Dominic Stone
The scapula, commonly referred to as the shoulder blade, is a flat, triangular bone that sits above the rib cage in the upper back. It provides attachment to several groups of muscles, including the intrinsic muscles, extrinsic muscles, and stabilizing and rotating muscles. The levator scapulae muscle is one of the muscles within the floor of the posterior triangle of the neck, and it helps to elevate and retract the scapula. It often works in combination with other muscles to produce downward rotation of the scapula and is important for the full function of the shoulder joint.
| Characteristics | Values |
|---|---|
| Definition | The scapula, commonly referred to as the shoulder blade, is a thick, flat, triangular-shaped bone that sits above the rib cage in the upper back. |
| Number of Surfaces | 2 |
| Number of Borders | 3 |
| Number of Angles | 3 |
| Number of Processes | 3 |
| Number of Directions in which the Scapula can Move | 6 |
| Muscles that Attach to the Scapula | Intrinsic: subscapularis, supraspinatus, infraspinatus, teres minor, teres major, rotator cuff muscles, levator scapulae, rhomboids, serratus anterior, and pectoralis minor. Extrinsic: biceps, triceps, and deltoid. |
| Nerves | Dorsal scapular nerve, upper and lower subscapular nerve, suprascapular nerve, and brachial plexus. |
| Veins | Axillary vein, suprascapular veins, and anastomotic tributaries. |
| Artery | Dorsal scapular artery. |
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What You'll Learn
- The scapula is a flat, triangular bone that sits above the rib cage in the upper back
- The bone provides attachment for three groups of muscles: intrinsic, extrinsic, and stabilising and rotating muscles
- The levator scapulae muscle is part of the latter group, along with the rhomboid major, rhomboid minor, serratus anterior, and trapezius
- The levator scapulae muscle elevates and retracts the scapula
- The scapula allows for full function of the shoulder joint through six motions: protraction, retraction, elevation, depression, upward rotation, and downward rotation
The scapula is a flat, triangular bone that sits above the rib cage in the upper back
The scapula, also known as the shoulder blade, is a flat, triangular bone located in the dorsal part of the thorax, between the second and seventh rib. It sits above the rib cage in the upper back, connecting the upper arm bone or humerus with the collarbone or clavicle. The scapula has two surfaces, three borders, three angles, and three processes.
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 subscapularis is a rotator cuff muscle that originates from the superolateral surface of the costal scapula. The medial two-thirds of the fossa feature three longitudinal oblique ridges, with another thick ridge adjoining the lateral border. These ridges provide attachment to the tendinous insertions, while the surfaces between them attach to the fleshy fibres of the subscapularis muscle. The lateral third of the fossa is smooth and covered by the fibres of this muscle.
The back of the scapula, or the dorsal or posterior surface, is arched from above downward and is subdivided into two unequal parts by the spine of the scapula. The most prominent feature of the posterior scapula is the spine, which runs transversely across the scapula. Above the spine of the scapula is the supraspinous fossa, which is concave, smooth, and broader at its vertebral end than at its humeral end. The medial two-thirds of the supraspinous fossa give origin to the supraspinatus muscle. The area below the spine of the scapula is the infraspinous fossa, which displays a convex shape. The infraspinatus muscle originates from this area.
The scapula provides an attachment site for muscles, including three groups of muscles: intrinsic, extrinsic, and stabilizing and rotating muscles. The intrinsic muscles include the muscles of the rotator cuff: the subscapularis, supraspinatus, infraspinatus, and teres minor. These muscles attach to the surface of the scapula and are responsible for the internal and external rotation of the shoulder joint, along with humeral abduction. The extrinsic muscles, including the biceps, triceps, and deltoid muscles, attach to various parts of the scapula and are responsible for several actions of the glenohumeral joint. The third group, which includes the trapezius, serratus anterior, levator scapulae, and rhomboid muscles, is primarily responsible for stabilization and rotation of the scapula.
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The bone provides attachment for three groups of muscles: intrinsic, extrinsic, and stabilising and rotating muscles
The scapula, or shoulder blade, is a thick, flat, triangular bone that sits above the rib cage in the upper back. It connects the clavicle to the humerus, forming the posterior of the shoulder girdle. The scapula has three groups of muscles attached to it: intrinsic, extrinsic, and stabilising and rotating muscles.
The intrinsic muscles of the scapula include the rotator cuff muscles, or SITS muscles: the subscapularis, supraspinatus, infraspinatus, and teres minor. These muscles attach to the surface of the scapula and are responsible for the internal and external rotation of the shoulder joint, along with humeral abduction. The supraspinatus originates in the medial two-thirds of the supraspinous fossa, a concave, smooth area above the spine of the scapula. The infraspinatus, on the other hand, attaches to the posterior surface, known as the infraspinous fossa, which is much larger than the supraspinous fossa. The subscapularis attaches to the broad concavity on the front of the scapula, called the subscapular fossa, and is separated from the infraspinatus by a fibrous septum attached to a ridge on the outer part of the back of the scapula. The teres minor attaches to the upper two-thirds of the surface between the ridge and the axillary border.
The extrinsic muscles include the triceps, biceps, and deltoid muscles. These muscles attach to different parts of the scapula, such as the coracoid process, supraglenoid tubercle, infraglenoid tubercle, and the spine of the scapula. They are responsible for several actions of the glenohumeral joint.
The third group of muscles, which includes the levator scapulae, trapezius, rhomboids, and serratus anterior, is mainly responsible for rotational movements and stabilization of the scapula. These muscles also assist in the elevation and retraction of the scapula and the shoulder girdle at the scapulothoracic joint. The levator scapulae, in particular, helps prevent the depression of the girdle when carrying heavy loads. It also participates in the stabilization of the scapula and the inferior rotation of the glenoid cavity.
The scapula's stability is dependent on the surrounding musculature, and it has various bony projections for the attachment of muscles, ligaments, and other soft-tissue structures. The movements of the scapula and the clavicle are crucial for the full elevation of the arm, with the scapula allowing for the full function of the shoulder joint, one of the most mobile and versatile joints in the human body.
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The levator scapulae muscle is part of the latter group, along with the rhomboid major, rhomboid minor, serratus anterior, and trapezius
The scapula, or shoulder blade, is a thick, flat bone that sits above the rib cage in the upper back. It creates the shoulder joint where it meets the head of the humerus, the bone of the upper arm. The scapula has three groups of muscles: intrinsic, extrinsic, and stabilizing and rotating muscles.
The levator scapulae muscle is a slender skeletal muscle that sits at the back and side of the neck. It is part of the extrinsic group of muscles, along with the rhomboid major, rhomboid minor, serratus anterior, and trapezius. The levator scapulae muscle originates from the transverse processes of the first four cervical vertebrae and inserts onto the upper portion of the medial border of the scapula.
The levator scapulae muscle is innervated by the anterior rami of spinal nerves C3 and C4, as well as the dorsal scapular nerve (C5), a branch of the brachial plexus. It is supplied by the dorsal scapular artery, which has a small branch that passes laterally to the supraspinatus fossa of the scapula. The main function of the levator scapulae muscle is to elevate the scapula and rotate its inferior angle medially. It also works with other muscles to produce downward rotation of the scapula and to stabilize the spine.
The levator scapulae muscle is susceptible to stiffening and chronic pain due to poor posture. It can be affected by a rare condition called "scapula alata," which causes winging of the scapula and atrophy of the levator scapulae and rhomboid muscles.
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The levator scapulae muscle elevates and retracts the scapula
The levator scapulae is a slender skeletal muscle situated at the back and side of the neck. It is one of the muscles within the floor of the posterior triangle of the neck. The levator scapulae muscle elevates and retracts the scapula, or shoulder blade, at the scapulothoracic joint. It also helps to prevent depression of the shoulder girdle when carrying heavy loads.
The levator scapulae muscle originates from the posterior tubercles of the transverse processes of cervical vertebrae C1-C4. It inserts onto the vertebral margin of the scapula, between the superior angle and the root of the spine. The muscle descends diagonally from its origin to its insertion. The levator scapulae is innervated by the anterior rami of spinal nerves C3 and C4 and the dorsal scapular nerve (C5), a branch of the brachial plexus. It is supplied by the dorsal scapular artery, which has a small branch that passes laterally to the supraspinatus fossa of the scapula.
The levator scapulae muscle is a muscle of scapular motion and works in combination with other muscles such as the rhomboids, pectoralis minor, and serratus anterior to produce downward rotation of the scapula and stabilize the spine. When the spine is fixed, contraction of the levator scapulae muscle elevates the scapula and rotates its inferior angle medially. When the shoulder is fixed, the levator scapulae rotates to the same side and flexes the cervical spine laterally.
The levator scapulae muscle is prone to stiffening and chronic pain due to poor posture in everyday life, such as carrying heavy shoulder bags or permanent lifting of the shoulders while sitting at a desk.
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The scapula allows for full function of the shoulder joint through six motions: protraction, retraction, elevation, depression, upward rotation, and downward rotation
The scapula, or shoulder blade, is a thick, flat bone that sits above the rib cage in the upper back. It is an important bone in the function of the shoulder joint, allowing for full-functional upper extremity movement through six motions: protraction, retraction, elevation, depression, upward rotation, and downward rotation.
Protraction is achieved through the actions of the serratus anterior, pectoralis major, and pectoralis minor muscles. The pectoralis minor and biceps short head can create an anterior tilt and protraction due to their pull on the coracoid. Retraction, on the other hand, is accomplished by the actions of the trapezius, rhomboids, and latissimus dorsi muscles.
The scapula contributes to elevation (flexion and abduction) by upwardly rotating the glenoid fossa, with the help of the trapezius, levator scapulae, and rhomboid muscles. The levator scapulae muscle is innervated by branches of the cervical nerves and the dorsal scapular nerve. It is supplied by the dorsal scapular artery, which has a small branch supplying the muscle in a third of cases. When the spine is fixed, the levator scapulae elevates the scapula and rotates its inferior angle medially.
Depression is accomplished through the force of gravity and the actions of several muscles, including the latissimus dorsi, serratus anterior, pectoralis major and minor, and the trapezius muscles. Upward rotation is also achieved through muscular action, specifically by the trapezius and serratus anterior muscles. Downward rotation, however, relies more on gravity, along with the actions of the latissimus dorsi, levator scapulae, rhomboids, and the pectoralis major and minor muscles.
The scapula plays a crucial role in the complex movement of the shoulder joint, allowing for a full range of motion through these six types of motion.
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Frequently asked questions
The scapula, commonly referred to as the shoulder blade, is a thick, flat, triangular-shaped bone that sits above the rib cage in the upper back. It connects the clavicle to the humerus and forms the posterior of the shoulder girdle.
The scapular muscles can be divided into three groups: intrinsic, extrinsic, and stabilizing and rotating muscles. The intrinsic muscles include the rotator cuff muscles, teres major, subscapularis, teres minor, and infraspinatus. The extrinsic muscles include the triceps, biceps, and deltoid. The third group, which is mainly responsible for stabilization and rotation of the scapula, includes the levator scapulae, trapezius, rhomboids, and serratus anterior.
The levator scapulae muscle is a superficial muscle of the back that primarily elevates and retracts the scapula. It also helps prevent depression of the girdle when carrying heavy loads and participates in the stabilization of the scapula and the inferior rotation of the glenoid cavity.
