Muscles of the Lower Limb

Overview of Lower Limb Anatomy

  • The lower limb is segmented into three main sections, with specific actions associated with the hip, knee, and foot.

Major Movements in the Hip

  • Flexion of the hip: Bending the hip joint to bring the thigh closer to the torso.

  • Extension of the hip: Straightening the hip joint to move the thigh away from the torso.

  • Abduction: Movement of the leg away from the midline of the body.

  • Adduction: Movement of the leg towards the midline of the body.

  • Hyperextension: Extension of the hip beyond its normal range.   

Muscles of the Hip and Thigh

  • Muscles typically involved in hip movements include:   - Gluteal muscles: Control hip actions, divided into three major groups:     - Gluteus Maximus: Largest muscle contributing to extension and lateral rotation of the hip.     - Gluteus Medius: Positioned laterally, plays a key role in abduction and stabilization of the pelvis when walking.     - Gluteus Minimus: Smallest of the gluteal muscles, assists in abduction and medial rotation.

  • Tensor of Fascia Lata:   - Long muscle that extends from the hip down to the knee, aids in stabilizing the pelvis and assists in hip flexion and abduction.

  • Lateral Rotators: These muscles are crucial for hip rotation, located around the hip joint:   - Piriformis   - Superior Gemellus   - Obturator Internus   - Inferior Gemellus   - Quadratus Femoris

  • Relation to Sciatic Nerve:   - The sciatic nerve runs between the gluteal muscles and the lateral rotators. Compression of this nerve by muscle spasm can lead to significant pain and may require orthopedic intervention (e.g., injections).

Muscles of the Knee

  • Knee extensors: Act on the knee by originating above it:   - Quadriceps Femoris: Major group responsible for knee extension, consisting of:     - Rectus Femoris: Crosses both the hip and knee joints, contributing to flexion of the hip and extension of the knee.     - Vastus Medialis: Stabilizes the patella.     - Vastus Lateralis: Largest part of the quadriceps, involved in knee extension.     - Vastus Intermedius: Lies beneath the rectus femoris, aiding in extension.

  • Knee flexors: Located primarily in the posterior thigh:   - Biceps Femoris: Functions to flex the knee and extends the hip, antagonistic to the rectus femoris.   - Semitendinosus: Assists in knee flexion and also extends the hip.   - Semimembranosus: Works in conjunction with other hamstring muscles.   - Sartorius: Aids in flexion, abduction, and lateral rotation of the hip, and also contributes to knee flexion.

Muscles of the Foot

  • Key Actions: Dorsiflexion (lifting toes), plantar flexion (pointing toes), inversion (turning foot inward), eversion (turning foot outward).

  • Dorsiflexors:   - Tibialis Anterior: Principal dorsiflexor, located next to the tibia.   - Extensor Digitorum Longus: Extends toes and assists with dorsiflexion.

  • Plantar Flexors:   - Gastrocnemius: Major calf muscle, performs plantar flexion and contributes to knee flexion.   - Soleus: Works beneath the gastrocnemius, provides stability and contributes to walking and running.   - Plantaris: Smaller muscle, aids in plantar flexion.

  • Inverters and Everters:   - Tibialis Posterior: Primary inverter, located deep along the medial side of the foot.   - Fibularis Longus: Aids in eversion of the foot, running laterally from the fibula to the first metatarsal.