Thigh Region Anatomy Notes

Objectives

  • Identify bone markings:

    • Linea aspera: A prominent ridge running along the posterior aspect of the femur, serving as an attachment site for many thigh muscles.

    • Supracondylar ridges: Ridges located above the epicondyles of the femur, providing additional surface area for muscle attachments related to knee movements.

    • Epicondyles and condyles: Epicondyles are projections located on the sides of the condyles of the femur, serving as attachment sites for ligaments. Condyles are the rounded surfaces at the distal end of the femur that articulate with the tibia.

    • Popliteal and patella surfaces: The popliteal surface is a flattened area on the posterior side of the femur, proximal to the condyles. The patellar surface is located on the anterior side of the femur between the condyles, where the patella glides during knee movement.

  • Identify bone markings of the proximal tibia and fibula:

    • Tibial tuberosity: A prominent elevation on the anterior aspect of the tibia, just below the condyles, serving as the insertion point for the patellar tendon.

    • Condyles: The medial and lateral condyles are the expanded, relatively flat surfaces on the proximal end of the tibia that articulate with the femoral condyles to form the knee joint.

    • Popliteal surface: A triangular area located on the posterior aspect of the proximal tibia, serving as an attachment site for the popliteus muscle.

    • Fibula head: The proximal end of the fibula that articulates with the lateral aspect of the tibia.

  • Consider the developmental rotation and its implications for muscle actions and naming in the thigh and distal limb: Muscles in the thigh rotate during development, influencing their action and nomenclature in the lower limb.

  • Identify and describe the main origins and insertions of muscles within the anterior, medial, and posterior thigh compartments: Discuss the specific origins (fixed attachment points) and insertions (movable attachment points) of key muscles in each compartment of the thigh.

  • Demonstrate and correctly name the movements produced at the hip and knee by the action of these muscles: Actively perform and name the movements (e.g., flexion, extension, adduction, abduction, rotation) resulting from the contraction of specific thigh muscles at the hip and knee joints.

  • Describe the boundaries of the femoral triangle: Define the anatomical borders of the femoral triangle, a significant area in the upper thigh.

Introduction to Thigh Musculature

  • Reconsider hip and knee movements:

    • Flexion and extension: Flexion decreases the angle between bones, while extension increases it.

    • Adduction of the limb: Movement of the limb toward the midline of the body.

Developmental Rotation

  • Remember the developmental rotation changes the movements produced distal to the hip joint to opposites: The rotation shifts the relative positions of muscles, resulting in altered actions at the knee and ankle.

Review of Pelvic Origins

  • Posterior surface:

    • Ischial tuberosity and ramus: Origin for hamstrings and adductor magnus. The hamstring muscles (biceps femoris, semitendinosus, semimembranosus) and the adductor magnus originate from these sites.

  • Anterior surface:

    • ASIS (Anterior Superior Iliac Spine): origin for sartorius. The sartorius muscle originates here, contributing to hip flexion, abduction, and external rotation, as well as knee flexion.

    • AIIS (Anterior Inferior Iliac Spine): origin for rectus femoris. The rectus femoris muscle originates from here, serving as a hip flexor and knee extensor.

    • Pubic region: origin for the adductor group. The adductor muscles (adductor longus, adductor brevis, adductor magnus, pectineus, and gracilis) originate from this region, enabling thigh adduction.

Insertions

  • Posterior and anterior femur:

    • Linea aspera: Insertion point for many thigh muscles, including adductors and vastus muscles.

    • Condyles: The femoral condyles articulate with the tibia, and muscles inserting near these condyles affect knee movement.

    • Trochanters: The greater and lesser trochanters are insertion sites for hip rotator muscles.

    • Adductor tubercle: Located on the medial aspect of the distal femur, it is the insertion point for the adductor magnus.

  • Also consider the patella, upper tibia, and fibula as insertion points:

    • Fibula head: Insertion point for the biceps femoris muscle.

    • Tibial condyles: Insertion points for the semitendinosus, semimembranosus, and sartorius muscles.

    • Tibial tuberosity: Insertion point for the quadriceps femoris muscle group via the patellar tendon.

    • Patella: Serves as an attachment site for the quadriceps femoris tendon.

Muscles of the Thigh

  • Three compartments:

    • Anterior: Flexors of hip & extensors of knee.

      • Sartorius: flexes hip and knee; a unique muscle that crosses both the hip and knee joints, facilitating a combination of movements.

    • Medial: Adductors of hip. Primary function is to adduct the thigh, drawing it toward the midline of the body; also involved in hip flexion and rotation.

    • Posterior: Extensors of hip, flexors of knee. These muscles facilitate hip extension and knee flexion and play a key role in locomotion.

Anterior Compartment

  • Key muscles:

    • Knee extensors: Crucial in activities such as walking, running, and jumping.

    • Sartorius: A long, strap-like muscle that is an important landmark in the thigh.

    • Quadriceps Femoris (rectus femoris, vastus medialis, vastus lateralis, vastus intermedius): The primary knee extensors, forming the bulk of the anterior thigh.

  • Hip flexors: Assist in lifting the thigh toward the abdomen.

Quadriceps and Sartorius

  • Sartorius:

    • Origin: Anterior Superior Iliac Spine (ASIS): This origin gives it leverage to flex, abduct, and externally rotate the hip.

    • Insertion: Medial tibia: Its insertion allows it to contribute to knee flexion and internal rotation of the tibia on the femur.

    • Action: Flexes and laterally rotates the femur and flexes the knee: This combination of actions allows it to assist in crossing the legs.

  • Rectus Femoris:

    • Origin: Anterior Inferior Iliac Spine (AIIS) and superior acetabulum: Its dual origin allows it to act as both a hip flexor and knee extensor.

  • Vastus medialis:

    • Origin: Medial aspect of linea aspera: Specific origin helps in the final degrees of knee extension.

  • Vastus lateralis:

    • Origin: Greater trochanter and linea aspera: Its broad origin provides significant force for knee extension.

  • Vastus intermedius:

    • Origin: Linea aspera and anterior femur: Located deep to the rectus femoris, it contributes to powerful knee extension.

  • All quadriceps insert onto the patella and tibial tuberosity: This common insertion unites their forces to extend the knee.

  • Action of quadriceps: Knee extension (+ hip flexion for rectus femoris): Essential for walking, running, and jumping; the rectus femoris also aids in hip flexion.

Posterior Compartment

  • Hamstrings:

    • Aid gluteus maximus in extending the hip during walking: Work synergistically with the gluteus maximus to propel the body forward.

    • Flexion of the knee joint: Important for gait and activities like squatting and kneeling.

    • Common origin: Ischial tuberosity: This common origin allows them to coordinate hip extension and knee flexion.

    • Biceps femoris:

      • Long head (2 joints).

      • Short head (1 joint; Origin: linea aspera). Unlike the long head, the short head only crosses the knee joint.

      • Lateral insertion to fibula head: Its lateral insertion contributes to lateral knee stability.

    • Semitendinosus:

      • More tendinous insertion – medial tibial condyle: Allows for efficient transfer of force to flex the knee and medially rotate the tibia.

    • Semimembranosus:

      • More membranous insertion – medial tibial condyle: Provides broad support for the medial aspect of the knee joint.

Medial Thigh

  • Adductor compartment:

    • Common origin: Adductor magnus, adductor longus, and gracilis (Insertion: medial tibia).

    • Linea aspera: Attachment site for the adductor muscles, facilitating thigh adduction and stabilization.

    • Adductor tubercle: Distal insertion point for adductor magnus, providing leverage for powerful adduction.

    • Adductor hiatus: A gap in the adductor magnus muscle that allows the femoral artery and vein to pass from the anterior to the posterior thigh.

Lateral Compartment - Iliotibial Tract

  • Thickening of fascia latae: Provides lateral stability to the hip and knee.

  • Two muscles insert onto the tract:

    • Tensor fascia latae: Helps maintain tension on the iliotibial tract.

    • Gluteus maximus: Contributes to hip extension and abduction and stabilizes the iliotibial tract.

  • Functions:

    • Hip extension & lateral support of knee joint: Provides stability during movement and weight-bearing activities.

    • Blends into strong retinacula of the patella region: Assists in patellar tracking and knee extension.

    • Inserts into the lateral aspect of the tibia: Anchors the tract, contributing to lateral knee stability.

The Femoral Triangle

  • Boundaries:

    • Base: Inguinal ligament: Superior border, running from the anterior superior iliac spine (ASIS) to the pubic tubercle.

    • Lateral: Sartorius: The lateral border, forming the outer edge of the triangle.

    • Medial: Adductor longus: The medial border, contributing to the inner edge of the triangle.

    • Apex: Where sartorius meets adductor longus: The inferior tip of the triangle.

    • Floor: Pectineus and iliopsoas: These muscles form the base upon which the contents of the triangle rest.

  • Contents:

    • Femoral nerve, artery, vein, empty space, lymph nodes: Important structures passing from the abdomen to the lower limb.

    • Mnemonic: NAVEL (N