Serratus Anterior

Serratus comes from the Latin term serrare (saw”), and it does look like a saw to some extent.
The serratus anterior, also known as the “boxer’s muscle,” is largely responsible for the protraction of the scapula.
Serratus anterior normally originates by nine or ten muscle slips – arising from either the 1st to 8th ribs, or the 1st to 9th ribs; because two slips usually arise from the 2nd rib, the number of slips is greater than the number of ribs from which they originate

Weakness leads to

  • Shoulder blade/scapular wingingprotrudes like the wing of a bird.
  • Decreased ability to raise the arm, oftentimes becomes increasingly difficult
  • Rounded shoulder
  • Pec minor will overwork
  • Weak serratus can lead to unwanted movement within the shoulder joint (excessive humeral elevation and anterior translation), poor mechanics and eventual injury such as an impingement or rotator cuff tear.

Strengthen by

  • Proper posture
  • Relaxing the stiffness
  • Destraining the overstretched
  • Building muscle strength

Anatomy

Serratus anterior, showing origin from lower ribs (origin from upper ribs obscured by pectoralis major and other superficial muscles)

Long thoracic nerve is a good name, since this nerve is particularly long (it can measure up to 25 cm – 10 inches) and runs across the chest wall or thorax. It originates from the cervical roots 5, 6 and 7 (occasionally 8), forming part of the so-called brachial plexus. After passing under the collarbone, it lies on the surface of the serratus anterior and innervates each of its muscular slips. This superficial position on the side of the chest wall makes the long thoracic nerve particularly vulnerable to injury.

Physiology

Upward Rotation Contributor

The serratus anterior acts with the upper and lower fibers of the trapezius muscle to sustain upward rotation of the scapula, which allows for overhead lifting. The upward and lateral pull of the serratus anterior and the downward pull of the lower trapezius create a torque that rotates the scapula upward. The upper trapezius maintains tension to support the scapula’s position.

Protraction of the scapula

A movement that occurs when throwing a punch.

Good Posture

A well-functioning and strong serratus can help to alleviate neck and shoulder pain and reduce forward head posture and rounded shoulders. It can also help with performance and tolerance for push-ups and planks. The serratus can improve core function through its connections with the external obliques for better hip function and reduced back pain. It can even increase lymphatic drainage and decrease neural compression.

Stabilizer

Is a key scapular stabiliser, keeping the shoulder blades against the ribcage when at rest and during movement

What’s stopping me???

General

  • The serratus helps to hug the scapula onto the rib cage. A lack of this hugging is identified as scapular winging.
  • Injury to long thoracic nerve can cause weakness of the serratus anterior muscle and dynamic winging of scapula.

Muscles

  • Strained contracted state
  • Weak overstretched state

Bibliography