Trunk Rotation Muscles and Anatomy

Which primary muscle is primarily responsible for trunk rotation?

What is one of the factors limiting the range of motion in trunk rotation?

What are the primary nerves supplying the external oblique muscle?

In what position is trunk rotation possible until the scapula on the forward shoulder side is raised?

Which accessory muscle is NOT involved in trunk rotation?

What is the action of the internal oblique muscle in relation to trunk movement?

Which of the following insertions is NOT associated with the external oblique muscle?

What is the main role of the external oblique muscle besides trunk rotation?

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.