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The rhomboid muscles are a group of muscles located in the upper back, under the trapezius muscle, and are associated with the scapula. There are two rhomboid muscles on each side of the back: the rhomboid major and the rhomboid minor. These muscles are responsible for scapular retraction and rotation, and play a vital role in upper limb movement and stability of the shoulder girdle and scapula. The rhomboids receive their innervation from the dorsal scapular nerve, which is crucial for scapular stability and control.
| Characteristics | Values |
|---|---|
| Number of rhomboid muscles | Two on each side of the upper back |
| Shape | Rhomboid |
| Location | Under the trapezius muscle, in the upper part of the thoracic region of the back |
| Function | Retraction, elevation, and rotation of the scapula |
| Innervation | Dorsal scapular nerve (C4-C5), a branch of the brachial plexus |
| Vascular supply | Dorsal scapular artery, a branch of the subclavian artery |
| Pathology | Winged scapula due to rhomboid palsy, caused by damage to the dorsal scapular nerve |
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What You'll Learn
The rhomboid major and minor
The rhomboids are a collective group of muscles formed by the rhomboid major and minor. They are found deep to the trapezius muscle, which covers them. The rhomboids are important for upper limb movement and stability of the shoulder girdle and scapula. They help to anchor the scapula and prevent winging. The rhomboid minor is a cylindrical muscle that originates at the ligamentum nuchae and C7 and T1 vertebra. It inserts at the scapula's medial border near the base of the spine of the scapula. The rhomboid major is a quadrangular muscle located inferior to the rhomboid minor. It originates from the spinous processes of the second to fifth thoracic vertebrae (T2-T5).
Functionally, the rhomboid muscles retract, elevate and rotate the scapula. They also protract the medial border of the scapula, keeping it in position at the posterior thoracic wall. The rhomboids are vital for actions such as pulling and throwing, and they play a large role in overhead arm movement. The deep shoulder girdle muscles, including the rhomboid major and minor, are derived from thoracic somitic cells. They receive innervation from the dorsal scapular nerve, and their vascular supply is the dorsal scapular artery.
The rhomboids can have a significant impact on upper body posture and shoulder mechanics. Poor upper body posture can lead to pain in the upper back, especially along the medial border of the scapulae. Strengthening the rhomboid muscles can help to relieve this pain and improve posture. The constant postural strain experienced by the rhomboids can make them dysfunctional, which can limit the superior rotation of the scapula and glenoid cavity, resulting in poor shoulder mechanics. This can lead to soft tissue injuries in the shoulder region, especially during activities that involve arm elevation above shoulder height.
Variants of the rhomboid muscles are rare but present interesting cases when discovered. There have been a few reported cases of an additional rhomboid muscle found in humans. These variants usually originate at the level of the occipital bone or the superior nuchal line and insert into the rhomboid major and minor muscles at the level of the spine of the scapula.
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Innervation and vascular supply
The rhomboids are a group of muscles formed by the rhomboid major and minor. They are located in the upper back, immediately deep to the trapezius. The rhomboid minor is a cylindrical muscle that originates at the ligamentum nuchae and C7 and T1 vertebra, inserting at the scapula's medial border near the base of the spine of the scapula. The rhomboid major is a quadrangular muscle located inferior to the rhomboid minor.
Innervation
The rhomboid muscles receive innervation from the dorsal scapular nerve (DSN), a branch of the brachial plexus. The DSN originates from the ventral ramus of the spinal nerve root C5 and courses posteriorly and inferiorly through the middle scalene muscles and between the posterior scalene, levator scapulae, and serratus posterior superior. It then continues deep into the brachial plexus to innervate both the rhomboid minor and major muscles at their anterior border. This innervation is crucial for the coordinated action required for scapular stability and control.
Vascular Supply
The vascular supply to the rhomboids is primarily through the dorsal scapular artery, a branch of the subclavian artery. The dorsal scapular artery generally arises from either the second or third portion of the subclavian artery, although some studies have shown variations where it stems from the thyrocervical trunk. The rhomboid muscles also receive arterial blood from two other sources: the deep branch of the transverse cervical artery, which stems from the thyrocervical trunk, and the dorsal branch of the upper five or six posterior intercostal arteries, which are branches of the thoracic aorta.
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Function and movement
The rhomboids are a group of muscles formed by the rhomboid major and minor. They are located in the upper back, extending between the nuchal ligament, spinous processes of the thoracic vertebrae, and scapula. The rhomboid major is a quadrangular muscle located inferior to the rhomboid minor, which is a smaller, cylindrical muscle.
The main function of the rhomboid muscles is scapular retraction, or the movement of the scapula superomedially and toward the vertebral column. This helps to maintain correct posture when sitting, standing, and walking. The rhomboids also work to elevate and rotate the scapula, keeping it in position at the posterior thoracic wall. This provides stability to the scapula and reinforces the shoulder.
The rhomboids are important in upper limb movement and stability, particularly in actions such as pulling, throwing, and overhead arm movement. They work in conjunction with other muscles such as the levator scapulae, serratus anterior, trapezius, and pectoralis muscles to form the shoulder girdle and anchor the scapula, preventing winging.
The motor function of the rhomboid muscles is controlled by the dorsal scapular nerve (DSN), which provides innervation to both the rhomboid minor and major muscles. The DSN originates from the ventral ramus of the spinal nerve root C5 and courses through the middle scalene muscles. The rhomboids receive their vascular supply from the dorsal scapular artery.
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Rhomboid injuries and pathologies
The rhomboid muscles are a group of muscles formed by the rhomboid major and minor. They are located deep to the trapezius to form parallel bands that pass from the vertebrae to the medial border of the scapula. The rhomboid minor is a cylindrical muscle that originates at the ligamentum nuchae and C7 and T1 vertebra, while the rhomboid major is a quadrangular muscle located inferior to the rhomboid minor.
One common pathology associated with the rhomboids is winged scapula, or rhomboid palsy, which occurs due to damage to the dorsal scapular nerve. This nerve provides innervation to both the rhomboid minor and major muscles. Entrapment of the nerve is the most frequent cause of rhomboid palsy, but it can also result from direct injury through trauma, anterior shoulder dislocation, or overuse in overhead athletics like baseball and volleyball. Patients with rhomboid palsy often experience medial scapular pain, abnormal shoulder motion, and discomfort in the neck, back, and shoulder. The condition is often underdiagnosed due to its subtle presentation and the deep anatomical position of the rhomboids.
Another condition related to the rhomboid muscles is scapular winging, which can be caused by dysfunction, weakness, or loss of nerve function in the rhomboids. This results in the medial border of the scapula protruding or "winging" outward. The rhomboids are vital for actions such as pulling and throwing, so injuries or pathologies affecting these muscles can significantly impact upper limb movement and shoulder stability.
Treatment for rhomboid injuries and pathologies may include conservative approaches such as cervical spine stabilization, muscle relaxants, physical therapy, and NSAIDs. In extreme cases, surgery may be considered.
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Treatment and diagnosis
The rhomboid muscles are a group of deep intrinsic shoulder muscles that include the rhomboid major and minor. They are located deep to the trapezius, forming parallel bands that pass from the vertebrae to the medial border of the scapula.
Rhomboid muscles are responsible for retracting, elevating, and rotating the scapula, as well as protracting the medial border of the scapula, keeping it in position at the posterior thoracic wall. Dysfunction, weakness, or loss of nerve function in the rhomboids can cause issues such as winging of the medial border of the scapula and inferior scapular angle rotation.
The rhomboids are also vital for pulling motions and play a significant role in throwing and overhead arm movements. Their importance in these movements means that injuries to the rhomboid muscles are usually posture-related, such as incorrect shoulder placement when playing sports, carrying heavy objects, or having a forward head posture. Those who do not exercise regularly may find that their rhomboid muscles become weak and more prone to strains and tears.
To diagnose issues with the rhomboid muscles, a physical examination is often performed. This may involve palpating the rhomboids by relaxing the trapezius and placing the hand in the small of the back. The patient may be asked to lift their hand off the back, and the rhomboids will push the fingers out. Pain from rhomboid issues generally extends from the edge of the shoulder blades to the spine.
One of the more common pathologies associated with the rhomboids is winged scapula, which is caused by rhomboid palsy. This condition occurs due to damage to the dorsal scapular nerve, often from entrapment or direct injury. Rhomboid palsy can cause medial scapular pain, abnormal shoulder motion, and neck, back, and shoulder discomfort. EMG is the most specific tool for diagnosing rhomboid palsy, revealing prolonged muscle latency of the muscle action potential.
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Frequently asked questions
The rhomboid muscles are located in the upper back, under the trapezius muscle.
The rhomboid major is a quadrangular muscle located inferior to the rhomboid minor. It is an extrinsic muscle of the shoulder.
The rhomboid muscles are responsible for retracting, elevating and rotating the scapula. They are also vital for actions such as pulling and throwing.
Rhomboid palsy is a common pathology specific to the rhomboid muscle group, often caused by damage to the dorsal scapular nerve. It can result in medial scapular pain, abnormal shoulder motion, and neck, back, and shoulder discomfort.
In MSR, the rhomboid muscles are important for addressing thoracic and scapular dysfunctions. MSR interventions focus on improving the flexibility and strength of the rhomboids to correct scapular winging and enhance scapular stability.
