The most important principle of function of the shoulder complex is the optimization of arm movements with the greatest radius possible and to provide a mobile and stable base for the arm movements. End-range arm elevation is one of the most complex movements of our body.
The intricate interplay between the individual components of the shoulder complex can lead to a variety of dysfunctions. A cause of restricted shoulder elevation, for example, can be found in every single mobile articulation in the cervicobrachial region.
There are a comparatively large number of causes for shoulder/arm pain. Pain may be referred or projected from the cervical spine and the thoracic outlet, or may be due to several other possible causes ranging from arthritis, ligamentous laxity and instability to soft-tissue lesions such as internal or external impingement or labral lesions and ruptures of the rotator cuff muscles.
Therapists should be familiar with the location and form of the articular structures in all shoulder joints, as well as the location, course, and attachments of clinically important muscles, for example, the subscapularis. A good spatial sense is of advantage as the clinically important structures are found close to each other, especially in the GH joint. Knowledge of the shape of the spine of the scapula and the acromion, of the proximal humerus, the dimensions of the clavicle, and the position of the joint spaces is especially important (▶ Fig. 2.1, ▶ Fig. 2.2, ▶ Fig. 2.3).
The glenoid cavity or glenoid fossa is the socket of the humeral head. Its concavity is directed laterally, forward, and somewhat upward as an extension of the scapular spine. Since the scapula adapts itself to the shape of the thorax as a relatively flat bone, the socket tips in an anterior direction in the sagittal plane so that the anteroposterior surface of the cavity is not transverse. The head of the humerus is almost spherical; in the transverse plane it exhibits a retrotorsion of approximately 30° to the line connecting the epicondyles of the humerus. This retrotorsion determines the range of motion in outward and inward rotation. A slight retrotorsion leads to a smaller outward rotation. In the frontal plane, the humeral head is angled at 45° to the shaft of the humerus. Since the insertion of the capsule lies at the anatomical neck, directly adjacent to the head of the humerus, the superior portions of the capsule are stretched when the arm is allowed to hang. For equal tension on the superior and inferior portions of the capsule, the arm must be abducted by about 45°. This is the resting position.
On the basis of the anatomy seen in radiographs, it was claimed that the shoulder joint was incongruent and that the radii of curvature of the two members of the joint provided a poor fit. According to this finding, the socket would hardly be able to contribute to the stability of the shoulder joint. However, studies of anatomical preparations and modern imaging techniques (CT and MRI) show a high degree of congruence between head and socket. The decisive factor is the shape of the cartilaginous lining of the socket and the glenoid labrum. The drawing in ▶ Fig. 2.4 summarizes what is known today about the interrelations of shapes in the glenohumeral joint. The cartilage is thicker at the edges than in the center of the socket. The depth of the socket and the resulting congruence play a decisive role in the stability of the glenohumeral joint. The glenoid labrum is a fibrocartilaginous structure that increases the contact surface and functions like a suction cup. Furthermore, it is the origin of the long biceps tendon and the capsule of the labrum.
Overall, the high degree of congruence creates such a strong adhesion between the joint surfaces that it is hardly possible to separate the head from the socket in the direction of traction. In 2003, Gokeler et al. were able to demonstrate in a study that it is not possible to separate head and socket with 14 kg of tractive force.
▶ Fig. 2.5 shows a view of the glenoid cavity with the fibrocartilaginous ring (glenoid labrum) and the interior of the capsule with the reinforcing structures as well as the position of the rotator cuff tendons. The capsular fibers are somewhat twisted in their arrangement, in a clockwise direction in the right shoulder, so that the capsule tenses more rapidly in extension than in flexion. Approximately half of the capsular surface is the area of insertion for the rotator cuff muscles, which greatly strengthens the capsule. The subscapularis (SSC) has the broadest tendon; this muscle supports the capsule anteriorly. In the superior part of the capsule there is a gap in the muscle insertion. At this point, the long head of the biceps brachii leaves the capsule and continues in the intertubercular sulcus. The so-called rotator interval is reinforced and overlapped by two bands of the coracohumeral ligament (Werner et al., 2000).
The three glenohumeral ligaments, the superior, middle, and inferior glenohumeral ligaments, arise at the edge of the labrum. They reinforce the anterior inferior capsule and limit certain movements of the humerus by increasing tension. The effect of this increasing tension is to center the head in the socket with increasing extent of motion. The axillary recess runs between the two portions of the inferior ligament. The most important centering function is performed by the anterior portion of the inferior glenohumeral ligament. With increasing abduction and outward rotation (the back-swing phase of the throwing motion) it wraps around the head of the humerus and thus prevents abnormal forward displacement (subluxation) of the head. The subscapular muscle plays a decisive reinforcing role here.
The acromion, the coracoacromial ligament, and the coracoid process form the summit of the shoulder, the fornix humeri. The tendons of the rotator cuff and the subacromial bursa (not illustrated) lie in the subacromial space. In inflammatory processes, the tendons and the bursa can become impinged (clamped) between the tubercula and the fornix humeri. The tendons of the supraspinatus (SSP) and the infraspinatus (ISP) overlap. Only the teres minor (TM) cannot be clamped in this external impingement.
However, the joint is very small, with an intra-articular space of only about 1 cm long (▶ Fig. 2.6). Many people have an intra-articular disk. There are numerous variations in the shape of the acromial end of the clavicle in the frontal and transverse planes (De Palma, 1963; Moseley, 1968) and the clavicle is not always convex. Colegate-Stone et al. (2010) describe an even distribution of vertical, oblique, and curved (convex clavicle) shapes in the acromioclavicular joints of the specimens they studied.
Intrinsic ligaments: Superior and inferior acromioclavicular ligaments. The superior ligament is very strong and primarily limits all transverse movements, for instance the translatory tests of manual therapy (see ▶ Fig. 2.36).
Extrinsic ligaments: The coracoclavicular ligaments (conoid and trapezoid ligaments). Except in passive elevation of the shoulder, they are never completely relaxed. They guarantee stability in the face of large, transverse forces (e.g., when the intrinsic ligaments are torn) and limit vertical movements between acromion and clavicle.
Since the AC joint is an amphiarthrosis, it has no motor muscle supply of its own. Nevertheless, fibers in the descending portion of the trapezius muscle and the clavicular portion of the deltoid muscle can extend across the intraarticular space and, at a deep level, make contact with the capsule. For this reason, both muscles are suitable for active stabilization of the joint.
In the sternoclavicular (SC) joint, the movements of the shoulder girdle are facilitated while the forces for the shoulder girdle movements are exerted more on the scapula (▶ Fig. 2.7). During support of the arm and hand, it transfers compression forces on the thorax. Likewise, end-range arm elevations are transmitted via the first rib to the cervicothoracic transition.
It is anatomically classified as a sellar joint. However, the rotation of the clavicle during arm elevation means that it functions as a ball-and-socket joint. The narrow sternal end of the clavicle articulates with the joint surface of the sternal manubrium by means of a disk that subdivides each joint into two compartments. The joint space tilts in the frontal plane by approximately 45° from superomedial to inferolateral.
The costoclavicular ligament is particularly interesting in terms of biomechanics. It is 3 to 10 mm long and is fused directly to the lateral edge of the sternoclavicular (SC) joint (Tubbs et al., 2009). End-range arm elevations are transferred to the first rib via tension of the costoclavicular ligament and further to the cervicothoracic transition. During protraction and retraction, this ligament tenses up and thus becomes a rotational axis. The clavicle therefore behaves consistently with the convex rule during movements in both planes. When a patient falls on an arm with a shoulder in protraction, in the worst case the clavicle can become dislocated in a posterior direction.
When the important structures in the shoulder girdle are being located in detail, a practice starting position (SP) is taken: upright-sitting on a stool or a treatment table with the arms hanging loosely by the sides. In this SP, all components of the shoulder complex are usually found in a neutral position and all structures can be reached with ease. Dorsal orientation in this region begins by observing the topographical location of the scapula in relation to the spinal column and the thorax. The position of the most familiar bony landmarks (inferior angle and acromion) is also checked. To do this, the therapist stands behind the patient.
According to Winkel (2004), Kapandji (2006), and Williams (2009), the superior angle of the scapula is found at the level of the T1 spinous process and the second rib. The inferior angle of the scapula can be clearly palpated and is found at the same level as the T7 spinous process and the seventh rib. The triangular origin of the spine of the scapula can be located at the level of the T3 spinous process (▶ Fig. 2.8).
The correlations described above are very constant, but only apply when the shoulder is relaxed and a sitting or upright SP is used. They are no longer reliable, however, if the patient changes position, for example, into side-lying, as the position of the scapula has changed (e.g., there is more elevation or abduction).
When the shoulder joint rotates medially, the scapula follows and the medial border of the scapula moves away from the thoracic wall (▶ Fig. 2.9). This assists movement of the arm and is normal. It should not be considered pathological. Only the timing and the range of motion allow the therapist to draw conclusions about the ability of the shoulder joint to rotate medially. Extensive outward movement of the scapula indicates a decreased ability of the glenohumeral joint to rotate inward.
The medial border of the scapula is usually only visible when weakness in the rhomboids and serratus anterior results in insufficient thoracic stabilization of the scapula. Considerable weakness or paralysis in these muscles causes winging of the scapula especially when the arm is raised and is also known as scapula alata (▶ Fig. 2.10).
Following completion of the introductory orientation on the posterior aspect of the shoulder, first several important bony structures will be located. The palpation starts medially, over the spine of the scapula toward the lateral region of the shoulder. The different sections of the acromion are of special interest here and guide the therapist to two structures of great clinical importance: the supraspinatus and infraspinatus.
The inferior angle of the scapula is an important reference point when assessing movement of the scapula. Therapists use this structure for orientation when they are assessing the range of scapular motion during abduction and inward and outward rotation in relation to the spinal column.
To assess rotation of the scapula, the therapist first palpates the inferior angle of the scapula in its resting position. The patient is then instructed to raise the arm. With regard to scapular movement, it is of no significance whether this is done through flexion or abduction. Once the arm has been raised as far as possible, the therapist palpates the position of the angle again and assesses the range of motion (▶ Fig. 2.11). This is also compared with the other side. It is more difficult to locate the inferior angle when the latissimus dorsi is well developed.
Range of motion is not the only aspect of interest when analyzing movement of the scapula. Asymmetrical or even jerky movements of the inferior angle as it moves to assist elevation of the arm indicate poor coordination and a possible weakness of the serratus anterior. Two types of movement can be distinguished, particularly at the start and the end of arm elevation—scapular winging and scapular tipping. Scapular winging describes the brief swinging outward of the medial border of the scapula in the transverse plane. Scapular tipping describes the brief lifting of the inferior angle in the sagittal plane. A lack of support by the scapula for arm elevation not only limits the overall movement but can also be the cause of various forms of external or internal impingement of the shoulder joint.
The medial border of the scapula is located using a perpendicular technique and palpating from inferior to superior. This is the first opportunity for students to consciously use this technique and to differentiate between the soft and elastic consistency of the muscles and the hard resistance of the edge of bone.
The palpating fingertips come from a medial position and push against the border (▶ Fig. 2.12). It is easy to locate the inferior part of the border as relatively few muscles are found here that impede access. If the border is followed in a cranial direction, precise palpation becomes difficult.
If circumstances make it difficult to locate the border, it can help to ease the shoulder into medial rotation so that the medial border of the scapula wings out (see also ▶ Fig. 2.9). However, the aim of this palpatory exercise is to be able to find the edge of bone in any shoulder and with different tissue conditions.
It is very difficult to palpate the superior angle of the scapula. The trapezius that runs past it and the inserting levator scapulae are often very tense, making it difficult for the therapist to differentiate between the elevated muscle tension and the superior angle. Moreover, the first costotransverse joint, which is often sensitive, lies directly cranial. The therapist can avoid this problem by passively elevating the shoulder girdle. This can be done in any SP. The therapist elevates the shoulder girdle by pushing along the axis of the hanging arm. The superior angle is then recognized by its pressure from caudal against the palpating finger (▶ Fig. 2.13).
The spine of the scapula is another important bony reference point when palpating the posterior aspect. From this point, the therapist has reliable access to the acromion to the side and to the bellies of clinically prominent muscles (supraspinatus and infraspinatus). The spine of the scapula points toward the opening of the socket of the shoulder joint (glenoid cavity) and is the direction for manual therapeutic traction at the GH joint. For this reason, before applying traction to the joint, the manual therapist should determine the direction by palpating the spine of the scapula.
The inferior and superior edges of the spine of the scapula are palpated using the perpendicular technique we are already familiar with. The supraspinatus and infraspinatus are often quite tense, which makes locating the spine of the scapula more difficult than on the medial border of the scapula.
The inferior edge is palpated from medial to lateral. The spine of the scapula has a rolling, undulating shape that has developed as a result of the pull of muscular attachments, for example, the ascending part of the trapezius.
To locate the inferior edge exactly, the therapist uses the finger pads to push against the elastic resistance of the skin and muscles on the posterior side of the scapula and moves the palpating fingers in a superior direction until the finger pads encounter hard resistance (▶ Fig. 2.14).
At the lateral end of the inferior edge there is an angle that is distinctly prominent when the arm is hanging down—the acromial angle (▶ Fig. 2.15). At this point, the inferior edge of the spine describes an almost right-angle bend and runs anteromedial as the edge of the acromion.
The acromion is also an important reference point. The height of the acromion in the resting position can indicate the presence of an elevated shoulder. During arm elevation, the acromion is also used for orientation to assess the range and speed of shoulder girdle elevation and, when observed from the side, retraction.
In the next stage of the palpation, the superior edge of the spine of the scapula is followed from medial to lateral until it meets up with the posterior edge of the clavicle. The therapist will discover that the spine of the scapula is significantly thicker than imagined. When the superior and inferior edges are projected and drawn onto the skin, they are almost parallel to each other, appear very broad, and are approximately 2 cm apart.
Palpation uses the same technique of perpendicular palpation, this time with the pad of the finger pushing against the edge from cranial and following the edge from the medial origin of the spine in a lateral direction (▶ Fig. 2.16).
The spine of the scapula can be followed from its base to the acromion. The palpation finishes laterally when the fingertips encounter another hard structure. This is the posterior edge of the clavicle. Both of these bony edges (superior edge of the spine of the scapula and the posterior border of the clavicle) taper in toward each other and connect, forming a posterior V (see ▶ Fig. 2.27).
The muscle belly of the supraspinatus is found in its bony depression between the superior edge of the spine of the scapula and the descending part of the trapezius. Its muscle belly, and further lateral, the muscle-tendon transition, are palpable between the superior angle and the posterior V.
To locate the muscle belly, the patient does not have to adopt a certain position and may remain sitting upright. The shoulder should be easily accessible from the side. For better access to the muscle-tendon transition, the muscle can be brought closer to the level of the scapula by passive abduction (scaption) (▶ Fig. 2.17). In this way, the position of the muscle-tendon transition is shifted and becomes more accessible to palpation.
The muscle belly of the supraspinatus is found deep in the supraspinous fossa and only the slender superficial section of the muscle can be reached directly. The therapist must therefore use a technique that can be applied to tight spaces but is nevertheless intense enough to reach the affected area.
Transverse friction is used for palpation. This technique is used during the assessment to confirm that this structure is symptomatic. It is also used with other techniques to treat tendinitis or tendinosis at the muscle-tendon junction or in injuries to the muscle belly.
The suitable technique here is to come from the side, positioning the middle finger parallel to the muscle fibers and applying pressure. The index finger is placed over the middle finger as support (▶ Fig. 2.17). Transverse friction is performed with deep pressure, moving from posterior to anterior by supination of the underarm. This technique can be used over the entire length of the muscle between the superior angle of the scapula and the posterior V.
The muscle becomes tendinous laterally. Its insertion into the greater tubercle is of clinical interest but is not accessible when the arm is positioned in neutral, as it is then found underneath the acromion. Location of this tendon is discussed in the section “Local Palpation—Anterolateral” below (Chapter 2.7).
The patient must assume a difficult position in order to make the clinically relevant parts of the infraspinatus accessible (muscle-tendon transition, tendon and its insertion). The patient is prone, very close to the edge of the treatment table on the side to be palpated.
The patient supports themselves on the forearms and a cushion is placed under the abdomen to prevent an uncomfortable hyperlordosis. This position produces a 70° flexion in the shoulder joint. In addition, the joint is slightly adducted (approx. 10°, elbows approximately 1 hand width from the edge of the treatment table) with approximately 20° external rotation (the hand has a firm grip on the edge of the treatment table) (▶ Fig. 2.18). Through the flexion the insertion at the greater tubercle, which is otherwise difficult to access under the acromion, is rotated outward and dorsally (▶ Fig. 2.19).
This position was described by Cyriax in 1984 and confirmed by studies of Mattingly and Mackarey in 1996. The tendon of the infraspinatus is tensed by the adduction and the support on the elbows, with a cranial push to the humerus, and acquires a firmer consistency. This makes it easier to define the boundary between the muscle-tendon transition and surrounding structures. During application of this technique as therapeutic transverse friction, the muscle-tendon transition and the tendon remain stable under the treating finger and do not slide away.
The patient lies flat on the stomach (not supporting themselves on the forearms). The affected arm hangs down over the side of the treatment table and the forearm rests on a stool. The therapist then attempts to place the GH joint in slight adduction and lateral rotation again (▶ Fig. 2.20).
The patient sits on a stool at the head-end of the table. The head-end of the treatment table is lowered and the arm is placed in the position described above, resting on the head-end of the table (not illustrated). Mattingly and Mackarey were able to confirm in 1996 that the insertion is accessible in the same way.
All alternative starting positions are more comfortable for patients but are not particularly conducive to finding the tendon and the insertion site. They have the drawback that insufficient axial pressure is applied to the humerus to tighten up the tendon. The tendon feels less firm underneath the palpating finger and it is more difficult to differentiate it from the surrounding tissue and its insertion into the bone. The tendon gives way under the pressure applied during transverse friction.
The palpation starts at the already familiar posterior angle of the acromion (acromial angle, see ▶ Fig. 2.15). The location of the broad muscle-tendon transition of the infraspinatus can be found approximately 2 cm from the acromial angle toward the axilla (▶ Fig. 2.21). The palpating finger feels the muscle-tendon transition as a flat, tense structure that offers a firm, but still elastic resistance to transverse palpation. In order to find the tendon, palpation continues along the structure with transverse friction movements approximately 2 cm laterally, parallel to the scapular spine. The resistance felt by the finger is distinctly firmer. To find the insertion at the middle facet of the greater tubercle (see ▶ Fig. 2.60), palpation continues along the tendon, which becomes progressively flatter, further in a lateral direction until a hard resistance is felt. This is the tenoosseous junction, the infraspinatus insertion. This line of palpation can be repeatedly disturbed by coarse fiber bundles of the deltoid muscle. Their course is typically oblique, rising to the superomedial.