4

Shoulder

Mohini Rawat, DPT, MS, ECS, OCS, RMSK

Contents

• Anterior Shoulder and Rotator Cuff
  
  
  
  • Long Head of the Biceps Tendon
    
  • Subscapularis
    
  • Supraspinatus
    
  • Infraspinatus
    
  • Teres Minor
    
  • Anterior Joint
    
  • Coracoid Process Attachments
    
  • Pectoralis Major
  
  
• Posterior Shoulder
  
  
  
  • Posterior Joint
    
  • Suprascapular Nerve at the Spinoglenoid Notch
  
  
• Acromioclavicular Joint
  
• Sternoclavicular Joint
  
• Ligaments
  
  
  
  • Coracohumeral Ligament
    
  • Coracoacromial Ligament
  
  
• Rotator Interval
  
• Rotator Cable

ANTERIOR SHOULDER AND ROTATOR CUFF

Long Head of the Biceps Tendon

1. Patient position: Sitting with shoulder in neutral position with elbow flexed and resting on a leg or pillow with no active supination or pronation of the forearm
   
2. Probe/transducer position: The probe is placed transversely on the anterior aspect of the shoulder to visualize the long head of the biceps tendon in the short axis (SX) view in the bicipital groove. The probe is then rotated 90 degrees to visualize the tendon in the long axis (LX) view (Figures 4-1 and 4-2).
   
   
   

   

   
   

   Figure 4-1. SX view of the long head of the biceps tendon. (A) Probe placement. (B) SX view of the long head of the biceps tendon (white arrow) between the greater tuberosity (GT) and lesser tuberosity (LT), with overlying transverse humeral ligament (white triangle). Also shown is the anterior circumflex artery (red arrow). (C) SX of the long head of the biceps tendon with color Doppler to show color signal in the anterior circumflex artery.

   
   

   
   

   
   

   

   
   

   Figure 4-2. LX view of the long head of the biceps tendon. (A) Probe placement. (B) LX view of the long head of the biceps tendon (white arrow) overlying the hyperechoic bony interface of the humerus.

   
   
3. Relevant anatomy: The long head of the biceps tendon originates from the supraglenoid tubercle and superior labrum. From its origin, the tendon courses obliquely toward the bicipital groove or intertubercular groove. The tendon is stabilized by the medial sling formed by the coracohumeral ligament and superior glenohumeral ligament. It is intra-articular and extrasynovial. After it exits the bicipital groove, it joins the short head of the biceps tendon in the upper arm. After joining the short head of the biceps tendon, both tendons transition into muscle bellies, continue distally, and form the distal biceps tendon (Figure 4-3).^1,2
   
   
   

   

   
   

   Figure 4-3. Anterior shoulder anatomy showing the long head of the biceps (LHB) tendon between the intertubercular groove, covered by the transverse humeral ligament. Distally, the long head of the biceps tendon joins the short head of the biceps (SHB) and coracobrachialis to form the common biceps brachii muscle belly. The short head of the biceps and coracobrachialis originate from the coracoid process (CP). The pectoralis minor (PM) attaches to the medial aspect of the coracoid process. Also shown is the coracoacromial ligament (CAL). (Pec Major = pectoralis major.)

   
   
4. Points to remember: The long head of the biceps exhibits anisotropy in the SX and LX views, which results in a hypoechoic appearance of the tendon. The probe should be placed parallel to the long head of the biceps to minimize anisotropy in the LX view. In the SX view, a tilting or fanning movement of the probe can help visualization of the tendon. The anterior circumflex artery can be seen lateral to the long head of the biceps tendon in the intertubercular groove.

Subscapularis

1. Patient position: Sitting with the elbow flexed to 90 degrees and the shoulder in neutral, then externally rotated
   
2. Probe/transducer position: The probe is first positioned over the long head of the biceps tendon in the SX view. The patient is then asked to externally rotate the shoulder to bring the subscapularis into view. In neutral position, the subscapularis tendon is under the coracoid process and therefore cannot be visualized. With external rotation, the tendon moves laterally and is accessible for sonographic visualization. For the SX view of the tendon, the probe is rotated 90 degrees from the LX view (Figures 4-4 and 4-5).
   
   
   

   

   
   

   Figure 4-4. LX view of the subscapularis. (A) Probe placement. (B) LX view of the subscapularis tendon (white arrow) attaching to the lesser tuberosity (LT).

   
   

   
   

   
   

   

   
   

   Figure 4-5. SX view of the subscapularis. (A) Probe placement. (B) SX view of the subscapularis tendon (white arrow). Also shown is the lesser tuberosity (LT).

   
   
3. Relevant anatomy: The subscapularis originates from the anterior surface of the scapula and courses laterally, passing under the coracoid process to insert on the lesser tuberosity where the tendinous portion blends with the fibers of the joint capsule.3 Subscapularis insertion on the lesser tuberosity is divided into the tendinous insertion on the superior two-thirds and the thin membranous muscular insertion on the inferior one-third.⁴ The footprint of the subscapularis is about 4 cm in length (superior to inferior) and 1.6 cm in width (medial to lateral) (Figures 4-6 and 4-7).^3,4
   
   
   

   

   
   

   Figure 4-6. Relevant anatomy of the subscapularis tendon and approximate dimensions of the footprint, which is about 4 cm in length (superior to inferior) and 1.6 cm in width (medial to lateral).

   
   

   
   

   
   

   

   
   

   Figure 4-7. (A) Panoramic SX view of the subscapularis tendon. (B) Focused view showing the wide tendon insertion comprising the hyperechoic tendinous insertion on the superior two-thirds (between double-headed blue arrow) and hypoechoic thin membranous muscular insertion on the inferior one-third (between double-headed white arrow).

   
   
4. Points to remember: In the SX view of the tendon, tendinous tissue (hyperechoic) is seen interdigitating with muscular tissue (hypoechoic); therefore, the SX view is only used to confirm tendon defects visualized in the LX view of the tendon.

Supraspinatus

1. Patient position: Sitting with the shoulder in internal rotation and hyperextension, with the elbow flexed and the dorsal aspect of hand on the lower back midline (Crass position) or the hand on the posterior aspect of the iliac crest or in the back pocket (Middleton or modified Crass position).^5,6 These positions bring the supraspinatus out from beneath the acromion for sonographic visualization (Figure 4-8).
   
   
   

   

   
   

   Figure 4-8. Patient position for supraspinatus scanning. (A) Crass position. (B) Middleton or modified Crass position.

   
   
2. Probe/transducer position: The probe is placed in the oblique LX along the LX of the supraspinatus tendon with the proximal end of the probe pointing toward the ipsilateral ear. For SX visualization, the probe is oriented transversely across the tendon (Figures 4-9 and 4-10).
   
   
   

   

   
   

   Figure 4-9. LX view of the supraspinatus tendon. (A) Probe placement. (B) LX view of the supraspinatus (white arrow) attaching to the superior facet of the greater tuberosity (GT). Just above the supraspinatus tendon, the hyperechoic subacromial bursa (white triangle) is seen. Overlying the muscle is the deltoid above the bursa. The head of the humerus is lined by anechoic cartilage (blue arrow).

   
   

   
   

   
   

   

   
   

   Figure 4-10. SX view of the supraspinatus tendon. (A) Probe placement. (B) SX view of the supraspinatus tendon (white arrow).

   
   
3. Relevant anatomy: The supraspinatus originates from the supraspinous fossa of the scapula and then courses laterally, passing beneath the acromion to insert on the superior facet of the greater tuberosity. Posterior fibers of the supraspinatus interdigitate, or blend, with the infraspinatus tendon. The footprint of the supraspinatus is about 0.6 cm in width (medial to lateral), 2 cm in medial length (anterior to posterior), and 0.6 cm in lateral length (anterior to posterior; Figures 4-11 and 4-12).⁷
   
   
   

   

   
   

   Figure 4-11. Relevant anatomy of the rotator cuff showing the supraspinatus, infraspinatus, and teres minor tendons attaching to the greater tuberosity. Posterior fibers of the supraspinatus blend with the infraspinatus tendon (green triangle). (ACR = acromion; CL = clavicle; CP = coracoid process; LHB = long head of the biceps.)

   
   

   
   

   
   

   

   
   

   Figure 4-12. Footprint of the supraspinatus (Supra), infraspinatus (Infra), and teres (T) minor on the greater tuberosity showing the inferior (I), middle (M), and superior (S) facets of the greater tuberosity. (LT = lesser tuberosity.)

   
   
4. Points to remember: The Crass or modified Crass position helps bring the tendon out from beneath the acromion. In neutral position, a limited view of the distal portion of the tendon is visible. The posterior portion of the tendon can appear disorganized or may lack normal parallel fibrillary echotexture due to the transition zone or interdigitating infraspinatus and supraspinatus fibers. This zone should not be confused with tendon pathology.

Infraspinatus

1. Patient position: Sitting with a neutral shoulder or holding the opposite arm to stretch the tendon for better visualization
   
2. Probe/transducer position:
   

   a. LX view: The probe is placed transversely on the posterior aspect of the scapula over the infraspinatus muscle belly, just under the spine of the scapula, and then the infraspinatus is followed laterally as it crosses the glenohumeral joint to insert on the middle facet of the greater tuberosity of the humerus.

   
   

   b. SX view: The probe is rotated 90 degrees to visualize the tendon (Figures 4-13 and 4-14).

   
   
   
   

   

   
   

   Figure 4-13. LX view of the infraspinatus tendon. (A) Probe placement. (B) LX view of the infraspinatus (Infra) muscle belly overlying the posterior shoulder joint. (HH = humeral head.) (C) LX view of the infraspinatus tendon (white arrow) attaching to the middle facet of the greater tuberosity (GT).

   
   

   
   

   
   

   

   
   

   Figure 4-14. SX view of the infraspinatus tendon. (A) Probe placement. (B) SX view of the infraspinatus tendon (white arrow). (GT = greater tuberosity.)

   
   
3. Relevant anatomy: The infraspinatus originates from the infraspinous fossa of the scapula and then courses superiorly and laterally to insert on the greater tuberosity. The footprint of the infraspinatus is about 1.2 cm in width (medial to lateral), 2.3 cm in medial length (anterior to posterior), and 2.6 cm in lateral length (anterior to posterior).7
   
4. Points to remember: Some cortical irregularities under the infraspinatus at the level just proximal to the greater tuberosity is a normal finding and should not be confused with erosions.

Teres Minor

1. Patient position: Same as for the infraspinatus
   
2. Probe/transducer position: After obtaining the infraspinatus LX view, the probe is moved inferiorly to scan the teres minor tendon, which is immediately inferior to the infraspinatus tendon. The SX view is obtained by rotating the probe 90 degrees from the LX view (Figures 4-15 and 4-16).
   
   
   

   

   
   

   Figure 4-15. LX view of the teres minor tendon. (A) Probe placement. (B) LX view of the teres minor tendon (white arrow) attaching to the inferior facet of the greater tuberosity (GT).

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