Trunk Rotation Muscles and Anatomy

Trunk Rotation Muscles

• Primary Muscles:

  • External oblique muscle
  • Internal oblique muscle

• Accessory Muscles (aid in rotation):

  • Latissimus dorsi
  • Semispinalis
  • Multifidus
  • Rectus abdominis

Trunk Rotation Range of Motion

• In a supine position, trunk rotation is limited by the side the scapula is raised.

Factors Limiting Trunk Rotation

• Tension in the annulus fibrosus between vertebrae
• Tension in oblique abdominal muscles on the opposite side
• Tension in costovertebral ligaments in the thoracic area

External Oblique Muscle Anatomy

• Origin: Anterior angles of the lower eight ribs
• Insertion:
  • Outer anterior half of the iliac crest
  • Inguinal ligament
  • Pubic tubercle and crest
  • Intertwines with the opposite muscle, forming the linea alba, extending from the xiphoid process to the symphysis pubis
• Action: Rotates the trunk; supports the abdominal wall; assists forced expiration; raises intra-abdominal pressure
• Nerve Supply: Anterior primary rami (T7-T12)

Internal Oblique Muscle Anatomy

• Origin: Lumbar fascia; anterior two-thirds of the iliac crest; lateral two-thirds of the inguinal ligament
• Insertion: Costal cartilages of ribs 8-12; crest of the pubis; medial part of the pectineal line; linea alba
• Action: Rotates the trunk; supports the abdominal wall; assists forced expiration; raises intra-abdominal pressure
• Nerve Supply: Anterior primary rami (T7-T12)

This quiz explores the primary and accessory muscles involved in trunk rotation, their anatomy, and factors affecting rotation range of motion. Test your knowledge on muscles such as the external and internal oblique muscles along with their functions and limitations.