• Origin

Serratus Posterior Superior:
• Nuchal ligament, spinous processes of C7–T3.

Serratus Posterior Inferior:
• Spinous processes of T11–L2.

• Insertion

Serratus Posterior Superior:
• Superior borders of ribs 2–5 (just lateral to their angles)

Serratus Posterior Inferior:
• Inferior borders of ribs 9–12 (just lateral to their angles)

• Agonist(s)

Superior:

- External intercostals (assist with rib elevation during inhalation).

Inferior:

- Internal intercostals and abdominal muscles (assist with forced expiration and rib depression).

• Antagonist(s)

Superior:

- Internal intercostals (depress the ribs during expiration).

Inferior:

- Diaphragm,

- External intercostals (elevate ribs during inspiration).

• Function

Serratus Posterior Superior: Assists in elevating ribs 2–5 during deep or labored inhalation.

Serratus Posterior Inferior: Assists in depressing ribs 9–12 during forced expiration.

May play a proprioceptive role due to high density of muscle spindles.

Assists in stabilizing the lower thoracic and upper lumbar rib cage during breathing.

TRIGGER POINT(S)

• Location

Serratus Posterior Superior:

Trigger points are often found just lateral to the spine in the region of the upper thoracic vertebrae (T2–T5), deep beneath the rhomboids

Serratus Posterior Inferior:

Trigger points are commonly located near the thoracolumbar junction, lateral to the lower thoracic and upper lumbar vertebrae (T11–L2), beneath the latissimus dorsi.

• Pain Referral Pattern

Superior:

Pain may be felt deep in the upper back or posterior shoulder region, and sometimes mimics interscapular or rhomboid pain.

Inferior:

Referred pain may present as a dull, aching discomfort in the lower back or flank, often mistaken for kidney or visceral pain.

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Potential Causes

• Poor breathing mechanics and chronic shallow breathing.

• Repetitive overhead lifting or pulling motions.

• Prolonged forward head posture or slouching.

• Chronic coughing or labored breathing (asthma, bronchitis).

• Weak core stability leading to overuse of accessory breathing muscles.

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Prevention Tips

• Practice deep diaphragmatic breathing to reduce reliance on accessory respiratory muscles.

• Address postural imbalances through strengthening and stretching programs.

• Avoid overuse of upper thoracic muscles during lifting or exercise.

• Use appropriate ergonomic setup during seated tasks.

• Strengthen core and lumbar stabilizers to support lower back mechanics.