MSK Anatomy: Abdominal Muscles

Anterior Abdominal Muscle Group

• External Oblique

  • Origin: External surfaces of the 5th to 12th ribs.
  • Insertion: Anterior superior iliac spine, anterior half of iliac crest, pubic tubercle, and linea alba.
  • Function: Flexes the trunk, lateral flexion (ipsilateral), contralateral rotation, and rib depression.

• Internal Oblique

  • Origin: Thoracolumbar fascia, iliac crest, inguinal ligament.
  • Insertion: Inferior borders of the 10th to 12th ribs, adjacent costal cartilages, linea alba, and pecten pubis.
  • Function: Flexes the trunk, lateral flexion (ipsilateral), and ipsilateral rotation.

• Rectus Abdominis

  • Origin: Pubic crest and symphysis.
  • Insertion: Xiphoid process and costal cartilages of the 5th to 7th ribs.
  • Function: Flexes the trunk.

• Transverse Abdominis

  • Origin: Costal cartilages of the 7th to 12th ribs, thoracolumbar fascia, iliac crest, and inguinal ligament.
  • Insertion: Linea alba, pubic crest, and pecten pubis.
  • Function: Compresses abdominal contents and provides structural support.

Posterior Muscle Group

• Latissimus Dorsi

  • A large muscle of the back contributing to arm movement and stability.

• Longissimus Thoracis

  • Part of the erector spinae group, involved in the extension and lateral flexion of the spine.

• Iliocostalis

  • Also part of the erector spinae, involved in the extension and lateral flexion of the spine.

• General Erector Spinae Mass

  • Composed of three muscle columns: iliocostalis, longissimus, and spinalis, critical for maintaining posture.

• Quadratus Lumborum

  • Located in the lower back, it assists in lateral flexion of the vertebral column and stabilizes the pelvis.

Lower Limb Muscle Groups

• Quadriceps Group

  • Major muscle group in the front of the thigh, responsible for knee extension.

• Adductors

  • Inner thigh muscles that are primarily responsible for the adduction of the hip.

• Hamstring Group

  • Located at the back of the thigh, these muscles facilitate knee flexion and hip extension.

• Tibialis Anterior

  • Located anteriorly in the lower leg, responsible for dorsiflexion of the foot.

• Gastrocnemius

  • Calf muscle that aids in plantarflexion and knee flexion.

• Soleus

  • Located beneath the gastrocnemius, important for plantarflexion, especially during walking and running.

Test your knowledge of the origin, insertion, and function of the external oblique, internal oblique, and rectus abdominis muscles. This quiz covers key anatomical features and their roles in trunk movement. Perfect for students and professionals studying musculoskeletal anatomy.