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Sacral Spinal Nerve 2
The sacral spinal nerve 2 (S2) is a spinal nerve of the sacral segment. Nervous System -- Groups of Nerves It originates from the from below the 2nd body of the 
Muscles S2 supplies many muscles, either directly or through nerves originating from S2. They are not innervated with S2 as single origin, but partly by S2 and partly by other spinal nerves. They are most ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spinal Nerve
A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into the corresponding cervical, thoracic, lumbar, sacral and coccygeal regions of the spine. There are eight pairs of cervical nerves, twelve pairs of thoracic nerves, five pairs of lumbar nerves, five pairs of sacral nerves, and one pair of coccygeal nerves. The spinal nerves are part of the peripheral nervous system. Structure Each spinal nerve is a mixed nerve, formed from the combination of nerve fibers from its dorsal and ventral roots. The dorsal root is the afferent sensory root and carries sensory information to the brain. The ventral root is the efferent motor root and carries motor information from the brain. The spinal nerve emerges from the spinal column through an opening (intervertebral foramen) between adjacent vertebrae. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sacral Segment
The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spinal cord, which contains cerebrospinal fluid. The brain and spinal cord together make up the central nervous system (CNS). In humans, the spinal cord begins at the occipital bone, passing through the foramen magnum and then enters the spinal canal at the beginning of the cervical vertebrae. The spinal cord extends down to between the first and second lumbar vertebrae, where it ends. The enclosing bony vertebral column protects the relatively shorter spinal cord. It is around long in adult men and around long in adult women. The diameter of the spinal cord ranges from in the cervical and lumbar regions to in the thoracic area. The spinal cord functions primarily in the transmission of nerve signals from the motor cortex to the body, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spinal Column
The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordates has been replaced by a segmented series of bone: vertebrae separated by intervertebral discs. Individual vertebrae are named according to their region and position, and can be used as anatomical landmarks in order to guide procedures such as lumbar punctures. The vertebral column houses the spinal canal, a cavity that encloses and protects the spinal cord. There are about 50,000 species of animals that have a vertebral column. The human vertebral column is one of the most-studied examples. Many different diseases in humans can affect the spine, with spina bifida and scoliosis being recognisable examples. The general structure of human vertebrae is fairly typical of that found in mammals, reptiles, and birds. The shape of the vertebra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sacrum
The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part of the pelvic cavity, between the two wings of the pelvis. It forms joints with four other bones. The two projections at the sides of the sacrum are called the alae (wings), and articulate with the ilium at the L-shaped sacroiliac joints. The upper part of the sacrum connects with the last lumbar vertebra (L5), and its lower part with the coccyx (tailbone) via the sacral and coccygeal cornua. The sacrum has three different surfaces which are shaped to accommodate surrounding pelvic structures. Overall it is concave (curved upon itself). The base of the sacrum, the broadest and uppermost part, is tilted forward as the sacral promontory internally. The central part is curved outward toward the posterior, allowing greater room for the pel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sphincter Urethrae
The urethral sphincters are two muscles used to control the exit of urine in the urinary bladder through the urethra. The two muscles are either the male or female external urethral sphincter and the internal urethral sphincter. When either of these muscles contracts, the urethra is sealed shut. The external urethral sphincter originates at the ischiopubic ramus and inserts into the intermeshing muscle fibers from the other side. It is controlled by the deep perineal branch of the pudendal nerve. Activity in the nerve fibers constricts the urethra. * The internal sphincter muscle of urethra: located at the bladder's inferior end and the urethra's proximal end at the junction of the urethra with the urinary bladder. The internal sphincter is a continuation of the detrusor muscle and is made of smooth muscle, therefore it is under involuntary or autonomic control. This is the primary muscle for prohibiting the release of urine. * The female or male external sphincter muscle of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gluteus Maximus Muscle
The gluteal muscles, often called glutes are a group of three muscles which make up the gluteal region commonly known as the buttocks: the gluteus maximus, gluteus medius and gluteus minimus. The three muscles originate from the ilium and sacrum and insert on the femur. The functions of the muscles include extension, abduction, external rotation, and internal rotation of the hip joint. Structure The gluteus maximus is the largest and most superficial of the three gluteal muscles. It makes up a large part of the shape and appearance of the hips. It is a narrow and thick fleshy mass of a quadrilateral shape, and forms the prominence of the buttocks. The gluteus medius is a broad, thick, radiating muscle, situated on the outer surface of the pelvis. It lies profound to the gluteus maximus and its posterior third is covered by the gluteus maximus, its anterior two-thirds by the gluteal aponeurosis, which separates it from the superficial fascia and skin. The gluteus minimus is t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Piriformis Muscle
The piriformis muscle () is a flat, pyramidally-shaped muscle in the gluteal region of the lower limbs. It is one of the six muscles in the lateral rotator group. The piriformis muscle has its origin upon the front surface of the sacrum, and inserts onto the greater trochanter of the femur. Depending upon the given position of the leg, it acts either as external (lateral) rotator of the thigh or as abductor of the thigh. It is innervated by the piriformis nerve. Structure The piriformis is a flat muscle, and is pyramidal in shape. Origin The piriformis muscle originates from the anterior (front) surface of the sacrum by three fleshy digitations attached to the second, third, and fourth sacral vertebra. It also arises from the superior margin of the greater sciatic notch, the gluteal surface of the ilium (near the posterior inferior iliac spine), the sacroiliac joint capsule, and (sometimes) the sacrotuberous ligament (more specifically, the superior part of the pelvic sur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Obturator Internus Muscle
The internal obturator muscle or obturator internus muscle originates on the medial surface of the obturator membrane, the ischium near the membrane, and the rim of the pubis. It exits the pelvic cavity through the lesser sciatic foramen. The internal obturator is situated partly within the lesser pelvis, and partly at the back of the hip-joint. It functions to help laterally rotate femur with hip extension and abduct femur with hip flexion, as well as to steady the femoral head in the acetabulum. Structure Origin The internal obturator muscle arises from the inner surface of the antero-lateral wall of the pelvis. It surrounds the obturator foramen. It is attached to the inferior pubic ramus and ischium, and at the side to the inner surface of the hip bone below and behind the pelvic brim. It reaches from the upper part of the greater sciatic foramen above and behind to the obturator foramen below and in front. It also arises from the pelvic surface of the obturator membran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superior Gemellus Muscle
The gemelli muscles are the inferior gemellus muscle and the superior gemellus muscle, two small accessory fasciculi to the tendon of the internal obturator muscle. The gemelli muscles belong to the lateral rotator group of six muscles of the hip that rotate the femur in the hip joint. Superior gemellus muscle The gemelli muscles are two small muscular fasciculi, accessories to the tendon of the internal obturator muscle which is received into a groove between them. The superior gemellus muscle is the higher placed gemellus muscle that arises from the outer (gluteal) surface of the ischial spine, and blends with the upper part of the tendon of the internal obturator. It is smaller than the inferior gemellus. In some people, the fibres of the gemellus superior extend further than average, and are prolonged onto the medial surface of the greater trochanter of the femur. The superior and inferior gemelli are supplied by the inferior gluteal artery. Nerve supply to the superior geme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semitendinosus Muscle
The semitendinosus () is a long superficial muscle in the back of the thigh. It is so named because it has a very long tendon of insertion. It lies posteromedially in the thigh, superficial to the semimembranosus. Structure The semitendinosus, remarkable for the great length of its tendon of insertion, is situated at the posterior and medial aspect of the thigh. It arises from the lower and medial impression on the upper part of the tuberosity of the ischium, by a tendon common to it and the long head of the biceps femoris; it also arises from an aponeurosis which connects the adjacent surfaces of the two muscles to the extent of about 7.5 cm. from their origin. The muscle is fusiform and ends a little below the middle of the thigh in a long round tendon which lies along the medial side of the popliteal fossa; it then curves around the medial condyle of the tibia and passes over the medial collateral ligament of the knee-joint, from which it is separated by a bursa, and is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gastrocnemius Muscle
The gastrocnemius muscle (plural ''gastrocnemii'') is a superficial two-headed muscle that is in the back part of the lower leg of humans. It runs from its two heads just above the knee to the heel, a three joint muscle (knee, ankle and subtalar joints). The muscle is named via Latin, from Greek γαστήρ (''gaster'') 'belly' or 'stomach' and κνήμη (''knḗmē'') 'leg', meaning 'stomach of the leg' (referring to the bulging shape of the calf). Structure The gastrocnemius is located with the soleus in the posterior (back) compartment of the leg. The lateral head originates from the lateral condyle of the femur, while the medial head originates from the medial condyle of the femur. Its other end forms a common tendon with the soleus muscle; this tendon is known as the calcaneal tendon or Achilles tendon and inserts onto the posterior surface of the calcaneus, or heel bone. It is considered a superficial muscle as it is located directly under skin, and its shape may often ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
