Serratus Anterior: Difference between revisions
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In the third test the patient is in a seated or supine position, with his arm flexed 90-100 degrees and his elbow fully extended. The therapist resists the maximally protracting force by the patient. In case of serratus anterior muscle weakness the patient’s scapula is pushed into a retracted and internally rotated position leading to scapular winging appearance.<ref name=":3" /> | In the third test the patient is in a seated or supine position, with his arm flexed 90-100 degrees and his elbow fully extended. The therapist resists the maximally protracting force by the patient. In case of serratus anterior muscle weakness the patient’s scapula is pushed into a retracted and internally rotated position leading to scapular winging appearance.<ref name=":3" /> | ||
{{#ev:youtube|9Jqy6CoknGU}} | {{#ev:youtube|9Jqy6CoknGU}} | ||
== | == Exercises for Activating Serratus Anterior == | ||
[[Press-Up|Push-up plus]] | [[Press-Up|Push-up plus]] | ||
Revision as of 13:33, 31 October 2020
Original Editor - Esraa Mohamed Abdullzaher
Top Contributors - Lucinda hampton, Kholoud Abd Elghany, Kim Jackson, Joao Costa, Lilian Ashraf, Esraa Mohamed Abdullzaher and Oyemi Sillo
Description[edit | edit source]
The serratus anterior muscle is a fan-shaped muscle at the lateral wall of the thorax. Its main part lies deep under the scapula and the pectoral muscles. It is easy to palpate between the pectoralis major and latissimus dorsi muscles.
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Origin[edit | edit source]
It originates on the top lateral surface of the eight or nine upper ribs. [1]
Insertion[edit | edit source]
It inserts exactly at the front border of the scapula, or shoulder blade.[1] The muscle is divided into three parts :
- Upper / Superior : 1st to 2nd rib → superior angle of scapula.
- Middle / Intermedius : 2nd to 3rd rib → medial border of scapula.
- Lower / Inferior : 4th to 9th rib → medial border and inferior angle of scapula. It is the most powerful and prominent part.[2]
Nerve[edit | edit source]
The long thoracic nerve, which arises from C5 to C7 nerve roots of the brachial plexus.[3]
Blood supply[edit | edit source]
Lateral thoracic artery, the superior thoracic artery and the thoracodorsal artery.[3]
Action[edit | edit source]
The main actions are protraction and upward rotation of the scapulothoracic joint, moving the scapula forward across the thoracic wall. It also keeps the medial boarder and inferior angle of the scapula close to the thoracic wall.[4]
Functional Considerations[edit | edit source]
Scapular protraction function of serratus anterior occurs simultaneously when reaching forward or pushing objects away from the body, increasing the functional length of the arm. Also in push-up plus exercise, the reverse protraction action of both serratus anterior results in lifting the trunk and ribs upwards.
The force-couple of the serratus anterior and trapezius muscles results in scapula upwards rotation which is essential during shoulder abduction and flexion.
The serratus anterior and trapezius muscles form another forcre-couple that guides scaplular posterior tilt and outwards rotation, which maintains the volume of the subacromial space.[5]
When the shoulder blade is in fixed position , e.g : breathing after a sprint , the serratus anterior lifts the ribcage and thus supports breathing.[2]
Clinical Relevance[edit | edit source]
Scapular Winging[edit | edit source]
Dysfunction of the serratus anterior muscle is from the causes of scapular winging. Weakness of the serrratus anterior muscle, leads to the unopposed action of the glenohumeral abductors which result in scapula downwards rotation, inwards rotation and anterior tilt during shoulder abduction and flexion. If this position is maintained it’d lead to adaptive shortening of the pectoralis minor muscle resulting in more scapular anterior tilt and inwards rotation. Explaining the scapular “winging” posture associated with weak serratus anterior.[5]
The most common cause of scapular winging is injury to the long thoracic nerve, leading to serratus anterior palsy. The long thoracic nerve descends across the lateral thoracic wall, making it susceptible to injury during anterolateral thorax surgeries . Other causes of isolated serratus anteiro palsy are traumas, strenrous work, athletics, anesthesia, infection and idiopathic causes. Neuropraxia of the long thoracic nerve could result from compression or stretch injuries.
Muscular avulsion of the serratus anterior muscle is from the less recognized causes of scapular winging.[6]
Subacromial Impingement[edit | edit source]
Weakness of the serratus anterior leads to altered line of pull of the rotator cuff muscle which could increase the risk of subacromial impingement syndrome.
Also, serratus anterior is needed for scapula upward rotation. posterior tilt and, to a lesser extent, external rotation of the scapula which may increase or maintain the volume of the subacromial space reducing the likelihood of subacromial impingement.[5]
Serratus Anterior Muscle Pain Syndrome (SAMPS) And Trigger Points[edit | edit source]
Chronic chest pain of noncardiac origin is a heterogeneous disorder, and myofascial pain syndrome is often an overlooked cause that can affect a single muscle or several functional muscle units; it is characterized by taut bands, commonly described as trigger points. The syndrome includes a constellation of symptoms one of which is pain overlying the fifth to seventh ribs in the midaxillary line. Referred pain may radiate toward the anterior chest wall, the medial aspect of the arm, and finally, toward the ring and little finger on the ipsilateral side . The pain of SAMPS can be intermittent or constant. The serratus mainly contributes to :
- Pain between shoulder blades
- Golfers elbow pain
- Rib pain
- Arm pain[7]
Differential Diagnosis
Intercostal Nerve Neuralgia
It can be differentiated through palpation. In SAMPS , palpation of trigger points will produce the pain that occurs spontaneously. In intercostal neuralgia , palpation will not produce pain or referred pain because the pain of intercostal neuralgia is situated along a dermatome.
Assessment[edit | edit source]
Palpation[edit | edit source]
The serratus anterior muscle is very thin and covers the side of the ribcage.
- You can feel it by putting your hand just below the arm pit.
- It also helps to experience how your ribs feel, so that you can distinguish the ribs and this thin and superficial muscle.
- To do so, just feel the first ribs under your nipple.
- Now you will be able to distinguish the muscle from the ribs.
Muscle Test[edit | edit source]
First, the Wall push up test, the patient is asked to flex his arm to 90 degrees and do a wall push up. Weak serratus anterior muscle would result in winging of the scapula medial border. [8]
The second is the shoulder abduction test, the therapist applies a downwards resisting force against the scapular plane abduction of the shoulder at about 120–130° and against upward rotation of the scapula. A weak serratus anterior would result in the patient failing to resist the therapist’s force resulting in the shoulder breaking into adduction and the scapula can't rotate upwards significantly. [5]
In the third test the patient is in a seated or supine position, with his arm flexed 90-100 degrees and his elbow fully extended. The therapist resists the maximally protracting force by the patient. In case of serratus anterior muscle weakness the patient’s scapula is pushed into a retracted and internally rotated position leading to scapular winging appearance.[5]
Exercises for Activating Serratus Anterior[edit | edit source]
Dynamic hug
Serratus anterior punch
Wall slide tasks[5]
References[edit | edit source]
- ↑ 1.0 1.1 https://www.healthline.com/human-body-maps/serratus-anterior-muscle#2
- ↑ 2.0 2.1 M. Schünke/E. Schulte/U. Schumacher: Prometheus – LernAtlas der Anatomie – Allgemeine Anatomie und Bewegungssystem, 2.Auflage, Thieme Verlag (2007), S.294-295 J. E. Muscolino: The muscular system manual – The skeletal muscles of the human body, 2.Auflage, Elsevier Mosby (2005), S.214-217 P. Berlit: Klinische Neurologie, 3.Auflage, Springer Verlag (2011), S.345 [1]
- ↑ 3.0 3.1 Lung K, Lui F. Anatomy, Thorax, Serratus Anterior Muscles. InStatPearls [Internet] 2018 Dec 9. StatPearls Publishing.
- ↑ Richard D. Gray’s anatomy for students.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Neumann DA, Camargo PR. Kinesiologic considerations for targeting activation of scapulothoracic muscles-part 1: serratus anterior. Brazilian journal of physical therapy. 2019 Nov 1;23(6):459-66.
- ↑ Didesch JT, Tang P. Anatomy, etiology, and management of scapular winging. The Journal of hand surgery. 2019 Apr 1;44(4):321-30.
- ↑ Calais-German, Blandine. Anatomy of Movement. Seattle: Eastland Press, 1993. Print Davies, Clair, and Davies, Amber. The Trigger Point Workbook: Your Self-Treatment Guide For Pain Relief. Oakland: New Harbinger Publications, Inc., Print Simons, David G., Lois S. Simons, and Janet G. Travell. Travell & Simons’ Myofascial Pain and Dysfunction: The Trigger Point Manual. Baltimore, MD: Williams & Wilkins, 1999. Print. Schünke, Michael., Schulte, Erik, and Schumacher, Udo. Prometheus: Lernatlas der Anatomie. Stuttgart/New York: Georg Thieme Verlag, 2007. Print [2]
- ↑ David J. Magee. Orthopedic Physical Assessment. 6th edition. Elsevier. 2014.
