The teres major muscle is located in the upper limbs and makes up the shoulder, together with other neighboring musculoskeletal structures, it is responsible for adduction and internal rotation of the arm.
The teres major is a short muscle and is one of the six muscles that make up the scapulohumeral group, that is, they join the scapula bone with the humerus, which is the upper arm bone. It is part of the so-called intrinsic muscles of the shoulder.
Teres major muscle. Image taken from:
Isolated injury to this muscle is rare, but can occur in high-performance athletes. Its clinical importance is based on the fact that it can be used as a graft when there is a tear injury to other shoulder muscles.
It is also of great importance as an anatomical reference for the surgeon in any surgical procedure that involves the armpit, since it establishes, together with other muscles, the limit between the axillary hollow and the arm.
Anatomy
The teres major is one of the muscles that makes up the shoulder. It is short and cylindrical in shape. It extends from the scapula to the humerus, if it were projected towards the skin its route would be from the lower part of the armpit to the middle part of the arm.
By Mikael Häggström. When using this image in external works, it may be cited as: Häggström, Mikael (2014). "Medical gallery of Mikael Häggström 2014". WikiJournal of Medicine 1 (2). DOI: 10.15347 / wjm / 2014.008. ISSN 2002-4436. Public Domain.orBy Mikael Häggström, used with permission. - Image: Gray810.png, Public Domain, It is closely related to the muscles: teres minor and latissimus dorsi, also known as latissimus dorsi. Its fibers run parallel to those of this last muscle.
It receives a blood supply from a branch of the scapular circumflex artery, which is a major axillary blood vessel. The inferior subscapular nerve is responsible for innervation.
The muscle is of particular importance in surgical anatomy, as it forms the region known as the humerotricipital quadrilateral located in the axilla. This region defines the boundary between the armpit and the arm when performing surgeries in that region.
Together with the teres minor muscle and the triceps, the teres major forms this axillary anatomical region through which important vascular and neurological elements, such as the axillary nerve and the posterior circumflex artery, enter.
Function
Thanks to its insertion both in the scapula and in the upper part of the humerus, the teres major muscle is responsible for the performance of three movements of the arm.
Its activation achieves internal rotation of the arm, adduction and also retroversion, which is to bring the arm behind the back. Thus, when we try to touch the opposite shoulder in front or behind the body it is thanks to the activation of the teres major.
Its close relationship with the latissimus dorsi muscle leads it to perform accessory functions in some of the movements that the latter performs when activated. Its fibers and those of the dorsalis run parallel, joining at some point in certain movements, especially the extension of the shoulder.
Clinical considerations
Injuries
Injury to the teres major is a rare event but it can occur and should always be on the mind of the physician or coach as a potential site of injury. Due to its location, it is difficult to establish that the teres major is the injured muscle.
Those exercises that lead to muscle overload can cause injury. Movements such as pull-ups and sports such as tennis, skiing, rowing, and swimming, are activities to consider in the medical questioning of a patient with signs of teres major trauma.
Symptoms of injury typically include pain that can be felt down the back of the arm, toward the deltoid or triceps muscle, which form the outer shoulder, even toward the elbow.
Despite the fact that the muscle attaches to the scapula, it is rare that the pain is in this location.
The physician should try to reveal the muscle injury through some clinical maneuvers. You should first attempt passive mobilization, that is, helping the patient to perform movement and then begin palpation of painful points or pain trigger points.
By Bundesarchiv, Bild 183-1986-1126-015 / CC-BY-SA 3.0, CC BY-SA 3.0 de, Due to the location of the muscle, it is difficult to palpate it. A simple way used by clinicians to palpate pain trigger points in the teres major is by following the fibers of the latissimus dorsi muscle.
The fibers of this muscle run parallel to the teres major. In this way, when palpating the latissimus dorsi we locate the teres major, palpating in the same direction, but on the inside.
Treatment
Most injuries to the teres major improve with clinical therapy. This means that, with rest and oral analgesics, it is enough to observe the healing of the trauma.
Muscle massages performed by a professional physiotherapist or chiropractor are also of great help for complete improvement.
In some cases, especially when there is a tear or detachment, surgical therapy is necessary. However, it is important to clarify that these injuries are not common.
Strengthening
To avoid muscle injury, health professionals recommend doing exercises that strengthen the muscle.
Very few people put an emphasis on training this muscle either out of ignorance of its existence or because they consider it of little importance. This exclusion from the exercise routine can lead to muscle injury.
Strengthening exercises for the teres major are similar to those for the latissimus dorsi muscle. The important thing is not to overload the muscle, but to train it progressively until the increase in resistance is achieved.
Activities that can be performed both in the gym and outdoors include rowing and pull-ups. Once mastery of these activities has been achieved you can begin adding weight exercises to your training activities.
One of the most effective exercises for strengthening the teres major is the so-called dumbbell row.
This activity is accomplished using a controllable weight dumbbell. The knee and hand of the arm opposite the one to be exercised should be supported on an exercise bench.
By No machine-readable author provided. GeorgeStepanek assumed (based on copyright claims). - No machine-readable source provided. Own work assumed (based on copyright claims)., CC BY-SA 3.0, With your back straight, you bring your elbow back, raising the dumbbell, as if imitating the movement of the row. With this exercise, you work on the teres major and the dorsal muscle, strengthening them and avoiding injuries.
References
- Miniato MA; Varacallo M. (2019). Anatomy, Shoulder and Upper Limb, Shoulder. StatPearls. Taken from: ncbi.nlm.nih.gov
- Mostafa E; Varacallo M. (2018). Anatomy, Shoulder and Upper Limb, Humerus. StatPearls. Taken from: ncbi.nlm.nih.gov
- Dancker, M.; Lambert, S; Brenner, E. (2017). Teres major muscle - insertion footprint. Journal of anatomy; 230, 631–638
- Cousin, J; Crenn, V; Fouasson-Chailloux, A; Dauty, M; Fradin, P; Gouin, F; Venet, G. (2018). Isolated Rupture of the Teres Major Muscle When Water Skiing: A Case Report and Literature Review. Case reports in orthopedics. Taken from: nlm.nih.gov
- Donohue, BF; Lubitz, MG; Kremcheck, TE. (2017) Sports Injuries to the Latissimus Dorsi and Teres Major. The American Journal of Sports Medicine. Taken from: nlm.nih.gov