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Pudendal Nerve Motor Latency Test
The pudendal nerve is the main nerve of the perineum. It is a mixed (motor and sensory) nerve and also conveys sympathetic autonomic fibers. It carries sensation from the external genitalia of both sexes and the skin around the anus and perineum, as well as the motor supply to various pelvic muscles, including the male or female external urethral sphincter and the external anal sphincter. If damaged, most commonly by childbirth, loss of sensation or fecal incontinence may result. The nerve may be temporarily anesthetized, called pudendal anesthesia or pudendal block. The pudendal canal that carries the pudendal nerve is also known by the eponymous term "Alcock's canal", after Benjamin Alcock, an Irish anatomist who documented the canal in 1836. Structure Origin The pudendal nerve is paired, meaning there are two nerves, one on the left and one on the right side of the body. Each is formed as three roots immediately converge above the upper border of the sacrotubero ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Posterior Cutaneous Nerve Of Thigh
The posterior cutaneous nerve of the thigh (also called the posterior femoral cutaneous nerve) is a sensory nerve of the thigh. It is a branch of the sacral plexus. It supplies the skin of the posterior surface of the thigh, leg, buttock, and also the perineum. Unlike most nerves termed "cutaneous" which are subcutaneous, only the terminal branches of this nerve pass into subcutaneous tissue before being distributed to the skin, with most of the nerve itself situated deep to the deep fascia. Structure Origin The posterior cutaneous nerve of the thigh is a branch of the sacral plexus. It arises from the posterior divisions of the S1- S2, and the anterior divisions of S2- S3 sacral spinal nerves. Course It leaves the pelvis through the greater sciatic foramen inferior to the piriformis muscle. It then descends deep to the gluteus maximus muscle, medial or posterior to the sciatic nerve, and alongside the inferior gluteal artery. It descends within the posterior thigh dee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
External Anal Sphincter
The external anal sphincter (or sphincter ani externus) is an oval tube of skeletal muscle fibers. Distally, it is adherent to the skin surrounding the margin of the anus. It exhibits a resting state of tonical contraction and also contracts during the bulbospongiosus reflex. Anatomy The external anal sphincter is far more substantial than the internal anal sphincter. The proximal portion of external anal sphincter overlaps the internal anal sphincter (which terminates distally a little distance proximal to the anal orifice) superficially; where the two overlap, they are separated by the intervening conjoint longitudinal muscle. Structure Historically, the sphincter was described as consisting of three parts (deep, superficial, and subcutaneous). This is not supported by current anatomical knowledge. Some sources still describe it in two layers, deep (or proximal) and superficial (or distal or subcutaneous). Some of the muscles fibres decussate at the anterior midline and po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greater Sciatic Foramen
The greater sciatic foramen is an opening (:wikt:foramen, foramen) in the posterior human pelvis. It is formed by the sacrotuberous ligament, sacrotuberous and sacrospinous ligaments. The piriformis muscle passes through the foramen and occupies most of its volume. The greater sciatic foramen is wider in women than in men. Structure It is bounded as follows: * anterolaterally by the greater sciatic notch of the Ilium (bone), ilium. * posteromedially by the sacrotuberous ligament. * inferiorly by the sacrospinous ligament and the ischial spine. * superiorly by the anterior sacroiliac ligament. Function The piriformis, which exits the pelvis through the foramen, occupies most of its volume. The following structures also exit the pelvis through the greater sciatic foramen: See also *Lesser sciatic foramen References External links * * (, ) {{Authority control Anatomy Bones of the pelvis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coccygeus
The coccygeus muscle or ischiococcygeus is a muscle of the pelvic floor located posterior to levator ani and anterior to the sacrospinous ligament. Structure The coccygeus muscle is posterior to levator ani and anterior to the sacrospinous ligament in the pelvic floor. It is a triangular plane of muscular and tendinous fibers. It arises by its apex from the spine of the ischium and sacrospinous ligament. It is inserted by its base into the margin of the coccyx and into the side of the lowest piece of the sacrum. In combination with the levator ani, it forms the pelvic diaphragm. The pudendal nerve runs between the coccygeus muscle and the piriformis muscle, superficial to the coccygeus muscle. Nerve supply The coccygeus muscle is innervated by the pudendal nerve, which runs between it and the piriformis muscle. Function The coccygeus muscle assists the levator ani and piriformis muscle in closing in the back part of the outlet of the pelvis. This helps to support the vagi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Piriformis Muscle
The piriformis muscle () is a flat, pyramidally-shaped muscle in the buttock, 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 Pelvic surface of sacrum, anterior (front) surface of the sacrum by three fleshy digitations attached to the Sacrum, second, third, and fourth sacral vertebra. It also arises from the superior margin of the greater sciatic notch, the gluteal surface of the Ilium (bone), ilium (near the posterior inferior iliac spine), the sacroiliac joint capsule, and (sometimes) the sacrotuberous ligament (m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sacral Spinal Nerves
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 root 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 ve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ventral Rami
The ventral ramus (: rami) (Latin for 'branch') is the anterior division of a spinal nerve. The ventral rami supply the antero-lateral parts of the trunk and the limbs. They are mainly larger than the dorsal rami. Shortly after a spinal nerve exits the intervertebral foramen, it branches into the dorsal ramus, the ventral ramus, and the ramus communicans. Each of these three structures carries both sensory and motor information. Each spinal nerve is a mixed nerve that carries both sensory and motor information, via efferent and afferent nerve fibers—ultimately via the motor cortex in the frontal lobe and to somatosensory cortex in the parietal lobe—but also through the phenomenon of reflex. In the thoracic region they remain distinct from each other and each innervates a narrow strip of muscle and skin along the sides, chest, ribs, and abdominal wall. These rami are called the intercostal nerves. In regions other than the thoracic, ventral rami converge with ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sacrospinous Ligament
The sacrospinous ligament (small or anterior sacrosciatic ligament) is a thin, triangular ligament in the human pelvis. The base of the ligament is attached to the outer edge of the sacrum and coccyx, and the tip of the ligament attaches to the ischial spine, spine of the ischium, a bony protuberance on the human pelvis. Its fibres are intermingled with the sacrotuberous ligament. Structure The sacrotuberous ligament passes behind the sacrospinous ligament. In its entire length, the sacrospinous ligament covers the equally triangular coccygeus muscle, to which its closely connected.Gray's Anatomy 1918 Function The presence of the ligament in the greater sciatic notch creates an opening (:wikt:foramen, foramen), the greater sciatic foramen, and also converts the lesser sciatic notch into the lesser sciatic foramen.Platzer (2004), p 188 The greater sciatic foramen lies above the ligament, and the lesser sciatic foramen lies below it. The pudendal vessels and pudendal nerve, nerv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coccygeus Muscle
The coccygeus muscle or ischiococcygeus is a muscle of the pelvic floor located posterior to levator ani and anterior to the sacrospinous ligament. Structure The coccygeus muscle is posterior to levator ani and anterior to the sacrospinous ligament in the pelvic floor. It is a triangular plane of muscular and tendinous fibers. It arises by its apex from the spine of the ischium and sacrospinous ligament. It is inserted by its base into the margin of the coccyx and into the side of the lowest piece of the sacrum. In combination with the levator ani, it forms the pelvic diaphragm. The pudendal nerve runs between the coccygeus muscle and the piriformis muscle, superficial to the coccygeus muscle. Nerve supply The coccygeus muscle is innervated by the pudendal nerve, which runs between it and the piriformis muscle. Function The coccygeus muscle assists the levator ani and piriformis muscle in closing in the back part of the outlet of the pelvis. This helps to support the vagi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sacrotuberous Ligament
The sacrotuberous ligament (great or posterior sacrosciatic ligament) is situated at the lower and back part of the pelvis. It is flat, and triangular in form; narrower in the middle than at the ends. Structure It runs from the sacrum (the lower transverse sacral tubercles, the inferior margins sacrum and the upper coccyx) to the tuberosity of the ischium. It is a remnant of part of biceps femoris muscle. The sacrotuberous ligament is attached by its broad base to the posterior superior iliac spine, the posterior sacroiliac ligaments (with which it is partly blended), to the lower transverse sacral tubercles and the lateral margins of the lower sacrum and upper coccyx. Its oblique fibres descend laterally, converging to form a thick, narrow band that widens again below and is attached to the medial margin of the ischial tuberosity. It then spreads along the ischial ramus as the falciform process, whose concave edge blends with the fascial sheath of the internal pudendal vessels ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benjamin Alcock
Benjamin Alcock (1801 – 1865) was an Irish anatomist. He is remembered for his description of the pudendal nerve sheath, which came to be known as Alcock's canal, later more usually called the pudendal canal, and an associated disease, Alcock canal syndrome, also known as pudendal nerve entrapment or pudendal neuralgia. Born in Kilkenny, Ireland, he was the eldest of three sons and at least two daughters of Deborah Prim and Nathaniel Alcock (1770-1836), medical officer of the Kilkenny Dispensary. He became an accomplished anatomist working for some time under the leading Irish surgeon, Abraham Colles. After studying at Kilkenny College, he entered the University of Dublin, Trinity College in 1816, coming first in the College Entrance Examination and graduating B.A. in 1821. In 1825 Alcock became a licentiate of the Royal College of Surgeons in Ireland and obtained his M.B. degree from Trinity College Dublin in 1827. He became a member of the Royal College of Surgeons late ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
