Pelvis and Thigh Anatomy

Pelvis and Thigh

Overview of Muscles

• Understanding the muscle groups in the pelvis and thigh is essential for studying biomechanics and anatomy.

Quadriceps

Origin Points

• Rectus Femoris: Anterior Inferior Iliac Spine

• Vastus Medialis: Medial Lip of Linea Aspera

• Vastus Lateralis: Lateral Lip of Linea Aspera, Gluteal Tuberosity, Greater Trochanter

• Vastus Intermedius: Anterior and Lateral Shaft of the Femur

Insertion

• All muscles insert at the Tibial Tuberosity through the patellar tendon.

Function

• The quadriceps collectively extend the knee at the Tibiofemoral Joint.

• Rectus Femoris also functions to flex the hip at the Coxal Joint.

Hamstring Muscles

Muscle Groups

• Biceps Femoris: Composed of Long Head and Short Head

• Semitendinosus

• Semimembranosus

Origin and Insertion

• Biceps Femoris

  • Long Head: Origin - Ischial Tuberosity; Insertion - Head of Fibula

  • Short Head: Origin - Lateral Lip of Linea Aspera; Insertion - Head of Fibula

Function

• Biceps Femoris: Flexes the knee, laterally rotates the tibia, extends the hip (long head), and tilts the pelvis posteriorly.

Function of Semitendinosus

Origin and Insertion

• Origin: Ischial Tuberosity

• Insertion: Proximal, Medial Shaft of the Tibia at Pes Anserinus Tendon.

Function

• Flex the knee, medially rotate the flexed knee, extend the hip, assist in medial rotation of the hip, and tilt the pelvis posteriorly.

Function of Semimembranosus

Origin and Insertion

• Origin: Ischial Tuberosity

• Insertion: Posterior Aspect of Medial Condyle of Tibia.

Function

• Flex the knee, medially rotate the flexed knee, extend the hip, assist in medial rotation of the hip, and tilt the pelvis posteriorly.

Gluteal Muscles

Gluteus Maximus

Origin and Insertion

• Origin: Coccyx, Edge of Sacrum, Posterior Iliac Crest, Sacrotuberous and Sacroiliac Ligament

• Insertion: Iliotibial Tract (Upper Fibers) and Gluteal Tuberosity (Lower Fibers).

Function

• Extend the hip, laterally rotate the hip, abduct the hip, and adduct the hip (lower fibers).

Gluteus Medius

Origin and Insertion

• Origin: Gluteal surface of ilium, between posterior and anterior gluteal lines

• Insertion: Lateral aspect of greater trochanter.

Function

• Abduct the hip, flex and medially rotate (anterior fibers), and extend and laterally rotate the hip (posterior fibers).

Gluteus Minimus

Origin and Insertion

• Origin: Gluteal surface of ilium between the anterior and inferior gluteal lines

• Insertion: Anterior aspect of the greater trochanter.

Function

• Abduct the hip, medially rotate the hip, and flex the hip.

Adductor Group

Components

• Includes Adductor Magnus, Adductor Longus, Adductor Brevis, Pectineus, and Gracilis.

Function

• All assist in adducting and medially rotating the hip joint. All except Gracilis assist in flexing the hip, while Gracilis flexes the tibiofemoral joint and medially rotates the flexed tibiofemoral joint.

Individual Origins and Insertion

• Adductor Magnus: Origin - Inferior Ramus of the Pubis, Ramus of Ishium, Ischial Tuberosity; Insertion - Medial Lip of Linea Aspera, Adductor Tubercle.

• Adductor Longus: Origin - Pubic Tubercle; Insertion - Medial Lip of Linea Aspera.

• Adductor Brevis: Origin - Inferior Ramus of Pubis; Insertion - Pectineal Line, Medial Lip of Linea Aspera.

• Pectineus: Origin - Superior Ramus of Pubis; Insertion - Pectineal Line of Femur.

• Gracilis: Origin - Inferior Ramus of Pubis; Insertion - Proximal, Medial Shaft of Tibia at Pes Anserinus Tendon.

Tensor Fasciae Latae

Origin and Insertion

• Origin: Iliac crest, posterior to the Anterior Superior Iliac Spine

• Insertion: Iliotibial Tract.

Function

• Flex the hip joint, medially rotate the hip joint, and abduct the hip joint.

Sartorius

Origin and Insertion

• Origin: Anterior Superior Iliac Spine

• Insertion: Proximal, Medial Shaft of the Tibia at the Pes Anserinus Tendon.

Function

• Flex the hip joint, laterally rotate the hip joint, abduct the hip joint, flex the knee joint, and medially rotate the flexed knee joint.

Lateral Rotators ("Deep Six")

Components

• Piriformis

• Gemellus Superior

• Gemellus Inferior

• Quadratus Femoris

• Obturator Internus

• Obturator Externus

Function

• All laterally rotate the hip joint; specifically, Piriformis also abducts the hip when flexed.

Psoas Major

Origin and Insertion

• Origin: Bodies and transverse processes of lumbar vertebrae;

• Insertion: Lesser trochanter.

Function

• Flex the hip joint with origin fixed, may laterally rotate. When insertion is fixed, flex the trunk toward the thigh and tilt the pelvis anteriorly.

Iliacus

Origin and Insertion

• Origin: Iliac Fossa;

• Insertion: Lesser trochanter.

Function

• Flex the hip joint with the origin fixed, may laterally rotate. When insertion is fixed, flex the trunk toward the thigh and tilt the pelvis anteriorly.

Pelvic Tilts

Types

• Anterior Pelvic Tilt: Associated with increased lumbar lordosis.

• Posterior Pelvic Tilt: Associated with decreased lumbar lordosis and increased thoracic kyphosis.

• Proper pelvic alignment is crucial for good posture.