Serratus posterior

Serratus posterior is a muscle group located in the back, divided into two distinct muscles: the Serratus posterior superior and the Serratus posterior inferior. These muscles play a role in the movement and stabilization of the thoracic region.

Anatomy

The serratus posterior muscles are part of the extrinsic back muscles group, which are primarily involved in the movement of the upper limbs and the thoracic cage.

Serratus Posterior Superior

The Serratus posterior superior is situated at the upper part of the back. It originates from the nuchal ligament and the spinous processes of the C7 to T3 vertebrae. The muscle inserts into the upper borders of the 2nd to 5th ribs. Its primary function is to elevate the ribs, aiding in the process of inhalation.

Serratus Posterior Inferior

The Serratus posterior inferior is located at the lower part of the back. It originates from the spinous processes of the T11 to L2 vertebrae and inserts into the lower borders of the 9th to 12th ribs. This muscle functions to depress the lower ribs, assisting in exhalation.

Function

The primary functions of the serratus posterior muscles are related to the movement of the ribs during breathing. The Serratus posterior superior assists in elevating the ribs during inhalation, while the Serratus posterior inferior helps in depressing the ribs during exhalation. These actions are crucial for the expansion and contraction of the thoracic cavity, facilitating effective respiration.

Innervation

The serratus posterior muscles are innervated by the intercostal nerves. The Serratus posterior superior receives innervation from the 2nd to 5th intercostal nerves, whereas the Serratus posterior inferior is innervated by the 9th to 12th intercostal nerves.

Blood Supply

The blood supply to the serratus posterior muscles is provided by branches of the intercostal arteries. These arteries ensure that the muscles receive adequate oxygen and nutrients to perform their functions effectively.

Clinical Significance

Dysfunction or injury to the serratus posterior muscles can lead to pain and restricted movement in the thoracic region. Conditions such as myofascial pain syndrome can affect these muscles, leading to discomfort and impaired respiratory function.

Related Pages

• Serratus anterior
• Intercostal muscles
• Thoracic diaphragm
• Respiratory system
• Extrinsic back muscles