Dominic Stone
The supraspinatus muscle is one of the four rotator cuff muscles, along with the infraspinatus, teres minor, and subscapularis muscles. It is the smallest and most superiorly located of the four, residing in the supraspinous fossa of the scapula, superior to the scapular spine. The supraspinatus muscle and tendon pass deep to the acromion process to insert onto the superior facet of the greater tuberosity of the humerus.
| Characteristics | Values |
|---|---|
| Location | Supraspinatus is located deep to the trapezius muscle in the posterior scapular region |
| It extends from the supraspinous fossa of the scapula to the proximal humerus | |
| It is the most superiorly located of the rotator cuff muscles | |
| It is the smallest of the four muscles that comprise the rotator cuff | |
| Function | Supraspinatus helps to resist the gravitational forces that act on the shoulder joint |
| It stabilizes the shoulder joint by keeping the head of the humerus firmly pressed medially against the glenoid fossa of the scapula | |
| It assists in the abduction of the arm | |
| It contributes weakly to the lateral rotation of the humerus | |
| Innervation | Suprascapular nerve, formed by the anterior rami of spinal nerves C5 and C6 |
| Blood Supply | Suprascapular artery, a branch of the thyrocervical trunk of the subclavian artery |
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What You'll Learn
The supraspinatus muscle is one of the rotator cuff muscles
The supraspinatus muscle is one of the four rotator cuff muscles, along with the infraspinatus, teres minor, and subscapularis muscles. It is the smallest and most superiorly located of the four. The supraspinatus muscle resides in the supraspinous fossa of the scapula, superior to the scapular spine. The muscle fibres converge onto a tendon that runs inferior to the acromion of the scapula. This tendon passes under the acromion process and over the head of the humerus, blending into the glenohumeral joint capsule. The supraspinatus tendon inserts onto the superior facet of the greater tuberosity of the humerus.
The supraspinatus muscle and tendon play a crucial role in stabilising the glenohumeral (shoulder) joint. They work together to keep the head of the humerus firmly pressed against the glenoid fossa of the scapula. This dynamic stabilisation promotes the structural integrity of the joint during movements of the upper limb. Additionally, the supraspinatus assists in the abduction of the arm, which is the movement of the arm away from the body. It also contributes weakly to the lateral rotation of the humerus.
The supraspinatus muscle is located deep to the trapezius muscle and superior to the spine of the scapula and infraspinatus muscle. It receives its nerve supply from the suprascapular nerve, formed by the anterior rami of spinal nerves C5 and C6. The arterial blood supply to the supraspinatus primarily comes from the suprascapular artery, a branch of the thyrocervical trunk of the subclavian artery. Occasionally, the muscle receives a collateral blood supply via the dorsal scapular artery.
The supraspinatus muscle is essential for resisting gravitational forces acting on the shoulder joint due to the weight of the upper limb. Its function in stabilisation and abduction of the humerus helps to initiate shoulder movements and prevent inferior displacement of the humeral head. The muscle is consistently recruited prior to movement of the limb, demonstrating its role in counterbalancing anterior translational forces during flexion. The Empty Can Test and Full Can Test are commonly used to examine the supraspinatus muscle and tendon for impingement or integrity.
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It stabilises the shoulder joint
The supraspinatus muscle is one of the four rotator cuff muscles, along with the infraspinatus, teres minor, and subscapularis muscles. It is the smallest and most superiorly located of the four. The supraspinatus muscle plays a crucial role in stabilising the shoulder joint, ensuring the structural integrity of the joint and preventing injuries.
The supraspinatus muscle originates in the supraspinous fossa of the scapula, which is a concave depression located above the spine of the scapula. From here, the muscle fibres converge onto a tendon that extends laterally, passing under the acromion process and over the head of the humerus. The tendon inserts onto the superior facet of the greater tuberosity of the humerus, which is the upper arm bone.
The supraspinatus muscle helps to resist the gravitational forces acting on the shoulder joint, pulling downward due to the weight of the upper limb. It stabilises the humeral head in the shoulder joint by keeping the head of the humerus firmly pressed medially against the glenoid fossa of the scapula. This prevents the humeral head from sliding off the glenoid fossa during joint movements, maintaining the stability of the shoulder joint.
Additionally, the supraspinatus muscle has a role in the initiation and continuation of abduction of the humerus throughout its range of motion. It assists in lifting the arm away from the body and contributes weakly to the lateral rotation of the humerus. The deltoid muscle, located on the uppermost part of the arm and the top of the shoulder, also contributes to abduction by pulling the humerus toward the acromion.
The supraspinatus muscle and its associated tendons have a complex structure that enables them to withstand the stresses and forces exerted during movements. By stabilising the shoulder joint and coordinating its actions with other rotator cuff muscles, the supraspinatus muscle helps maintain the proper positioning of the humeral head, contributing to the overall stability and function of the shoulder joint.
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It assists in the abduction of the arm
The supraspinatus muscle is one of the four rotator cuff muscles, along with the infraspinatus, teres minor, and subscapularis muscles. It is the smallest and most superiorly located of the four. The supraspinatus muscle plays a crucial role in the abduction of the arm, working alongside the deltoid muscle.
The supraspinatus muscle originates in the supraspinous fossa of the scapula, which is a concave depression located above the spine of the scapula. From here, the muscle fibres converge onto a tendon that runs underneath the acromion process of the scapula and passes over the head of the humerus. The tendon then inserts onto the superior facet of the greater tuberosity of the humerus, which is the upper arm bone. This insertion point is located on the lateral aspect of the humerus, just above the glenohumeral joint.
The supraspinatus muscle is responsible for initiating and assisting in the abduction of the arm. It abducts the arm from 0 to 15 degrees and then works with the deltoid muscle to produce abduction up to 90 degrees. This movement involves lifting the arm away from the body, as in reaching out to the side. The deltoid muscle, located on the uppermost part of the arm and the top of the shoulder, has three distinct functions that correspond to its three bands of muscle fibres. The lateral fibres of the deltoid are responsible for abducting the arm by pulling the humerus towards the acromion.
The supraspinatus muscle also helps to stabilise the shoulder joint. It keeps the head of the humerus firmly pressed against the glenoid fossa of the scapula, which is a shallow depression in the scapula. This stabilisation helps to resist the gravitational forces acting on the shoulder joint due to the weight of the upper limb. Additionally, the supraspinatus muscle contributes weakly to the lateral rotation of the humerus.
Overall, the supraspinatus muscle plays a crucial role in the abduction of the arm, working in conjunction with the deltoid muscle to achieve a full range of motion. Its attachments to the scapula and humerus enable it to stabilise the shoulder joint and initiate abduction, contributing to the complex mechanics of the human body.
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The muscle fibres converge onto a tendon that runs inferior to the acromion
The supraspinatus muscle is a rotator cuff muscle that abducts the arm and stabilises the humeral head in the shoulder joint. It is the smallest and most superiorly located of the four rotator cuff muscles, residing in the supraspinous fossa of the scapula, superior to the scapular spine. The muscle fibres converge onto a tendon that runs inferior to the acromion. The acromion is the lateral end of the scapula, or shoulder blade. The tendon of the supraspinatus muscle extends laterally, passing under the acromion process and over the head of the humerus.
The supraspinatus muscle and tendon pass deep to the acromion process to insert onto the superior facet of the greater tuberosity of the humerus. The inferior portion of the tendon blends with the joint capsule about 1 cm before the attachment on the bone. The supraspinatus tendon is separated from the coracoacromial ligament, the acromion, and the deltoid muscle by the subacromial bursa.
The supraspinatus muscle has motor involvement in both the initiation and continuation of abduction throughout the range of motion. It also contributes weakly to the lateral rotation of the humerus. Together with the other rotator cuff muscles, the infraspinatus, teres minor, and subscapularis, the supraspinatus forms part of the dynamic stabilization for the glenohumeral joint. These four muscles act in a coordinated fashion to stabilise the head of the humerus on the shallow glenoid fossa and promote the structural integrity of the joint.
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The supraspinatus muscle is innervated by the suprascapular nerve
The supraspinatus muscle is one of the four rotator cuff muscles, along with the infraspinatus, teres minor, and subscapularis muscles. It is the smallest and most superiorly located of the four. The supraspinatus muscle originates in the supraspinous fossa of the scapula, superior to the scapular spine, and attaches to the superior facet of the greater tuberosity of the humerus. This attachment allows the supraspinatus muscle to stabilize the head of the humerus on the glenoid fossa of the scapula and assist in the abduction of the arm.
The suprascapular nerve is a mixed nerve, providing both sensory and motor innervation. It supplies sensation to the acromioclavicular and glenohumeral joints and motor innervation to the supraspinatus and infraspinatus muscles. The nerve is formed by the anterior rami of spinal nerves C5 and C6, and sometimes also receives nerve fibers from C4.
The suprascapular nerve is susceptible to injury, which can result in pain, muscle weakness, and weakened abduction and external rotation of the shoulder. This can be caused by traumatic injury to the nerve or compression at the suprascapular and spinoglenoid notches. Thus, knowledge of the anatomy of the suprascapular nerve is important for diagnosing and treating suprascapular nerve injuries.
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Frequently asked questions
The supraspinatus muscle attaches onto the superior facet of the greater tuberosity of the humerus.
The supraspinatus muscle is a rotator cuff muscle that abducts the arm and stabilizes the humeral head in the shoulder joint.
The supraspinatus muscle is located deep to the trapezius muscle in the posterior scapular region.
