Dominic Stone
Periscapular muscles are the muscles that attach to the scapula, a large, flat bone that forms the shoulder girdle. The scapula has a critical role in shoulder function and must be dynamically stabilized during arm use to maximize the activation of the muscles that originate from it. The trapezius is the most superficial periscapular muscle and serves a primary role in scapular stabilization and motion. Other periscapular muscles include the serratus anterior, levator scapulae, rhomboid major, rhomboid minor, and pectoralis. The importance of coordinated scapulothoracic motion in facilitating full, pain-free motion of the shoulder complex has been increasingly studied, leading to a renewed interest in scapular-based reconstructions to improve shoulder girdle motion through muscle advancements and tendon transfers.
| Characteristics | Values |
|---|---|
| Definition | Periscapular muscles are the muscles that attach to the scapula, a large, flat bone that serves as a critical site of muscle attachment. |
| Number of Periscapular Muscles | Six: serratus anterior, trapezius, levator scapulae, rhomboid major, rhomboid minor, and pectoralis. |
| Functions | The periscapular muscles have various functions, including stabilization of position, control of dynamic coupled motion, scapular stabilization, and motion. They also play a role in shoulder function, shoulder girdle motion, and shoulder pain. |
| Innervation | The periscapular muscles are innervated by nerves such as the posterior branch of the axillary nerve and the subscapular nerve. |
| Blood Supply | The blood supply to the periscapular muscles is primarily through a network of periosteal vessels that originate from muscular insertions. |
| Anatomy | The periscapular muscles have a complex anatomy, with the scapula showing signs of ossification by the 5th week of embryologic development. The acromion has broadened and lateralized to allow mechanical advantage for the deltoid muscle. |
| Clinical Relevance | Understanding the anatomy and function of the periscapular muscles is important for clinicians to diagnose and treat conditions such as scapular dyskinesis and shoulder impingement. Techniques like tendon transfers and scapular repositioning are used to improve shoulder function. |
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What You'll Learn
- The trapezius is the most superficial periscapular muscle
- The scapula is a thin sheet of bone that serves as a critical site of muscle attachment
- The importance of coordinated scapulothoracic motion for pain-free shoulder motion
- The serratus anterior, trapezius, levator scapulae, rhomboid major, rhomboid minor, and pectoralis are the six periscapular muscles
- The scapula's role in shoulder function and its relation to shoulder pain
The trapezius is the most superficial periscapular muscle
The trapezius muscle is the most superficial periscapular muscle. It is a large, triangular, paired muscle located on the posterior aspect of the neck and thorax. When viewed together, the pair forms a diamond or trapezoid shape, hence its name. The trapezius has many attachment points, extending from the skull and vertebral column to the shoulder girdle. It is regarded as having superior, middle, and lower components, inserting on the acromion and lateral scapular spine, superior scapular spine, and inferomedial scapular spine, respectively.
The trapezius muscle has several origin points along the midline of the posterior neck and back. The superior portion attaches to the skull and neck, with the middle portion attaching to the upper part of the spinous processes of C7-T12. The inferior portion, or lower part of C7-T12, depresses the scapula. The trapezius muscle is made up of particularly long muscle fibres that span a large width of the upper back. This enables the trapezius to assist in mainly postural attributes, allowing and supporting the spinal column to remain erect when the person is standing.
The function of the trapezius is to stabilize and move the scapula. The upper fibres can elevate and upwardly rotate the scapula and extend the neck. The middle fibres adduct the scapula, and the lower fibres depress and aid the upper fibres in upwardly rotating the scapula. These motions allow for the scapula to rotate against the levator scapulae and the rhomboid muscles. The trapezius muscle works in conjunction with several muscles to produce coordinated movements, primarily involving the scapula. Some key muscle pairings include the rhomboids and the levator scapulae.
The trapezius is also responsible for upward rotation of the scapula, along with the serratus anterior muscle. This allows us to raise our arm above our heads beyond the level of the shoulder. The deltoid muscle is the primary muscle for shoulder abduction and works closely with the trapezius for arm elevation. During shoulder abduction, the deltoid initiates the movement, while the trapezius stabilizes and rotates the scapula to allow a full range of motion. This collaboration ensures smooth and powerful arm elevation.
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The scapula is a thin sheet of bone that serves as a critical site of muscle attachment
The scapula is a thin, flat, triangular bone that forms the shoulder blade. It is a critical site of muscle attachment, providing a point of attachment for a number of muscles that make up the arm and shoulder. The scapula has two surfaces, three borders, three angles, and three processes. The main body of the scapula consists of a somewhat triangular-shaped flat blade, with an inferiorly pointing apex, referred to as the inferior angle, and lateral and superior angles. The medial border, also known as the vertebral border or medial margin, is the longest of the three borders, extending from the superior angle to the inferior angle.
The front of the scapula, also known as the costal or ventral surface, has a broad concavity called the subscapular fossa, to which the subscapularis muscle attaches. The subscapular fossa is a shallow fossa that articulates with the head of the humerus, forming the glenohumeral joint. The scapula also articulates with the clavicle, forming the acromioclavicular joint. The medial aspect of the scapula is not directly attached to the axial skeleton but is held in place and connected to the thorax and vertebral column by muscles. This allows the scapula to move freely across the posterior thoracic wall (scapulothoracic joint), enabling a wide range of movement and mobility for the upper limb.
The scapula has various bony projections for the attachment of muscles, ligaments, and other soft-tissue structures. For example, the levator scapulae attaches at the superior angle of the scapula, while the teres major attaches at the inferior angle. The rhomboids major and minor attach to the medial border of the scapula, while the serratus anterior attaches to the medial margin. The subscapularis originates on the anterior surface of the scapula, also known as the subscapular fossa, and the infraspinatus attaches to the posterior surface, or infraspinous fossa. The superior portion of the posterior side is the supraspinous fossa, where the supraspinatus attaches.
The trapezius is the most superficial periscapular muscle and plays a primary role in scapular stabilization and motion. It originates in the cervical spine and inserts into the scapula, acromion process, and clavicle. The deltoid muscle also attaches to the scapula, arising from the lower border of the crest of the spine and the lateral border of the acromion.
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The importance of coordinated scapulothoracic motion for pain-free shoulder motion
The shoulder complex is made up of 14 muscles, 8 of which cross the glenohumeral joint. The trapezius is the most superficial periscapular muscle and serves a primary role in scapular stabilization and motion. It is commonly regarded as having superior, middle, and lower components.
The importance of coordinated scapulothoracic motion in facilitating full, pain-free motion of the shoulder complex has been increasingly studied over the past decade. The scapulothoracic and glenohumeral joints work together to ensure smooth and stable motion while maintaining the alignment of the humeral head within the glenoid fossa. This coordination minimizes stress on the shoulder structures and prevents injuries.
The upper trapezius, middle trapezius, and lower trapezius play distinct yet complementary roles in scapular movement. The upper trapezius initiates upward rotation and helps elevate the scapula during the early phases of arm elevation. The middle trapezius stabilizes the scapula against the thoracic wall, ensuring that it does not wing outward. The lower trapezius contributes to the final phases of upward rotation, particularly as the arm approaches full elevation. The serratus anterior is another crucial muscle in scapular mechanics.
Disruptions in muscle coordination can lead to significant shoulder dysfunctions. Insufficient activation of the trapezius or serratus anterior can result in incomplete scapular rotation, while overactivation of the upper trapezius may cause excessive elevation and muscle imbalances. These issues often manifest as shoulder pain, reduced range of motion, and pathologies such as rotator cuff injuries.
A broader understanding of 'normal' shoulder motion is required to fully comprehend the intricacies of the scapulothoracic rhythm and its impact on pain-free shoulder motion.
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The serratus anterior, trapezius, levator scapulae, rhomboid major, rhomboid minor, and pectoralis are the six periscapular muscles
The periscapular muscles are a group of muscles that surround the scapula, or shoulder blade, and play a crucial role in shoulder function and stability. The six periscapular muscles include the serratus anterior, trapezius, levator scapulae, rhomboid major, rhomboid minor, and pectoralis. These muscles work together to facilitate movement and maintain the stability of the shoulder joint, which is one of the most mobile and versatile joints in the human body.
The serratus anterior muscle is an important muscle that contributes to protraction, upward rotation, and depression of the scapula. It is also responsible for anchoring the scapula and preventing a condition known as "winged scapula," where the scapula protrudes posteriorly due to paralysis or weakness in the surrounding muscles.
The trapezius muscle is the most superficial periscapular muscle and serves a primary role in scapular stabilization and motion. It has superior, middle, and lower components that insert on different parts of the scapula. The trapezius is involved in retraction, elevation, and downward rotation of the scapula.
The levator scapulae muscle works in conjunction with the rhomboids to elevate and retract the scapula. It also provides innervation to the dorsal scapular nerve, which controls the motor function of the rhomboid muscles.
The rhomboid muscles, consisting of the rhomboid major and rhomboid minor, are a group of deep intrinsic shoulder muscles. They play a crucial role in upper limb movement, shoulder stability, and scapular retraction. The rhomboids, along with the serratus anterior, trapezius, and pectoralis muscles, form the shoulder girdle and help in anchoring the scapula to prevent winging.
The pectoralis muscle, specifically the pectoralis major and pectoralis minor, contribute to protraction and depression of the scapula. They work alongside other periscapular muscles to ensure a full range of motion and stability in the shoulder joint.
These six periscapular muscles coordinate their actions to enable the scapula to perform six types of motion: protraction, retraction, elevation, depression, upward rotation, and downward rotation. This complex interplay of muscles and movements allows for the full functional range of motion in the upper extremity.
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The scapula's role in shoulder function and its relation to shoulder pain
The scapula, or shoulder blade, is a flat triangular bone in the upper back that forms the back part of the socket of the shoulder joint. It is unique in that it is a floating bone, supported and surrounded by a complex system of 17 muscles, 12 tendons, six ligaments, and two nerves. These connections allow the shoulder to move in six directions, more than any other joint in the body.
The scapula has several roles in shoulder function, including control of static position and motion. The trapezius, the most superficial periscapular muscle, serves a primary role in scapular stabilization and motion. The serratus anterior and lower trapezius muscles contribute to the upward rotation force couple that produces acromial elevation. If this force couple is altered, movement is abnormal. For example, paralysis of the serratus anterior results in reductions in both glenohumeral flexion and abduction.
Scapular dyskinesis, a condition characterized by a lack of upward rotation, a lack of posterior tilting, and increased internal or medial rotation of the scapula, is a common cause of shoulder pain. It can be caused by macrotrauma, microtrauma-induced strain, or inhibited by painful shoulder conditions such as labral lesions, arthrosis, or instability. Shoulder kinematics and associated muscle activity have been shown to be altered in people with symptoms of shoulder impingement.
Physical therapy exercises that focus on strengthening and stretching the muscles around the shoulder can help improve symptoms of scapular dyskinesis. In most cases, nonsurgical treatments such as nonsteroidal anti-inflammatory drugs (NSAIDs) and physical therapy are effective. However, if scapular dyskinesis is caused by an injury to the shoulder joint, a procedure to repair or reconstruct the injured tissues may be necessary.
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Frequently asked questions
Periscapular muscles are those that are attached to the scapula, a large, flat bone that forms from a collection of mesenchymal cells and shows signs of ossification by the 5th week of embryonic development. The scapula serves as a critical site of muscle attachment and is unique because, except for its connection to the clavicle, it is a floating bone almost completely stabilized by muscles.
There are six periscapular muscles: the serratus anterior, trapezius, levator scapulae, rhomboid major, rhomboid minor, and pectoralis. The trapezius is the most superficial periscapular muscle and plays a crucial role in scapular stabilization and motion.
Understanding the anatomy and function of periscapular muscles is essential for clinicians to grasp scapular roles and normal scapular function. This knowledge assists in the diagnosis and treatment of shoulder injuries and pathologies. Research has also focused on the role of periscapular tendon transfers in improving shoulder girdle motion and addressing complex shoulder issues.
