kns 332 exam two shoulder girdle

e. Weakness of which muscle(s) could lead to medial winging of the scapula? f. Weakness of which muscle(s) could lead to lateral winging of the scapula?

E. serratus anterior F. rhomboid major and minor

trapezius

Origin Upper fibers: base of skull, occipital protuberance, and posterior ligaments of neck Middle fibers: spinous processes of seventh cervical and upper three thoracic vertebrae Lower fibers: spinous processes of fourth through twelfth thoracic vertebrae Insertion Upper fibers: posterior aspect of the lateral third of the clavicle Middle fibers: medial border of the acromion process and upper border of the scapular spine Lower fibers: triangular space at the base of the scapular spine Action Upper fibers: elevation of the scapula, upward rotation, and extension and rotation of the head at the neck Middle fibers: elevation, upward rotation, and adduction (retraction) of the scapula Lower fibers: depression, adduction (retraction), and upward rotation of the scapula Application, strengthening, and flexibility The upper fibers are a thin and relatively weak part of the muscle. They provide some elevation of the clavicle. Due to their origin on the base of the skull, they assist in extension of the head. The middle fibers are stronger and thicker and provide strong elevation, upward rotation, and adduction (retraction) of the scapula. Rarely is this portion of the muscle weak, because it is so active in positioning the shoulder for function and posture. As a result, it is often a source of tenderness and discomfort due to chronic tension. The lower fibers depress the scapula, assist in adduction (retraction) and rotate the scapula upward. This portion is typically weak, particularly in individuals whose activities demand a significant amount of scapula abduction. When all the parts of the trapezius are working together, they tend to pull upward and adduct at the same time. This may be seen in lifting the handles of a wheelbarrow. Typical action of the trapezius muscle is fixation of the scapula for deltoid action. Continuous action in upward rotation of the scapula permits the arms to be raised over the head. The muscle is always used in preventing the glenoid fossae from being pulled down during the lifting of objects with the arms. It is also typically seen in action during the holding of an object overhead. Holding the arm at the side horizontally shows typical fixation of the scapula by the trapezius muscle, while the deltoid muscle holds the arm in that position. The muscle is used strenuously when lifting with the hands, as in picking up a heavy wheelbarrow. The trapezius must prevent the scapula from being pulled downward. Carrying objects on the tip of the shoulder also calls this muscle into play. Strengthening of the upper and middle fibers can be accomplished through shoulder-shrugging exercises. The middle and lower fibers can be strengthened through bent-over rowing and shoulder joint horizontal abduction exercises from a prone position. The lower fibers can be emphasized with a chestproud shoulder retraction exercise attempting to place the elbows in the back pants pockets with depression. Parallel dips or body dips are also helpful for emphasizing the lower trapezius. See Appendix 2 for more commonly used exercises to address the trapezius and other muscles in this chapter. To stretch the trapezius, each portion needs to be specifically addressed. The upper fibers may be stretched by using one hand to pull the head and neck forward into flexion or slight lateral flexion to the opposite side while the ipsilateral hand is hooked under a table edge to maintain the scapula in depression. The middle fibers are stretched to some extent with the procedure used for the upper fibers, but they may be stretched further by using a partner to passively pull the scapula into full protraction. The lower fibers are perhaps best stretched with the subject in a side-lying position while a partner grasps the lateral border and inferior angle of the scapula and moves it passively into maximal elevation and protraction.

What are the landmarks of the scapula?

Key bony landmarks for studying the shoulder girdle are the manubrium, clavicle, coracoid process, acromion process, glenoid fossa, lateral border, inferior angle, medial border, superior angle, and spine of the scapula.

Serratus anterior

Posterior and lateral muscles Serratus anterior origin: Surface of the upper 9 ribs at the side of the chest Insertion: Anterior aspect of the whole length of the medial border of the scapula Abduction: Transverse plane Upward rotation: Frontal plane Innervation: Long thoracic nerve (C5-C7)

What are the joints of the shoulder girdle? What bony landmarks articulate to form them?b. What type of joints are they?i. How does that affect their function?c. What motion(s) occur at each joint?i. In which planes of motion and about which axes of rotation can these joints move?

Acromioclavicular (AC) joint: This joint is classified as an arthrodial joint. It has a 20- to 30-degree total gliding and rotational motion accompanying other shoulder girdle and shoulder joint motions. In addition to the strong support provided by the coracoclavicular ligaments (conoid and trapezoid), the superior and inferior acromioclavicular ligaments provide stability to this often-injured joint.

What are the joints of the shoulder girdle? What bony landmarks articulate to form them?b. What type of joints are they?i. How does that affect their function?c. What motion(s) occur at each joint?i. In which planes of motion and about which axes of rotation can these joints move?

Coracoclavicular (CC) joint: The coracoclavicular joint, classified as a syndesmotic-type joint, functions through its ligaments to greatly increase the stability of the acromioclavicular joint.

Pectoralis minor

Origin Anterior surfaces of the third to fifth ribs Insertion Coracoid process of the scapula Action Abduction (protraction): draws the scapula forward and tends to tilt the lower border away from the ribs Downward rotation: as it abducts, it draws the scapula downward Depression: when the scapula is rotated upward, it assists in depression Application, strengthening, and flexibility The pectoralis minor muscle is used, along with the serratus anterior muscle, in true abduction (protraction) without rotation. This is seen particularly in movements such as push-ups in which true abduction of the scapula is necessary. Therefore, the serratus anterior draws the scapula forward with a tendency toward upward rotation, the pectoralis minor pulls forward with a tendency toward downward rotation, and the two pulling together give true abduction. These muscles will be seen working together in most movements of pushing with the hands. The pectoralis minor is most used in depressing and rotating the scapula downward from an upwardly rotated position, as in pushing the body upward on dip bars or in body dips. The pectoralis minor is often tight due to being overused in activities involving abduction, which may lead to forward and rounded shoulders. As a result stretching may be indicated, which can be accomplished with a wall push-up in the corner as used for stretching the serratus anterior. Additionally, lying supine with a rolled towel directly under the thoracic spine while a partner pushes each scapula into retraction places this muscle on stretch.

Rhomboids

Origin Spinous processes of the seventh cervical and first five thoracic vertebrae Insertion Medial border of the scapula, below the spine of the scapula Action The rhomboid major and minor muscles work together. Adduction (retraction): draw the scapula toward the spinal column Downward rotation: from the upward rotated position; draw the scapula into downward rotation Elevation: slight upward movement accompanying adduction Application, strengthening, and flexibility The rhomboid muscles fix the scapula in adduction (retraction) when the muscles of the shoulder joint adduct or extend the arm. These muscles are used powerfully in chinning. As one hangs from the horizontal bar, suspended by the hands, the scapula tends to be pulled away from the top of the chest. When the chinning movement begins, it is the rhomboid muscles that rotate the medial border of the scapula down and back toward the spinal column. Note their favorable position to do this. Related to this, the rhomboids work in a similar manner to prevent scapula winging. The trapezius and rhomboid muscles working together produce adduction with slight elevation of the scapula. To prevent this elevation, the latissimus dorsi muscle is called into play. Chin-ups, dips, and bent-over rowing are excellent exercises for developing strength in this muscle. The rhomboids may be stretched by passively moving the scapula into full protraction while maintaining depression. Upward rotation may assist in this stretch as well.

Subclavius

Origin Superior aspect of first rib at its junction with its costal cartilage Insertion Inferior groove in the midportion of the clavicle Action Stabilization and protection of the sternoclavicular joint Depression Abduction (protraction) Application, strengthening, and flexibility The subclavius pulls the clavicle anteriorly and inferiorly toward the sternum. In addition to assisting in abducting and depressing the clavicle and the shoulder girdle, it has a significant role in protecting and stabilizing the sternoclavicular joint during upper-extremity movements. It may be strengthened during activities in which there is active depression, such as dips, or active abduction, such as push-ups. Extreme elevation and retraction of the shoulder girdle provide a stretch to the subclavius.

Levator scapulae

Origin Transverse processes of the upper four cervical vertebrae Insertion Medial border of the scapula from the superior angle to the scapular spine Action Elevates the medial margin of the scapula Weak downward rotation Weak adduction Application, strengthening, and flexibility Shrugging the shoulders calls the levator scapulae muscle into play, along with the upper trapezius muscle. Fixation of the scapula by the pectoralis minor muscle allows the levator scapulae muscles on both sides to extend the neck or to flex laterally if used on one side only. The levator scapulae is perhaps best stretched by rotating the head approximately 45 degrees contralaterally and flexing the cervical spine actively while maintaining the scapula in a relaxed, depressed position. Like the trapezius, the levator scapulae is a very common site for tightness, tenderness, and discomfort secondary to chronic tension and from carrying items with straps over the shoulder.

Shoulder girdle muscles a. What are the agonists of shoulder girdle motions? d. What do they look like (shape, fiber orientation, etc.) and how does that relate to their agonist functions?

Shoulder girdle muscles—location and action Anterior Pectoralis minor—abduction, downward rotation, and depression Subclavius—depression and abduction Posterior and laterally Serratus anterior—abduction and upward rotation Posterior Trapezius Upper fibers—elevation and extension and rotation of the head at the neck Middle fibers—elevation, adduction, and upward rotation Lower fibers—adduction, depression, and upward rotation Rhomboid—adduction, downward rotation, and elevation Levator scapulae—elevation It is important to understand that muscles may not necessarily be active throughout the absolute full range of motion for which they are noted as being agonists. Table 4.2 provides a detailed breakdown of the muscles responsible for primary movements of the shoulder girdle.

What is the relationship between the shoulder girdle and glenohumeral joint?

Shoulder joint movement and function depend on a stable girdle and its position

What are the joints of the shoulder girdle? What bony landmarks articulate to form them?b. What type of joints are they?i. How does that affect their function?c. What motion(s) occur at each joint?i. In which planes of motion and about which axes of rotation can these joints move?

Sternoclavicular (SC) joint: This is classified as a (multiaxial) arthrodial joint although there is anatomical justification to classify it as a sellar joint. In relation to the manubrium of the sternum, the clavicle moves anteriorly 15 degrees with protraction and moves posteriorly 15 degrees91with retraction. Some rotation of the clavicle along its axis during various movements of the shoulder girdle results in slight rotary gliding movement at the sternoclavicular joint. It is supported anteriorly by the anterior sternoclavicular ligament and posteriorly by the posterior sternoclavicular ligament. The costoclavicular and interclavicular ligaments also provide stability against superior displacement.

What bones form the shoulder girdle?

Two bones are primarily involved in movements of the shoulder girdle. They are the scapula and the clavicle, which generally move as a unit.

4. Where does the shoulder girdle attach to the trunk?

Two bones are primarily involved in movements of the shoulder girdle. They are the scapula and the clavicle, which generally move as a unit. Their only bony link to the axial skeleton is provided by the clavicle's articulation with the sternum. The only attachment of the upper extremity to the axial skeleton is via the scapula and its attachment through the clavicle at the sternoclavicular joint.