Serratus Anterior: An Underrated Muscle

Structure and Function:

The serratus anterior is a broad, fan-shaped muscle that originates from the first to eighth upper ribs or from the first to ninth upper ribs, at the lateral wall of the chest. Serratus means “saw-tooth edge” which gives the muscle its unique shape, while anterior is defined as “positioned at or towards the front”. It is divided into three different sections in accordance with the points of insertion:

  • Serratus anterior superior (with insertion near the superior angle)
  • Serratus anterior intermediate (with insertion along the medial border)
  • Serratus anterior inferior (with insertion near the inferior angle)
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Contraction of the serratus anterior muscle will cause the muscle to pull the scapula forward towards the thorax, thereby creating protraction of the scapula where the shoulder blades are moved away from the spine. Protraction of the scapula typically occurs when we are reaching forward (e.g. in Paschimottanasana) or pushing objects away from the body (e.g. in Phalakasana where we actively push our fingers into the mat to extend our elbows and lengthen our arms). The serratus anterior muscle is also known as the “boxer’s muscle” since it is mainly responsible for protraction of the scapula, which occurs when throwing a punch.

Another main function of the serratus anterior muscle is upward rotation of the scapulothoracic joint through anterolateral (i.e., towards the front and to the side) motion of the scapula along the ribs. This in turn allows us to elevate our arms upwards, and overhead, during shoulder abduction and flexion (e.g. during Virabhadrasana 1 or Utkatasana where our arms are flexed above our head). When the shoulder girdle is in a fixed position, the serratus anterior muscle works to lift the ribs for inhalation, hence assisting in respiration.

Additionally, when both the serratus anterior superior and serratus anterior inferior contract simultaneously, they help to stabilize the scapula against the ribcage by working with the rhomboid muscles to pull the scapula tightly against the back of the ribcage.

Importance of Serratus Anterior:

Weakness or injury in the serratus anterior muscle can lead to medial winging of the scapula, whereby the medial border of the scapula protrudes out from the back like wings. As a result of the scapular winging, patients are likely to experience weakness in the shoulders, limited range of flexion and abduction in the upper extremity, as well as pain. All these symptoms can significantly affect one’s ability to lift, pull and push objects, as well as to perform daily living activities such as carrying bags and moving objects from one point to another.

When practicing yoga asanas, the serratus anterior muscle also plays a key role in stabilizing the scapula and holding the scapula in upward rotation, especially in poses that require arm balance or inversion. By engaging the serratus anterior to help stabilize the scapula and elevate the arms, this will prevent us from putting too much weight onto our rotator cuff and shoulder muscles while in the pose, which can in turn cause rotator cuff injuries and shoulder pain in the long run. However, we often tend to overlook this muscle as we primarily focus on building strength in the larger groups of muscles such as the shoulders, abdomen, back, and legs in order to obtain a stable posture. One other reason is also due to the location of the serratus anterior muscle, which makes it hard for us to see, feel or activate the muscle. Hence, it is not uncommon for many of us to have a weak serratus anterior.

Without a strong serratus anterior muscle to stabilize the scapula, we may find ourselves easily wobbling or having trouble getting/staying up in inversion poses such as Sirsasana and Pincha Mayurasa, as we lack the upper body strength required to lift and hold our body vertically up against gravity’s pull. Although the serratus anterior muscle is less evident than the upper body muscles such as shoulder and abdominal muscles, it can help to support a great load of body weight, along with the shoulder and abdominal muscles, thanks to its broad size.

With all that being said, it is still not late for us to start noticing and appreciating the efforts of our serratus anterior muscle, and to start strengthening this muscle to find stability in our yoga asanas!

Exercises to Strengthen the Serratus Anterior:

1. Wall Angels

  • Stand with the back against a wall, and press the entire back flat against the wall. Ensure that there are no gaps in between the back and the wall.
  • Abduct the arms to the sides and flex the elbows in a 90° angle, such that the arms are in cactus position against the wall, fingers facing up. Keep the elbows in line with the shoulders, and keep the elbows and forearms against the wall.
  • Draw the shoulders away from the ears.
  • Slide the arms upwards to extend the elbows and try to reach the arms as high up as possible, without elevating or tensing up the shoulders. Keep the elbows, forearms and entire back in constant contact with the wall at all times.
  • Flex the elbows and lower the arms back to the starting cactus position.
  • Repeat the movement for 20 times.

2. High Planks

When doing planks, we often focus on activating the core muscles to maintain a neutral spine alignment and steady posture. In addition to engaging the core muscles, it is also important to engage the serratus anterior muscles at the same time, so that our body weight can be distributed evenly from the shoulders to the core and to the legs for greater stability. To engage the serratus anterior muscle, we would need to actively push our palms onto the mat and create protraction of the shoulders.

  • Start in a tabletop position on the mat, with hands shoulder-width apart and knees hip-width apart. Make sure that the wrists and elbows are aligned with the shoulders.
  • Step both legs back such that the knees are extended, and ground all ten toes onto the mat. Keep both legs straight and firm.
  • Activate the core muscles to stabilize the hips.
  • Press both palms and all of the fingers actively and evenly into the mat, and feel the arms elongating. This will create a slight protraction of the scapula and rounding of the upper back. Draw the shoulders away from the ears to keep the neck and shoulders relaxed.
  • Hold in the high plank position for 8-10 breaths.

3. Transition between High Plank and Downward Dog

  • Starting in a high plank position, lift the hips towards the ceiling and shift the shoulders back to form an inverted V shape for the downward dog. Depress the shoulders and draw the scapula towards the midline of the spine.
  • From the downward dog, lower the hips and shift the shoulders forward back into the high plank, such that the hips and shoulders form a parallel line to the mat.
  • Transit between the high plank and downward dog for 20 repetitions.

Application – Sirsasana:

After building strength in our serratus anterior muscle, the next step is to know how to activate this muscle in our asanas. Take sirsasana (headstand) as an example. When we are in the sirsasana pose, we want to actively draw the shoulders away from the neck, and draw the scapula down the back and towards the midline of the spine. By doing so, this will engage our serratus anterior muscle to help stabilize the shoulder girdle and upper body in the inversion and at the same time, lighten the weight on our head to prevent unwanted compression of the neck.

All in all, the serratus anterior muscle plays a crucial role in providing greater stability and reducing the risk of unwanted injuries in our yoga asanas, and definitely deserves more attention in knowing how to strengthen and correctly activate it in order to enjoy the benefits it provides.