Anatomy of the Hip Muscles Quiz

Anatomy of the Gluteal Region

• The pelvic girdle's bones are connected by strong ligaments
• Two important ligaments are the sacrospinous and sacrotuberous ligaments
• These ligaments transform the greater and lesser sciatic notches into foramina (openings)
• The greater sciatic foramen allows nerves and arteries to pass to the gluteal region
• The lesser sciatic foramen also provides a pathway though which structures can pass

Gluteal Muscles

• Gluteal muscles can be divided into superficial and deep layers
• The superficial layer includes gluteus maximus, medius, and minimus, and tensor fasciae latae
• The deep layer consists of six short lateral rotators (piriformis, superior gemellus, inferior gemellus, obturator internus, obturator externus, quadratus femoris)
• All deep layer muscles originate adjacent to the intertrochanteric crest and insert on the greater trochanter.
• Deep layer muscles contribute to hip stabilization, particularly posteriorly.

Muscle Names

• Piriformis (pear-shaped)

• Superior Gemellus (two-part)

• Inferior Gemellus (two-part)

• Obturator Internus

• Quadratus Femoris

• Obturator Externus

• Four major muscles can be viewed (three cannot) during dissection: piriformis, gluteus medius, gluteus maximus (partially visible), quadratus femoris

• Piriformis is a landmark muscle origination from the sacrum, passing through the greater sciatic foramen, and attaching to the superior border of the greater trochanter

Piriformis - A Key Landmark of the Gluteal Region

• Originates from the anterior surface of the sacrum
• Passes through the greater sciatic foramen near the greater sciatic notch.
• Attaches to the superior border of the greater trochanter.
• Also marks the naming of the gluteal vessels and nerves, giving rise to superior and inferior gluteal nerve and artery.

Gemellus & Obturator Internus

• Gemellus muscles originate from the ischial bone (superior or inferior ischial spine/tuberosity).
• The Gemellus muscles and obturator internus blend with the tendon and attach to the greater trochanteric fossa.
• Obturator internus originates from the pelvic surface of the obturator membrane.
• It exits through the lesser sciatic notch.
• Obturator internus muscle fibers and gemellus muscle fibers are difficult to distinguish.

Quadratus Femoris

• Originates from the lateral border of the ischial tuberosity.
• Attaches to the intertrochanteric crest.

Obturator Externus

• Originates from the margins of the obturator foramen and membrane.
• Passes under the neck of the femur.
• Attaches to the trochanteric fossa.
• Covered by other lateral rotators

Gluteus Medius & Minimus

• Originate from the external surface of the ilium.
• Shape is fan-like
• Attach to the anterior superior region of the greater trochanter.
• Key function is abduction of the thigh.
• Anterior fibers medially rotate the thigh.

Superior Gluteal Nerve & Artery

• Gluteus medius and minimus muscles are supplied by the superior gluteal nerve and artery (L4-L5 & S1).
• Supplies nerve and blood vessels to these muscles.
• How frequently do humans abduct (move outwards away from center line) their thighs?

Crucial Role in Walking

• Gluteus medius and minimus muscles on the stance leg stabilize the pelvis (during walking or other activities) so it does not collapse, ensuring the body supports weight over one leg during stance phase of walking
• Gluteus muscles help to keep the pelvis relatively level during walking
• Paralysis of the superior gluteal nerve results in Trendelenburg gait (pelvic drop on the opposite side).

Medial & Lateral Rotation in Walking

• Medial/lateral hip rotation of stance and advancing leg creates a smooth gait.
• The advancing limb's lateral rotation works with the medial rotation of the planted (fixed) limb to make continuous movement while walking.

Iliotibial Tract (IT Band)

• Fibrous reinforcement of the fascia lata.
• Originates from the anterolateral superior iliac tubercle.
• Inserts on the anterolateral tubercle of the tibia (Gerdy's tubercle)
• Forms part of the lateral intermuscular septum of the thigh.
• Operates as aponeurosis of the associated muscles.

Gluteus Maximus

• Originates from the posterior third of the iliac crest, sacrum, coccyx, and sacrotuberous ligament
• Inserts majorly into the iliotibial tract, some fibers directly to the gluteal tuberosity, of the femur.
• Main actions: hip extension and lateral rotation.

Why Do We Have Gluteus Maximus?

• Strongest hip extensor in humans, often not used for walking.
• Used more in activities involving climbing stairs, climbing hills, or forceful hip extension.

Inferior Gluteal Nerve & Artery

• Gluteus maximus is innervated and supplied by the inferior gluteal nerve and artery.
• The inferior gluteal nerve (L5–S1–S2) aids in movement, while artery maintains blood supply.

Tensor of the Fascia Lata

• Synergist muscle for other muscles and supports the action of iliopsoas and rectus femoris.
• Actions include hip flexion and assists in abduction/medial rotation of the thigh.
• Innervated by the superior gluteal nerve.

Gluteal Bursae (Trochanteric, Ischial & Gluteofemoral)

• These are small fluid-filled sacs that reduce friction between muscles and other tissues, allowing for smooth movement within the hip and surrounding structures.
• Trochanteric bursa is the largest of the three and is commonly affected by bursitis.
• Ischial bursa is often absent.

Sciatic Nerve

• Sciatic nerve courses alongside the greater trochanter and ischial tuberosity.
• A landmark to visualize
• Useful for clinical examination for diagnosis

Gluteal Intramuscular Injections

• Common injection site is the proximal part of the gluteus medius, located in the superolateral quadrant.
• This location minimizes potential harm to nearby nerves and vessels