Serratus Anterior Anatomy

Serratus Anterior Muscle

Origin: Attaches to the outer surface of the upper 8 to 9 ribs
Insertion: Attaches to the anterior surface of the vertebral margin of the scapula
Actions: Rotation, protraction, and depression of the scapula
Innervation: Long thoracic nerve (C5, C6, C7)
Blood Supply: Lateral thoracic branch of the axillary artery

Primary Actions of the Serratus Anterior

1. Upward rotation of the scapula

Agonists:

  • Trapezius (upper and lower parts)

Antagonists:

  • Levator Scapulae
  • Serratus Anterior (upper fibers)
  • Rhomboid Major
  • Rhomboid Minor
  • Pectoralis Minor

The middle part of the trapezius is a stabilizer.

2. Downward rotation of the scapula

  Agonists:

  • Levator Scapulae
  • Rhomboid Major
  • Rhomboid Minor
  • Pectoralis Minor
  • Trapezius (middle part)

Antagonists:

  • Trapezius (upper and lower fibers)
  • Serratus Anterior (lower fibers)

The middle part of the trapezius is a stabilizer.

3. Protraction of the scapula

  Agonists:

  • Pectoralis Minor

  Antagonists:

  • Trapezius (middle fibers)
  • Rhomboid Major
  • Rhomboid Minor

4. Depression of the scapula

  Agonists:

  • Pectoralis Minor
  • Trapezius (lower part)

  Antagonists:

  • Trapezius (upper part)
  • Levator Scapulae

5. Stabilizes the medial border of the scapula to the chest wall during movement of the arm at the shoulder.

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