating the skin of the scrotum and the medial surface of the thigh.<\/li><\/ul><\/li>
- Lateral to the psoas major muscle (lateral femoral cutaneous nerve <\/strong>and femoral nerve<\/strong>)
- The lateral femoral cutaneous nerve arises from L2-L3, runs on the surface of the quadratus lumborum muscle, passing in the lacuna musculonervosa of the subinguinal hiatus, and emerges below the inguinal ligament, innervating the skin of the lateral thigh.<\/li>
- The femoral nerve is one of the major nerves from the lumbar plexus, arising from L2-L4 it runs lateral to the iliopsoas muscle, and similarly to the lateral femoral cutaneous nerve, it passes in the lacuna musculonervosa, entering the femoral triangle of the thigh, laterally to the femoral artery.
- It innervates all of the anterior muscles of the thigh, the iliacus and pectineus muscles, the skin of the anterior thigh and knee, and the medial ankle and foot.<\/li><\/ul><\/li><\/ul><\/li>
- Piercing the psoas major muscle (genitofemoral nerve<\/strong>)
- The genitofemoral nerve arises from L1-L2 and divides into the genital and femoral branches.<\/li>
- The genital branch passes to the inguinal canal within the spermatic cord, innervating the cremaster muscle and the scrotum.<\/li>
- The femoral branch passes through the lacuna vasorum of the subinguinal hiatus, innervating a small portion of the skin of the medial upper thigh.<\/li><\/ul><\/li>
- Medial to the psoas major muscle (obturator nerve<\/strong>)
- The obturator nerve arises from L2-L4, passing on the lateral wall of the pelvis, entering through the obturator canal together with the obturator artery, to innervate the obturator externus muscle, the adductor muscles of the thigh (except adductor magnus), and the skin of the medial and upper thigh.<\/li><\/ul><\/li><\/ul>\n\n\n<\/span>\n
Sacral plexus<\/h4>\n<\/span>\n\n\nFormed by the lumbosacral trunk (L4 and L5) and the anterior rami of S1 to S4, the plexus forms in front of the piriformis muscle:<\/p>\n\n\n\n
- Sciatic nerve<\/strong>
- Arises from L4-S3 and is the largest nerve of the body.<\/li>
- It forms on the anterior surface of the piriformis muscle and leaves the pelvic cavity through the greater sciatic foramen, inferior to the piriformis.<\/li>
- As it passes through the gluteal region into the thigh, it divides into the common peroneal and tibial nerves.<\/li>
- It innervates muscles in the posterior compartment of the thigh, in the leg and foot, carrying sensory fibers from the skin of the foot and lateral leg.<\/li><\/ul><\/li>
- Pudendal nerve<\/strong>
- The pudendal nerve arises from the ventral divisions of S2-S4.<\/li>
- It enters the gluteal region by leaving the pelvic cavity through the greater sciatic foramen, inferior to the piriformis muscle.<\/li>
- It courses into the perineum by immediately passing around the sacrospinous ligament, where this joins the ischial spine, and through the lesser sciatic foramen.<\/li>
- It innervates the skin and skeletal muscles of the perineum.<\/li><\/ul><\/li>
- Superior gluteal nerve<\/strong>
- The superior gluteal nerve arises from the dorsal divisions of L4-S1, it leaves the pelvic cavity through the greater sciatic foramen, superior to the piriformis muscle, innervating the gluteus medius, gluteus minimus, and tensor of fascia lata muscles.<\/li><\/ul><\/li>
- Inferior gluteal nerve<\/strong>
- The inferior gluteal nerve arises from the dorsal divisions of L5-S2, it leaves the pelvic cavity through the greater sciatic foramen, inferior to the piriformis muscle, innervating the gluteus maximus.<\/li><\/ul><\/li>
- The\u00a0nerve to the obturator internus<\/strong>
- The nerve to obturator internus arises from the ventral divisions of L5-S2, leaving the pelvic cavity through the greater sciatic foramen, inferior to the piriformis muscle. It enters into the perineum similarly to the pudendal nerve.<\/li><\/ul><\/li>
- The\u00a0nerve to the quadratus femoris and inferior gemellus muscles<\/strong>, and the\u00a0posterior femoral cutaneous nerve<\/strong>
- Arise from\u00a0 L4-S1 (nerve to quadratus femoris and inferior gemellus muscles) and S1 and S3 (posterior femoral cutaneous nerve)<\/li>
- Leave the pelvic cavity through the greater sciatic foramen, inferior to the piriformis muscle, coursing to muscles (the muscular branch) and skin (the cutaneous branch) in the lower limb.<\/li>
- The posterior femoral cutaneous nerve innervates the skin of the posterior surface of the thigh.<\/li><\/ul><\/li>
- Other nerves include the\u00a0perforating cutaneous nerve<\/strong>, which leaves the pelvic cavity by penetrating directly through the sacrotuberous ligament, innervating the skin over the inferior aspect of the buttocks, and the\u00a0nerve to the piriformis<\/strong>\u00a0and several small nerves to the levator ani and coccygeus muscles, which do not leave the pelvic cavity.<\/li><\/ul>\n\n\n<\/span>\n
Attributes<\/h4>\n<\/span>\n\n\n- Figure 1. OpenStax,\u00a0CC BY-SA 4.0<\/a><\/li><\/ul>\n<\/span>
- Both nerves rise from the L1 spinal nerve and enter between the abdominal muscles.<\/li>
- The iliohypogastric nerve passes between and innervates the transversus abdominis and internal oblique muscles, with terminal branches innervating the abdominal skin.<\/li>
- The ilioinguinal nerve passes between the abdominal muscles to blend with the spermatic cord, passing through the inguinal canal, innervating the skin of the scrotum and the medial surface of the thigh.<\/li><\/ul><\/li>
- Lateral to the psoas major muscle (lateral femoral cutaneous nerve <\/strong>and femoral nerve<\/strong>)
- The lateral femoral cutaneous nerve arises from L2-L3, runs on the surface of the quadratus lumborum muscle, passing in the lacuna musculonervosa of the subinguinal hiatus, and emerges below the inguinal ligament, innervating the skin of the lateral thigh.<\/li>
- The femoral nerve is one of the major nerves from the lumbar plexus, arising from L2-L4 it runs lateral to the iliopsoas muscle, and similarly to the lateral femoral cutaneous nerve, it passes in the lacuna musculonervosa, entering the femoral triangle of the thigh, laterally to the femoral artery.
- It innervates all of the anterior muscles of the thigh, the iliacus and pectineus muscles, the skin of the anterior thigh and knee, and the medial ankle and foot.<\/li><\/ul><\/li><\/ul><\/li>
- Piercing the psoas major muscle (genitofemoral nerve<\/strong>)
- The genitofemoral nerve arises from L1-L2 and divides into the genital and femoral branches.<\/li>
- The genital branch passes to the inguinal canal within the spermatic cord, innervating the cremaster muscle and the scrotum.<\/li>
- The femoral branch passes through the lacuna vasorum of the subinguinal hiatus, innervating a small portion of the skin of the medial upper thigh.<\/li><\/ul><\/li>
- Medial to the psoas major muscle (obturator nerve<\/strong>)
- The obturator nerve arises from L2-L4, passing on the lateral wall of the pelvis, entering through the obturator canal together with the obturator artery, to innervate the obturator externus muscle, the adductor muscles of the thigh (except adductor magnus), and the skin of the medial and upper thigh.<\/li><\/ul><\/li><\/ul>\n\n\n<\/span>\n
Sacral plexus<\/h4>\n<\/span>\n\n\n
Formed by the lumbosacral trunk (L4 and L5) and the anterior rami of S1 to S4, the plexus forms in front of the piriformis muscle:<\/p>\n\n\n\n
- Sciatic nerve<\/strong>
- Arises from L4-S3 and is the largest nerve of the body.<\/li>
- It forms on the anterior surface of the piriformis muscle and leaves the pelvic cavity through the greater sciatic foramen, inferior to the piriformis.<\/li>
- As it passes through the gluteal region into the thigh, it divides into the common peroneal and tibial nerves.<\/li>
- It innervates muscles in the posterior compartment of the thigh, in the leg and foot, carrying sensory fibers from the skin of the foot and lateral leg.<\/li><\/ul><\/li>
- Pudendal nerve<\/strong>
- The pudendal nerve arises from the ventral divisions of S2-S4.<\/li>
- It enters the gluteal region by leaving the pelvic cavity through the greater sciatic foramen, inferior to the piriformis muscle.<\/li>
- It courses into the perineum by immediately passing around the sacrospinous ligament, where this joins the ischial spine, and through the lesser sciatic foramen.<\/li>
- It innervates the skin and skeletal muscles of the perineum.<\/li><\/ul><\/li>
- Superior gluteal nerve<\/strong>
- The superior gluteal nerve arises from the dorsal divisions of L4-S1, it leaves the pelvic cavity through the greater sciatic foramen, superior to the piriformis muscle, innervating the gluteus medius, gluteus minimus, and tensor of fascia lata muscles.<\/li><\/ul><\/li>
- Inferior gluteal nerve<\/strong>
- The inferior gluteal nerve arises from the dorsal divisions of L5-S2, it leaves the pelvic cavity through the greater sciatic foramen, inferior to the piriformis muscle, innervating the gluteus maximus.<\/li><\/ul><\/li>
- The\u00a0nerve to the obturator internus<\/strong>
- The nerve to obturator internus arises from the ventral divisions of L5-S2, leaving the pelvic cavity through the greater sciatic foramen, inferior to the piriformis muscle. It enters into the perineum similarly to the pudendal nerve.<\/li><\/ul><\/li>
- The\u00a0nerve to the quadratus femoris and inferior gemellus muscles<\/strong>, and the\u00a0posterior femoral cutaneous nerve<\/strong>
- Arise from\u00a0 L4-S1 (nerve to quadratus femoris and inferior gemellus muscles) and S1 and S3 (posterior femoral cutaneous nerve)<\/li>
- Leave the pelvic cavity through the greater sciatic foramen, inferior to the piriformis muscle, coursing to muscles (the muscular branch) and skin (the cutaneous branch) in the lower limb.<\/li>
- The posterior femoral cutaneous nerve innervates the skin of the posterior surface of the thigh.<\/li><\/ul><\/li>
- Other nerves include the\u00a0perforating cutaneous nerve<\/strong>, which leaves the pelvic cavity by penetrating directly through the sacrotuberous ligament, innervating the skin over the inferior aspect of the buttocks, and the\u00a0nerve to the piriformis<\/strong>\u00a0and several small nerves to the levator ani and coccygeus muscles, which do not leave the pelvic cavity.<\/li><\/ul>\n\n\n<\/span>\n
Attributes<\/h4>\n<\/span>\n\n\n
- Figure 1. OpenStax,\u00a0CC BY-SA 4.0<\/a><\/li><\/ul>\n<\/span>
- Sciatic nerve<\/strong>
- The obturator nerve arises from L2-L4, passing on the lateral wall of the pelvis, entering through the obturator canal together with the obturator artery, to innervate the obturator externus muscle, the adductor muscles of the thigh (except adductor magnus), and the skin of the medial and upper thigh.<\/li><\/ul><\/li><\/ul>\n\n\n<\/span>\n