Which muscle retracts rotates and fixes the scapula

This muscle also retracts and rotates the scapula. The rhomboid minor muscle lies superior to the rhomboid major muscle and inferior to levator scapulae in the back.

It spans from the vertebra to the scapula. The rhomboid minor muscle originates from the inferior nuchal ligament and C7-T1 spinous processes. This muscle then inserts into the medial border of the scapula superior to rhomboid major. Rhomboid major works in conjunction with other muscles to fix the scapula to the thoracic wall. It also functions to rotate and retract the scapula. Clinical Examination.

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Diagnosis is easily made upon visible inspection of the scapula, with serratus anterior paralysis resulting in medial winging of the scapula. This is in contrast to the lateral winging generated by trapezius and rhomboid paralysis. Most cases of serratus anterior paralysis spontaneously resolve within 24 months, while conservative treatment of trapezius paralysis is less effective. A conservative course of treatment is usually followed for rhomboid paralysis. To allow time for spontaneous recovery, a 6—24 month course of conservative treatment is often recommended, after which if there is no recovery, patients become candidates for corrective surgery.

Cosmetically, some patients may be distressed by pronounced winging [ 2 ]. Disrupting scapulohumeral rhythm, scapular winging contributes to loss of power and limited flexion and abduction of the upper extremity and can be a source of considerable pain [ 3 — 8 ].

A condition due to a number of etiologies, most cases are due to lesions of the long thoracic and spinal accessory nerves that innervate the serratus anterior and trapezius muscles, respectively. Rarely, it may also be due to a lesion to the dorsal scapular nerve that innervates the rhomboid muscles. These scapular muscles Fig. In addition, the scapula may translate medially or laterally along the posterior thoracic wall due to unopposed muscle contraction of the other functioning scapular muscles, a distinction known as medial serratus anterior paralysis or lateral trapezius or rhomboid paralysis winging Table 1.

Scapular winging may present in a variety of clinical contexts, and may be due to traumatic- or sports-related injury [ 2 , 4 , 5 , 8 — 22 ], iatrogenic injury [ 1 , 2 , 12 , 15 , 16 , 19 , 23 — 27 ], or spontaneous in nature [ 6 — 8 , 11 , 27 — 30 ]. Here we discuss incidence and demographics, pertinent anatomy, the nature of the injury, diagnostic tests, and treatment options for scapular winging due to serratus anterior, trapezius, and rhomboid muscle paralysis.

Anatomical relationship of the serratus anterior, trapezius, and rhomboid muscles around the scapula, with the rhomboids just deep to the trapezius. Modified from Ref. Scapular winging due to serratus anterior palsy is a rare lesion. Fardin et al. Overpeck and Ghormley [ 31 ] found only one case of serratus anterior paralysis in 38, patients observed at the Mayo Clinic, while Remak [ 32 ] diagnosed three cases of serratus anterior paralysis in a series of 12, neurological examinations.

Gregg et al. Incidence of scapular winging due to trapezius paralysis is rare and difficult to assess. Awareness of the possibility of iatrogenic injury to the spinal accessory nerve during neck surgery has led to newer techniques that have reduced the incidence of trapezius palsy since its peak in the s [ 7 ].

There are no published reports in the English language literature stating the incidence of scapular winging due to rhomboid paralysis. Indeed, there are only anecdotal statements describing rhomboid paralysis as rare and its functional effects as even rarer [ 33 , 34 ].

Athletic injuries have also been attributable to trapezius [ 7 , 37 ] and rhomboid paralysis [ 20 , 21 , 38 , 39 ]. Occupational injuries causing serratus anterior paralysis have been reported in the literature in individuals working as car mechanics, navy airmen, scaffolders, welders, carpenters, laborers, and a seamstress [ 11 , 40 — 43 ].

The serratus anterior is a broad flattened sheet of muscle originating from the first nine ribs and passes posteriorly around the thoracic wall before inserting into the costal surface of the medial border of the scapula [ 44 ].

The serratus anterior has three functional components [ 4 , 8 ]. The superior component originates from the first and second ribs and inserts into the superior medial angle of the scapula [ 4 , 8 ]. This component serves as the anchor that allows the scapula to rotate when the arm is lifted overhead [ 4 ]. The middle component of the serratus anterior originates from the third, fourth, and fifth ribs and inserts on the vertebral border of the scapula, serving to protract the scapula [ 4 , 8 ].

The inferior component originates from the sixth to ninth ribs and inserts on the inferior angle of the scapula [ 4 , 8 ]. This third portion serves to protract the scapula and rotate the inferior angle upward and laterally [ 4 ]. As a whole, the main function of the serratus anterior is to protract and rotate the scapula, keeping it closely opposed to the thoracic wall and optimizing the position of the glenoid for maximum efficiency for upper extremity motion [ 4 , 8 , 44 ].

The serratus anterior is solely innervated by the long thoracic nerve, originating from the anterior rami of the fifth, sixth, and seventh cervical nerves [ 4 , 8 , 44 ].

Branches from the fifth and sixth cervical nerves pass anteriorly through the scalenus medius muscle before joining the seventh cervical nerve branch that coursed anteriorly to the scalenus medius [ 4 , 8 , 45 ]. The long thoracic nerve then dives deep to the brachial plexus and the clavicle to pass over the first rib [ 4 , 8 ].

Here, the nerve enters a fascial sheath [ 45 , 46 ] and continues to descend along the lateral aspect of the thoracic wall to innervate the serratus anterior muscle Fig. An average of 24 cm in length [ 27 ], it is this long and winding course that is postulated to make the nerve susceptible to mechanical injury.

Course of the long thoracic nerve to its innervations of the serratus anterior muscle. The trapezius muscle, like the serratus anterior, serves to elevate, retract, and rotate the scapula [ 7 ]. The muscle originates from the skull and the spinous processes of the first cervical vertebra through the 12th thoracic vertebra [ 7 , 44 ].

The primary insertion is along the spine of the scapula [ 7 , 44 ]. Separated into three components, the superior portion elevates the scapula and rotates the lateral angle upwardly, the middle portion adducts and retracts, and the inferior portion depresses the scapula and rotates the inferior angle laterally [ 7 , 12 ]. The trapezius is solely innervated by the spinal accessory nerve, or cranial nerve XI, which crosses the posterior cervical triangle superficially before diving vertically along the deep surface of the trapezius [ 7 , 44 ].

Just deep to the trapezius, the two rhomboid muscles work together to retract and elevate the scapula and rotate its lateral border downward [ 5 , 22 , 44 , 47 , 48 ]. The smaller rhomboid minor is a cyndrical muscle that finds its origin in the ligamentum nuchae of the neck and the spinous processes of the seventh cervical and first thoracic vertebrae [ 44 , 47 ]. It projects downward and laterally to the medial border of the scapula at the base of the scapular spine [ 44 , 47 ]. The larger and more inferior rhomboid major originates from the spinous processes of the second through fifth thoracic vertebrae and inserts on the medial border of the scapula, from the insertion of the rhomboid minor to the inferior angle of the scapula [ 44 , 47 ].

Both rhomboid muscles are innervated by the dorsal scapular nerve, with its fibers predominantly derived from the C5 nerve root with minor contributions from C4 or C6 [ 22 , 44 , 49 , 50 ].

Like some of the fibers of the long thoracic nerve, the dorsal scapular nerve penetrates the scalenus medius muscle, before heading to the levator scapulae, giving off innervating fibers to the muscle [ 44 , 49 ]. The nerve then may pass deep to or pierce the levator scapulae muscle before diving under the brachial plexus and running to the anterior surface of the rhomboid muscles [ 22 , 34 , 44 , 49 ].

The commonest cause of scapular winging is serratus anterior paralysis, a dysfunction attributed to traumatic [ 2 , 4 , 8 , 9 , 11 ], non-traumatic [ 6 , 8 , 11 , 28 , 41 , 51 — 53 ], and idiopathic [ 6 , 8 , 11 , 28 — 30 ] lesions of the long thoracic nerve.

Reported causes of non-traumatic injury to the long thoracic nerve include viral illness influenza [ 11 ]; tonsillitis-bronchitis [ 6 , 28 ]; poliomyelitis [ 6 ] , allergic-drug reactions [ 28 ], drug overdose [ 11 ], toxic exposure herbicides and tetanus antitoxin [ 28 ] , muscular dystrophy-fascioscapulohumeral dystrophy [ 41 , 54 — 56 ], C7 radiculopathy [ 52 ], and aortic coarctation [ 6 ].

Most trauma-induced long thoracic nerve injury are neurapraxias as a result of blunt trauma [ 4 , 8 , 9 , 11 ], such as sudden depression of the shoulder girdle [ 9 ] or unusual twisting of the neck and shoulder [ 4 ]. Trauma may also be due to repetitive movements, as seen in athletics [ 4 , 13 ] and house-hold activities such as hedge-clipping [ 11 ], digging [ 11 ], car washing [ 57 ], or prolonged lying in bed with the arms abducted and propping up the head to read [ 7 ].

In addition, long thoracic nerve palsy may be due to direct mechanical pressure by an inflamed and enlarged subcoracoid or subscapular bursa along the pathway of the nerve [ 58 ]. Long thoracic nerve injury may also be iatrogenic as consequence of chiropractic manipulation [ 26 ], the use of a single axillary crutch [ 59 ], mastectomies with axillary node dissection [ 1 , 25 ], scalenotomies [ 1 ], surgical treatment of spontaneous pneumothorax [ 1 ], and post-general anesthesia for various clinical reasons [ 1 , 2 ].

Electrical shock may also cause long thoracic nerve palsy [ 40 ]. Although the association between serratus anterior paralysis and trauma is well established, there is no consensus of exactly how trauma injures the long thoracic nerve. Initial hypotheses were linked to the observation that the fifth and sixth cervical branches of the long thoracic nerve pass through the substance of the scalenus medius muscle, suggesting that spasms of this muscle could block conduction through the long thoracic nerve [ 32 ].

This hypothesis is unlikely, though, as the nerve to the unaffected rhomboids also passes through the scalenus medius muscle and the seventh cervical branch passes anterior to the muscle, bypassing the proposed causative spasm [ 4 , 9 , 11 ].

Later, Gregg et al. They hypothesized that sudden or recurrent irritating traction force may cause serratus anterior paralysis. Foo and Swan [ 11 ] were not convinced, though, citing that since the nerve is long, it must be capable of a reasonable amount of stretch, supported by the fact that traction injuries to the brachial plexus are not always accompanied by long thoracic nerve injury. Gozna and Harris [ 9 ] showed in their cadaver study that a forceful downward pull on the arm could pinch the nerve between the second rib and the scapula and concluded this to be the site of traumatic palsy of the serratus anterior.

However, there is evidence that under such extreme force, damage to the long thoracic nerve should be accompanied by damage to the brachial plexus and axillary vessels as well [ 4 ]. Paralysis to the trapezius muscle, like serratus anterior paralysis, is primarily neurogenic, but from injuries to the spinal accessory nerve.

The superficial course of the nerve makes it susceptible to closed traction lesions in assault cases [ 16 ], motor vehicle accidents [ 12 , 15 ], and direct trauma to the posterior cervical region [ 15 ]. Other direct traumas to the spinal accessory nerve include heavy lifting [ 14 , 60 ], biting to the posterior cervical triangle [ 10 ], penetrating wounds to the area [ 14 , 17 , 19 ], and other forms of blunt trauma to the posterior cervical triangle [ 12 , 14 , 15 ].

By far, the most common cause of spinal accessory nerve palsy is iatrogenic, primarily sustained during surgeries for cervical lymph node biopsy [ 14 , 16 , 19 , 27 ] and cervical mass excision [ 12 , 14 — 16 , 24 , 27 ]. In a similar study, Williams et al. Spontaneous or idiopathic trapezius paralysis has also been reported [ 7 , 27 ]. Similarly, rhomboid paralysis tends to be primarily neurogenic in nature, involving the dorsal scapular nerve.

An entrapment injury is the most common cause of injury reported in the literature [ 22 , 39 , 48 , 49 ], although the site of entrapment is not well known. Unlike the long thoracic nerve, there is some strong evidence that the dorsal scapular nerve can become entrapped in the scalenus medius muscle as some have suggested [ 22 , 48 , 49 ].

Desong et al. Similar findings have not been reported elsewhere. Ravindran et al. There were six other siblings who did not play volleyball and did not have the condition, leading Ravindran et al. However, no site of entrapment was suggested. In addition to entrapment syndromes, direct injury to the nerve has been reported to cause rhomboid paralysis.

Saeed et al. In addition, anterior shoulder dislocation can also cause direct injury to the dorsal scapular nerve, as reported in a Judo player who developed extreme instability of the glenohumeral joint, resulting in six dislocations in 2 weeks [ 21 ]. A C5 radiculopathy has also been suggested as a causative factor [ 34 ].

Finally, muscle injury during overhead athletics has been implicated as well, as the deceleration of the scapula during the follow-through motion of a pitcher or volleyball player can strain and injure the rhomboids [ 20 ].

Although primarily due to serratus anterior palsy, and less frequently trapezius and rhomboid palsy, these are not the only conditions that present with scapular winging. Rhomboid and trapezius muscle rupture [ 61 ] and other direct injuries to scapulothoracic muscles [ 62 ] can also cause scapular winging. Structural abnormalities can also present similarly and include rotator cuff pathology, shoulder instability, mal-united acromial fractures, aseptic necrosis of the humeral head, fibrotic shortening of the middle and posterior deltoid, and acromegalic arthropathy of the shoulder [ 4 , 5 , 62 ].

Purported by Wiater and Bigliani [ 7 ] and Wiater and Flatow [ 8 ], the physician evaluation should include a detailed history including questions regarding hand dominance, occupation, hobbies, and current and previous level of function, answers to which will dictate the use of conservative or surgical treatment. In cases of traumatic etiology, the exact mechanism of injury should be elucidated, along with a history of surgery of the neck, shoulder, thorax, or axilla, and recent illness and immunizations [ 7 , 8 ].

Key features of the physical exam relating to winging due to serratus anterior, trapezius, or rhomboid palsy is outlined in Table 1. The typical patient suffering from serratus anterior palsy will present with pain around the affected shoulder usually the right side , which either arises spontaneously or linked to some traumatic event [ 4 , 11 ]. This pain may radiate down the arm and to the scapula [ 3 ].

Pain in the shoulder is usually localized to the rhomboid and levator scapulae muscles due to spasm secondary to unopposed contraction in the absence of serratus anterior tone [ 8 ]. In addition, patients will typically complain of shoulder weakness [ 8 ], while athletes may complain of reduced performance [ 4 ]. Severe pain should raise suspicion of a neuritis, such as Parsonage—Turner syndrome [ 8 ].

In one series of 14 patients with traumatic lesions, pain was localized to the lower pole of the scapula immediately after injury and was described as having a burning quality [ 9 ].

The authors of that study consider this to be a strong diagnostic clue and advocate asking all patients with shoulder weakness after sustaining an injury specifically if they have such a burning pain. Typically, the pain usually resolves spontaneously over the next several weeks, but the patient is left with a winged scapula that is noticed by others or is occasionally felt while sitting in a chair [ 4 , 11 ].

Upon physical examination, classical or medial scapular winging is usually evident at rest, with the medial and inferior borders closer to the spine and lifted superiorly when compared to the normal side [ 4 , 63 ].

Scapular winging can be accentuated when the patient is asked to forward flex his arms to the horizontal Fig. In this position, the vertebral border of the scapula lifts further from the thoracic wall due to the loss of serratus anterior scapular protraction. In addition, because the scapula cannot be stabilized against the thorax, forward flexion of the arm past the horizontal may be limited or impossible [ 4 , 8 , 63 ]. Winging of the right scapula due to serratus anterior palsy, accentuated by active flexion of the arms.

In addition to the medial border lifting off the posterior thoracic wall, note the medial and superior translation of the right scapula when compared to the normal left side [ 83 , Fig. As summarized nicely by Wiater and Flatow [ 8 ], more common diseases may mimic serratus anterior palsy and lead to initial misdiagnosis.

They cite examples of rotator cuff tear, fracture malunion, trapezius palsy, glenohumeral instability, impingement, acromioclavicular joint disease, biceps tendonitis, neurologic disorders, suprascapular nerve entrapment, scoliosis, and scapular osteochondroma. In previous reports, such misdiagnoses have led to 17 surgical procedures to be performed on five patients without improvement of symptoms [ 63 ] and a diagnostic delay in 10 of 14 patients [ 9 ].

Typical presentation includes stiffness, pain, and weakness of the shoulder girdle, especially with overhead activity and upon prolonged exertion [ 7 , 15 ]. Pain can be quite debilitating and can be the result of the strain and spasm of overcompensating periscapular muscles [ 7 , 12 , 15 ]. Patients may complain of a dull ache and heaviness around the shoulder [ 12 , 15 ] and may describe the feeling as having a brick on the shoulder [ 15 ].

Trapezius paralysis and subsequent deficient rotation of the scapula may also cause pain associated with subacromioclavicular impingement [ 7 , 12 , 15 ]. Consistently, patients are limited in all overhead activities [ 7 , 12 , 15 ]. Physical examination elicits an asymmetrical neckline with drooping of the effected shoulder. This may be accompanied with lateral displacement and winging of the scapula [ 12 , 15 , 16 ]. Typically, winging is minimal and is accentuated during arm abduction, with the scapula moving upwards with the superior angle more lateral to the midline than the inferior angle [ 5 ].

Winging may disappear during forward flexion of the arm due to the action of the serratus anterior muscle [ 5 ]. Chan et al. Any medial winging of the scapula is indicative of accessory nerve palsy Fig. A patient with pronounced winging of the left scapula during active external rotation against resistance, typical of trapezius palsy.

Note the lateral displacement of the scapula with the superior angle more lateral to the midline than the inferior angle [ 64 , Fig. Identification of trapezius palsy is not straight forward, and like serratus anterior paralysis, is easily misdiagnosed.

Wiater and Bigliani [ 7 ] summarize conditions with signs and symptoms that are similar to trapezius palsy and include paralysis of the rhomboid and serratus anterior muscles, herniated nucleus pulposus, scoliosis, progressive neuromuscular disease, scapular osteochondroma, fracture mal-union, stroke, herpes zoster infection, and glenohumeral instability. Other misdiagnoses include thoracic outlet syndrome, subacromial impingement, and pain about the shoulder [ 15 ].

The typical patient will present with pain down the medial aspect of the scapula [ 5 , 34 , 65 ], with pain sometimes radiating down the arm to the C5 and C6 dermatomes [ 48 , 49 , 65 ]. The patient may also suggest a feeling of abnormal shoulder motion [ 22 ] or traction [ 49 ] when raising the effected arm.

In the only published cohort of patients with dorsal scapular nerve palsy, Desong et al. In addition, neck pain was often aggravated by changes in the weather, and insomnia was common due to shoulder discomfort [ 49 ]. Symptoms were unilateral in 34 of 36 patients, and there was a preponderance of females, 28 in all [ 49 ]. Upon examination, rhomboid palsy produces a very subtle winging of the scapula, with the scapula laterally translated and the inferior angle rotated laterally [ 5 , 34 , 38 ].

Winging may be accentuated by having the patient extend his or her arm from a fully flexed position, during which the inferior angle of the scapula is pulled laterally and dorsally off the thoracic wall [ 5 , 34 ]. If allowed to progress, atrophy of the rhomboids may be evident [ 5 , 21 , 39 ]. Weakness of the rhomboids can be tested by having the patient try to bring his or her scapulas together medially [ 22 ], or by having the patient push his or her elbows backwards against resistance with hands on hips [ 34 , 47 ].

Difficulty with either task suggests weakness of the rhomboids, but this may be masked by trapezius hypertrophy [ 21 ]. Due to the rhomboids anatomical position deep to the trapezius muscle and the subtleness of the scapular winging, rhomboid paralysis is a difficult diagnosis. In the cohort of Desong et al. This difficulty has led some authors to suggest dorsal scapular nerve palsy to be an under-diagnosed cause of shoulder pain [ 22 , 50 , 65 ].

Currently, electromyographic testing is the only definitive diagnostic test for serratus anterior, trapezius, and rhomboid muscle paralysis, and is essential for determining which muscle is involved and to what degree of denervation [ 29 , 35 , 37 , 66 ].

Electromyographic testing typically shows resting denervation potentials, decreased motor unit recruitment and polyphasic motor unit potentials during volitional activity [ 4 , 5 , 13 , 21 , 22 , 26 , 28 , 29 , 34 , 35 , 37 , 39 , 40 , 42 , 43 , 48 , 53 , 59 , 65 , 66 ].

Although diagnostically helpful in determining muscle involvement and detecting improvement and reinnervation, the initial degree of denervation cannot be used to predict the extent of recovery [ 28 , 66 ]. Improvement over time on serial electromyographic examination may [ 35 ] or may not [ 66 ] correlate with clinical outcome.

Nerve conduction studies of the long thoracic nerve may also be helpful in determining the severity of the lesion [ 30 , 67 ]. Plain radiographs of the neck, chest, shoulder, and thoracic inlet are rarely diagnostic, but should be obtained to rule out structural abnormalities such as mal-united or greenstick fractures [ 7 , 8 , 11 , 61 , 68 ].

Computed tomography CT and magnetic resonant imaging MRI are rarely needed, but may be useful to rule out other diagnoses, such as neurofibromatous-related injury [ 37 ], disk disease and radiculopathy [ 52 ], and mass lesions [ 7 , 8 ]. Isolated serratus anterior palsy responds well to conservative treatment, with most cases functionally resolving within 1—24 months [ 3 , 4 , 9 , 11 , 13 , 24 , 25 , 28 , 35 , 57 , 63 , 69 ]. Mild deficits in endurance functioning and asymptomatic scapular winging may persist after functional recovery [ 4 , 11 ].

The skeletal muscles of the abdomen form part of the abdominal wall, which holds and protects the gastrointestinal system. Five muscles form the abdominal wall, divided into vertical and flat groups. The flat muscles act to flex, laterally flex, and rotate the trunk.

The fibers run in different directions and cross each other, strengthening the abdominal wall. The vertical muscles aid in compressing the abdominal cavity, stabilizing the pelvis, and depressing the ribs when a person is walking. Toward the midline, the muscles form aponeuroses, which merge into the linea alba.

Location of the external obliques : Highlighted in orange, the external obliques lie inferior to the pectoral muscles. Muscles of the posterior portion of the trunk include muscles of the back, suboccipital region, and perineum region. The posterior or back muscles perform a wide range of functions, including movement of the shoulder, head, and neck and assisting in respiration, posture, and balance. Posterior muscles are split into three groups depending on their physiological location.

Location of the latissimus dorsi muscle : Highlighted in orange, the latissimus dorsi is a muscle of the posterior torso. The superficial posterior muscles are associated with movement of the shoulder. As the name suggests, they are the most superficially located of the muscles covering the intermediate and intrinsic layers. The intermediate muscles of the posterior contribute to movements of the ribcage during respiration.

Serratus Posterior Superior — The serratus posterior superior is a thin, rectangular-shaped muscle lying below the rhomboid muscles. Serratus Posterior Inferior : The serratus posterior inferior is a broad muscle lying beneath the latissimus dorsi.

The intrinsic muscles of the posterior are responsible for maintaining posture and facilitating movement of the head and neck. They are divided into three layers. Location of the splenius muscle. Three columnar muscles in the intermediate layer are responsible for flexing and extending the neck as well as maintaining posture.

All three originate from a common tendon associated with the pelvis.