Serratus posterior inferior muscle

Serratus posterior

Serratus Posterior Inferior Muscle is a thin, quadrilateral muscle located at the junction of the thorax and the lumbar region. It is part of the deep muscles of the back, lying beneath the erector spinae and is considered as one of the respiratory muscles due to its role in breathing.

Anatomy

The Serratus Posterior Inferior originates from the spinous processes of the T11 to L2 vertebrae, and extends upwards and laterally to insert into the lower borders of the 9th to 12th ribs. This muscle is innervated by the anterior rami of the lower thoracic nerves, specifically T9 to T12. Its blood supply comes from the posterior intercostal arteries.

Function

The primary function of the Serratus Posterior Inferior is to assist in the process of respiration. It aids in depressing the lower ribs, which is crucial during forced expiration. By anchoring the lower ribs, it prevents their elevation during diaphragmatic contraction, thus facilitating the upward movement of the diaphragm and enhancing expiratory volume.

Clinical Significance

Pain or discomfort in the area of the Serratus Posterior Inferior can be mistaken for kidney pain, as its location overlaps with the area where kidney pain is often felt. Conditions such as muscle strain or myofascial pain syndrome affecting this muscle can lead to symptoms that mimic other thoracic or lumbar pathologies.

See Also

• Muscles of the human body
• Respiratory system
• Thorax
• Lumbar region