Lower limb muscles

BONES OF THE PELVIS & THIGH
A. Hip Bone

  1. Ilium: The ilium is the uppermost and largest part of the hip bone. Important landmarks include the anterior superior iliac spine and iliac crest.

  2. Ischium: The ischium forms the lower and back part of the hip bone. Notable feature: ischial tuberosity.

  3. Pubis: The pubis forms the anterior portion of the hip bone.

B. Sacrum: A triangular bone at the base of the spine, part of the pelvis.
C. Coccyx: Also known as the tailbone, located at the very end of the vertebral column.
D. Femur: The thigh bone, the longest and strongest bone in the body.

  • Greater trochanter: A large, palpable bony prominence on the upper part of the femur.

2. THIGH MUSCLES (FIG. 12.16, TABLE 12.9)
A. Muscle Compartments

  1. Anterior thigh: Muscles in this compartment flex the thigh and extend the leg. Located at the front of the thigh.

  2. Medial thigh: These muscles flex and adduct the thigh. Located on the inner side of the thigh.

  3. Posterior thigh (hamstrings): Muscles in this compartment extend the thigh and/or flex the leg, located at the back of the thigh.

  4. Lateral thigh: Muscles in this compartment abduct the thigh.

3. Anterior Compartment (Fig. 12.17)

  1. Iliacus: This muscle flexes the thigh at the hip joint, connecting the hip bone to the lesser trochanter of the femur.

  2. Psoas major: Flexes the thigh, running from the vertebrae to the lesser trochanter of the femur.

  3. Sartorius: The longest muscle in the body. It flexes the thigh and also flexes the leg at the knee joint. It runs from the anterior superior iliac spine to the tibia.

Muscles that extend the leg at the knee joint

  1. Quadriceps Femoris: Composed of four muscles, all attaching via the quadriceps tendon:
    a. Rectus femoris: The only quadriceps muscle that crosses the hip joint.
    b. Vastus medialis: Located medially on the thigh.
    c. Vastus intermedius: Positioned between the other vastus muscles.
    d. Vastus lateralis: Located on the lateral side of the thigh.

C. Medial Compartment

  1. Muscles in the medial compartment adduct and flex the thigh.

  2. Adductors: Includes three muscles: longus, brevis, and magnus, which adduct the thigh.

  3. Pectineus: Adducts and flexes the thigh.

  4. Gracilis: Flexes the leg at the knee joint.

D. Lateral Thigh

  1. Tensor fasciae latae: Abducts the thigh and connects to the iliotibial tract.

E. Posterior Hip and Posterior Thigh

  1. Gluteal muscles: Located at the posterior hip. The gluteus maximus is the largest and extends the thigh at the hip joint (e.g., used when getting up from a chair).

  2. Gluteus medius: Abducts the thigh.

  3. Gluteus minimus: Abducts the thigh.

Hamstring muscles

  1. Biceps femoris: Laterally placed muscle with two heads, extends the thigh and flexes the leg.

  2. Semitendinosus: A posterior thigh muscle that also extends the thigh and flexes the leg.

  3. Semimembranosus: Medially placed, extends the thigh and flexes the leg.