Podcast
Questions and Answers
What is the primary function of the piriformis muscle?
What is the primary function of the piriformis muscle?
Which anatomical structure does the piriformis muscle leave the pelvis through?
Which anatomical structure does the piriformis muscle leave the pelvis through?
What structures are found in the infrapiriform recess?
What structures are found in the infrapiriform recess?
What is the consequence of inflammation or spasm of the piriformis muscle?
What is the consequence of inflammation or spasm of the piriformis muscle?
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What level of pelvic support is primarily provided by the uterosacral and cardinal ligaments?
What level of pelvic support is primarily provided by the uterosacral and cardinal ligaments?
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What is the main function of the pelvic girdle?
What is the main function of the pelvic girdle?
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Which bony landmark is considered the 'socket' for the hip joint?
Which bony landmark is considered the 'socket' for the hip joint?
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What structure provides passage for the terminal perineum while containing and protecting pelvic viscera?
What structure provides passage for the terminal perineum while containing and protecting pelvic viscera?
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Which of the following is NOT a component of the pelvis?
Which of the following is NOT a component of the pelvis?
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What is the degree of inclination of the pelvic brim?
What is the degree of inclination of the pelvic brim?
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Which line is part of the pelvic brim that helps define its boundaries?
Which line is part of the pelvic brim that helps define its boundaries?
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What structure serves as the 'ball' of the hip joint?
What structure serves as the 'ball' of the hip joint?
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Which part of the pelvic girdle is formed from the fusion of the ilium and ischium?
Which part of the pelvic girdle is formed from the fusion of the ilium and ischium?
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Which artery is a direct branch from the abdominal aorta supplying the ovaries?
Which artery is a direct branch from the abdominal aorta supplying the ovaries?
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What is the role of the internal iliac artery ligation in relation to blood flow?
What is the role of the internal iliac artery ligation in relation to blood flow?
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Which of the following arteries branches from the anterior trunk of the internal iliac artery?
Which of the following arteries branches from the anterior trunk of the internal iliac artery?
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Which arterial anastomosis is NOT associated with the ligation of the internal iliac artery?
Which arterial anastomosis is NOT associated with the ligation of the internal iliac artery?
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What is the primary venous drainage route for the right ovarian vein?
What is the primary venous drainage route for the right ovarian vein?
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Which artery branches directly from the internal iliac artery to supply the gluteal region?
Which artery branches directly from the internal iliac artery to supply the gluteal region?
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What structure does the internal iliac artery primarily supply?
What structure does the internal iliac artery primarily supply?
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What condition might result from ligation of the internal iliac artery?
What condition might result from ligation of the internal iliac artery?
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What anatomical structure forms the pudendal canal?
What anatomical structure forms the pudendal canal?
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Which area is NOT anesthetized during a pudendal block?
Which area is NOT anesthetized during a pudendal block?
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What is a characteristic feature of epidural anesthesia compared to other methods?
What is a characteristic feature of epidural anesthesia compared to other methods?
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Which procedure is caudal anesthesia particularly useful for?
Which procedure is caudal anesthesia particularly useful for?
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What shape does the perineum form when the thighs are abducted?
What shape does the perineum form when the thighs are abducted?
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What causes anterior pelvic tilt?
What causes anterior pelvic tilt?
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In posterior pelvic tilt, which landmarks are positioned correctly?
In posterior pelvic tilt, which landmarks are positioned correctly?
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What is lateral pelvic tilt characterized by?
What is lateral pelvic tilt characterized by?
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Which condition can cause posterior pelvic tilt?
Which condition can cause posterior pelvic tilt?
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Which muscle is NOT mentioned in relation to pelvic tilt?
Which muscle is NOT mentioned in relation to pelvic tilt?
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Which of the following best describes the function of the psoas major?
Which of the following best describes the function of the psoas major?
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What imbalance characterizes lower crossed syndrome?
What imbalance characterizes lower crossed syndrome?
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Which nerve emerges lateral to the psoas major muscle?
Which nerve emerges lateral to the psoas major muscle?
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Study Notes
Bony Landmarks of the Pelvis
- Acetabulum is the socket of the hip joint, the femoral head is the ball.
- Greater and Lesser Trochanter are bony prominences on the femur.
- Femoral Neck is the segment of the femur connecting the head to the shaft.
- Pubis, Ischium, and Ilium are the three bones that fuse to form the hip bone.
- Anterior Sacral Foramen houses the ventral rami of sacral spinal nerves.
- Posterior Sacral Foramen holds the dorsal rami of sacral spinal nerves.
- Sacral Hiatus contains fat, filum terminale, S5 nerve, and coccygeal nerve.
Pelvis and Pelvic Girdle
- The pelvic girdle bears weight and transfers it from the axial skeleton to the lower appendicular skeleton.
- It provides attachment points for muscles involved in locomotion of the lower extremity and pelvic floor muscles and membranes.
- The pelvis is formed by the bilateral hip bones, sacrum, and coccyx.
- The hip bone is the result of the fusion of the ilium, ischium, and pubis, which meet at the acetabulum.
Function of the Pelvic Girdle
- Contains and protects pelvic and inferior abdominal viscera while enabling passage of the terminal perineum.
- Supports abdominopelvic viscera and the gravid uterus.
- Provides attachment for erectile bodies of the external genitalia.
- Serves as an attachment point for muscles and membranes.
Pelvic Brim
- Also known as the Linea Terminalis, Superior Pelvic Aperture, or Pelvic Inlet.
- Comprises:
- Sacral Promontory
- Ala of the sacrum
- Arcuate line
- Pectineal line
- Pubic Crest
- The pelvic brim is inclined at 55 degrees, meaning the pelvis slopes downwards and forwards.
- Pelvic tilt refers to the angle of the pelvis relative to the vertical axis.
- Posterior Pelvic Tilt: Front of pelvis tilts upward and backward; ASIS is posterior and superior; PSIS is posterior and inferior.
- Anterior Pelvic Tilt: Front of pelvis tilts forward; ASIS is anterior and inferior; PSIS is anterior and superior.
- Lateral Pelvic Tilt: Pelvis shifts side to side, one side being higher than the other.
Muscles of the Pelvis
-
Psoas Major:
- Origin: Bodies and transverse processes of lumbar vertebrae.
- Insertion: Lesser trochanter of femur.
- Function: Flexes and laterally bends the lumbar vertebral column.
- Nerve: Branches of ventral primary rami of spinal nerves L2-L4.
- Relationships: Genitofemoral nerve pierces the anterior surface; Femoral nerve emerges lateral; Obturator nerve is medial.
-
Psoas Minor:
- Function: Flexes and laterally bends the lumbar vertebral column.
- Nerve: Branches of the ventral primary ramus of spinal nerves L1-L2.
- Artery: Lumbar artery.
-
Piriformis:
- Creates two recesses: Suprapiriform recess contains superior gluteal neurovascular bundle; Infrapiriform recess holds inferior gluteal neurovascular bundle, sciatic nerve, and pudendal neurovascular bundle.
- Function: Laterally rotates and abducts the thigh; assists in holding the femoral head in the acetabulum.
- Distal attachment: Greater trochanter of the femur.
Levels of Support
- Level I: Provided by uterosacral and cardinal ligaments; support uterus and vaginal apex.
- Level II: By lateral attachments of endopelvic fascia and vagina to arcus tendineus fascia pelvis; supports bladder, vagina, and rectum.
- Level III: Perineal membrane and perineal body; supports the ureterovesical junction and perineum.
Pelvic Vasculature, Lymphatics, and Nerve Supply
-
Arterial Supply:
- Abdominal aorta branches into common iliac arteries.
- External iliac artery supplies the lower extremity and branches into the inferior epigastric artery and the deep circumflex iliac artery.
- Internal Iliac artery supplies pelvic organs, gluteal muscles, and peritoneum.
-
Branches of the Internal Iliac Artery:
- Posterior Trunk: Iliolumbar, Lateral Sacral, and Superior Gluteal arteries.
- Anterior Trunk: Internal Pudendal, Inferior Vesical, Obturator, Inferior Rectal, Deferential, Scrotal/Labial, Vas Deferens (male), Uterine (female), Umbilical, Superior Vesical, Middle Vesical, Middle Rectal (Hemorrhoidal), Vaginal (female), Vesicular (male).
- Ligation of the Internal Iliac Artery: Does not completely stop blood flow due to arterial anastomoses between the lumbar and iliolumbar, median sacral and lateral sacral, and superior rectal and middle rectal arteries.
-
Blood Supply to the Ovaries:
- Arterial supply: Ovarian artery (direct branch from the abdominal aorta).
- Venous drainage: Left ovarian vein to left renal vein; Right ovarian vein to the inferior vena cava.
- Venous Return to the Pelvis: Internal iliac vein and external iliac vein join to form the common iliac vein.
- Pudendal Canal: Also known as Alcock's canal; formed by the obturator internus fascia; contains the internal pudendal artery, veins, and nerve.
Anesthesia for Childbirth
- Spinal: Administered at L3-L4 subarachnoid space; anesthetizes everything from the waist down.
- Pudendal: Blocks S2-S4 dermatomes (sensory block); anesthetizes the lower 1/4 of the vagina and most of the perineum; cervix, uterus, and upper vagina remain unaffected; useful for episiotomies; palpate the ischial spine to localize the nerve region.
- Epidural: Administered at nerve roots S2-S4; affects pain fibers from the uterus and upper vagina, as well as afferent fibers from the pudendal nerve; anesthetizes the birth canal, most of the perineum, and pelvic floor, while sparing the lower extremities.
- Caudal Anesthesia: Useful for sub-umbilical procedures in children, such as inguinal hernia repair, urological interventions, and anal atresia repair; palpate the sacral hiatus for caudal epidural injections.
The Perineum and External Genitalia
- The perineum is the area below the pelvic diaphragm, covering the pelvic outlet.
- In anatomical position, it is a narrow space between the thighs.
- Abducted thighs form a diamond shape with the ischial tuberosities, extending from the pubis to the coccyx.
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Description
Explore the key bony landmarks of the pelvis, including the acetabulum, femoral neck, and trochanters. This quiz covers the structural components and functions of the pelvic girdle, crucial for understanding human anatomy. Test your knowledge on the bones that form the hip and their roles in locomotion.
