The lumbar vertebrae are, in human anatomy, the five vertebrae between the rib cage and the pelvis. They are the largest segments of the vertebral column and are characterized by the absence of the foramen transversarium within the transverse process (since it is only found in the cervical region) and by the absence of facets on the sides of the body (as found only in the thoracic region). They are designated L1 to L5, starting at the top. The lumbar vertebrae help support the weight of the body, and permit movement.
Position of human lumbar vertebrae (shown in red). It consists of 5 bones, from top to down, L1, L2, L3, L4 and L5.
A typical lumbar vertebra
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The figure on the left depicts the general characteristics of the first through fourth lumbar vertebrae. The fifth vertebra contains certain peculiarities, which are detailed below.
As with other vertebrae, each lumbar vertebra consists of a vertebral body and a vertebral arch. The vertebral arch, consisting of a pair of pedicles and a pair of laminae, encloses the vertebral foramen (opening) and supports seven processes.
The vertebral body of each lumbar vertebra is large, wider from side to side than from front to back, and a little thicker in front than in back. It is flattened or slightly concave above and below, concave behind, and deeply constricted in front and at the sides.
The pedicles are very strong, directed backward from the upper part of the vertebral body; consequently, the inferior vertebral notches are of considerable depth. The pedicles change in morphology from the upper lumbar to the lower lumbar. They increase in sagittal width from 9 mm to up to 18 mm at L5. They increase in angulation in the axial plane from 10 degrees to 20 degrees by L5. The pedicle is sometimes used as a portal of entrance into the vertebral body for fixation with pedicle screws or for placement of bone cement as with kyphoplasty or vertebroplasty.
The laminae are broad, short, and strong. They form the posterior portion of the vertebral arch. In the upper lumbar region the lamina are taller than wide but in the lower lumbar vertebra the lamina are wider than tall. The lamina connects the spinous process to the pedicles.
The spinous process is thick, broad, and somewhat quadrilateral; it projects backward and ends in a rough, uneven border, thickest below where it is occasionally notched.
The superior and inferior articular processes are well-defined, projecting respectively upward and downward from the junctions of pedicles and laminae. The facets on the superior processes are concave, and look backward and medialward; those on the inferior are convex, and are directed forward and lateralward. The former are wider apart than the latter since in the articulated column, the inferior articular processes are embraced by the superior processes of the subjacent vertebra.
The transverse processes are long and slender. They are horizontal in the upper three lumbar vertebrae and incline a little upward in the lower two. In the upper three vertebrae they arise from the junctions of the pedicles and laminae, but in the lower two they are set farther forward and spring from the pedicles and posterior parts of the vertebral bodies. They are situated in front of the articular processes instead of behind them as in the thoracic vertebrae, and are homologous with the ribs.
Three portions or tubercles can be noticed in a transverse process of a lower lumbar vertebrae: the lateral or costiform process, the mammillary process, and the accessory process. The costiform is lateral, the mammillary is superior (cranial), and the accessory is inferior (caudal). The mammillary is connected in the lumbar region with the back part of the superior articular process. The accessory process is situated at the back part of the base of the transverse process. The tallest and thickest costiform process is usually that of L5.
The first lumbar vertebra is level with the anterior end of the ninth rib. This level is also called the important transpyloric plane, since the pylorus of the stomach is at this level. Other important structures are also located at this level, they include; fundus of the gall bladder, celiac trunk, superior mesenteric artery, termination of spinal cord, beginning of filum terminalis, renal vessels, middle suprarenal arteries, and hila of kidneys.
The fifth lumbar vertebra is characterized by its body being much deeper in front than behind, which accords with the prominence of the sacrovertebral articulation; by the smaller size of its spinous process; by the wide interval between the inferior articular processes, and by the thickness of its transverse processes, which spring from the body as well as from the pedicles. The fifth lumbar vertebra is by far the most common site of spondylolysis and spondylolisthesis.
Most individuals have five lumbar vertebrae, while some have four or six. Lumbar disorders that normally affect L5 will affect L4 or L6 in these latter individuals.
The range of segmental movements in a single segment is difficult to measure clinically, not only because of variations between individuals, but also because it is age and gender dependent. Furthermore, flexion and extension in the lumbal spine is the product of a combination of rotation and translation in the sagittal plane between each vertebra.
Ranges of segmental movements in the lumbal spine (White and Panjabi, 1990) are (in degrees): 
African apes have three and four lumbar vertebrae, (bonobos have longer spines with an additional vertebra) and humans normally five. This difference, and because the lumbar spines of the extinct Nacholapithecus (a Miocene hominoid with six lumbar vertebrae and no tail) are similar to those of early Australopithecus and early Homo, it is assumed that the Chimpanzee-human last common ancestor also had a long vertebral column with a long lumbar region and that the reduction in the number of lumbar vertebrae evolved independently in each ape clade.  The limited number of lumbar vertebrae in chimpanzees and gorillas result in an inability to lordose (curve) their lumbar spines, in contrast to the spines of Old World monkeys and Nacholapithecus and Proconsul, which suggests that the last common ancestor was not "short-backed" as previously believed. 
The 2009 Indy Grand Prix of Sonoma was the fourteenth round of the 17-race 2009 IndyCar Series season, and was held on August 23, 2009 at the 2.303-mile (3.706 km) Infineon Raceway in Sonoma, California. Will Power and Nelson Philippe both missed the race, after they were hospitalized after a practice accident on Saturday. Philippe spun at the blind turn 3A, and stalled the car on-track. E. J. Viso hit the Frenchman's car, before Power t-boned it a few seconds later. Power suffered fractures to two lumbar vertebrae, Philippe fractured his left foot and Viso escaped uninjured.Cisterna chyli
The cisterna chyli (or cysterna chyli, and etymologically more correct, receptaculum chyli) is a dilated sac at the lower end of the thoracic duct in most mammals into which lymph from the intestinal trunk and two lumbar lymphatic trunks flow. It receives fatty chyle from the intestines and thus acts as a conduit for the lipid products of digestion. It is the most common drainage trunk of most of the body's lymphatics. The cisterna chyli is a retro-peritoneal structure. In humans, it is located posterior to the abdominal aorta on the anterior aspect of the bodies of the first and second lumbar vertebrae (L1 and L2). There it forms the beginning of the primary lymph vessel, the thoracic duct, which transports lymph and chyle from the abdomen via the aortic opening of the diaphragm up to the junction of left subclavian vein and internal jugular veins. In dogs, it is located to the left and often ventral to the aorta; in cats it is left and dorsal; in guinea pigs it runs to the left and drains into the left innominate vein.Gaenslen's test
Gaenslen's test, also known as Gaenslen's maneuver, is a medical test used to detect musculoskeletal abnormalities and primary-chronic inflammation of the lumbar vertebrae and sacroiliac joint. This test is often used to test for spondyloarthritis, sciatica, or other forms of rheumatism, and is often performed during checkup visits in patients who have been diagnosed with one of the former disorders. It is named after Frederick Julius Gaenslen, the orthopedic surgeon who invented the test. This test is often performed alongside Patrick's test and Yeoman's test.
To perform Gaenslen's test, the hip joint is flexed maximally on one side and the opposite hip joint is extended, stressing both sacroiliac joints simultaneously. This is often done by having the patient lying on his or her back, lifting the knee to push towards the patient's chest while the other leg is allowed to fall over the side of an examination table, and is pushed toward the floor, flexing both sacroiliac joints. The test can also be performed with the patient in the lateral recumbent position. The patient lies with the involved side up and passively flexes the uninvolved hip as far as comfortable to their chest. The involved hip is taken into extension while stability is maintained in the pelvis. The test is considered positive if the patient experiences pain while this test is performed, and may indicate a need for further testing, such as an X-ray or lumbar CT scan.Interspinales muscles
The interspinales are short muscular fasciculi, found in pairs between the spinous processes of the contiguous vertebrae, one on either side of the interspinal ligament.
In the cervical region the cervical interspinales are most distinct, and consist of six pairs, the first being situated between the axis and third vertebra, and the last between the seventh cervical and the first thoracic. They are small narrow bundles, attached, above and below, to the apices of the spinous processes.
In the thoracic region the thoracic interspinales are found between the first and second vertebrae, and sometimes between the second and third, and between the eleventh and twelfth.
In the lumbar region there are four pairs of lumbar interspinales in the intervals between the five lumbar vertebrae. There is also occasionally one between the last thoracic and first lumbar, and one between the fifth lumbar and the sacrum.Intervertebral foramen
The intervertebral foramen (also called neural foramen, and often abbreviated as IV foramen or IVF), is a foramen between two spinal vertebrae. Cervical, thoracic, and lumbar vertebrae all have intervertebral foramina.
The foramina, or openings, are present between every pair of vertebrae in these areas. A number of structures pass through the foramen. These are the root of each spinal nerve, the spinal artery of the segmental artery, communicating veins between the internal and external plexuses, recurrent meningeal (sinu-vertebral) nerves, and transforaminal ligaments.
When the spinal vertebrae are articulated with each other, the bodies form a strong pillar that supports the head and trunk, and the vertebral foramen constitutes a canal for the protection of the medulla spinalis (spinal cord).
The size of the foramina is variable due to placement, pathology, spinal loading, and posture.
Foramina can be occluded by arthritic degenerative changes and space-occupying lesions like tumors, metastases, and spinal disc herniations.
Specifically, the intervertebral foramen is bordered by the superior notch of the adjacent vertebra, the inferior notch of the vertebra, the intervertebral joint and the intervertebral disc.KL2 (classification)
The KL 2 class is for paracanoe paddlers with partial leg and trunk function alongside good arm strength. A KL2 class paddler should be able to sit upright within the kayak but may require a backrest. These athletes may be able to use a footboard to propel the canoe depending on leg function. Eligible paddlers typically meet one of the following:
Limb loss of deficiency equivalent to double above leg amputation.
Significant muscle strength loss in both legs equivalent to complete spinal cord injury at L3 lumbar vertebrae, or incomplete lesion at L1 lumbar vertebrae.
Impaired range of motion: In lower limbs and trunkLumbar
In tetrapod anatomy, lumbar is an adjective that means of or pertaining to the abdominal segment of the torso, between the diaphragm and the sacrum.
The lumbar region is sometimes referred to as the lower spine, or as an area of the back in its proximity.
In human anatomy the five lumbar vertebrae (vertebrae in the lumbar region of the back) are the largest and strongest in the movable part of the spinal column, and can be distinguished by the absence of a foramen in the transverse process, and by the absence of facets on the sides of the body. In most mammals, the lumbar region of the spine curves outward.
The actual spinal cord (Angelamedulla spinalis) terminates between vertebrae one and two of this series, called L1 and L2. The nervous tissue that extends below this point are individual strands that collectively form the cauda equina. In between each lumbar vertebra a nerve root exits, and these nerve roots come together again to form the largest single nerve in the human body, the sciatic nerve. The sciatic nerve runs through the back of each leg and into the feet. This is why a disorder of the low back that affects a nerve root, such as a spinal disc herniation, can cause pain that radiates along the sciatic nerve (sciatica) down into the foot.
There are several muscles in the low back that assist with rotation, flexibility and strength. These muscles are susceptible to injury, especially while lifting heavy objects, or lifting while twisting. A low back muscle strain can be extremely painful but will usually heal within a few days or weeks.
The lumbar portion of the spine bears the most body weight and also provides the most flexibility, a combination that makes it susceptible to injury and wear and tear over time. This is why low back pain is so prevalent.Lumbar arteries
The lumbar arteries are arteries located in the lower back or lumbar region. The lumbar arteries are in parallel with the intercostals.
They are usually four in number on either side, and arise from the back of the aorta, opposite the bodies of the upper four lumbar vertebrae.
A fifth pair, small in size, is occasionally present: they arise from the middle sacral artery.
They run lateralward and backward on the bodies of the lumbar vertebrae, behind the sympathetic trunk, to the intervals between the adjacent transverse processes, and are then continued into the abdominal wall.
The arteries of the right side pass behind the inferior vena cava, and the upper two on each side run behind the corresponding crus of the diaphragm.
The arteries of both sides pass beneath the tendinous arches which give origin to the psoas major, and are then continued behind this muscle and the lumbar plexus.
They now cross the quadratus lumborum, the upper three arteries running behind, the last usually in front of the muscle.
At the lateral border of the quadratus lumborum they pierce the posterior aponeurosis of the transversus abdominis and are carried forward between this muscle and the obliquus internus.
They anastomose with the lower intercostal, the subcostal, the iliolumbar, the deep iliac circumflex, and the inferior epigastric arteries.Lumbocostal ligament
The Lumbocostal ligament is a fibrous band that crosses from the twelfth rib to the tips of the transverse processes of the first and second lumbar vertebrae.Masracetus
Masracetus (from Arabic Masr, "Egypt", and Greek ketos, "whale") is an extinct genus of basilosaurid ancient whale known from the Late Eocene (Priabonian, 37.2 to 33.9 million years ago) of Egypt.Masracetus was briefly described in an addendum by Gingerich 2007 and is known from just an assemblage of vertebrae and a poorly reconstructed skull from 1908. The lumbar vertebrae are large but relatively short (anteroposteriorly) compared to those of other archaeocetes; the diameter is almost the same as for Basilosaurus isis but the length is less than half of the latter. Masracetus is larger than Cynthiacetus.The species name honours Richard Markgraf, palaeontologist Ernst Stromer's fossil collector, who collected the type specimen in 1905.Masracetus' type locality is the Birket Qarun Formation in Dimê (29.5°N 30.7°E / 29.5; 30.7, paleocoordinates 24.9°N 26.6°E / 24.9; 26.6) north of lake Birket Qarun, but specimens have also been found in the Qattara Depression and Fayum.Median sacral artery
The median sacral artery (or middle sacral artery) is a small vessel that arises posterior to the abdominal aorta and superior to its bifurcation.
It descends in the middle line in front of the fourth and fifth lumbar vertebræ, the sacrum and coccyx, ending in the glomus coccygeum (coccygeal gland).
Minute branches pass from it, to the posterior surface of the rectum.
On the last lumbar vertebra it anastomoses with the lumbar branch of the iliolumbar artery; in front of the sacrum it anastomoses with the lateral sacral arteries, sending offshoots into the anterior sacral foramina.
It is crossed by the left common iliac vein and accompanied by a pair of venæ comitantes; these unite to form a single vessel that opens into the left common iliac vein.
The median sacral artery is morphologically the direct continuation of the abdominal aorta. It is vestigial in humans, but large in animals with tails such as the crocodile.Paraaortic lymph nodes
The paraaortic lymph nodes (also known as periaortic, and lumbar) are a group of lymph nodes that lie in front of the lumbar vertebrae near the aorta. These lymph nodes receive drainage from the gastrointestinal tract and the abdominal organs.Pork tenderloin
The pork tenderloin, also called pork fillet or Gentleman's Cut, is a long thin cut of pork.
As with all quadrupeds, the tenderloin refers to the psoas major muscle along the central spine portion, ventral to the lumbar vertebrae. This is the most tender part of the animal, because these muscles are used for posture, rather than locomotion.Pott disease
Pott disease or Pott's disease is a form of tuberculosis that occurs outside the lungs whereby disease is seen in the vertebrae. Tuberculosis can affect several tissues outside the lungs including the spine, a kind of tuberculous arthritis of the intervertebral joints. The disease is named after Percivall Pott (1714–1788), a British surgeon. The lower thoracic and upper lumbar vertebrae are the areas of the spine most often affected. The formal name for the disease is tuberculous spondylitis.
Pott’s disease results from haematogenous spread of tuberculosis from other sites, often the lungs. The infection then spreads from two adjacent vertebrae into the adjoining intervertebral disc space. If only one vertebra is affected, the disc is normal, but if two are involved, the disc, which is avascular, cannot receive nutrients and collapses. In a process called caseous necrosis the disc tissue dies leading to vertebral narrowing and eventually to vertebral collapse and spinal damage. A dry soft tissue mass often forms and superinfection is rare.Retroaortic lymph nodes
The retroaortic lymph nodes (or postaortic lymph nodes) are placed below the cisterna chyli, on the bodies of the third and fourth lumbar vertebrae.
They receive lymphatic trunks from the lateral and preaortic glands, while their efferents end in the cisterna chyli.Sacral plexus
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). A sacral plexopathy is a disorder affecting the nerves of the sacral plexus, usually caused by trauma, nerve compression, vascular disease, or infection. Symptoms may include pain, loss of motor control, and sensory deficits.T-bone steak
The T-bone and porterhouse are steaks of beef cut from the short loin (called the sirloin in Commonwealth countries and Ireland). Both steaks include a "T"-shaped lumbar vertebrae with sections of abdominal internal oblique muscle on each side. Porterhouse steaks are cut from the rear end of the short loin and thus include more tenderloin steak, along with (on the other side of the bone) a large strip steak. T-bone steaks are cut closer to the front, and contain a smaller section of tenderloin. The smaller portion of a T-bone, when sold alone, is known as a filet mignon, especially if cut from the small forward end of the tenderloin.
There is little agreement among experts on how large the tenderloin must be to differentiate a T-bone steak from porterhouse. The United States Department of Agriculture's Institutional Meat Purchase Specifications state that the tenderloin of a porterhouse must be at least 1.25 inches (32 mm) thick (i.e. measuring from the bone) at its widest, while that of a T-bone must be at least 0.5 inches (13 mm) wide. However, steaks with a large tenderloin are often called a "T-bone" in restaurants and steakhouses despite technically being porterhouse.Owing to their large size and the fact that they contain meat from two of the most prized cuts of beef (the short loin and the tenderloin), T-bone steaks are generally considered one of the highest quality steaks, and prices at steakhouses are accordingly high. Porterhouse steaks are even more highly valued owing to their larger tenderloin.
In the United States, the T-bone has the meat-cutting classification IMPS 1174; the porterhouse is IMPS 1173.
In British usage, followed in the Commonwealth countries, "porterhouse" often means a British sirloin steak (i.e. US strip steak) on the bone, i.e. without the tenderloin on the other side of T-bone. However, nowadays some British on-line butchers also offer American style porterhouse steaks.In New Zealand and Australia, a Porterhouse is striploin steak off the bone.Thoracic vertebrae
In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebrae and they are intermediate in size between the cervical and lumbar vertebrae; they increase in size going towards the lumbar vertebrae, with the lower ones being a lot larger than the upper. They are distinguished by the presence of facets on the sides of the bodies for articulation with the heads of the ribs, as well as facets on the transverse processes of all, except the eleventh and twelfth, for articulation with the tubercles of the ribs. By convention, the human thoracic vertebrae are numbered T1–T12, with the first one (T1) located closest to the skull and the others going down the spine toward the lumbar region.Vertebra
In the vertebrate spinal column, each vertebra is an irregular bone with a complex structure composed of bone and some hyaline cartilage, the proportions of which vary according to the segment of the backbone and the species of vertebrate.
The basic configuration of a vertebra varies; the large part is the body, and the central part is the centrum. The upper and lower surfaces of the vertebra body give attachment to the intervertebral discs. The posterior part of a vertebra forms a vertebral arch, in eleven parts, consisting of two pedicles, two laminae, and seven processes. The laminae give attachment to the ligamenta flava (ligaments of the spine). There are vertebral notches formed from the shape of the pedicles, which form the intervertebral foramina when the vertebrae articulate. These foramina are the entry and exit conducts for the spinal nerves. The body of the vertebra and the vertebral arch form the vertebral foramen, the larger, central opening that accommodates the spinal canal, which encloses and protects the spinal cord.
Vertebrae articulate with each other to give strength and flexibility to the spinal column, and the shape at their back and front aspects determines the range of movement. Structurally, vertebrae are essentially alike across the vertebrate species, with the greatest difference seen between an aquatic animal and other vertebrate animals. As such, vertebrates take their name from the vertebrae that compose the vertebral column.