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Questions and Answers
What is the primary function of the obturator internus muscle?
What is the innervation of the gemellus inferior muscle?
From where does the quadratus femoris originate?
Which structures traverse the infrapiriform foramen?
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What is the insertion point of the obturator externus muscle?
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What is the main function of the gluteus maximus muscle?
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Which muscle is involved in the Trendelenburg sign?
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What is the innervation of the gluteus medius muscle?
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Which of the following muscles is responsible for laterally rotating the extended thigh?
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Where does the gluteus minimus muscle insert?
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Which muscle is primarily responsible for laterally rotating the thigh and has its origin at the ischial tuberosity?
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What is the primary action of the quadratus femoris muscle?
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Which structure traverses the lesser sciatic foramen?
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What nerve innervates the obturator externus muscle?
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Which of the following muscles has its insertion at the trochanteric fossa?
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What is the origin of the gluteus maximus muscle?
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Which muscle functions as the most powerful abductor of the thigh?
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What nerve innervates the gluteus minimus muscle?
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Which muscle's origin is on the dorsal surface of the ischial spine?
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What is the primary function of the piriformis muscle?
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What is the primary function of the gluteus minimus muscle?
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Which muscle is innervated by the inferior gluteal nerve?
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What is the innervation of the obturator internus muscle?
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What is the insertion point of the piriformis muscle?
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Which of the following muscles assists in adduction of the thigh?
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What is the common function of the obturator internus, gemellus inferior, and obturator externus muscles?
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Which structure is affected when a Trendelenburg sign is observed?
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Where does the gemellus inferior muscle insert?
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Which muscle primarily abducts and medially rotates the thigh?
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Which of the following structures traverses the suprapiriform foramen?
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Study Notes
Gluteal Region
-
Cutaneous Nerves:
- Cluneal nerves: superior, middle, and inferior
-
Gluteus Maximus Muscle:
- Origin: Ilium (posterior to the post. gluteal line), posterolateral aspect of sacrum & coccyx, sacrotuberal ligament, gluteal fascia
- Insertion: Gluteal tuberosity & ilitibial tract
- Nerve: Inferior Gluteal nerve
- Function: Most powerful extensor of thigh. Upper fibers abduct, lower fibers adduct thigh. Tenses fascia lata.
-
Gluteus Medius Muscle:
- Origin: Lateral surface of ilium between the posterior & anterior gluteal lines
- Insertion: Lateral aspect of greater trochanter
- Nerve: Superior Gluteal nerve
- Function: Most powerful abductor of thigh. Anterior fibers medially rotate & flex, posterior fibers laterally rotate & extend thigh.
Trendelenburg Sign
- This indicates a lesion to the gluteus medius & gluteus minimus muscles (superior gluteal nerve).
- Causes dipping of the pelvis on the good side.
-
Gluteus Minimus Muscle:
- Origin: Lateral surface of ilium between anterior & inferior gluteal lines
- Insertion: Upper part of greater trochanter
- Nerve: Superior Gluteal nerve
- Function: Medial rotation, abduction, & flexion of the thigh
-
Piriformis Muscle:
- Origin: Anterolateral aspect of pelvic sacral foramina 2-4, sacrotuberal ligament & articular capsule of sacroiliac joint
- Insertion: Upper part of greater trochanter
- Nerve: Sacral plexus (L5 - S2)
- Function: Laterally rotates extended thigh, abducts flexed thigh
-
Gemellus Superior Muscle
- Origin: Dorsal surface of ischial spine
- Insertion: Joins obturator internus muscle and inserts to trochanteric fossa
- Nerve: Sacral plexus (L5 -S1)
- Function: Laterally rotates thigh
-
Obturator Internus Muscle:
- Origin: Pelvic surface of obturator foramen & obturator membrane
- Insertion: Traverses lesser sciatic foramen & inserts to trochanteric fossa
- Nerve: Nerve to obturator internus (L5 - S1)
- Function: Laterally rotates thigh
-
Gemellus Inferior Muscle:
- Origin: Ischial tuberosity
- Insertion: Trochanteric fossa
- Nerve: Sacral plexus (L5 - S1)
- Function: Laterally rotates thigh
-
Quadratus Femoris Muscle:
- Origin: Lateral aspect of ischial tuberosity
- Insertion: Intertrochanteric crest
- Nerve: Nerve to quadratus femoris (L5 - S1)
- Function: Laterally rotates the thigh, assists adduction.
-
Obturator Externus Muscle:
- Origin: Lateral surface of obturator foramen & obturator membrane
- Insertion: Trochanteric fossa
- Nerve: Posterior branch of obturator nerve (L3-4)
- Function: Laterally rotates thigh
Foramina in the Gluteal Region
-
Suprapiriform Foramen:
- Superior gluteal vessels
-
Infrapiriform Foramen:
- Inferior gluteal vessels
- Internal pudendal vessels
- Pudendal nerve
- Sciatic nerve
- Posterior cutaneous nerve of thigh
-
Lesser Sciatic Foramen:
- Internal pudendal artery, vein, and pudendal nerve
- Obturator internus muscle
Arteries of the Region
- Internal iliac artery
Palpable Structures
- Iliac crest
- Anterior superior iliac spine (ASIS)
- Posterior superior iliac spine (PSIS)
- Ischial tuberosity
- Greater trochanter
- Median sacral crest
- Coccyx
Gluteal Region Anatomy
- Cutaneous Nerves: The gluteal region is innervated by the cluneal nerves which are branches of the posterior rami of spinal nerves. These are divided into: superior, middle, and inferior cluneal nerves.
- Gluteus Maximus: This is the largest and most superficial muscle in the gluteal region, responsible for extending the thigh and assisting in abduction and adduction depending on the fiber location.
- Gluteus Medius: Located laterally and superior to the gluteus maximus muscle, this muscle is responsible for abducting the thigh and assists in rotation depending on fiber location. The superior gluteal nerve innervates this muscle.
- Gluteus Minimus is considered the deepest muscle in the gluteal region, acting as an internal rotator, abductor, and flexor of the thigh. Innervated by the superior gluteal nerve. This muscle is integral to the Trendelenburg sign.
- Trendelenburg Sign: If the superior gluteal nerve or gluteus medius and minimus are damaged, weakness in the hip abductors occurs. This results in the dipping of the pelvis on the healthy side when the patient stands on one leg. This is known as the Trendelenburg sign.
- Piriformis: Another major muscle in the gluteal region, this muscle externally rotates the thigh when extended, and abducts the thigh when flexed.
- Gemellus Superior and Inferior - These muscles are accessory rotators of the thigh, working in conjunction with the obturator internus muscle.
- Obturator Internus: Extends from the pelvic surface of the obturator foramen and attaches to the trochanteric fossa, this muscle is responsible for external rotation of the thigh.
- Quadratus Femoris: Located inferiorly to the gemelli muscles, this muscle acts as an external rotator and adductor of the thigh.
- Obturator Externus: Externally rotates the thigh and is located on the lateral side of the obturator foramen.
- Blood Supply The gluteal region is primarily supplied by the internal iliac artery.
### Neurovascular Foramina
- Suprapiriform Foramen: The superior gluteal artery and vein pass through the suprapiriform foramen.
- Infrapiriform Foramen: The inferior gluteal artery and vein, internal pudendal artery and vein, pudendal nerve, sciatic nerve and posterior cutaneous nerve of the thigh pass through the infrapiriform foramen.
- Lesser Sciatic Foramen: This foramen allows the passage of the internal pudendal artery and vein, as well as the pudendal nerve and the obturator internus muscle.
Palpable Structures
- The following structures are palpable in the gluteal region:
- Iliac Crest
- Anterior Superior Iliac Spine (ASIS)
- Posterior Superior Iliac Spine (PSIS)
- Ischial Tuberosity
- Greater Trochanter
- Median Sacral Crest
- Coccyx
Cutaneous Nerves
- The gluteal region is innervated by the cluneal nerves which include the superior, middle, and inferior clunial nerves.
Gluteus Maximus Muscle
- The gluteus maximus is the largest and most superficial gluteal muscle.
- It originates from the posterior iliac spine, sacrum, and coccyx.
- It inserts into the gluteal tuberosity and iliotibial tract.
- It is innervated by the inferior gluteal nerve.
- It is the most powerful extensor of the thigh.
- It functions in abduction and adduction of the thigh depending on the fibers being used.
- It tenses the fascia lata.
Gluteus Medius Muscle
- The gluteus medius muscle originates from the lateral surface of the ilium between the posterior and anterior gluteal lines.
- It inserts into the lateral aspect of the greater trochanter.
- It's innervated by the superior gluteal nerve.
- It's the most powerful abductor of the thigh.
- Anterior fibers medially rotate and flex the thigh.
- Posterior fibers laterally rotate and extend the thigh.
Trendelenburg Sign
- This is a sign of a lesion to the gluteus medius and minimus muscles, which are innervated by the superior gluteal nerve.
- It is characterized by a dipping of the pelvis on the unaffected side.
- It can be observed when a person stands on one leg.
Gluteus Minimus Muscle
- The gluteus mimimus muscle originates from the lateral surface of the ilium between the anterior and inferior gluteal lines.
- It inserts into the upper part of the greater trochanter.
- It's innervated by the superior gluteal nerve.
- It functions in medial rotation, abduction, and flexion of the thigh.
Piriformis Muscle
- The piriformis muscle originates from the anterolateral aspect of the pelvic sacral foramina 2-4, the sacrotuberal ligament, and the articular capsule of the sacroiliac joint.
- It inserts into the upper part of the greater trochanter.
- It's innervated by the sacral plexus (L5 - S2).
- It laterally rotates the extended thigh.
- It abducts the flexed thigh.
Gemellus Superior Muscle
- The gemellus superior muscle originates from the dorsal surface of the ischial spine.
- It joins the obturator internus muscle and inserts into the trochanteric fossa.
- It's innervated by the sacral plexus (L5 - S1).
- It laterally rotates the thigh.
Obturator Internus Muscle
- The obturator internus muscle originates from the pelvic surface of the obturator foramen and obturator membrane.
- It traverses the lesser sciatic foramen and inserts into the trochanteric fossa.
- It's innervated by the nerve to the obturator internus (L5 - S1).
- It laterally rotates the thigh.
Gemellus Inferior Muscle
- The gemellus inferior muscle originates from the ischial tuberosity.
- It inserts into the trochanteric fossa.
- It's innervated by the sacral plexus (L5 - S1).
- It laterally rotates the thigh.
Quadratus Femoris Muscle
- The quadratus femoris originates from the lateral aspect of the ischial tuberosity.
- It inserts into the intertrochanteric crest.
- It's innervated by the nerve to the quadratus femoris (L5 - S1).
- It laterally rotates the thigh.
- It assists with adduction of the thigh.
Obturator Externus Muscle
- The obturator externus muscle originates from the lateral surface of the obturator foramen and obturator membrane.
- It inserts into the trochanteric fossa.
- It's innervated by the posterior branch of the obturator nerve (L3-4).
- It laterally rotates the thigh
Foramina of the Gluteal Region
- The suprapiriform foramen houses the superior gluteal vessels.
- The infrapiriform foramen is traversed by the inferior gluteal vessels, internal pudendal vessels, pudendal nerve, sciatic nerve, and posterior cutaneous nerve of the thigh.
- The lesser sciatic foramen contains the internal pudendal artery, vein, and pudendal nerve, as well as the obturator internus muscle
Arteries of the Gluteal Region
- The internal iliac artery is the main artery supplying the gluteal region.
Palpable Structures
- The iliac crest, anterior superior iliac spine (ASIS), posterior superior iliac spine (PSIS), ischial tuberosity, greater trochanter, median sacral crest, and coccyx are all palpable bony landmarks in the gluteal region.
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Description
Explore the anatomy of the gluteal region, including key muscles like the gluteus maximus, medius, and their functions. Understand the roles of cutaneous nerves and learn about the Trendelenburg sign as it relates to gluteal muscle lesions. This quiz is essential for students of anatomy and physical therapy.
