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The lumbar vertebrae are located between the thoracic vertebrae and pelvis. They form the lower part of the back in humans, and the tail end of the back in quadrupeds. In humans, there are five lumbar vertebrae. The term is used to describe the anatomy of humans and quadrupeds, such as horses, pigs, or cattle.
The lower border of first lumbar vertebra lies at the level of the transpyloric plane. [3] Despite the conus medullaris, the end of the spinal cord, being understood to typically terminate at the level of the transpyloric plane, there is significant variability. Up to 40% of people have spinal cords ending below the transpyloric plane. [2] [4]
The transverse process of a lumbar vertebra is also sometimes called the costal [9] [10] or costiform process [11] because it corresponds to a rudimentary rib (costa) which, as opposed to the thorax, is not developed in the lumbar region.
Iliocostalis muscle has a common origin from the iliac crest, the sacrum, the thoracolumbar fascia, and the spinous processes of the vertebrae from T11 to L5. [1]Iliocostalis cervicis (cervicalis ascendens) arises from the angles of the third, fourth, fifth, and sixth ribs, and is inserted into the posterior tubercles of the transverse processes of the fourth, fifth, and sixth cervical vertebrae.
The longissimus thoracis et lumborum is the intermediate and largest of the continuations of the erector spinae.. In the lumbar region (longissimus lumborum), where it is as yet blended with the iliocostalis, some of its fibers are attached to the whole length of the posterior surfaces of the transverse processes and the accessory processes of the lumbar vertebrae, and to the anterior layer of ...
The number of vertebrae in a region can vary but overall the number remains the same. In a human spinal column, there are normally 33 vertebrae. [3] The upper 24 pre-sacral vertebrae are articulating and separated from each other by intervertebral discs, and the lower nine are fused in adults, five in the sacrum and four in the coccyx, or tailbone.
The posterior layer is attached to the spinous processes of lumbar and sacral vertebrae, and to the supraspinous ligament. [ 2 ] : 814–815 At sacral levels, the posterior layer attaches to the posterior superior iliac spines, and posterior iliac crest, fuses with the underlying erector spinae muscle aponeurosis, [ 2 ] : 814–815 and extends ...
For instance, the S1–S5 vertebrae of a horse will fuse, the S1–S3 of a dog will fuse, and four pelvic vertebrae of a rat will fuse between the lumbar and the caudal vertebrae of its tail. [ 3 ] The Stegosaurus dinosaur had a greatly enlarged neural canal in the sacrum, characterized as a " posterior brain case ".