In tetrapod Tetrapods are vertebrate animals having four feet, legs or leglike appendages. Amphibians, reptiles, birds, and mammals are all tetrapods, and even the limbless snakes are tetrapods by descent. The earliest tetrapods radiated from the Sarcopterygii, or lobe-finned fish anatomy Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy (zootomy) and plant anatomy (phytotomy). In some of its facets anatomy is closely related to embryology, comparative anatomy and comparative embryology, through common roots in, lumbar is an adjective An adjective is a word signifying a conceptual representation of an ontological possibility that means of or pertaining to the abdominal In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax (chest) and pelvis. The region enclosed by the abdomen is termed the abdominal cavity. In arthropods it is the most distal section of the body which lies behind the thorax or cephalothorax segment of the torso Trunk or torso is an anatomical term for the central part of the many animal bodies from which extend the neck and limbs. The trunk includes the thorax and abdomen, between the diaphragm In the anatomy of mammals, the thoracic diaphragm or sometime simply, the diaphragm, is a sheet of internal muscle that extends across the bottom of the rib cage. The diaphragm separates the thoracic cavity from the abdominal cavity and performs an important function in respiration. A diaphragm in anatomy can refer to other flat structures such as and the sacrum In vertebrate anatomy the sacrum is a large, triangular bone at the base of the spine and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones. Its upper part connects with the last lumbar vertebra, and bottom part with the coccyx (tailbone). In children, it consists of usually five unfused (pelvis In human anatomy, the pelvis is the part of the trunk inferioposterior (below-behind) to the abdomen in the transition area between the trunk (torso) and the lower limbs (legs). The term is used to denote several structures:). The lumbar region is sometimes referred to as the lower spine. In human anatomy Human anatomy , which, with human physiology and biochemistry, is a complementary basic medical science, is primarily the scientific study of the morphology of the human body. Anatomy is subdivided into gross anatomy and microscopic anatomy. Gross anatomy (also called topographical anatomy, regional anatomy, or anthropotomy) is the study of the five vertebrae A vertebra is an individual bone in the flexible column that defines vertebrate animals, e.g., humans. The vertebral column encases and protects the spinal cord, which runs from the base of the cranium down the dorsal side of the animal until reaching the pelvis. From there, vertebrae continue into the tail in the lumbar region of the back are the largest and strongest in the movable part of the spinal column In human anatomy, the vertebral column is a column usually consisting of 24 vertebrae, the sacrum, intervertebral discs, and the coccyx situated in the dorsal aspect of the torso, separated by spinal discs. It houses the spinal cord in its spinal canal, and can be distinguished by the absence of a foramen The foramen transversarium pierces the transverse processes of the seven cervical vertebrae. It gives passage to the vertebral artery and vein as well as a plexus of sympathetic nerves in each of the vertebræ except the seventh, which lacks the artery. In the foramen transversarium, the kliider is responsible for holding the arteries in place in the transverse process The transverse or costal processes of a vertebra, two in number, project one at either side from the point where the lamina joins the pedicle, between the superior and inferior articular processes. They serve for the attachment of muscles and ligaments, and by the absence of facets on the sides of the body. In most mammals Mammals are a class of vertebrate, air-breathing animals whose females are characterized by the possession of mammary glands while both males and females are characterized by hair and/or fur, three middle ear bones used in hearing, and a neocortex region in the brain. Some mammals have sweat glands, but most do not, the lumbar region of the spine curves outward.

The actual spinal cord The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system. The spinal cord extends down to the space between the first and second lumbar vertebrae; it does not extend the entire length of the vertebral column. It is around 4 (medulla spinalis) terminates between vertebrae one and two of this series, called L1 and L2. The nervous The central nervous system is the part of the nervous system that coordinates the activity of all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish. It contains the majority of the nervous system and consists of the brain and the spinal cord, as well as tissue that extends below this point are individual strands that collectively form the cauda equina The cauda equina is a structure within the lower end of the spinal column of most vertebrates, that consists of nerve roots and rootlets from above. The space in which the cerebrospinal fluid is present is actually an extension of the subarachnoid space. In between each lumbar vertebra a nerve A peripheral nerve, or simply nerve is an enclosed, cable-like bundle of peripheral axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons. Nerves are found only in the peripheral nervous system. In the central nervous system, the analogous structures are known as tracts root exits, and these nerve roots come together again to form the largest single nerve in the human body The human body is the entire structure of a human organism, and consists of a head, neck, torso, two arms and two legs. By the time the human reaches adulthood, the body consists of close to 50 trillion cells, the basic unit of life. These cells are organised biologically to eventually form the whole body, the sciatic nerve The sciatic nerve is a large nerve fiber in humans and other animals. It begins in the lower back and runs through the buttock and down the lower limb. It is the longest and widest single nerve in the human body. 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 A spinal disc herniation , informally and misleadingly called a "slipped disc", is a medical condition affecting the spine, in which a tear in the outer, fibrous ring (annulus fibrosus) of an intervertebral disc (discus intervertebralis) allows the soft, central portion (nucleus pulposus) to bulge out. Tears are almost always posterior-, can cause pain that radiates along the sciatic nerve (sciatica Sciatica is a set of symptoms including pain that may be caused by general compression and/or irritation of one of five spinal nerve roots that give rise to each sciatic nerve, or by compression or irritation of the left or right or both sciatic nerves. The pain is felt in the lower back, buttock, and/or various parts of the leg and foot. In) down into the foot.

There are several muscles Muscle is the contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to produce force and cause motion. Muscles can cause 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 A strain is an injury to a muscle or tendon in which the muscle fibers tear as a result of overstretching. Strains are also colloquially known as pulled muscles. The equivalent injury to a ligament is a sprain 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 Low back pain is a common musculoskeletal disorder affecting 80% of people at some point in their lives. It accounts for more sick leave and disability than any other medical condition. It can be either acute, subacute or chronic in duration. Most often, the symptoms of low back pain show significant improvement within a few weeks from onset with is so prevalent.

See also

References

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External links

Categories: Skeletal system The skeleton, the human skeletal system, is an endoskeleton made up of bones

 

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