The function of the middle joint of the upper limb (elbow joint) is to increase or decrease the distance between the hand and the body or face. Its second function is hand rotation, which occurs in the forearm. The fact that rotation of the distal portion of the extremity is not located exclusively in the middle joint is functionally and also anatomically the most significant difference between this joint and the middle joint of the lower extremity, the knee joint. Flexion and extension mainly take place in the humeroulnar joint (HUJ). The most important joint for controlling rotation of the hand is the proximal radioulnar joint (PRUJ). The humeroradial joint (HRJ) merely functions as an adapter between the center for flexion/extension in the HUJ and the rotational movements of pronation/supination in the PRUJ.
All three joints are found within a capsule that provides sufficient freedom of movement for the very large range of flexion/extension movements and lateral stability when the elbow is extended (collateral ligaments). Moreover, the annular ligament of the radius holds the radius to the ulna and thus directly assures the stability of the PRUJ.
Most bony structures can be reached laterally and posteriorly; only a few can be reached medially. Apart from a few exceptions, the joint space is usually hidden underneath well-developed soft tissue. It is therefore necessary to enlist the help of guiding muscles and spatial relationships to locate the joint. By way of example, when therapists want to reach the anterior radius, they must orient themselves on the medial edge of the brachioradialis, then palpate from this point deep into the tissues.
The accuracy of hand placement, for example, for manual therapeutic tests of joint play, depends on identification of the bony articular components and perception of how articular surfaces are spatially positioned.
In addition to the intricate bony structure, the elbow joint is also characterized by an arrangement of many, at times slender, muscles, which can be subdivided into one extensor (biceps brachii) and several flexors. It is particularly these that become symptomatic with stress syndromes of tendons and insertions (tennis or golfer’s elbow) and make it necessary for the therapist to find the precise location of the lesion. These synergists originate on or near the epicondyles of the humerus.
A wide variety of techniques are used to assess and treat the elbow joint, including blood-pressure measurement, testing reflexes in the biceps and triceps, electrotherapy and cryotherapy, as well as local transverse friction and manual therapeutic techniques applied to the individual parts of the joint.
Precise palpation used to recognize and differentiate deep-lying structures is only valuable if the therapist can relate the findings to existing knowledge of topographical relationships. When searching for structures, therapists therefore need to have a good idea of how the bones of the elbow joint are spatially positioned. They must be able to visualize and identify the most important structures from different perspectives.
The lower extremity of the humerus forms the proximal body of the elbow joint (condyle of the humerus) that is divided into the capitulum and the trochlea (▶ Fig. 3.1). Seen in the sagittal plane, the trochlea is convex from anterior to posterior. In the frontal plane, it is concave due to a longitudinal central groove.
The HUJ is a hinge joint with an axis that varies in flexion and extension. This axis has a three-dimensional orientation so that the movement takes place in three anatomical directions. In extension, the ulna always moves in valgus. In flexion, its movement is variable, either in varus or in valgus (Matthijs et al., 2003). The ulna is considerably more massive proximally than distally and with the trochlear notch forms an articular surface with a deep socket that is inclined approximately 45° with reference to the ulnar shaft. The passive stability of the humeroulnar joint is produced chiefly by the shape of the articular surface; the deep trochlear notch surrounds the trochlea by about 180° (Milz et al., 1997). This type of stability is called form closure it occurs when both articulation surfaces have a small, almost identical radius of curvature (Matthijs et al., 2003).
The anatomy of the cartilaginous coating of the trochlear notch can vary. Many notches have no, or almost no cartilaginous coating (Milz et al., 1997). This means that in numerous humeroulnar joints there is no contact in the middle or that there is a certain incongruence between the notch and the trochlea.
Since 1993, Eckstein et al. have reported on this incongruence in several publications. According to them, the trochlea is often larger than the notch and in nonweight-bearing position is braced against the walls of the notch. With increasing load, the trochlea sinks deeper into the notch and the congruence increases (Eckstein et al., 1995).
The spherical shape of the capitulum has a very small radius and points in an anterodistal direction. Proximally, the radius is rather delicate in comparison to its distal end and with its head forms two articular surfaces that articulate simultaneously with the humerus and the ulna (▶ Fig. 3.2). The facet of the head forms a kind of trochoginglymus with the capitulum of the humerus. In contrast to the HUJ, the passive stability is not due to the bony construction of the articular surfaces but rather to the structure of the capsular ligaments, a so-called force closure. In this case, it is the capsule and the ligaments that, when they are stretched, create a force that maintains the physiological contact zones of the articular surfaces (Matthijs et al., 2003). As a result of the incongruence between the two articulating surfaces, the capsular folds (plicae) protrude into the articular space. In the HRJ, 60% of the axial load is transmitted from the lower arm to the upper arm, and compression is increased even more by extension (with valgus) and pronation, as well as by the action of the hand extensors. Thus it is understandable that muscle action of the hand extensors can provoke pain from osteoarthritis or impingement of capsular folds. This complicates differentiation in investigation of lateral elbow pain in grasping movements, since, in addition, laxity and instability of the HRJ are also causes of lateral elbow pain (O’Driscoll et al., 1991).
The PRUJ is formed by the radial circumference acting as articular head and the radial notch of the ulna with the annular ligament of the radius as the articular socket; it is a rotatory joint (▶ Fig. 3.2). The articular surface of the ulnar radial notch runs from anteromedial to posterolateral. In turning motions of the lower arm, the head of the radius is centered in an osteofibrous ring composed of the notch and the ligament. Although the entire circumference is lined with cartilage, one part never comes into contact with the ulnar articular surface but articulates exclusively with the annular ligament of the radius. The annular ligament of the radius lies directly on the circumference and therefore cannot contract. Thus, a laxity is to be expected as a pathologically altered mobility rather than capsule-determined hypomobility (Matthijs et al., 2003).
Due to a lateral overhang, the head of the radius is not exactly positioned as an extension of the radial shaft. The longer diameter of the oval is in the null position. In this position, the shaft moves further away from the ulna in a radial direction, which leaves room for the radial tuberosity (with the insertion of the long biceps tendon and an intervening bursa) to pass between the two lower arm bones. At the end of the pronation the radial tuberosity can be felt pressing out through the soft tissue in a lateral direction, thus becoming accessible for local therapeutic interventions. In complete supination, the radial tuberosity points forward and can be palpated in the depth of the cubital fossa.
Soft-tissue lesions are among the most frequent complaints seen in physical therapy practice in the area of the elbow joint. Knowing the names and position of muscles that arise at the humeral epicondyle is among the therapist’s anatomical skills. The muscles to be palpated will be described in more detail in later sections of the chapter. For the moment, a few interesting aspects can be described.
In 90° flexion, the lateral elbow muscles are almost parallel to each other (▶ Fig. 3.3). Clinically unremarkable, the brachioradialis (lateral margin of the humerus) and the extensor carpi radialis longus (medial supracondylar ridge) arise in a direct line. Several muscles arise directly on the lateral epicondyle; their tendons very often blend into each other and are in contact with the humeroradial capsule—extensor carpi radialis brevis and extensor digitorum, extensor carpi ulnaris and anconeus. Knowledge about the precise position of the origins comes from studies of preparations by Omer Matthijs at Texas Tech University in Lubbock. The short radial hand extensor is one of the structures that most commonly suffer from soft-tissue irritation such as insertion tendinopathy or tendinosis (tennis elbow). It is often therapeutically stretched. However, the stretched position used up to now (elbow extension and pronation and flexion and ulnar abduction of the wrist) was not the optimal position for the lengthening of its sarcomeres. In 1997, Lieber et al. described the fact that extension is not a stretching position and Ljung et al. stand by the idea that pronation does not contribute to the lengthening of the extensor carpi radialis brevis (Ljung et al., 1999). The pulling sensation in the usual stretching position could also be caused by stretching of the superficial ramus of the radial nerve. The extensor carpi ulnaris, anconeus, and supinator muscles also arise at the lateral epicondyle, but at the elbow they are clinically rather unremarkable.
Some superficial muscles of the upper arm that contribute to flexion of the wrist originate with a common tendon (common head) at the distal tip of the medial epicondyle (▶ Fig. 3.4): flexor carpi radialis muscles, palmaris longus, flexor carpi ulnaris, and, deeper, the humeral head of the flexor digitorum superficialis. The common head, which is up to 1 cm long, can cause medial elbow pain (golfer’s elbow). Only the pronator teres originates separately, from a plateau on the anterior side of the epicondyle. A few centimeters distal to the elbow joint, a tendinous, sharp-edged structure radiates from the biceps brachii to the fascia of the lower arm—the bicipital aponeurosis or lacertus fibrosus (see ▶ Fig. 3.12).
In the therapeutic investigation of a joint, neural structures play a special role and are of great interest for differential diagnosis. Therefore, it is important to realize that all three main nerves for the innervation of the lower arm and hand (median, radial, and ulnar nerves) must pass by the elbow joint (▶ Fig. 3.5). In doing this, each one runs through at least one muscular passage that can develop into a bottleneck and exert pressure on the nerve. For this reason, peripheral nerve compression is an alternative to soft-tissue irritation that must be taken seriously, such as tennis or golfer’s elbow.
In the radial tunnel (▶ Fig. 3.6), it passes through the sharp-edged tendon of the extensor carpi radialis brevis muscle and the sharp-edged arcade of the supinator muscle, where it can be affected by neurocontusion (Moradi et al., 2015), which is often misdiagnosed as tennis arm.
The groove for the ulnar nerve is the most well-known neural passage at the elbow. The ulnar nerve is the only large peripheral nerve of the arm that crosses over the posterior side of the elbow (▶ Fig. 3.7). Largely unknown are possible nerve compressions on entry into the cubital tunnel (CT). Andreisek et al. (2006) write that cubital tunnel syndrome is the second most common nerve compression syndrome of the upper extremity. Even moderate compression of the CT, such as the physiological example of a vigorous flexion, causes a distinct decrease in volume. In his 2001 monograph, Grana describes cubital tunnel syndrome, next to medial epicondylopathy, as a common cause of medial elbow pain in US throwing-event athletes. The pathology was known as long ago as 100 years but Feindel and Stratford first coined the name in 1958 (Robertson and Saratsiotis, 2005).
A very detailed description of the CT is given by O’Driscoll et al. in their publication (1991b). The basis is the bony groove for the ulnar nerve between the trochlea and the medial epicondyle. The floor of the tunnel is formed by the HUJ capsule and the ulnar collateral ligament that runs in it (Robertson and Saratsiotis, 2005). The roof is formed by the humeral and ulnar heads of the flexor carpi ulnaris that arise from the lateral epicondyle and the olecranon respectively. They form a 3-cm-long triangle over which the deep aponeurosis of the muscle spreads and covers the tunnel. In 70% of O’Driscoll et al.’s preparations, the proximal boundary is formed by an approximately 4-mm-long ligament-like retinaculum (cubital tunnel retinaculum or Osborne ligament). It extends between the epicondyle and the olecranon. If the retinaculum is present, it can be palpated 90% of the time. With increasing flexion, it tightens itself and raises the pressure in the cubital tunnel by up to 20 times (Polatsch et al., 2007); in extension, it becomes lax. The presence of the retinaculum is associated with possible neural compression pathology; the absence is associated with a possible anterior dislocation of the ulnar nerve over the medial epicondyle and possible friction neuritis. Further proximal, the ulnar nerve may be compressed by the triceps brachii.
The surface anatomy begins anteriorly at the crook of the elbow (cubital fossa). From here, palpation of the structures on the medial side, then the lateral elbow, and finally posterior structures is introduced. The cubital fossa has a triangular shape. The following structures form its boundaries (▶ Fig. 3.8):
The brachial artery and the median nerve run together in the cubital fossa under the lacertus fibrosus to the middle of the lower arm (see ▶ Fig. 3.8 and ▶ Fig. 3.13). Further on, the rounded tendons of the biceps brachii and brachialis insert at the corresponding tuberosities of the forearm bones.
The following starting position (SP) is suitable when practicing (▶ Fig. 3.9). The patient sits on a stool at the side of the treatment table on which the therapist is seated. The elbow is supported on the therapist’s thigh. The elbow joint is flexed and positioned mid-way between pronation and supination. The crook of the elbow should always be facing upward, indicating the neutral position of the upper arm.
Naturally, other positions can be used to reach the following structures. Nevertheless, care must always be taken to avoid squeezing soft tissue surrounding the elbow joint and to ensure that the position of the joint itself can be modified. Palpation on one’s own upper arm is also possible if the elbow joint is stably supported and the second hand has free access to the medial upper arm and the crook of the elbow (▶ Fig. 3.10)
Palpation of the anterior crook of the elbow begins quite far proximal in order to find reliable access to the boundaries of the cubital fossa. It is important for medial palpation of the upper arm that the triceps is hanging freely and the muscles are generally relaxed.
Large areas of the medial and lateral aspects of the humeral shaft can be accessed between the anterior elbow flexors and triceps brachii. This can be done on the medial side by lifting the flexor mass slightly with the flat hand and applying a slight, deep pressure with the finger pads (▶ Fig. 3.11).
This palpation technique locates the shaft of the humerus very quickly, and several thin structures can be observed running along the length of the shaft. Transverse palpation to the humerus is used here, that is, anterior-posterior. When palpating posteriorly, the therapist comes across the soft tissue of the triceps brachii, which is separated from the flexor side by a very firm intermuscular septum.
Generally, the contours of the biceps can be felt very well when the muscles contract against a slight resistance. The medial edge guides therapists to the bundle of nerves and vessels as well as certain structures in the cubital fossa.
The therapist looks for the muscle-tendon junction of the biceps brachii during continuous, slight muscle contraction. The muscle belly tapers distally and divides into two tendons that run in somewhat different directions. When hooked medially, it has very sharp edges, but when palpated anteriorly, the structure is flat and broad and presents as a coarse, collagenous plate (lacertus fibrosus or bicipital aponeurosis). It can be followed distally and medially but is then lost in the fascia of the forearm over the muscle belly of the pronator teres ( ▶ Fig. 3.4 and ▶ Fig. 3.10).
The therapist can reach the main biceps tendon by hooking around the muscle-tendon junction from a lateral position. The tendon can be felt even better by adding isometric contraction and supination in the SP described above. If it is followed systematically with transverse palpation on the tendon distally, it leads the palpating finger to the distal end of the cubital fossa.
To reach the radial tuberosity, the biceps tendon must be followed deeply, with increasing pressure, as far as the floor of the cubital fossa. The tendon disappears when the patient pronates the forearm maintaining isometric flexion. It reappears when supinated in isometric flexion and is more easily palpable. On the other hand, the tuberosity itself can be reached without muscle activity. The identification is confirmed by passive pronation and supination of the forearm. In supination, pressure is felt from the tuberosity against the palpating finger. The tendinous insertion is found here. During pronation, it wraps itself around the radius and penetrates between the two forearm bones to the posterior. There it can be felt to project at the same level (2 to 3 finger widths distal to the head of the radius during end-range pronation).
Palpation of tendon and insertion can be used as techniques for provocative diagnosis. Anterior pain in the crook of the elbow triggered by contraction indicates tendinopathy at the insertion. Passive pronation leads to the conclusion of a problematic passage of the tuberosity with attached soft tissue, usually because of a swollen bursa between the inserting tendon and the tuberosity (bicipitoradial bursa).
Two important peripheral motor nerves supplying the forearm and hand, as well as two large blood vessels, travel through the medial region of the upper arm (▶ Fig. 3.13):
The basilic vein, the deep brachial artery, and the median nerve form a neurovascular bundle that can be palpated over the entire length of the humerus. The ulnar nerve is also part of this bundle until the mid-upper arm. From there it travels separately and crosses the elbow joint posteromedially.
The other structures (median nerve and both blood vessels) run along the upper arm, first in the bicipital groove and then anteriorly and medially (through the cubital fossa) over the elbow joint to the forearm.
The patient is instructed to maintain a moderately strong isometric elbow flexion and supination. The same transverse palpation technique is used as for the humerus (see ▶ Fig. 3.11). The bundle of nerves and blood vessels is found slightly posterior to the medial border of the biceps, where it lies in a soft-tissue groove, the bicipital groove. This means that the palpating fingers have to be slightly flexed to enable the finger pads to reach these structures.
With the muscles now relaxed again, the pulsation of the brachial artery can be felt with moderate, flat pressure. It can be easily followed distally to the cubital fossa. The artery crosses underneath the bicipital aponeurosis and heads toward the middle of the cubital fossa (see ▶ Fig. 3.12). Then it divides into the radial artery and the ulnar artery, which cannot be found by palpation until they reach the distal forearm near the wrist.
If the therapist is not certain that the artery has been found, the palpation can be confirmed by finding the pulse at the wrist and then increasing the pressure applied to the point where the brachial artery is presumed to be. The pulse at the wrist will become weaker if the presumed location is correct. With the exception of severe vascular disease, there are no risks to the patient when pressure is applied for a short amount of time.
The median nerve accompanies the artery until just before the cubital fossa. First it runs under the lacertus fibrosus, which, in rare cases, can irritate the nerve (Gregoli et al., 2013). Before it begins its median course in the forearm, the nerve runs through a passage between the ulnar and humeral heads of the pronator teres. Compression neuropathies of the median nerve can arise when this muscle is very tense.
The nerve will roll back and forth underneath the transversely palpating fingers on the medial upper arm when slightly more pressure is applied to the humerus (see ▶ Fig. 3.10). This feeling is typical for the palpation of a neural structure.
It is relatively easy to differentiate the median nerve from the parallel blood vessel. It goes without saying that the nerve neither pulsates nor changes the quality of the radial pulse at the wrist. The location and pathway of a nerve can be confirmed by palpating the nerve as it is placed under alternating tension and relaxation. This procedure carries no risk for the patient as peripheral nerves can usually cope quite well with short, moderate pressure. Pressure occasionally causes formication in the periphery.
First the therapist returns to the medial muscle-tendon transition of the biceps. Proceeding from anterior to medial along an imaginary line from the muscle-tendon transition to the medial epicondyle (see ▶ Fig. 3.23), one first reaches the brachial artery and the median nerve. Under these and on the line to medial, there is a portion of the brachial muscle belly that continues to the ulnar tuberosity, lying somewhat under the pronator teres. One or two finger pads are placed flat from anterior onto the assumed spot where they encounter the muscle-tendon transition of the biceps (not illustrated). The location is confirmed by alternating contraction and relaxation of the flexed muscle.
The cubital fossa is formed medially by the lateral edge of the pronator teres. This muscle has already been encountered during palpation of the bicipital aponeurosis (see ▶ Fig. 3.14). It originates on the humerus proximal to the medial epicondyle and crosses over the proximal forearm onto the shaft of the radius (▶ Fig. 3.14).
Following the palpated muscle belly of the brachialis distally, the therapist encounters the lateral edge of the pronator teres. The identification is confirmed by end-range active pronation performed by the patient with some degree of pressure. The edge of the pronator teres can be followed distally to the end of the cubital fossa before it disappears under the muscle belly of the brachioradialis.
This muscle is the only flexor of the elbow joint innervated by the radialis nerve. Its slender muscle belly forms the lateral boundary of the cubital fossa (▶ Fig. 3.15). It becomes distinctly noticeable particularly with contraction against resistance in flexion, in a position that is neutral for pronation/supination.
If the medial edge of the constantly contracted muscle belly is followed proximally it leads the palpating finger to the distal third of the humerus on the lateral side, to the lateral margin of the humerus and to palpation of the radial nerve (see ▶ Fig. 3.36). With pronounced isometric tension, it pulls the soft tissue of the lateral upper arm flat and usually forms an easily recognized concavity at the level of the fleshy insertion.
The medial border of the brachioradialis precisely marks the junction between the head of the radius and the ulna at the cubital fossa (▶ Fig. 3.15).
One palpating finger is placed in the middle of the cubital fossa, between the lateral biceps tendon and the medial edge of the brachioradialis. With marked deep pressure in the cubital fossa and somewhat laterally, the movement of the radial head can be felt when the forearm is turned over. The therapist now has an idea of where the PRUJ can be found: on the medial border of the brachioradialis at the height of the head of the radius.
It is very important that all therapists be aware of the exact position of the neurovascular bundle on the medial side of the humerus. Colleagues who experience the position and size of these structures for the first time during courses on palpation are surprised at the ease with which these structures can be reached and, therefore, compressed.
Whether applying classical massage therapy, underwater massage, or a manipulative technique in manual therapy, the therapist must protect the medial upper arm and the crook of the elbow from any permanent pressure or tension. Local and precise applications to well-defined areas are an exception.
Translational movements of the radial head with respect to the ulna or the humerus for diagnostic or therapeutic purposes are part of every manual therapist’s repertoire. Knowledge of how far to medial the head of the radius extends and its boundaries with the ulna ensures the use of the correct technique. These tests, together with fixation of the humerus in the HRJ, are used to confirm capsular hypomobility or laxity, and in the PRUJ (▶ Fig. 3.16), with fixation of the ulna, exclusively to confirm laxity.