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The scapula, or shoulder blade, is a flat, triangular-shaped bone that connects the clavicle (collarbone) to the humerus (upper arm bone). It forms the posterior of the shoulder girdle and is a site of attachment for many muscles, tendons, and ligaments. The intrinsic muscles of the scapula include the rotator cuff muscles, teres major, subscapularis, teres minor, and infraspinatus. These muscles attach to the scapular surface and assist with movements such as abduction and external and internal rotation of the glenohumeral joint. The extrinsic muscles include the triceps, biceps, and deltoid. The third group of muscles includes the levator scapulae, trapezius, rhomboids, and serratus anterior, which are responsible for rotational movements and stabilization of the scapula. The scapula is a crucial bone for the proper movement of the arms and shoulders, allowing for a wide range of motion and mobility in the upper limbs.
| Characteristics | Values |
|---|---|
| Common Name | Shoulder Blade |
| Description | A thin, flat, triangular-shaped bone |
| Location | Upper thoracic region on the dorsal surface of the rib cage |
| Surfaces | 2 (Ventral and Dorsal) |
| Borders | 3 (Medial, Lateral/Axillary, Superior) |
| Angles | 3 (Superior/Medial, Lateral, Inferior) |
| Processes | 3 (Acromion, Spine, Coracoid) |
| Ligaments | Acromioclavicular Ligament |
| Nerves | Dorsal Scapular, Upper and Lower Subscapular, Suprascapular |
| Veins | Axillary Vein, Suprascapular Veins |
| Muscles | 17, including Levator Scapulae, Rhomboids, Serratus Anterior, Deltoid, Latissimus Dorsi, Trapezius, Biceps Brachii, Coracobrachialis, Pectoralis Minor, Triceps Brachii |
| Functions | Provides attachment for muscles that make up the arm and shoulder, allowing for a wide range of movement |
| Injuries | Rare to hurt scapula in isolation, but shoulder injuries can damage it; common shoulder injuries include sprains, dislocations, fractures |
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What You'll Learn
- The scapula is a flat, triangular bone that forms the shoulder joint
- It connects to 17 muscles, including the serratus anterior and levator scapulae
- The scapula's stability depends on surrounding muscles, with several attaching directly
- It has three surfaces, three borders, three angles, and three processes
- The scapula permits a wide range of motion for the shoulder
The scapula is a flat, triangular bone that forms the shoulder joint
The scapula, or shoulder blade, is a flat, triangular bone that forms the shoulder joint. It is one of three bones that make up the shoulder joint, connecting the clavicle (collarbone) to the humerus (upper arm bone). The scapula has two surfaces, three borders, three angles, and three processes. It is located in the upper thoracic region on the dorsal surface of the rib cage.
The scapula's flat, triangular shape is why it is commonly referred to as the shoulder blade. It has three surfaces: the costal (anterior) surface, the lateral surface, and the posterior (inferior) surface. The main part of the costal surface forms a slightly indented cup (the subscapular fossa) that supports one of the rotator cuff muscles. The lateral surface includes the glenoid fossa, an indentation that makes up the back of the shoulder socket, and the posterior surface includes the spine (apex), a slightly pointed tip that forms the top of the shoulder blade.
The scapula is an important bone as it provides a point of attachment for many muscles that make up the arm and shoulder. These muscles include the levator scapulae, rhomboids, serratus anterior, and trapezius. The scapula also allows for a wide range of motion in the shoulder, with the ability to move in six directions, more than any other joint in the body.
The scapula is susceptible to various injuries and conditions, such as shoulder sprains, dislocations, and fractures, although it is rarely broken in isolation. It can also be affected by shoulder impingement syndrome, arthritis, and bursitis.
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It connects to 17 muscles, including the serratus anterior and levator scapulae
The scapula, or shoulder blade, is a flat, triangular-shaped bone that forms the posterior of the shoulder girdle. It connects the clavicle (or collarbone) to the humerus, forming the glenohumeral (shoulder) joint. The scapula is a crucial bone as it provides an attachment point for numerous muscles that make up the arm and shoulder.
The scapula is connected to 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 17 muscles that attach to the scapula include the serratus anterior and levator scapulae. The serratus anterior muscles stretch across the first eight ribs, starting at the sides and reaching across the back to the scapula. These muscles enable you to round your shoulders forward and are also involved in protraction, upward rotation, and depression movements of the scapula.
The levator scapulae muscles, on the other hand, are found on either side of the back of the neck along the spine. They lift the scapula, allowing you to shrug your shoulders. The levator scapulae attach at the superior angle of the scapula.
Other muscles that attach to the scapula include the rotator cuff muscles (supraspinatus, infraspinatus, subscapularis, and teres minor), teres major, rhomboids major and minor, deltoid, latissimus dorsi, trapezius, biceps, triceps, coracobrachialis, and pectoralis minor. These muscles assist with various movements and stabilization of the scapula.
The scapula has several bony projections and surfaces that facilitate muscle attachment. The subscapular fossa, for example, is a shallow concavity on the anterior surface of the scapula where the subscapularis muscle originates. The infraspinous fossa, located directly below the spine, is another area where muscles attach. The scapula's lateral surface includes the glenoid fossa, where the biceps muscle attaches, and the infraglenoid tubercle, where the triceps muscle attaches.
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The scapula's stability depends on surrounding muscles, with several attaching directly
The scapula, or shoulder blade, is a flat, triangular-shaped bone that forms the posterior of the shoulder girdle. It connects the clavicle (or collarbone) to the humerus, forming the glenohumeral (shoulder) joint. The scapula is a crucial bone as it serves as an anchor for many muscles in the arm, upper back, and shoulder.
The scapula's stability depends on the surrounding muscles, with several attaching directly to the scapula itself. The intrinsic muscles of the scapula include the rotator cuff muscles (supraspinatus, infraspinatus, subscapularis, and teres minor), teres major, and levator scapulae. The extrinsic muscles include the triceps, biceps, and deltoid. The third group of muscles, responsible for rotational movements and stabilization of the scapula, includes the trapezius, rhomboids, serratus anterior, and levator scapulae.
The scapula has various bony projections that serve as attachment points for muscles, ligaments, and other soft-tissue structures. 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, and 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, known as the infraspinous fossa.
The scapula's stability and movement are closely linked to the proper functioning of these surrounding muscles. For example, the serratus anterior muscle, which stretches across the first eight ribs, allows individuals to round their shoulders forward. The upper trapezius muscle, which forms a diamond shape in the back, enables individuals to shrug their shoulders and lift their arms overhead. Any imbalance, tightness, weakness, or detachment of these muscles can lead to abnormal function or mobility of the scapula, a condition known as scapular dyskinesis. Physical therapy can help strengthen and stretch these muscles, and in some cases, surgery may be required to repair injured muscle tissue.
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It has three surfaces, three borders, three angles, and three processes
The scapula, or shoulder blade, is one of three bones that make up the shoulder joint. It is a flat, triangular bone that connects the upper limb to the trunk. The scapula has three surfaces, three borders, three angles, and three processes.
Surfaces
The three surfaces of the scapula are the costal (anterior) surface, the lateral surface, and the posterior (inferior) surface. The costal surface is the front of the scapula, facing the ribcage. It forms a slightly indented cup, known as the subscapular fossa, which supports one of the rotator cuff muscles. The lateral surface is the outside edge of the scapula, pointing toward the humerus. It includes the glenoid fossa, the back of the shoulder socket, and the superglenoid tubercle, where the biceps muscle attaches. The posterior surface is the rear part of the scapula, facing the back. It includes the spine, a slightly pointed tip that forms the top of the shoulder blade, and the acromion, which moves with the clavicle during shoulder movement.
Borders
The three borders of the scapula are the superior, lateral, and medial borders. The superior border is the shortest and thinnest of the three. The medial border is thin and runs parallel to the vertebral column, often called the vertebral border. The lateral border, also known as the axillary border, is the thickest and strongest of the three borders, running towards the apex of the axilla. It includes the glenoid cavity, a shallow fossa that articulates with the head of the humerus to form the glenohumeral joint.
Angles
The three angles of the scapula are the superior, lateral, and inferior angles. The superior angle is formed by the meeting of the superior and lateral borders. The lateral angle is where the superior and medial borders meet. The inferior angle is where the medial and lateral borders meet.
Processes
The scapula has three processes: the spine, the coracoid process, and the acromion process. The spine is the most prominent feature of the posterior surface, running transversely across the scapula and dividing it into two sections. The coracoid process is a hook-like projection that extends from the superior border, anchoring three muscles. The acromion process is a palpable lateral extension of the posterior spine, arching over the glenohumeral joint and articulating with the clavicle to form the acromioclavicular joint.
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The scapula permits a wide range of motion for the shoulder
The scapula, or shoulder blade, is a flat, triangular bone that forms the posterior of the shoulder girdle. It is one of three bones that make up the shoulder joint, connecting the clavicle to the humerus. The scapula is a crucial component of the shoulder's socket, enabling movement and functionality.
The scapula connects to 17 muscles, 12 tendons, six ligaments, and two nerves. These connections allow the shoulder to move in six directions, a greater range than any other joint in the body. The scapula engages in six types of motion, including protraction, retraction, elevation, depression, upward rotation, and downward rotation. These motions facilitate full-functional upper extremity movement, providing a wide range of motion for the shoulder.
The intrinsic muscles of the scapula include the rotator cuff muscles, teres major, subscapularis, teres minor, and infraspinatus. These muscles attach to the scapular surface and assist with abduction and external and internal rotation of the glenohumeral joint. The extrinsic muscles, including the triceps, biceps, and deltoid, are responsible for rotational movements and stabilization of the scapula.
The scapula's stability is dependent on the surrounding musculature, with several muscles attaching directly to it. 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, and the serratus anterior attaches to the medial margin.
The scapula's unique structure and muscular attachments enable it to provide a wide range of motion for the shoulder. Through its upward rotation, posterior tilt, and external rotation, the scapula plays a crucial role in achieving full elevation of the arm. This scapulohumeral rhythm involves the coordinated movement of the scapula, clavicle, and humerus, resulting in a full range of motion for the shoulder joint.
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Frequently asked questions
The scapula, or shoulder blade, is a flat, triangular-shaped bone that connects the clavicle (collarbone) to the humerus.
The scapula has 17 muscle attachments, including the levator scapulae, rhomboids, serratus anterior, pectoralis major and minor, trapezius, triceps, biceps, deltoid, and coracobrachialis.
The scapula allows for a wide range of motion in the shoulder, including protraction, retraction, elevation, depression, upward rotation, and downward rotation.
Common injuries related to the scapula include shoulder sprains, dislocations, separations, and fractures. Conditions affecting the scapula include shoulder impingement syndrome, shoulder arthritis, and scapular winging.
