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The infraspinatus muscle is a thick, triangular muscle that is part of the rotator cuff muscles in the shoulder. It is located on the dorsal surface of the scapula, deep to the trapezius, deltoid, and latissimus dorsi muscles. The infraspinatus muscle plays a crucial role in stabilizing the shoulder joint and enabling a wide range of arm motions. This muscle can be prone to pain and injuries, such as strains and tears, which can impact daily activities and sports performance. The correct pronunciation of infraspinatus muscle is provided by online sources to help users accurately articulate this term.
| Characteristics | Values |
|---|---|
| Location | Dorsal surface of the scapula |
| Origin | Medial two-thirds of the infraspinous fossa |
| Insertion | Middle facet of the greater tuberosity of the humerus |
| Blood Supply | Suprascapular and circumflex scapular arteries |
| Innervation | Suprascapular nerve (C5 and C6) |
| Function | External rotation of the humerus, stabilization of the glenohumeral or shoulder joint |
| Relation to Other Muscles | Infraspinatus and supraspinatus are considered one functional unit |
| Pain | Ranges from mild strains to complete tears; tendinitis and myofascial pain syndrome |
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What You'll Learn
Infraspinatus muscle anatomy
The infraspinatus muscle is a thick, triangular muscle that occupies most of the dorsal surface of the scapula. It is one of the four muscles that make up the rotator cuff, along with the supraspinatus, subscapularis, and teres minor. The rotator cuff muscles function to stabilise and produce movements in the shoulder joint, allowing for a wide range of arm motion while keeping the head of the humerus centralised within the glenoid cavity.
The infraspinatus muscle arises from the infraspinous fossa of the scapula and connects to the proximal humerus. It is located deep to the trapezius and parts of the deltoid and latissimus dorsi muscles. The muscle fibres course towards the shoulder joint, almost parallel to the teres minor and major, and are separated from them by a thick fascia. As the infraspinatus approaches the shoulder joint, it is sometimes separated from the neck of the scapula by the infraspinatus bursa, which may communicate with the shoulder joint cavity.
The main function of the infraspinatus muscle is to externally rotate the humerus and stabilise the shoulder joint. It works together with the teres minor to oppose the upward pull of the deltoid muscle and to stabilise the humeral head against the glenoid fossa. This prevents the upward displacement of the humeral head and impingement on the coracoid process. The infraspinatus is frequently fused with the teres minor, and together they rotate the head of the humerus outward and assist in carrying the arm backward.
The infraspinatus muscle is innervated by the suprascapular nerve, which arises from the upper trunk of the brachial plexus (C5 and C6). It receives its arterial blood supply from the suprascapular and circumflex scapular arteries. Infraspinatus pain can be caused by various conditions, including tendinitis, myofascial pain syndrome, and nerve compression or pinching.
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Infraspinatus pain
The infrah-spin-A-tus muscle is located on the dorsal surface of the scapula, at the back of the shoulder. It is a thick triangular muscle that attaches the top of the humerus (upper arm bone) to the shoulder blade. The infraspinatus is one of four muscles that make up the rotator cuff, which is responsible for the shoulder joint's stability and a wide range of arm motions.
Nonsurgical treatments are typically recommended for infraspinatus pain and may include rest, ice therapy, and stretching exercises. Surgery may be considered if nonsurgical treatments are ineffective or in cases of severe tears.
To diagnose infraspinatus pain, a doctor will review the patient's medical history, perform a physical examination, and may use imaging techniques such as X-rays, ultrasounds, or MRIs. Treatment options can then be explored based on the specific cause and severity of the condition.
It is important to seek medical advice if you are experiencing infraspinatus pain to ensure proper diagnosis and treatment.
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Infraspinatus function
The infraspinatus muscle is a thick triangular muscle that occupies the majority of the dorsal surface of the scapula. It is one of the four muscles of the rotator cuff, alongside the subscapularis, teres minor, and supraspinatus muscles. The infraspinatus muscle's main function is to externally rotate the humerus and stabilize the shoulder joint.
The infraspinatus muscle works in conjunction with the teres minor muscle to produce a wide range of arm motions while maintaining the head of the humerus within the glenoid cavity. This stabilization mechanism prevents dislocation by transmitting forces. When the arm is abducted, the infraspinatus and teres minor work together to counteract the upward pull of the deltoid muscle and stabilize the humeral head against the glenoid fossa.
The infraspinatus muscle also plays a role in shoulder extension. With the arm in a fixed position, it abducts the inferior angle of the scapula, a movement known as scaption. Scaption increases the mobility of the scapula, assisting other shoulder muscles in achieving full shoulder abduction.
Additionally, the infraspinatus muscle provides the posterior force in the anterior-posterior force balance of the shoulder. It works in conjunction with the subscapular muscle, which provides the anterior force. This balance of forces ensures the stability and smooth movement of the shoulder joint.
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Infraspinatus muscle testing
The infrah-spin-ate-us muscle is one of the rotator cuff muscles, which function to abduct and laterally rotate the arm. The infraspinatus muscle is involved in shoulder pathologies, such as shoulder impingement and rotator cuff tears. Testing for infraspinatus muscle involvement in these pathologies can be done through the infraspinatus test.
The infraspinatus manual muscle test is a reproducible test used to determine deficits of the muscle being tested. The patient's arm should be at their side, not quite touching their trunk, with the elbow flexed to 90 degrees. The examiner places their hand on the dorsum of the patient's hand. The patient is then asked to externally rotate both forearms against the examiner's resistance. The test is positive when there is weakness or pain in external rotation, which suggests an infraspinatus tear.
It is important to accurately assess the strength of the infraspinatus muscle without the contribution of other synergistic muscles, such as the posterior deltoid. A new technique using EMG analysis has been described to decrease deltoid activity during testing. This involves placing surface electrodes over the muscle bellies of the infraspinatus and posterior deltoid of the right shoulder, along with a ground electrode over the C7 spinous process. EMG activity is recorded during resisted external rotation in different testing conditions, such as seated active and passive adduction.
The infraspinatus muscle is often involved in rotator cuff tears, which can range from mild strains to complete tears. These tears are usually painless, and external rotation weakness is a strong indicator of a tear. Rehabilitation programs for the infraspinatus muscle may include exercises such as prone horizontal abduction with the shoulder fully externally rotated and prone external rotation with the shoulder at 90 degrees abduction and the elbow at 90 degrees of flexion.
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Infraspinatus muscle pronunciation
The infraspinatus muscle is a thick, triangular muscle that occupies the dorsal surface of the scapula. It is one of the four muscles that make up the rotator cuff, which is responsible for the movement and stability of the shoulder joint. The infraspinatus muscle plays a crucial role in external rotation and stabilization of the humerus.
Now, let's break down the pronunciation of "infraspinatus muscle":
"Infraspinatus" is pronounced as in-frah-spahy-ney-tuhs. Here's a syllable-by-syllable breakdown:
- In-: pronounced as "in," as in the word "inform"
- Fra-: pronounced as "fray," as in the word "frame"
- Spi-: pronounced as "spy," as in the word "spyglass"
- Na-: pronounced as "nah," as in the word "name"
- Tus-: pronounced as "tuss," as in the word "tussle"
The word "muscle" is pronounced as muhs-uhl. Here's how you say it syllable by syllable:
- Muh-: pronounced as "muh," as in the word "muffin"
- -scl-: no specific pronunciation, but it forms part of the overall sound
- -e: no specific pronunciation, but it softens the end of the word
Putting it all together, you would pronounce "infraspinatus muscle" as in-frah-spahy-ney-tuhs muhs-uhl. Remember to connect the words smoothly and naturally when saying the full term.
It's important to note that pronunciation can vary slightly depending on your regional accent and the specific context in which the term is used. However, using the provided pronunciation guide, you should be able to confidently and accurately pronounce "infraspinatus muscle."
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Frequently asked questions
Infraspinatous.
The infraspinatus muscle is a thick, triangular muscle that is one of the four rotator cuff muscles of the shoulder. It is located anterior (deep) to the trapezius and deltoid muscles and the infraspinous fascia.
The infraspinatus muscle works together with the teres minor to stabilize the glenohumeral joint and prevent dislocation by translating forces. It also abducts and laterally rotates the arm.
