Gluteal Region and Posterior Thigh, and Popliteal Fossa Flashcards
What are the deep lateral rotators of the gluteal region?
A group of smaller muscles that mainly act to laterally rotate the femur. Includes the quadratus femoris, piriformis, gemellus superior, gemellus inferior and obturator internus.
Gluteus Maximus
The gluteus maximus is the largest of the gluteal muscles. It is also the most superficial, producing the shape of the buttocks. Attachments: Originates from the gluteal (posterior) surface of the ilium, sacrum and coccyx. It slopes across the buttock at a 45 degree angle, then inserts into the iliotibial tract and the gluteal tuberosity of the femur. Actions: It is the main extensor of the thigh, and assists with lateral rotation. However, it is only used when force is required, such as running or climbing. Innervation: Inferior gluteal nerve
Gluteus Medius
The gluteus medius muscle is fan-shaped and lies between to the gluteus maximus and the minimus. It is similar is shape and function to the gluteus minimus. Attachments: Originates from the gluteal surface of the ilium and inserts into the lateral surface of the greater trochanter. Actions: Abducts and medially rotates the lower limb. During locomotion, it secures the pelvis, preventing pelvic drop of the opposite limb. (Note: the posterior fibres of the gluteus medius are also thought to produce a small amount of lateral rotation). Innervation: Superior gluteal nerve.
Gluteus Minimus
The gluteus minimus is the deepest and smallest of the superficial gluteal muscles. It is similar is shape and function to the gluteus medius. Attachments: Originates from the ilium and converges to form a tendon, inserting to the anterior side of the greater trochanter. Actions: Abducts and medially rotates the lower limb. During locomotion, it secures the pelvis, preventing pelvic drop of the opposite limb. Innervation: Superior gluteal nerve.
Tensor Fascia Lata
Tensor fasciae lata is a small superficial muscle which lies towards the anterior edge of the iliac crest. It functions to tighten the fascia lata, and so abducts and medially rotates the lower limb. Attachments: Originates from the anterior iliac crest, attaching to the anterior superior iliac spine (ASIS). It inserts into the iliotibial tract, which itself attaches to the lateral condyle of the tibia. Actions: Assists the gluteus medius and minimus in abduction and medial rotation of the lower limb. It also plays a supportive role in the gait cycle. Innervation: Superior gluteal nerve.
Piriformis
The piriformis muscle is a key landmark in the gluteal region. It is the most superior of the deep muscles. Attachments: Originates from the anterior surface of the sacrum. It then travels infero-laterally, through the greater sciatic foramen, to insert into the greater trochanter of the femur. Actions: Lateral rotation and abduction. Innervation: Nerve to piriformis.
Obturator Internus
The obturator internus forms the lateral walls of the pelvic cavity. In some texts, the obturator internus and the gemelli muscles are considered as one muscle – the triceps coxae. Attachments: Originates from the pubis and ischium at the obturator foramen. It travels through the lesser sciatic foramen, and attaches to the greater trochanter of the femur. Actions: Lateral rotation and abduction. Innervation: Nerve to obturator internus.
The Gemelli – Superior and Inferior
The gemelli are two narrow and triangular muscles. They are separated by the obturator internus tendon. Attachments: The superior gemellus muscle originates from the ischial spine, the inferior from the ischial tuberosity. They both attach to the greater trochanter of the femur. Actions: Lateral rotation and abduction. Innervation: The superior gemellus muscle is innervated by the nerve to obturator internus, the inferior gemellus is innervated by the nerve to quadratus femoris.
Quadratus Femoris
The quadratus femoris is a flat, square-shaped muscle. It is the most inferior of the deep gluteal muscles, located below the gemelli and obturator internus. Attachments: It originates from the lateral side of the ischial tuberosity, and attaches to the quadrate tuberosity on the intertrochanteric crest. Actions: Lateral rotation. Innervation: Nerve to quadratus femoris
Biceps Femoris
Like the biceps brachii in the arm, the biceps femoris muscle has two heads – a long head and a short head. It is the most lateral of the muscles in the posterior thigh – the common tendon of the two heads can be felt laterally at the posterior knee.
Attachments: The long head originates from the ischial tuberosity of the pelvis. The short head originates from the linea aspera on posterior surface of the femur. Together, the heads form a tendon, which inserts into the head of the fibula.
Actions: Main action is flexion at the knee. It also extends the leg at the hip, and laterally rotates at the hip and knee.
Innervation: Long head innervated by the tibial part of the sciatic nerve, whereas the short head is innervated by the common fibular part of the sciatic nerve.
Semitendinosus
The semitendinosus is a largely tendinous muscle. It lies medially to the biceps femoris, and covers the majority of the semimembranosus.
Attachments: It originates from the ischial tuberosity of the pelvis, and attaches to the medial surface of the tibia.
Actions: Flexion of the leg at the knee joint. Extension of thigh at the hip. Medially rotates the thigh at the hip joint and the leg at the knee joint.
Innervation: Tibial part of the sciatic nerve.
Semimembranosus
The semimembranosus muscle is flattened and broad. It is located underneath the semitendinosus. Attachments: It originates from the ischial tuberosity, but does so more superiorly than the semitendinosus and biceps femoris. It attaches to the medial tibial condyle. Actions: Flexion of the leg at the knee joint. Extension of thigh at the hip. Medially rotates the thigh at the hip joint and the leg at the knee joint. Innervation: Tibial part of the sciatic nerve.
What are the superficial abductors and extenders of the gluteal region?
A group of large muscles that abduct and extend the femur. Includes the gluteus maximus, gluteus medius, gluteus minimus and tensor fascia lata.
What are the hamstring muscles ?
Biceps femoris, semitendinosis and semimembrinosus. Extend at the hip and flex at the knee.
What are the door borders of the popliteal fossa?
The popliteal fossa is diamond shaped, with four borders. These borders are formed by the muscles in the posterior compartment of the leg and thigh: Superomedial border: Semimembranosus. Superolateral border: Biceps femoris. Inferomedial border: Medial head of the gastrocnemius. Inferolateral border: Lateral head of the gastrocnemius and plantaris.
