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The lumbosacral trunk is formed by the union of the entire anterior ramus of lumbar nerve L5 and a part of L4 [clarification needed]. [1] [2] [3] L4 first issues its branches to the lumbar plexus, then emerges from the medial border of the psoas muscle [3] to unite with the anterior ramus of L5 just superior to the pelvic brim to form the thick, cord-like trunk which [4] crosses the pelvic ...
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The sacrum (pl.: sacra or sacrums [1]), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1–S5) between ages 18 and 30. [ 2 ] The sacrum situates at the upper, back part of the pelvic cavity , between the two wings of the pelvis .
The first three lumbar nerves, and the greater part of the fourth together form the lumbar plexus. The smaller part of the fourth joins with the fifth to form the lumbosacral trunk, which assists in the formation of the sacral plexus. The fourth nerve is named the furcal nerve, from the fact that it is subdivided between the two plexuses.
It is formed by the divisions of the first four lumbar nerves (L1-L4) and from contributions of the subcostal nerve (T12), which is the last thoracic nerve. Additionally, the ventral rami of the fourth lumbar nerve pass communicating branches, the lumbosacral trunk, to the sacral plexus. The nerves of the lumbar plexus pass in front of the hip ...
In human anatomy, the sacral plexus is a nerve plexus which provides motor and sensory nerves for the posterior thigh, most of the lower leg and foot, and part of the pelvis. It is part of the lumbosacral plexus and emerges from the lumbar vertebrae and sacral vertebrae (L4-S4). [ 1 ]
The lumbosacral trunk from the L4 and L5 roots descends between the sacral promontory and ala, and the S1 to S3 roots emerge from the ventral sacral foramina. These nerve roots unite to form a single nerve in front of the piriformis muscle. The nerve passes beneath the piriformis and through the greater sciatic foramen, exiting the pelvis.
The lumbar enlargement (or lumbosacral enlargement) is a widened area of the spinal cord that gives attachment to the nerves which supply the lower limbs. It commences about the level of T11 and ends at L2, and reaches its maximum circumference, of about 33 mm. Inferior to the lumbar enlargement is the conus medullaris .