Diagnostic ultrasound ( PDFDrive )

CHAPTER 24 The Shoulder 879
Acromion
Coracoid
process
Clavicle
Subscapularis
Supraspinatus
Supraspinatus
Capsular
ligament (cut)
Humerus
Teres minor
Scapula
Infraspinatus
Right Shoulder
Anterior View
Right Shoulder
Posterior View
FIG. 24.2 Illustration of Rotator Cuff Anatomy.
impingement. hese typically form at the attachment of the
coracoacromial ligament. Furthermore, osteoarthritis at the
acromioclavicular joint may result in osteophyte formation, which,
when present inferiorly, may cause rotator cuf tendon impingement.
he coracoid process is a ingerlike curved process
extending anteriorly from the scapular neck, giving attachment
to the short head of biceps, coracobrachialis, and pectoralis
minor muscles in addition to the coracohumeral ligament,
and also the coracoclavicular ligaments, which help stabilize
the acromioclavicular joint.
he rotator cuf consists of four muscles: the subscapularis,
supraspinatus, infraspinatus, and teres minor muscles (Fig. 24.2).
hese originate from the scapula and insert on the proximal
humerus. Normal rotator cuf tendons are about 4 to 6 mm in
thickness, 36 tapering out smoothly from medial to lateral along
the insertional footprint at the greater tuberosity. he subscapularis
muscle is a multipennate structure that originates from the
anterior surface of the scapula, which converges to a lat tendon
laterally to insert on the lesser tuberosity. Of note, the inferior
one-third of the subscapularis remains muscular to the level of
the lesser tuberosity. 37 he supraspinatus muscle originates from
and occupies the supraspinatus fossa, with its tendon extending
laterally to insert on the greater tuberosity of the humerus at its
anterior aspect. he tendon has a more cordlike component
anteriorly and is latter and more quadrilateral in short axis at
its mid and posterior ibers. he infraspinatus muscle originates
at the infraspinatus fossa and passes laterally to insert on the
posterosuperior aspect of the greater tuberosity. he ibers of
the supraspinatus and infraspinatus tendons merge at their
posterior and anterior borders, respectively, forming a conjoint
insertion. he teres minor originates along the lateral border of
the scapular body and inserts along the posterior aspect of the
greater tuberosity, inferior to the infraspinatus.
he long head of biceps tendon originates from a bony
tubercle at the superior glenoid, the supraglenoid tubercle, and
from the superior labrum. It passes inferolaterally between the
subscapularis and supraspinatus tendons, which form the inferior
and superior borders of the rotator interval (Fig. 24.3). Within
the rotator interval, the tendon is stabilized by a ligamentous
sling formed by the coracohumeral and superior glenohumeral
ligaments. Passing inferolaterally out of the rotator interval, the
long head of biceps tendon becomes extraarticular and extends
inferiorly in the bicipital or intertubercular groove, which lies
between the greater and lesser tuberosities. he biceps tendon
is stabilized in the groove by the transverse ligament, formed
by tendinous ibers at the subscapularis insertion. 38
he subacromial-subdeltoid bursa is a synovium-lined lat,
thin structure that lies between the rotator cuf tendons and the
overlying deltoid muscle and acromion. 39 It serves to reduce
friction between the rotator cuf and the overlying structures,
permitting smooth movement.
SCAN TECHNIQUE
For consistent and accurate shoulder ultrasound performance,
a standard protocol is suggested with comprehensive evaluation
in every case, rather than targeted scanning (Table 24.1). 40-44 he
patient should be sitting upright if possible, either on a rotating
stool or at the edge of a bed. A chair with a backrest should not
be used, because this would interfere with patient positioning.
Likewise, the sonographer should also sit on a rotating stool,
with the seat position somewhat higher than the patient’s, so