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Questions and Answers
What is the main function of the superior gluteal artery?
Which of the following structures receives most of the venous blood from the pelvis?
What nerve structure contributes to the sacral plexus?
Which nerve structure supplies the muscles of the pelvic floor and perineum?
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What structures unite to form the coccygeal plexus?
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Through which opening does the superior gluteal artery leave the pelvis?
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What is the main action of the piriformis muscle?
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Which nerve innervates the piriformis muscle?
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Where does the piriformis muscle attach in the lower limb?
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Which artery supplies the piriformis muscle?
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Through which foramen does the piriformis muscle leave the lesser pelvis?
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Which vertebrae contribute to the origin of the piriformis muscle?
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Which nerves provide sympathetic innervation to the pelvis?
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What is the function of the pelvic diaphragm?
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Which muscle forms a U-turn around the anorectal junction and creates the urogenital hiatus?
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Which nerve provides parasympathetic supply to the pelvis?
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What is the source for subsequent plexuses that innervate the pelvic viscera?
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What structures form the pelvic diaphragm?
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What is the main function of the levator ani muscle?
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Where does the levator ani muscle originate from?
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What nerve innervates the levator ani muscle?
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What is the function of the coccygeus muscle?
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How does the pelvic diaphragm contribute during childbirth (parturition)?
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Which part of the levator ani muscle is often torn during childbirth?
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What structures are supported by the levator ani muscle?
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What condition may arise due to weakening of the levator ani muscle and pelvic fascia during childbirth?
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Which type of prolapse is characterized by the descent of the uterus into the vagina?
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What is the clinical term for the prolapse of both the urethra and bladder into the vagina?
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In 3rd degree uterine prolapse (Procidentia uteri), what protrudes out of the vaginal opening?
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Which condition results from alterations in the position of the bladder neck and urethra due to weakening of pelvic structures?
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Study Notes
Piriformis Muscle
- Located on either side of the pelvic cavity, passing laterally and attaching to the superior border of the greater trochanter of the femur
- Forms part of the posterolateral wall of the pelvic cavity
- Arises from the superior aspect of the sacrum (from S2 to S4 vertebrae), lateral to the sacral foramina
- Innervated by the Nerve to piriformis (S1-S2 spinal nerve roots)
- Supplied by superior and inferior gluteal arteries, gemellar branches of the internal pudendal artery
- Actions: external rotation of the thigh, abduction of the thigh when the hip joint is flexed, stabilizes head of femur in acetabulum
Pelvic Diaphragm
- Comprises of two paired muscles and their fasciae: levator ani muscle and coccygeus muscle
- Supports the pelvic organs and prevents them from prolapse
- Forms the pelvic floor and supports all of the pelvic viscera
- Levator ani muscle consists of three parts: puborectalis, pubococcygeus, and iliococcygeus
- Puborectalis part makes a U-turn around the anorectal junction (puborectal sling), forming the urogenital hiatus
- Urogenital hiatus transmits the rectum, urethra, and vagina in females
Clinical Significance of Pelvic Diaphragm
- Weakening of the levator ani and pelvic fascia from stretching or tearing during childbirth may decrease support for the vagina, bladder, uterus, or rectum
- May cause urinary stress incontinence, characterized by dribbling of urine when intra-abdominal pressure is raised during coughing and lifting
- May lead to the prolapse of one or more pelvic organs, such as:
- Cystocele (prolapse of bladder into the vagina)
- Urethrocystocele (prolapse of both urethra and bladder into the vagina)
- Uterine prolapse (descent of uterus into vagina), classified into three degrees: 1st degree, 2nd degree, or 3rd degree (procidentia uteri)
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Description
Test your knowledge on the anatomy of the piriformis muscle, a muscle located on either side of the pelvic cavity which plays a crucial role in hip movement. Learn about its origin, attachments, and functions.
