The muscles of this chapter are involved with the motions of the shoulder girdle (scapula and clavicle), arm (humerus), and forearm (radius and ulna). The bellies of these muscles are located on the trunk, over the scapula, and on the arm. Trapezius, latissimus dorsi, and pectoralis major are large superficial muscles located on the trunk. Deltoid, triceps brachii, and biceps brachii (and to some degree the brachialis) are large superficial muscles located on the scapula and arm.

As a general rule, muscles that move the shoulder girdle have their origin (proximal attachment) on the trunk and their insertion (distal attachment) on the scapula or clavicle or both. These muscles move the scapula relative to the rib cage wall (trunk) at the scapulocostal joint and/or the clavicle at the sternoclavicular joint.

Muscles that move the arm have their origin (proximal attachment) on the trunk, clavicle, or scapula and their insertion (distal attachment) on the humerus. These muscles move the arm relative to the scapula at the glenohumeral joint.

Muscles that move the forearm have their origin (proximal attachment) on the scapula or humerus and their insertion (distal attachment) on the radius or ulna.

The companion CD at the back of this book allows you to examine the muscles of this body region, layer by layer, and individual muscle palpation technique videos are available in the Chapter 6 folder on the Evolve website.

OVERVIEW OF FUNCTION: MUSCLES OF THE ELBOW AND RADIOULNAR JOINTS

The following general rules regarding actions can be stated for the functional groups of muscles of the elbow and radioulnar joints:

 If a muscle crosses the elbow joint anteriorly with a vertical direction to its fibers, it can flex the forearm at the elbow joint by moving the anterior surface of the forearm toward the anterior surface of the arm.

 If a muscle crosses the elbow joint posteriorly with a vertical direction to its fibers, it can extend the forearm at the elbow joint by moving the posterior surface of the forearm toward the posterior surface of the arm.

 Reverse actions at the elbow joint involve moving the arm toward the forearm at the elbow joint. This movement usually occurs when the hand (and therefore the forearm) is fixed by holding onto an immovable object.*

 If a muscle crosses the radioulnar joints anteriorly with a horizontal orientation to its fibers, it will pronate the forearm at the radioulnar joints by crossing the radius over the ulna.

 If a muscle crosses the radioulnar joints posteriorly with a horizontal direction to its fibers, it will supinate the forearm at the radioulnar joints by moving the radius to be parallel with the ulna.

 Reverse actions of these standard (typical) mover actions at the radioulnar joints involve moving the ulna toward the radius at the radioulnar joints. This movement usually occurs when the hand (and therefore the radius) is fixed by holding onto an immovable object.*

SHOULDER GIRDLE AND ARM

Trapezius

Pronunciation tra-PEE-zee-us

The trapezius is a broad flat superficial muscle that overlies the neck and middle and upper back. It is considered to have three parts: upper, middle, and lower. The trapezius is functionally important for neck and shoulder girdle motions (Figure 6-4).

WHAT’S IN A NAME?

The name, trapezius, tells us that this muscle is shaped similar to a trapezoid ().

* Derivation:

trapezius: Gr. a little table (or trapezoid shape)

PALPATION

1. Ask the client to lie prone with the arm resting on the table at the side of the body.

2. To palpate the lower and middle trapezius, place the palpating finger pads just lateral to the lower and middle thoracic spine. Then ask the client to abduct the arm to 90 degrees with the elbow joint extended; and slightly retract the scapula by pinching the shoulder blade toward the spine. Adding gentle resistance to the client’s arm abduction with your support hand is usually helpful. Palpate perpendicular to the fibers between the spine and scapula (Figure 6-5, A).

3. To palpate the upper trapezius, ask the client to extend the head slightly. Look for the engagement of the upper trapezius and palpate it in the neck up to its occipital attachment (Figure 6-5, B).

4. Note that the upper trapezius is quite narrow; it only attaches to the medial one third of the superior nuchal line of the occiput. The semispinalis capitis muscle, the largest muscle in the neck, is deep to the upper trapezius.

TREATMENT CONSIDERATIONS

 Many positions require postural isometric contraction overuse of the upper trapezius. These positions include holding the head inclined anteriorly when working in front of the body using a hand-held electronic device such as a smart phone, carrying a purse or bag on the shoulder (regardless of the weight), crimping a telephone between the ear and the shoulder, holding the arm outward in an abducted position, or carrying a heavy weight in the hand.

 Weakness of the trapezius can contribute to the condition of rounded/slumped shoulders.

 Because the greater occipital nerve pierces through the upper trapezius, when the upper trapezius is tight, it can compress this nerve, which causes a tension headache. This condition is also known as greater occipital neuralgia.

SHOULDER GIRDLE AND ARM

Rhomboid Major; Rhomboid Minor

Pronunciation ROM-boyd MAY-jor • ROM-boyd MY-nor

The rhomboid muscles are located in the interscapular region between the spine and the scapula, deep to the trapezius and superficial to the erector spinae and transversospinalis musculature (Figure 6-6).

WHAT’S IN A NAME?

The name, rhomboids, tells us that these muscles have the geometric shape of a rhombus (a parallelogram or diamond shape). Major and minor tell us that the rhomboid major is larger than the rhomboid minor.

* Derivation:

rhomb: Gr. rhombos (geometric shape)

oid: Gr. shape, resemblance

major: L. larger

minor: L. smaller

PALPATION

1. Ask the client to lie prone or sit with the hand resting in the small of the back.

2. Ask the client to lift the hand away from the small of the back.

3. First look for the lower border of the rhomboids to become visible; then palpate the rhomboids between the spine and scapula (Figure 6-7).

TREATMENT CONSIDERATIONS

 Rounded/slumped shoulders is a common postural condition in which the scapulas are protracted (abducted) and depressed and the arms are medially rotated. Considering the rhomboids’ actions of both retraction and elevation of the scapula, when they are weak, they can contribute to this common condition because they are unable to oppose efficiently the tight protractors and depressors of the scapula (pectoralis muscles).

 The rhomboids often blend into the serratus anterior on the anterior side of the scapula; they are both part of the spiral line myofascial meridian.

 A good way to remember the direction of fibers of the rhomboids is to think of them as the “Christmas Tree Muscles.”

SHOULDER GIRDLE AND ARM

Levator Scapulae

Pronunciation le-VAY-tor SKAP-you-lee

The levator scapulae is a muscle of the shoulder girdle and neck. At its scapular attachment, it is located deep to the trapezius; at its spinal attachment, it is located deep to the sternocleidomastoid; its mid belly is superficial in the posterior triangle of the neck (Figure 6-8).

WHAT’S IN A NAME?

The name, levator scapulae, tells us that this muscle elevates the scapula.

* Derivation:

levator: L. lifter

scapulae: L. of the scapula

PALPATION

1. Ask the client to lie prone or sit with the hand resting in the small of the back (Figure 6-9, A). Place palpating finger pads immediately superior to the superior angle of the scapula.

2. Ask the client to perform a gentle, very short range of motion of elevation of the scapula and feel for the levator scapulae deep to the trapezius (Figure 6-9, B).

3. Continue palpating superiorly until you are off the trapezius and in the posterior triangle of the neck. Now you can ask the client to elevate the scapula more forcefully (Figure 6-9, C).

4. Follow superiorly and anteriorly toward the transverse processes of C1-C4.

Note: The transverse process of C1 is immediately inferior to the ear.

TREATMENT CONSIDERATIONS

 Many positions require postural isometric contraction overuse of the levator scapulae. These positions include holding the head inclined anteriorly when working in front of the body using a hand-held electronic device such as a “smart phone,” carrying a purse or bag on the shoulder (regardless of the weight), crimping a telephone between the ear and shoulder, or carrying a heavy weight in the hand.

 The levator scapulae often becomes tight and visible in middle and older age as it contracts to maintain the posture of the upper neck and head.

 At approximately the midpoint of the levator scapulae, a twist in the fibers creates an increased density that may be mistaken for a trigger point.

SHOULDER GIRDLE AND ARM

Serratus Anterior

Pronunciation ser-A-tus an-TEE-ri-or

The serratus anterior is a broad muscle that is located between the scapula and rib cage wall (along with the subscapularis). It hugs the rib cage wall and is superficial on the lateral rib cage wall, below the axilla (armpit) (Figure 6-10). When well developed, its slips of tissue look similar to ribs.

WHAT’S IN A NAME?

The name, serratus anterior, tells us that this muscle has a serrated appearance and is anterior (to the serratus posterior superior and serratus posterior inferior)

* Derivation:

serratus: L. notching

anterior: L. in front

PALPATION

1. The client is supine with the arm straight up in the air pointed toward the ceiling; place the finger pads against the lateral rib cage wall, directly inferior to the axilla (armpit).

2. Resist the client from reaching the hand toward the ceiling (Figure 6-11, A).

3. Palpate the serratus anterior where it is superficial on the rib cage (Figure 6-11, B); then palpate the rest of the muscle, reaching deep to the pectoralis major and the scapula.

TREATMENT CONSIDERATIONS

 When weak, the serratus anterior can contribute to winging (lateral tilt) of the scapula.

 The serratus anterior usually blends into the rhomboids on the anterior side of the scapula.

SHOULDER GIRDLE AND ARM: Pectoralis Group

Pectoralis Major; Pectoralis Minor

Pronunciation PEK-to-ra-lis MAY-jor • PEK-to-ra-lis MY-nor

The pectoralis major and minor muscles are located in the pectoral (chest) region. The pectoralis major is considered to have two heads, a clavicular head and a sternocostal head; it is superficial, attaches to the arm, and creates the anterior axillary fold of tissue that borders the axilla (the armpit) anteriorly. The pectoralis minor is deep to the pectoralis major and attaches to the scapula (Figure 6-12).

WHAT’S IN A NAME?

The name, pectoralis, tells us that these muscles are located in the pectoral (chest) region. Major and minor tell us that the pectoralis major is larger than the pectoralis minor.

* Derivation:

pectoralis: L. refers to the chest

major: L. larger

minor: L. smaller

ATTACHMENTS

Pectoralis Major

Origin (Proximal/Medial Attachment)

 Medial clavicle, sternum, and the costal cartilages of ribs one through seven

Insertion (Distal/Lateral Attachment)

 Lateral lip of the bicipital groove of the humerus

Pectoralis Minor

Origin (Proximal/Anterior Attachment)

 Ribs three through five

Insertion (Distal/Posterior Attachment)

 Coracoid process of the scapula

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4. How to Palpate 1. Basic Kinesiology Terminology 5. Bony Palpation 9. Muscles of the Head 11. Muscles of the Leg and Foot 7. Muscles of the Forearm and Hand

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