Origin of Major: Spinous processes of second through fifth thoracic vertebrae.
Insertion of Major: By fibrous attachment to medial border of the scapula between spine and inferior angle.
Origin of Minor: Ligamentum nuchae, spinous processes of seventh cervical and first thoracic vertebrae.
Insertion of Minor: Medial border at root of spine of the scapula.
Action: Adduct and elevate the scapula, and rotate it so that the glenoid cavity faces caudally.
Nerve: Dorsal scapular, C4, 5.
Origin: Transverse processes of the first four cervical vertebrae.
Insertion: Medial border of scapula, between superior angle and root of spine.
Action: With the origin fixed, elevates the scapula, and assists in rotation so that the glenoid cavity faces cau-dally. With the insertion fixed and acting unilaterally, laterally flexes the cervical vertebrae, and rotates toward the same side. Acting bilaterally, the levator may assist in extension of the cervical spine.
Origin of Upper Fibers: External occipital protuberance, medial V3 of superior nuchal line, ligamentum nuchae and spinous process of the seventh cervical vertebra.
Origin of Middle Fibers: Spinous processes of the first through fifth thoracic vertebrae.
Origin of Lower Fibers: Spinous processes of the sixth through 12th thoracic vertebrae.
Insertion of Upper Fibers: Lateral '/3 of the clavicle and acromion process of the scapula.
Insertion of Middle Fibers: Medial margin of the acromion and superior lip of the spine of the scapula.
Insertion of Lower Fibers: Tubercle at the apex of the spine of the scapula.
Action: With origin fixed, adduction of scapula, performed chiefly by the middle fibers, with stabilization by upper and lower fibers. Rotation of scapula so gle-noid cavity faces cranially, performed chiefly by upper and lower fibers, with stabilization by middle fibers. In addition, upper fibers elevate, and lower fibers depress, the scapula. With the insertion fixed and acting unilaterally, upper fibers extend, laterally flex, and rotate the head and joints of the cervical vertebrae so face turns toward the opposite side. With insertion fixed and acting bilaterally, the upper trapezius extends the neck. The trapezius also acts as an accessory muscle of respiration.
Nerve: Cervical, 3, 4 and Dorsal scapular, C4. 5.
Nerve: Spinal portion of cranial nerve XI (accessory) and ventral ramus, C2, 3, 4.
Fixation: None on the part of the examiner is necessary, but it is assumed that the adductors of the shoulder joint have been tested and found to be strong enough to hold the arm for use as a lever in this test.
Test: Adduction and elevation of the scapula, with medial rotation of the inferior angle. To obtain this position of the scapula and leverage for pressure in the test, the arm is placed in the position as illustrated. With the elbow flexed, the humerus is adducted toward the side of the body in slight extension and slight lateral rotation.
The test is to determine the ability of the rhomboids to hold the scapula in the test position as pressure is applied against the arm. (See alternate test, p. 328.)
Pressure: The examiner applies pressure with one hand against the patient's arm, in the direction of abducting the scapula and rotating the inferior angle laterally and against the patient's shoulder, with the other hand in the direction of depression.
Weakness: The scapula abducts and the inferior angle rotates outward. The strength of adduction and extension of the humerus is diminished by loss of rhomboid fixation of the scapula. Ordinary function of the arm is affected less by loss of the rhomboid strength than by loss of either trapezius or serratus anterior strength.
Shortness: The scapula is drawn into a position of adduction and elevation. Shortness tends to accompany paralysis or weakness of the serratus anterior, because the rhomboids are direct opponents of the serratus. (See p. 336.)
Modified Test: If the shoulder muscles are weak, the examiner places the scapula in the test position and attempts to abduct, depress, and derotate the scapula.
Note; The accompanying photograph shows the rhomboids in a state of contraction. (See p. 306for right rhomboids in neutral position and left rhomboids in elongated position.)
If a position of medial rotation of the humerus and elevation of the scapula is permitted during testing of the middle trapezius, it ceases to be a trapezius test. As seen in this illustration, the humerus is medially rotated, and the scapula is elevated, depressed anteriorly, and ad-ducted by rhomboid action rather than by middle trapez-ius action. A comparison of this photograph with the one on the facing page gives an example of what is meant by obtaining the specific action in which a muscle is the prime mover.
The marked difference that often exists between strength of the rhomboids and of the trapezius is dramatically demonstrated by careful testing.
Fixation: Same as for middle trapezius, except the middle deltoid does not assist as an intervening muscle and the elbow extensors are necessary intervening muscles.
Test: Adduction and elevation of scapula, with a downward rotation (medial rotation of the inferior angle). The position of the scapula is obtained by placing the shoulder in 90° abduction and in sufficient medial rotation to move the scapula into the test position. The palm of the hand faces in a caudal direction.
Pressure: Against the forearm, in a downward direction toward the table.
Fixation: The intervening shoulder joint extensors (posterior deltoid, teres minor, and infraspinatus, with assistance from the middle deltoid) must give necessary fixation of the humerus to the scapula to use the arm as a lever. To a lesser extent, the elbow extensors may need to give some fixation of the forearm to the humerus. However, with the shoulder laterally rotated, the elbow is also rotated into a position so that downward pressure on the forearm is exerted against the elbow laterally rather than in the direction of elbow flexion.
The examiner provides fixation by placing one hand on the opposite scapular area to prevent trunk rotation, as illustrated above. (The examiner's hand in the photograph merely indicates the downward direction of pressure.)
Test: Adduction of the scapula, with upward rotation (lateral rotation of the inferior angle) and without elevation of the shoulder girdle.
The test position is obtained by placing the shoulder in 90° abduction and in lateral rotation sufficient to bring the scapula into lateral rotation of the inferior angle.
The teres major is a medial rotator attached along the axillary border of the scapula. Traction on this muscle as the arm is laterally rotated draws the scapula into lateral rotation. The degree of shoulder rotation necessary to produce the effect on the scapula will vary according to the tightness or laxity of the medial rotators. Usually, rotation of the arm and hand into a position so that the palm of the hand faces cranially will indicate good positioning of the scapula.
Both the trapezius and the rhomboids adduct the scapula, but they differ in their action of rotation. Differentiating these muscles in testing is based on their rotation actions.
In addition to placing the parts in precise test position, it is necessary to observe the scapula during the testing to make sure that rotation is maintained as pressure is applied.
Pressure: Against the forearm, in a downward direction toward the table.
Weakness: Results in abduction of the scapula and a forward position of the shoulder.
The middle and lower trapezius reinforce the thoracic spine extensors. Weakness of these fibers of the trapezius increases the tendency toward a kyphosis.
LOWER TRAPEZIUS TEST
Fixation: The intervening shoulder extensors, particularly the posterior deltoid, must give the necessary fixation of the humerus to the scapula, and to a lesser extent, the elbow extensors need to hold the elbow in extension. (See explanation, p. 329.)
The examiner provides fixation by placing one hand below the scapula on the opposite side (not shown).
Test: Adduction and depression of the scapula, with lateral rotation of the inferior angle. The arm is placed diagonally overhead, in line with the lower fibers of the trapezius. Lateral rotation of the shoulder joint occurs along with elevation, so it usually is not necessary to further rotate the shoulder to bring the scapula into lateral rotation. (See explanation on previous page.)
Pressure: Against the forearm, in a downward direction toward the table.
Weakness: Allows the scapula to ride upward and tilt forward, with depression of the coracoid process. If the upper trapezius is tight, it helps to pull the scapula upward and acts as an opponent to a weak lower trapezius.
MODIFIED TRAPEZIUS TEST (NOT ILLUSTRATED)
For use when the posterior shoulder joint muscles are weak.
Patient: Prone, with the shoulder at the edge of the table and the arm hanging down over the side of the table.
Test: Supporting the weight of the arm, the examiner places the scapula in a position of adduction, with some lateral rotation of the inferior angle and without elevation of the shoulder girdle.
Pressure: As the support of the arm is removed, the weight of the suspended arm will exert a force that tends to abduct the scapula. A very weak trapezius will not hold the scapula adducted against this force. If the trape-zius can hold the scapula in adduction against the weight of the suspended arm, then resist against the middle portion by pressure in the direction of abduction and against the lower portion by pressure in a diagonal direction toward abduction and elevation. When recording the grade of strength, note that pressure was applied on the scapula, because the arm could not be used as a lever.
Not©: Tests for the lower and middle trapezius are especially important during examination of cases with faulty shoulder position or with upper back or arm pain.
Patient: Sitting. Fixation: None necessary.
Test: Elevation of the acromial end of the clavicle and scapula, and posterolateral extension of the neck, bringing the occiput toward the elevated shoulder with the face turned in the opposite direction.
The upper trapezius can be differentiated from other elevators of the scapula, because it is the only one that elevates the acromial end of the clavicle and the scapula. It also laterally rotates the scapula as it elevates, in contrast to the straight elevation that occurs when all elevators contract, as in shrugging the shoulders.
Pressure: Against the shoulder, in the direction of depression, and against the head, in the direction of flexion anterolateral I v.
Weakness: Unilaterally, weakness decreases the ability to approximate the acromion and the occiput. Bilaterally, weakness decreases the ability to extend the cervical spine (e.g., to raise the head from a prone position).
Shortness: Results in a position of elevation of the shoulder girdle (commonly seen in prize fighters and swimmers). In a faulty posture with a forward head position and kyphosis, the cervical spine is in extension, and the upper trapezius muscles are in a shortened position.
Contracture: Unilateral contracture frequently is seen in cases of torticollis. For example, the right upper trapez-ius usually is contracted along with a contracture of the right sternocleidomastoid and scaleni. (See p. 156.)
Weakness of Whole Trapezius: Results in abduction and medial rotation of the scapula, with depression of the acromion, and interferes with ability to raise the arm in abduction overhead. (See p. 337 for posture of shoulder when the entire trapezius is paralyzed.)
Origin: Outer surfaces and superior borders of the upper eight or nine ribs.
Insertion: Costal surface of the medial border of the scapula.
Action: With the origin fixed, abducts the scapula, rotates the inferior angle laterally and the glenoid cavity cranially, and holds the medial border of the scapula firmly against the rib cage. In addition, the lower fibers may depress the scapula, and the upper fibers may elevate it slightly.
Starting from a position with the humerus fixed in flexion and the hands against a wall (see the standing serratus test, p. 334), the serratus acts to displace the thorax posteriorly as the effort is made to push the body away from the wall. Another example of this type of action is a properly executed push-up.
With the scapula stabilized in adduction by the rhomboids, thereby fixing the insertion, the serratus may act in forced inspiration.
Fixation: None necessary, unless the shoulder or elbow muscles are weak, in which case the examiner supports the extremity in the perpendicular position during the test.
Test: Abduction of the scapula, projecting the upper extremity anteriorly (upward from the table). Movement of the scapula must be observed and the inferior anglepal-pated to ensure that the scapula is abducting. Projection of the extremity can be accomplished by action of the pectoralis minor (aided by the levator and rhomboids) when the serratus is weak, in which case the scapula tilts forward at the coracoid process and the inferior angle moves posteriorly and in the direction of medial rotation. The firm surface of the table supports the scapula. Therefore, there will be no winging, and the pressure against the hand may elicit what appears to be normal strength. Because this type of substitution can occur during this test, the test in the sitting position (as described on the facing page) is more accurate and is preferred.
Pressure: Against the subject's fist, transmitting the pressure downward through the extremity to the scapula in the direction of adducting the scapula. Slight pressure may be applied against the lateral border of the scapula as well as against the fist.
Fixation: If the trunk is stable, none by the examiner should be necessary. However, the shoulder flexors must be strong to use the arm as a lever in this test. Allow the subject to hold on to the table with one hand.
Test: The ability of the serratus to stabilize the scapula in a position of abduction and lateral rotation, with the arm in a position of approximately 120° to 130° of flexion. This test emphasizes the upward rotation action of the serratus in the abducted position, as compared to the emphasis on the abduction action shown during the supine and standing tests.
Pressure: Against the dorsal surface of the arm, between the shoulder and elbow, downward in the direction of extension, and slight pressure against the lateral border of the scapula, in the direction of rotating the inferior angle medially. The thumb against the lateral border (as shown in the drawing) acts more to track the movement of the scapula than to offer pressure.
For purposes of photography, the examiner in this case stood behind the subject and applied pressure with the fingertips on the scapula as illustrated. In practice, however, it is preferable to stand beside the subject and apply pressure as illustrated by the inset. It is not advisable to use a long lever by applying pressure on the forearm or at the wrist, because the intervening shoulder flexors will often break before the serratus.
Weakness: Makes it difficult to raise the arm in flexion. Results in winging of the scapula. With marked weakness, the test position cannot be held. With moderate or slight weakness, the scapula cannot hold the position when pressure is applied on the arm. Because the rhomboids are direct opponents of the serratus, the rhomboids become shortened in some cases of serratus weakness. (See also p. 338.)
Patient: Standing. Fixation: None necessary.
Test movement: Facing a wall and with the elbows straight, the subject places both hands against the wall, either at shoulder level or slightly above. To begin, the thorax is allowed to sag forward so that the scapulae are in a position of some adduction. The subject then pushes hard against the wall, displacing the thorax backward, until the scapulae are in a position of abduction.
Resistance: The thorax acts as resistance in this test. By fixation of the hands and extended elbows, the scapulae become relatively fixed, and the anterolateral rib cage is drawn backward toward the scapulae. (In contrast, the scapula is pulled forward, toward the fixed rib cage, during the forward thrust of the arm in the supine test shown on p. 332.) Because the resistance of displacing the weight of the thorax makes this a strenuous test, it will differentiate only between strong and weak for purposes of grading.
Weakness: Winging of the right scapula, as seen in the above photograph.
The photograph illustrates the posture of the shoulders and scapulae as seen in some cases of mild serratus weakness. Slight winging of the scapulae is readily visible because the upper back is straight. However, one must not assume the presence of serratus weakness only on the basis of appearance. When the upper back is straight, the scapulae may be prominent even if the ser-ratus is normal in strength.
With a round upper back, the scapulae will be elevated and adducted by the rhomboids, which are direct opponents of the serratus anterior.
Mild serratus weakness is more prevalent than generally realized, and weakness tends to be more on the left than on the right, regardless of handedness. When weakness exists, it can be aggravated by attempting strenuous exercises, such as push-ups.
The above photograph shows the extent to which the right arm could be elevated overhead with the subject in a standing position. With paralysis of the right serratus anterior, the arm could not be raised directly forward, and the right scapula could neither be abducted nor fully rotated as on the normal (left) side. The trapez-ius compensated, to some extent, in the rotation of the scapula by action of the upper and lower fibers, which stand out clearly. In repeating the movement five or six times, however, the muscle fatigued, and the ability to raise the arm above shoulder level decreased.
Subjects without any paralysis show a wide range of strength in the lower and middle trapezius. This variation in strength is associated with postural or occupational stress on these muscles. The grade of strength will range from fair to normal. Because of these wide differences, variations also are found in the ability to raise an arm overhead among those who develop marked weakness or isolated paralysis of the serratus. If an individual already has marked trapezius weakness of a postural or an occupational nature and, subsequently, incurs paraly sis of the serratus, that person will not be able to raise the arm overhead as in the accompanying illustration.
The serratus anterior assists in elevation of the arm in the forward plane by its actions of abduction and upward rotation. By its abduction action, it moves the arm in an anterior direction (i.e., protracts the arm). By its reverse action, during the push-up, it helps to move the upper trunk in a posterior direction. When the push-up is properly done, the scapulae abduct as the body is pushed upward. When the scapulae remain in an adducted position during the push-up, however, the excursion of the trunk movement is not as great as when the scapulae move into abduction.
The senior author of this text has tested the serratus anterior muscle in hundreds of "normal" individuals. The test in supine position, as the test is traditionally done (see p. 332), rarely discloses any weakness. The scapula will not wing, because it is supported by the table, and a strong pectoralis minor tilts the shoulder forward to hold the arm forward in (apparent) test position against pressure. When the same group of individuals is tested with the preferred test position (i.e., arm in -120° of flexion), the results are very different.
In groups of approximately 20 individuals, one or two might be strong on both the right and the left sides, and one might be weaker on the right than on the left side (regardless of handedness). The rest may be about equally divided between being weaker on the left than on the right or being bilaterally weak (with some propensity for the left side being weaker).
Aside from the usual distribution, it has been necessary, at times, to have a separate category for persons who exhibit good strength through part of the range of motion of abduction while attempting to support the weight of the arm in flexion. The scapula can be passively brought forward into the test position by pulling the arm diagonally upward and forward, but it immediately slips back as the subject attempts to hold the arm in test position. This weakness can best be described as a stretch weakness of the serratus. Stretching that has taken place is graphically illustrated on the following page. Invariably, those who fall into the special category are persons who have engaged in many push-ups, bench presses, or activities involving strong rhomboid action. A person may start doing push-ups properly, but when the serratus fatigues, the scapulae remain ad-ducted and the push-up is continued by the action of the pectoralis major and the triceps—to the detriment of the serratus.
Figure A: When the arm is raised in flexion, to position the scapula for the serratus test, the scapula does not move to the normal position of abduction, (see p. 333.) However, the Serratus appears to test strong in that position (probably because of over development of shoulder flexors). Figure F below shows the same subject. The winging of the scapula clearly indicates weakness of the serratus anterior
Figure B: The scapula can be brought forward to almost normal abduction if the subject relaxes the weight of the arm and allows the examiner to draw the arm diagonally forward into the test position.
Figure C: The scapula cannot hold the abducted and upwardly rotated position when the examiner releases the arm, and the subject attempts to hold it in position.
Figure D: This subject has routinely performed both bench presses and shoulder adduction exercises, including seated rowing and "bent-over rowing" with heavy weights. As seen in the photographs (Figures D-F). the rhomboids have become overdeveloped. The rhomboids are direct opponents of the serratus, and this type of exercise is contraindicated in the presence of serratus weakness.
Figure E: In a prone position, resting on the forearms, winging of the scapulae is observed. The serratus is unable to hold the abducted position against resistance cf-fered by the weight of the trunk in this position.
Figure F: This photograph shows the abnormal position that the scapulae assume at rest.
The left and right figures show two views of the same subject. He performed a push-up in spite of extreme weakness of the serratus anterior and without complaint of pain.
Note: See p.252 regarding muscles that an supplied by nerves that are motor only.
Note: See p.252 regarding muscles that an supplied by nerves that are motor only.
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