SHOULDER GIRDLE

SUMMARY OF PROJECTIONS

The icons in the Essential column indicate projections frequently performed in the United States and Canada. Students should become competent in these projections.

Shoulder Girdle

The shoulder girdle is formed by two bones—the clavicle and scapula. The function of these bones is to connect the upper limb to the trunk. Although the alignment of these two bones is considered a girdle, it is incomplete in front and in back. The girdle is completed in front by the sternum, which articulates with the medial end of the clavicle. The scapulae are widely separated in the back. The proximal portion of the humerus is part of the upper limb and not the shoulder girdle proper; however, because the proximal humerus is included in the shoulder joint, its anatomy is considered with that of the shoulder girdle (Figs. 5-1 and 5-2).

Fig. 5-1 A, Anterior aspect of shoulder girdle: clavicle and scapula. Girdle attaches to humerus and manubrium of sternum. B, Superior aspect of right clavicle.

Fig. 5-2 Axial CT scan of shoulder showing relationship of anatomy. Note 45- to 60-degree angle of scapula.

The clavicle, classified as a long bone, has a body and two articular extremities (see Fig. 5-1). The clavicle lies in a horizontal oblique plane just above the first rib and forms the anterior part of the shoulder girdle. The lateral aspect is termed the acromial extremity, and it articulates with the acromion process of the scapula. The medial aspect, termed the sternal extremity, articulates with the manubrium of the sternum and the first costal cartilage. The clavicle, which serves as a fulcrum for the movements of the arm, is doubly curved for strength. The curvature is more acute in males than in females.

Scapula

The scapula, classified as a flat bone, forms the posterior part of the shoulder girdle (Figs. 5-3 and 5-4). Triangular in shape, the scapula has two surfaces, three borders, and three angles. Lying on the superoposterior thorax between the second and seventh ribs, the medial border of the scapula runs parallel with the vertebral column. The body of the bone is arched from top to bottom for greater strength, and its surfaces serve as the attachment sites of numerous muscles. The flat aspect of the bone lies at about a 45- to 60-degree angle in relation to the anatomic position (see Fig. 5-2).

Fig. 5-3 Scapula. A, Costal surface (anterior aspect). B, Dorsal surface (posterior aspect).

Fig. 5-4 Lateral aspect of scapula.

The costal (anterior) surface of the scapula is slightly concave and contains the subscapular fossa. It is filled almost entirely by the attachment of the subscapularis muscle. The anterior serratus muscle attaches to the medial border of the costal surface from the superior angle to the inferior angle.

The dorsal (posterior) surface is divided into two portions by a prominent spinous process. The crest of spine arises at the superior third of the medial border from a smooth, triangular area and runs obliquely superior to end in a flattened, ovoid projection called the acromion. The area above the spine is called the supraspinous fossa and gives origin to the supraspinatus muscle. The infraspinatus muscle arises from the portion below the spine, which is called the infraspinous fossa. The teres minor muscle arises from the superior two thirds of the lateral border of the dorsal surface, and the teres major arises from the distal third and the inferior angle. The dorsal surface of the medial border affords attachment of the levator muscles of the scapulae, greater rhomboid muscle, and lesser rhomboid muscle.

The superior border extends from the superior angle to the coracoid process and at its lateral end has a deep depression, the scapular notch. The medial border extends from the superior to the inferior angles. The lateral border extends from the glenoid cavity to the inferior angle.

The superior angle is formed by the junction of the superior and medial borders. The inferior angle is formed by the junction of the medial (vertebral) and lateral borders and lies over the seventh rib. The lateral angle, the thickest part of the body of the scapula, ends in a shallow, oval depression called the glenoid cavity. The constricted region around the glenoid cavity is called the neck of the scapula. The coracoid process arises from a thick base that extends from the scapular notch to the superior portion of the neck of the scapula. This process projects first anteriorly and medially and then curves on itself to project laterally. The coracoid process can be palpated just distal and slightly medial to the acromioclavicular articulation.

Humerus

The proximal end of the humerus consists of a head, an anatomic neck, two prominent processes called the greater and lesser tubercles, and the surgical neck (Fig. 5-5). The head is large, smooth, and rounded, and it lies in an oblique plane on the superomedial side of the humerus. Just below the head, lying in the same oblique plane, is the narrow, constricted anatomic neck. The constriction of the body just below the tubercles is called the surgical neck, which is the site of many fractures.

Fig. 5-5 A, Anterior aspect of right proximal humerus. B, Photograph of anterior aspect of proximal humerus.

The lesser tubercle is situated on the anterior surface of the bone, immediately below the anatomic neck (Figs. 5-6 and 5-7; see Fig. 5-5). The tendon of the subscapular muscle inserts at the lesser tubercle. The greater tubercle is located on the lateral surface of the bone, just below the anatomic neck, and is separated from the lesser tubercle by a deep depression called the intertubercular (bicipital) groove. The superior surface of the greater tubercle slopes posteriorly at an angle of approximately 25 degrees and has three flattened impressions for muscle insertions. The anterior impression is the highest of the three and affords attachment to the tendon of the supraspinatus muscle. The middle impression is the point of insertion of the infraspinatus muscle. The tendon of the upper fibers of the teres minor muscle inserts at the posterior impression (the lower fibers insert into the body of the bone immediately below this point).

Fig. 5-6 Superior aspect of humerus.

Fig. 5-7 Superior aspect of humerus. Horizontal section through scapulohumeral joint showing normal anatomic relationships.

Bursae are small, synovial fluid–filled sacs that relieve pressure and reduce friction in tissue. They are often found between the bones and the skin, and they allow the skin to move easily when the joint is moved. Bursae are found also between bones and ligaments, muscles, or tendons. One of the largest bursae of the shoulder is the subacromial bursa (Fig. 5-8). It is located under the acromion process and lies between the deltoid muscle and the shoulder joint capsule. The subacromial bursa does not normally communicate with the joint. Other bursae of the shoulder are found superior to the acromion, between the coracoid process and the joint capsule, and between the capsule and the tendon of the subscapular muscle. Bursae become important radiographically when injury or age causes the deposition of calcium.

Fig. 5-8 Right shoulder bursae and muscles.

Shoulder Girdle Articulations

The three joints of the shoulder girdle are summarized in Table 5-1, and a detailed description follows.

TABLE 5-1

Joints of the shoulder girdle

SCAPULOHUMERAL ARTICULATION

The scapulohumeral articulation between the glenoid cavity and the head of the humerus forms a synovial ball-and-socket joint, allowing movement in all directions (Figs. 5-9 and 5-10). This joint is often referred to as the glenohumeral joint. Although many muscles connect with, support, and enter into the function of the shoulder joint, radiographers are chiefly concerned with the insertion points of the short rotator cuff muscles (Fig. 5-11). The insertion points of these muscles—the subscapular, supraspinatus, infraspinatus, and teres minor—have already been described.

Fig. 5-9 Articulations of scapula and humerus.

Fig. 5-10 A, Coronal MRI of shoulder. Note articular cartilage around humeral head and muscles closely surrounding bone. B, Axial CT of shoulder, mid-joint. Note position of bones relative to each other and articular cartilage in glenoid cavity. gc, glenoid cavity; h, humerus; sn, scapular neck. (From Kelley LL, Petersen CM: Sectional anatomy for imaging professionals, ed 2, St Louis, 2007, Mosby.)

Fig. 5-11 A, Muscles on costal (anterior) surface of scapula and proximal humerus. B, Muscles on dorsal (posterior) surface of scapula and proximal humerus. C, Axial MRI of shoulder (view from top) showing muscles of shoulder. Supraspinatus (sup) and deltoid (de) muscles are shown. Note scapular spine (sc) for reference. (From Kelley LL, Petersen CM: Sectional anatomy for imaging professionals, ed 2, St Louis, 2007, Mosby.)

An articular capsule completely encloses the shoulder joint. The tendon of the long head of the biceps brachii muscle, which arises from the superior margin of the glenoid cavity, passes through the capsule of the shoulder joint, goes between its fibrous and synovial layers, arches over the head of the humerus, and descends through the intertubercular (bicipital) groove. The short head of the biceps arises from the coracoid process and, with the long head of the muscle, inserts in the radial tuberosity. Because it crosses with the shoulder and elbow joints, the biceps help synchronize their action.

The interaction of movement among the wrist, elbow, and shoulder joints makes the position of the hand important in radiography of the upper limb. Any rotation of the hand also rotates the joints. The best approach to the study of the mechanics of joint and muscle action is to perform all movements ascribed to each joint and carefully note the reaction in remote parts.

ACROMIOCLAVICULAR ARTICULATION

The acromioclavicular (AC) articulation between the acromion process of the scapula and the acromial extremity of the clavicle forms a synovial gliding joint (see Fig. 5-12). It permits gliding and rotary (elevation, depression, protraction, and retraction) movement. Because the end of the clavicle rides higher than the adjacent surface of the acromion, the slope of the surfaces tends to favor displacement of the acromion downward and under the clavicle.

Fig. 5-12 Three-dimensional CT image of shoulder girdle. Note three articulations.

STERNOCLAVICULAR ARTICULATION

The sternoclavicular (SC) articulation is formed by the sternal extremity of the clavicle with two bones: the manubrium and the first rib cartilage (see Fig. 5-12). The union of the clavicle with the manubrium of the sternum is the only bony union between the upper limb and trunk. This articulation is a synovial double-gliding joint. The joint is adapted by a fibrocartilaginous disk, however, to provide movements similar to a ball-and-socket joint: circumduction, elevation, depression, and forward and backward movements. The clavicle carries the scapula with it through any movement.

Humerus (proximal aspect)

Head

Anatomic neck

Surgical neck

Intertubercular groove

Shoulder articulations

Scapulohumeral

Acromioclavicular

Sternoclavicular

ABBREVIATIONS USED IN CHAPTER 5

AC	Acromioclavicular
SC	Sternoclavicular

See Addendum A for a summary of all abbreviations used in Volume 1.

SUMMARY OF PATHOLOGY

Condition	Definition
Bursitis	Inflammation of the bursa
Dislocation	Displacement of a bone from the joint space
Fracture	Disruption in the continuity of bone
Hills-Sachs defect	Impacted fracture of posterolateral aspect of the humeral head with dislocation
Metastases	Transfer of a cancerous lesion from one area to another
Osteoarthritis or degenerative joint disease	Form of arthritis marked by progressive cartilage deterioration in synovial joints and vertebrae
Osteopetrosis	Increased density of atypically soft bone
Osteoporosis	Loss of bone density
Rheumatoid arthritis	Chronic, systemic, inflammatory collagen disease
Tendinitis	Inflammation of the tendon and tendon-muscle attachment
Tumor	New tissue growth where cell proliferation is uncontrolled
Chondrosarcoma	Malignant tumor arising from cartilage cells

EXPOSURE TECHNIQUE CHART ESSENTIAL PROJECTIONS

SHOULDER GIRDLE

s, small focal spot.

^*kVp values are for a three-phase, 12-pulse generator or high frequency.

^†Relative doses for comparison use. All doses are skin entrance for average adult at cm indicated.

^‡Bucky, 16:1 grid. Screen-film speed 300.

^§Tabletop, 8:1 grid. Screen-film speed 300.

^¶Tabletop, standard IR. Screen-film speed 300 or equivalent CR.

RADIOGRAPHY

Shoulder

Radiation Protection

Protection of the patient from unnecessary radiation is a professional responsibility of the radiographer (see Chapters 1 and 2 for specific guidelines). In this chapter, the Shield gonads statement at the end of the Position of part section indicates that the patient is to be protected from unnecessary radiation by using proper collimation and placing lead shielding between the gonads and the radiation source to restrict the radiation beam.

PROJECTIONS REMOVED

The following projections have been removed from the atlas because of the increased use of CT and MRI for imaging the shoulders. The projections may be reviewed in their entirety in the eleventh edition and all previous editions.

Shoulder joint

• Inferosuperior axial, Clements method

Acromioclavicular articulations

• PA axial oblique, Alexander method

Clavicle

• Tangential

Scapula

• PA oblique, Lorenz, Lilienfeld method

• Tangential

Shoulder

AP PROJECTION

External, neutral, internal rotation humerus

NOTE: Do not have the patient rotate the arm if fracture or dislocation is suspected.

Image receptor: 10 × 12 inch (24 × 30 cm) crosswise

Position of patient:

• Examine the patient in the upright or supine position, with coronal plane of thorax parallel to IR. Shoulder and arm lesions, whether traumatic or pathologic in origin, are extremely sensitive to movement and pressure. For this reason, the upright position should be used whenever possible.

Position of part:

• Center the shoulder joint to the midline of the grid.

• Adjust the position of the IR so that its center is 1 inch (2.5 cm) inferior to the coracoid process.

External rotation humerus:

• Ask the patient to supinate the hand, unless contraindicated (Table 5-2).

TABLE 5-2

Hand position and its effect on the proximal humerus

• Abduct the arm slightly, and rotate it so that the epicondyles are parallel with the plane of the IR. Externally rotating the entire arm from the neutral position places the shoulder and entire humerus in the true anatomic position (Fig. 5-13).

Fig. 5-13 A, AP shoulder, external rotation humerus, standing position. B, Same projection in supine position.

Neutral rotation humerus:

• Ask the patient to rest the palm of the hand against the thigh (see Table 5-2). This position of the arm rolls the humerus slightly internal into a neutral position, placing the epicondyles at an angle of about 45 degrees with the plane of the IR.

Internal rotation humerus:

• Ask the patient to flex the elbow, rotate the arm internally, and rest the back of the hand on the hip (see Table 5-2).

• Adjust the arm to place the epicondyles perpendicular to the plane of the IR.

• Shield gonads.

• Respiration: Suspend.

Central ray:

• Perpendicular to a point 1 inch (2.5 cm) inferior to the coracoid process

Collimation:

• Adjust to 10 × 12 inches (24 × 30 cm) on the collimator.

COMPENSATING FILTER

Use of a specially designed compensating filter for the shoulder improves the quality of the image. These filters are particularly useful when digital imaging (CR or DR) systems are used for this projection.

Structures shown: The image shows the bony and soft structures of the shoulder and proximal humerus in the anatomic position (Figs. 5-14 to 5-16). The scapulohumeral joint relationship is seen.

Fig. 5-14 A, AP shoulder, external rotation humerus: greater tubercle in profile (arrow). B, AP shoulder, neutral rotation humerus: greater tubercle (arrow).

Fig. 5-15 AP shoulder, internal rotation humerus: greater tubercle (arrow); lesser tubercle in profile (arrowhead).

Fig. 5-16 A, AP oblique projection of right shoulder without use of compensating filter. B, AP projection of same patient with compensating filter. Note improvement of visualization of bony and soft tissue areas with filter.

External rotation: The greater tubercle of the humerus and the site of insertion of the supraspinatus tendon are visualized (see Fig. 5-14, A).

Neutral rotation: The posterior part of the supraspinatus insertion, which sometimes profiles small calcific deposits not otherwise visualized (see Fig. 5-14, B), is seen.

Internal rotation: The proximal humerus is seen in a true lateral position. When the arm can be abducted enough to clear the lesser tubercle of the head of the scapula, a profile image of the site of the insertion of the subscapular tendon is seen (see Fig. 5-15).

EVALUATION CRITERIA

The following should be clearly shown:

Evidence of proper collimation

Superior scapula, lateral half of the clavicle, and proximal humerus

Soft tissue around the shoulder, along with bony trabecular detail

External rotation:

Humeral head in profile

Greater tubercle in profile on lateral aspect of the humerus

Scapulohumeral joint visualized with slight overlap of humeral head on glenoid cavity

Outline of lesser tubercle between the humeral head and greater tubercle

Neutral rotation:

Greater tubercle partially superimposing the humeral head

Humeral head in partial profile

Slight overlap of the humeral head on the glenoid cavity

Internal rotation:

Lesser tubercle in profile and pointing medially

Outline of the greater tubercle superimposing the humeral head

Greater amount of humeral overlap of the glenoid cavity than in the external and neutral positions

Shoulder Joint

Glenoid Cavity

AP OBLIQUE PROJECTION

GRASHEY METHOD

RPO or LPO position

Image receptor: 8 × 10 inch (18 × 24 cm) crosswise

Position of patient:

• Place the patient in the supine or upright position. The upright position is more comfortable for the patient and assists in accurate adjustment of the part.

Position of part:

• Center the IR to the scapulohumeral joint. The joint is 2 inches (5 cm) medial and 2 inches (5 cm) inferior to the superolateral border of the shoulder.

• Rotate the body approximately 35 to 45 degrees toward the affected side (Fig. 5-17).

Fig. 5-17 A, Upright AP oblique glenoid cavity: Grashey method. B, Note position of shoulder and patient in relationship to IR.

• Adjust the degree of rotation to place the scapula parallel with the plane of the IR. This is accomplished by orienting the plane through the superior angle of the scapula and acromial tip, parallel to the IR.^* The head of the humerus is in contact with the IR.

• If the patient is in the recumbent position, the body may need to be rotated more than 45 degrees (up to 60 degrees) to place the scapula parallel to the IR.

• Support the elevated shoulder and hip on sandbags (Fig. 5-18).

Fig. 5-18 Recumbent AP oblique glenoid cavity: Grashey method.

• Abduct the arm slightly in internal rotation, and place palm of the hand on the abdomen.

• Shield gonads.

• Respiration: Suspend.

Central ray:

• Perpendicular to the IR; the central ray should be at a point 2 inches (5 cm) medial and 2 inches (5 cm) inferior to the superolateral border of the shoulder

Collimation:

• Adjust to 8 × 10 inches (18 × 24 cm) on the collimator.

Structures shown: The joint space between the humeral head and the glenoid cavity (scapulohumeral joint) is shown (Figs. 5-19 and 5-20).

Fig. 5-19 AP oblique glenoid cavity: Grashey method.

Fig. 5-20 AP oblique glenoid cavity: Grashey method showing moderate deterioration of scapulohumeral joint.

EVALUATION CRITERIA

The following should be clearly shown:

Evidence of proper collimation

Open joint space between the humeral head and glenoid cavity

Glenoid cavity in profile

Soft tissue at the scapulohumeral joint along with trabecular detail on the glenoid and humeral head

Glenoid Cavity

AP OBLIQUE PROJECTION

APPLE METHOD

RPO or LPO position

The Apple method ¹ is similar to the Grashey method but uses weighted abduction to show a loss of articular cartilage in the scapulohumeral joint.

Image receptor: 10 × 12 inch (24 × 30 cm) crosswise

Position of patient:

• Place the patient in a seated or upright position.

Position of part:

• Center the IR to the scapulohumeral joint.

• Rotate the body approximately 35 to 45 degrees toward the affected side.

• The posterior surface of affected side is closest to the IR.

• The scapula should be positioned parallel to the plane of the IR (see Grashey method for positioning details).

• The patient should hold a 1-lb weight in the hand on the same side as the affected shoulder in a neutral position.

• While holding the weight, the patient should abduct the arm 90 degrees from the midline of the body (Fig. 5-21).

Fig. 5-21 Axial oblique projection: Apple method.

• Shield gonads.

• Respiration: Suspend.

Central ray:

• Perpendicular to the IR at the level of the coracoid process

NOTE: To avoid motion, have the correct technical factors set on the generator and be ready to make the exposure before the patient abducts the arm.

Structures shown: The scapulohumeral joint (Fig. 5-22) is seen.

Fig. 5-22 A, AP oblique projection: Grashey method, with shoulder showing normal scapulohumeral joint space. B, AP oblique projection: Apple method, with weighted abduction showing loss of articular cartilage (arrow).

EVALUATION CRITERIA

The following should be clearly shown:

Open joint space between the humeral head and the glenoid cavity

Glenoid cavity in profile

Soft tissue at the scapulohumeral joint along with trabecular detail on the glenoid and the humeral head

The arm in a 90-degree position

RESEARCH: Catherine E. Hearty, MS, RT(R), performed the research and provided this new projection for this edition of the atlas.

Shoulder

TRANSTHORACIC LATERAL PROJECTION

LAWRENCE METHOD

R or L position

The Lawrence ¹ method is used when trauma exists, and the arm cannot be rotated or abducted because of an injury. This projection shows the proximal humerus in a 90-degree projection from the AP projection and shows its relationship to the scapula and clavicle.

Image receptor: 10 × 12 inch (24 × 30 cm) lengthwise

Position of patient: