Sphincter ani externus muscle
Information about Sphincter ani externus muscle
| Sphincter ani externus muscle | ||
|---|---|---|
) | ||
| Coronal section through the anal canal. B. Cavity of urinary bladder V.D. Ductus deferens. S.V. Seminal vesicle. R. Second part of rectum. A.C. Anal canal. L.A. Levator ani. I.S. Sphincter ani internus. E.S. Sphinear ani externus. | ||
| Latin | musculus sphincter ani externus | |
| subject #120 425 | ||
| Origin: | ||
| Insertion: | ||
| Artery: | ||
| Nerve: | branch from the fourth sacral and twigs from the inferior hemorrhoidal branch of the pudendal nerve | |
| Action: | keep the anal canal and orifice closed | |
| Dorlands/Elsevier | m_22/12550801 | |
It measures about 8 to 10 cm in length, from its anterior to its posterior extremity, and is about 2.5 cm broad opposite the anus.
It consists of two strata, superficial and deep.
- The superficial, constituting the main portion of the muscle, arises from a narrow tendinous band, the anococcygeal raphé, which stretches from the tip of the coccyx to the posterior margin of the anus; it forms two flattened planes of muscular tissue, which encircle the anus and meet in front to be inserted into the central tendinous point of the perineum, joining with the Transversus perinæi superficialis, the Levator ani, and the Bulbocavernosus.
- The deeper portion forms a complete sphincter to the anal canal. Its fibers surround the canal, closely applied to the Sphincter ani internus, and in front blend with the other muscles at the central point of the perineum.
Posteriorly, they are not attached to the coccyx, but are continuous with those of the opposite side behind the anal canal.
The upper edge of the muscle is ill-defined, since fibers are given off from it to join the Levator ani.
Actions
The action of this muscle is peculiar.(1) It is, like other muscles, always in a state of tonic contraction, and having no antagonistic muscle it keeps the anal canal and orifice closed.
(2) It can be put into a condition of greater contraction under the influence of the will, so as more firmly to occlude the anal aperture, in expiratory efforts unconnected with defecation.
(3) Taking its fixed point at the coccyx, it helps to fix the central point of the perineum, so that the Bulbocavernosus may act from this fixed point.
Additional images
) Intestines | Schematic demonstrating the anatomy of hemorrhoids. | Muscles of male perineum. | Muscles of the female perineum. |
) Vertical section of bladder, penis, and urethra. |
External links
- LUC spha
- SUNY Labs 42:13-0100 - "The Male Perineum and the Penis: The External Anal Sphincter"
- Norman/Georgetown perineum (analtriangle3)
Muscles of torso | |
|---|---|
| BACK | splenius: (capitis - cervicis) - erector spinae (iliocostalis - longissimus - spinalis) - latissimus dorsi transversospinales: (semispinalis dorsi - semispinalis cervicis - semispinalis capitis - multifidus - rotatores) - interspinales - intertransversarii |
| SUBOCCIPITAL | rectus capitis posterior (major, minor) - obliquus capitis (inferior, superior) |
| CHEST | intercostales (external, internal, innermost) - subcostales - transversus thoracis - levatores costarum - serratus posterior (inferior, superior) - diaphragm |
| ABDOMEN | obliques (external, internal) - transversus abdominis - rectus abdominis - pyramidalis - cremaster - quadratus lumborum |
| PELVIS | levator ani (iliococcygeus, pubococcygeus, puborectalis) - coccygeus |
| PERINEUM | sphincter ani (externus, internus) - superficial perineal pouch (transversus perinei superficialis - bulbospongiosus - ischiocavernosus) - deep perineal pouch (transversus perinei profundus, sphincter urethrae membranaceae) |
The anal canal is the terminal part of the large intestine.
It is situated between the rectum and anus, below the level of the pelvic diaphragm. It lies in the anal triangle of perineum in between the right and left ischiorectal fossae.
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It is situated between the rectum and anus, below the level of the pelvic diaphragm. It lies in the anal triangle of perineum in between the right and left ischiorectal fossae.
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In anatomy, the urinary bladder is a hollow, muscular, and distensible (or elastic) organ that sits on the pelvic floor in mammals. It is the organ that collects urine excreted by the kidneys prior to disposal by urination.
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The vas deferens (plural: vasa deferentia), also called ductus deferens, (Latin: "carrying-away vessel") is part of the male anatomy of some species, including humans.
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The seminal vesicles are a pair of simple tubular glands posteroinferior to the urinary bladder of males.
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Anatomy
They are approximately 5 cm in length, though the full length of the gland is approximately 10 cm and curled up inside of the structure...... Click the link for more information.
The rectum (from the Latin rectum intestinum, meaning straight intestine) is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long.
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The Levator ani is a broad, thin muscle, situated on the side of the pelvis.
It is attached to the inner surface of the side of the lesser pelvis, and unites with its fellow of the opposite side to form the greater part of the floor of the pelvic cavity.
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It is attached to the inner surface of the side of the lesser pelvis, and unites with its fellow of the opposite side to form the greater part of the floor of the pelvic cavity.
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The Sphincter ani internus (or internal anal sphincter) is a muscular ring which surrounds about 2.5 cm of the anal canal; its inferior border is in contact with, but quite separate from, the Sphincter ani externus.
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The Sphincter ani externus (external anal sphincter) is a flat plane of muscular fibers, elliptical in shape and intimately adherent to the integument surrounding the margin of the anus.
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Latin}}}
Official status
Official language of: Vatican City
Used for official purposes, but not spoken in everyday speech
Regulated by: Opus Fundatum Latinitas
Roman Catholic Church
Language codes
ISO 639-1: la
ISO 639-2: lat
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Official status
Official language of: Vatican City
Used for official purposes, but not spoken in everyday speech
Regulated by: Opus Fundatum Latinitas
Roman Catholic Church
Language codes
ISO 639-1: la
ISO 639-2: lat
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bold refer to the diagram at right.)
In the skull (8):
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In the skull (8):
- 1-9. cranium
- 7. mandible
- malleus
- incus
- stapes
- hyoid
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bold refer to the diagram at right.)
In the skull (8):
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In the skull (8):
- 1-9. cranium
- 7. mandible
- malleus
- incus
- stapes
- hyoid
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Arteries are muscular blood vessels that carry blood away from the heart.[1] All arteries, with the exception of the pulmonary and umbilical arteries, carry oxygenated blood.
The circulatory system is extremely important for sustaining life.
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The circulatory system is extremely important for sustaining life.
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- Accessory nerve
- Accessory obturator nerve
- Alderman's nerve
- Anococcygeal nerve
- Ansa cervicalis
- Anterior interosseous nerve
- Anterior superior alveolar nerve
- Aortic plexus
- Auerbach's plexus
- Auriculotemporal nerve
- Axillary nerve
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The pudendal nerve is a nerve in the pelvic region that innervates the external genitalia of both sexes, as well as sphincters for the bladder and the rectum.
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Anatomy
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Kinesiology is the scientific study of the anatomy, physiology, and mechanics of body movement, especially in humans. [1] The word kinesiology is derived the Greek "kinesis" (motion) + the suffix -ology or -logy from the greek "logos" or "logia"(meaning a field of study).
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The anal canal is the terminal part of the large intestine.
It is situated between the rectum and anus, below the level of the pelvic diaphragm. It lies in the anal triangle of perineum in between the right and left ischiorectal fossae.
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It is situated between the rectum and anus, below the level of the pelvic diaphragm. It lies in the anal triangle of perineum in between the right and left ischiorectal fossae.
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Elsevier, the world's largest publisher of medical and scientific literature, forms part of the Reed Elsevier group. Based in Amsterdam, the company has substantial operations in the UK, USA and elsewhere.
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anus (from Latin ānus "ring, anus") is the external opening of the rectum. Closure is controlled by sphincter muscles. Feces are expelled from the body through the anus during the act of defecation, which is the primary function of the anus.
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anococcygeal raphé (or anococcygeal ligament), which extends between the coccyx and the margin of the anus.
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External links
- Image at rsnajnls.org
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The coccyx (pronounced kok-siks) (Latin: os coccygis), commonly referred to as the tailbone, is the final segment of the human vertebral column, of four fused vertebrae (the coccygeal vertebrae) below the sacrum.
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The perineal body is a fibrous point in the middle line of the perineum. It is found in both males and females, and it is between the vagina and anus, and about 1.25 cm. in front of the latter.
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The Transversus perinei superficialis (Transversus perinei; Superficial transverse perineal muscle) is a narrow muscular slip, which passes more or less transversely across the perineal space in front of the anus.
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The Levator ani is a broad, thin muscle, situated on the side of the pelvis.
It is attached to the inner surface of the side of the lesser pelvis, and unites with its fellow of the opposite side to form the greater part of the floor of the pelvic cavity.
..... Click the link for more information.
It is attached to the inner surface of the side of the lesser pelvis, and unites with its fellow of the opposite side to form the greater part of the floor of the pelvic cavity.
..... Click the link for more information.
Bulbospongiosus (bulbocavernous in older texts) is one of the superficial muscles of the perineum. It has a slightly different origin, insertion and function in males and females. In males, it covers the bulb of the penis. In females, it covers the vestibular bulb.
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The anal canal is the terminal part of the large intestine.
It is situated between the rectum and anus, below the level of the pelvic diaphragm. It lies in the anal triangle of perineum in between the right and left ischiorectal fossae.
..... Click the link for more information.
It is situated between the rectum and anus, below the level of the pelvic diaphragm. It lies in the anal triangle of perineum in between the right and left ischiorectal fossae.
..... Click the link for more information.
The Sphincter ani internus (or internal anal sphincter) is a muscular ring which surrounds about 2.5 cm of the anal canal; its inferior border is in contact with, but quite separate from, the Sphincter ani externus.
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In human anatomy, the perineum, also called the "taint", "grundel" or "gooch", is generally defined as the surface region in both males and females between the pubic symphysis and the coccyx.
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Decussation is used in biological contexts to describe a crossing.[1][2]
Examples include:
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Examples include:
- In the brain
- Decussation of the pyramids
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The Transversus perinei superficialis (Transversus perinei; Superficial transverse perineal muscle) is a narrow muscular slip, which passes more or less transversely across the perineal space in front of the anus.
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The coccyx (pronounced kok-siks) (Latin: os coccygis), commonly referred to as the tailbone, is the final segment of the human vertebral column, of four fused vertebrae (the coccygeal vertebrae) below the sacrum.
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