The Teres Minor Muscle: Anatomy, Function, and Treatment
The teres minor is a small but essential muscle in the shoulder, playing a key role in shoulder stability, rotation, and overall movement. While it doesn’t usually get as much attention as the larger rotator cuff muscles, it’s integral to keeping the shoulder functioning well, particularly for movements involving external rotation and stabilization. When something goes wrong with the teres minor—whether due to strain, injury, or trigger points—it can lead to discomfort and limited shoulder mobility, impacting daily activities and athletic performance.
In this article, we’ll do a deep dive into the anatomy, function, biomechanics, and common issues associated with the teres minor. We’ll also look at how to recognize, treat, and prevent problems related to this important shoulder muscle.
Anatomy of the Teres Minor
The teres minor muscle is part of the rotator cuff, a group of four muscles that stabilize the shoulder joint. It originates from the upper two-thirds of the lateral border of the scapula (the shoulder blade) and inserts onto the inferior facet of the greater tubercle of the humerus, which is the long bone of the upper arm.
The teres minor lies just below the infraspinatus muscle, with which it shares similar functions. Together, these muscles form the posterior portion of the rotator cuff, working to control the movement and position of the humeral head (the ball of the shoulder joint) within the glenoid cavity (the socket). This configuration allows for precise and stable shoulder movements, particularly external rotation and stabilization during overhead activities.
Function of the Teres Minor
The primary function of the teres minor is external (lateral) rotation of the shoulder, which involves turning the upper arm away from the body. It also assists in stabilizing the humeral head in the shoulder socket, helping to prevent dislocation and overuse injuries. Additionally, the teres minor works alongside the other rotator cuff muscles to modulate shoulder movements, particularly during tasks that require lifting, pulling, or rotating the arm.
The teres minor’s stabilizing function is particularly important during overhead sports (like baseball, tennis, and swimming) and resistance training exercises that involve shoulder rotation and abduction. This muscle is smaller than the infraspinatus but has a uniquely pivotal role in supporting shoulder stability and preventing joint impingement.
Biomechanics of the Teres Minor
In terms of biomechanics, the teres minor is part of a coordinated system that maintains shoulder balance and movement. When the teres minor contracts, it externally rotates the humerus, counteracting the forward pull of the larger pectoral muscles. This balance prevents the humeral head from moving too far forward or upward within the shoulder joint, which can lead to impingement and rotator cuff injuries.
Alongside the deltoid, the teres minor helps position the arm during tasks like lifting, throwing, and reaching. It works most effectively when the arm is in neutral or slightly abducted, and its activity is crucial in creating controlled, functional shoulder movements. Additionally, by maintaining tension in the posterior shoulder, the teres minor supports both active and passive stability in the shoulder joint, which helps reduce injury risk.
Common Injuries Associated with the Teres Minor
The teres minor can be susceptible to strains, tendinopathy, and overuse injuries, particularly in people who engage in repetitive shoulder movements or high-impact sports. Here are some of the most common injuries associated with the teres minor:
Rotator Cuff Tears: Although the teres minor is less commonly injured than other rotator cuff muscles like the supraspinatus, it can still be involved in partial or complete rotator cuff tears. These injuries often occur from acute trauma or degeneration and are most common in people over 40 or athletes performing repetitive overhead motions. Symptoms may include pain with external rotation, weakness, and difficulty lifting objects.
Tendinopathy: Chronic overuse of the teres minor can lead to tendinopathy, a condition marked by tendon irritation or degeneration. This issue is often seen in athletes or individuals who perform repetitive arm movements. Tendinopathy in the teres minor is typically felt as a dull ache in the shoulder, especially during or after physical activity.
Impingement Syndrome: Impingement occurs when the rotator cuff tendons (including the teres minor) get pinched between the shoulder blade and the head of the humerus. This can lead to inflammation and pain, especially during movements that require shoulder rotation or overhead reach.
Referred Pain and Dysfunction: Because of its proximity to other shoulder muscles, teres minor issues can sometimes cause referred pain in the neck, upper arm, or between the shoulder blades. Dysfunction in the teres minor may also lead to compensatory movement patterns, which can strain nearby muscles and further destabilize the shoulder.
Trigger Points in the Teres Minor
Trigger points are small, tender knots within muscle tissue that can refer pain to other areas. In the teres minor, trigger points are often located near the muscle’s attachment to the shoulder blade and humerus. These points can lead to pain that radiates down the back of the arm, around the shoulder blade, or even into the upper arm.
Symptoms of Teres Minor Trigger Points:
- Aching or burning sensation around the shoulder blade and back of the shoulder
- Referred pain down the outer side of the arm, sometimes reaching the wrist
- Pain when reaching overhead or across the body
- Limited range of motion with external rotation
Trigger points in the teres minor can be aggravated by overuse, poor posture, or repetitive shoulder activities. Athletes, particularly those in sports with overhead actions like swimming and baseball, are prone to developing these painful points. Left untreated, trigger points can limit shoulder movement, reduce strength, and lead to compensatory patterns that increase the risk of further injury.
Treating Teres Minor Injuries and Trigger Points
Treating issues in the teres minor often requires a combination of manual therapy, stretching, and strengthening exercises. Here’s a breakdown of some effective treatment methods:
Manual Therapy and Massage: Manual therapists often use techniques like deep tissue massage, myofascial release, and trigger point therapy to release tightness in the teres minor and surrounding shoulder muscles. Targeted massage can help alleviate tension, improve circulation, and reduce trigger point sensitivity.
Stretching Exercises: Gentle stretches targeting the teres minor and adjacent muscles are useful for improving flexibility and relieving tightness. A popular stretch involves bringing the arm across the chest while gently pulling the elbow towards the opposite shoulder. Hold for 20-30 seconds, making sure not to overstretch, and repeat as needed.
Strengthening Exercises: Strengthening the teres minor and the rest of the rotator cuff can enhance shoulder stability and prevent re-injury. Exercises like external rotation with a resistance band or dumbbell are effective for building teres minor strength. It’s best to start with low resistance and focus on proper form, gradually increasing intensity as strength improves.
Trigger Point Therapy: For those dealing with trigger points, trigger point therapy (or myofascial release) can be beneficial. A therapist may apply direct pressure to the trigger points using fingers or specialized tools, holding pressure until the muscle releases. This technique can also be performed using a massage ball against a wall, allowing for self-treatment at home.
Physical Therapy and Rehabilitation: For more severe injuries, a structured rehabilitation program with a physical therapist can guide recovery. A PT can assess shoulder mechanics, provide targeted exercises, and offer adjustments to daily movements to minimize strain on the teres minor and optimize shoulder function.
Preventing Teres Minor Injuries
Preventing injuries to the teres minor comes down to maintaining balanced shoulder strength, flexibility, and proper technique in overhead activities. Here are some tips to help keep your teres minor and shoulder healthy:
- Incorporate rotator cuff strengthening exercises into your workout routine, focusing on both the teres minor and other muscles like the infraspinatus, supraspinatus, and subscapularis.
- Warm up properly before engaging in any overhead activities, especially sports like swimming, tennis, or weightlifting.
- Stretch and mobilize the shoulder regularly to maintain flexibility, especially if you perform repetitive shoulder movements.
- Avoid overloading the shoulder joint with excessive weight or improper form, as this increases the risk of muscle strain and injury.
By maintaining a well-rounded shoulder care routine, you can help protect the teres minor from strain, reduce the likelihood of trigger points, and enjoy greater shoulder mobility and strength.
Conclusion
The teres minor may be small, but it plays a vital role in the shoulder’s complex system of muscles and movements. From stabilizing the humeral head during overhead activities to supporting shoulder rotation, this muscle is indispensable for anyone involved in sports or activities requiring strong, functional shoulders. Understanding its anatomy, function, and potential injuries can empower you to better care for this muscle, whether through preventive exercises, treatment of trigger points, or specialized rehabilitation following an injury.
If you’re dealing with pain or dysfunction in the teres minor, consider seeking out a manual therapist or physical therapist. Proper assessment, hands-on treatment, and a tailored exercise plan can make all the difference in resolving issues and restoring full shoulder function.
Disclaimer: This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a healthcare provider before starting new treatments or exercises, particularly if you have an existing shoulder injury.
References
Neumann, D. A. (2016). *Kinesiology of the Musculoskeletal System: Foundations forReferencesNeumann, D. A. (2016). Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. Elsevier Health Sciences.
Magee, D. J. (2013). Orthopedic Physical Assessment. Elsevier Health Sciences.
Travell, J. G., & Simons, D. G. (1999). Myofascial Pain and Dysfunction: The Trigger Point Manual, Volume 1: Upper Half of Body. Lippincott Williams & Wilkins.
