Anatomy, Head and Neck, Levator Scapulae Muscles (2024)

Introduction

The levator scapulae muscles aresuperficial extrinsicmuscles of the back that primarilyfunction to elevate the scapulae. Levator comes from the Latin levare, meaning "to raise." Scapulae refer to thescapulas, or shoulder blades, possibly originatingfrom the Greek "skaptein," meaning "to dig." In conjunction with other posterior axial-appendicular muscles, the levator scapulae can inferiorly rotate the glenoid cavityandextend and laterally flex the neck.The levator scapulae also serve a role in connecting the axial skeletonwith thesuperior appendicular skeleton. The levator scapulae can be involved in numerous pathologies, including snapping scapula syndrome, levator scapulae syndrome, Sprengel deformity, cervical myofascialpain, andfibromyalgia.

Structure and Function

The levator scapulae muscle originates from the posterior tubercles of transverse processes of C1 (atlas), C2 (axis), C3, and C4 vertebrae.[1][2]The muscle inserts on the posterior lip of the medial scapular border, typically between thesuperior angle androot ofthe scapular spine.[3][4]The sternocleidomastoid and trapezius overlay the superior and inferior aspects of the levator scapulae, respectively, with the levator scapulaecomprising part of the floor ofthe posterior triangle of the neck.[5]

The primary action of the levator scapulae is to elevate the scapula. The levator scapulaworks in conjunction with the trapezius and rhomboid muscles to accomplish this motion.The levator scapulae, along with the descending fibersof the trapezius, latissimus dorsi, rhomboids, pectoralis major and minor, and gravity, also inferiorly rotates the scapula, depressing the glenoid cavity.[6][7]The levator scapulae muscle also assists in neck extension, ipsilateral rotation, and lateral flexion.[8]

Embryology

Levator scapulae muscles derivefrom the paraxial mesoderm along with the rhomboid major and minor. Their development is induced by tailbud neuromesodermal progenitors by fibroblast growth factor (FGF) and Wnt signaling.The dorsal scapular nerve derives from the anterior (motor) ramiof C5. The anterior rootforms from the basal plate region of the spinal cord.[9][10]

Anatomic variation of the subclavianartery can be implicated in failedsupraclavicular brachial plexus blocks. Clinicians perform supraclavicularbrachial plexus blocksfor analgesia and anesthesia of the upper limb. Kohli et al. present a case of a variant branch of the subclavian artery visualized on ultrasound, whichis hypothesized to be the dorsal scapular artery, passing through the brachial plexus nerve bundle.[11]

Blood Supply and Lymphatics

Dorsal Scapular Artery

The dorsal scapular artery is the predominant blood supply of the levator scapulae muscle. The origin is currently in dispute in the literature. The origin most frequently cited is the subclavian artery, with the second most common being a branch of the thyrocervical trunk.[12]The transverse cervical artery, a branch of the thyrocervical trunk, divides into the superior and deep branches at the level of the levator scapulae.[6]The deep branch of the transverse cervical artery isalsoknown as the dorsal scapular artery.[13]

Anatomic Variation

Anatomic variation of the subclavianartery has implications for failedsupraclavicular brachial plexus blocks. Supraclavicularbrachial plexus blocks are usefulfor analgesia and anesthesia of the upper limb. Kohli et al. present a case of a variant branch of the subclavian artery visualized on ultrasound. They hypothesized it could be the dorsal scapular artery passing through the brachial plexus nerve bundle.[11]

Lymphatics

Generally, theshoulder bladeis associated with the axillary and supraclavicularlymph nodes. The lymph nodes from the right scapula drain into the right lymphatic duct. The left scapula drains directly into the thoracic duct.[7]

Nerves

Dorsal Scapular Nerve

The innervation of the levator scapulae is typically from the dorsal scapular nerve, or DSN, originatingfrom the C4 and C5 nerve roots. Thisnerve also provides motor innervation to the rhomboids. The DSN arises from the anterior rami of the C5 root, from the upper brachial plexus, and is typically the first nerve branch off the C5 root. Innervation can also be from cervical nerves (C3, C4) via the cervical plexus.[7][14]

Physiologic Variants

There are reports of anatomic variations of the levator scapulae origin and insertion. The clinical implications and significance are not definite.[2][6][15][16][17]

Surgical Considerations

Eden-Lange Procedure

Few surgical procedures primarilyinvolve the levator scapulae. The Eden-Lange procedure, first described in 1924, aims to recreate the functionality lost in trapezius muscle palsy, better known by the eponym "winged scapula." The tendon of the levator scapulae is transferred to the acromion, while the rhomboids areattached to the infraspinatusfossa.[4]

Modified Eden-Lange Procedure

Clinical Significance

Scapulothoracic Articulation

The scapulothoracic articulation is an intricate, sliding junction that composespart of the shoulder in conjunctionwith the glenohumeral, acromioclavicularand coracoclavicular joints. The scapula has a complex anatomical relationship, comprised of 17 muscular attachments that function to dynamically stabilize the scapula and control the position of the glenoid to permit a wide range of motion for the upper extremity through the glenohumeral joint. The scapula does not have anyligamentous connections to the thorax.Due to the complexity of the scapulothoracic articulation,scapulothoracic disorders can be presentand gounderdiagnosed or underestimated because ofthe various and often subtle morphological alterations in normal architecture.[6]

Levator Scapulae Syndrome

The most common clinical manifestation of levator scapulae pathology is levator scapulae syndrome or tendernessover the upper medial angle of the scapula. Though well documented, this condition is often unrecognized. Movements that stretchthe muscle tend to exaggerate symptoms. There is a hypothesis thatconstant trigger points, crepitation, and increased heat emission result from a combination ofanatomic variability and the confluence ofa bursa between theinsertion of the levator scapulae,origin serratus anterior, and the scapula. Effective treatment modalities include physical therapy and/or local corticosteroid injections.[16][20]

Snapping Scapula Syndrome

Significant shoulder dysfunctioncan present as painful crepitus or scapulothoracic bursitis, termed snapping scapula syndrome or "washboard syndrome." This condition commonly manifestssecondary to achronic injury, overuse, or muscle imbalance that impacts the scapulothoracicarticulation. Osseouslesionsat the superomedial angle of the scapula secondary to repetitiveinjury or avulsion of the levator scapulae have also been implicated in the clinical manifestation.[6][21]This condition may be more common in military personnel due to chronic stressand recurrent injury secondary to load-bearing activities of the upper extremity.Treatment is typically conservative, with an 80% success rate.[22]For those that fail conservative treatment, arthroscopic bursectomy with or without partial scapulectomy is the most effective treatment modality.[23][24]

Myofascial Pain

Cervical myofascial pain is a musculoskeletal disorderconsisting of pain attributed to muscles and theirsurrounding fascia. The levator scapulae are one of the most commonly involved muscles in the cervical spine. The etiology of myofascial pain is not completely understood but commonly results from postural mechanics, muscle overuse, trauma, or secondarily to another pathologic condition, such as fibromyalgia or arthropathies of zygapophyseal joints.[25][26] Cervical myofascial pain can be local, regional, or characterized by trigger points. Trigger points are hypersensitiveareas in muscle tissue that elicit pain withmechanical stimulationand can refer pain to surrounding tissue. The levator scapulae is a common location for trigger points and frequently has a tender point associated with the diagnosis of fibromyalgia.[27][28][29]

Other Clinical Considerations

There are also documented cases of active trigger points of the levator scapula with a high prevalence, including those secondary to an acutewhiplash injury.[30]Pain at the insertion site correlates with upper and median cervical spine dysfunction.[31]Varying degrees of levator scapulae atrophy areobservable in patients with Sprengel deformity.[32]

Other Issues

Association with Posterior Triangle of the Neck

The posteriortriangle of the neck, located in the lateral cervical region, is an important anatomic location for surgeons and anesthesiologists. The contents of this anatomic region include the entire brachial plexus, cervical sympathetic ganglions, deep cervical lymph nodes, and the major vascular structures of the neck/upper extremity. Other nerves, such as the spinal accessory, phrenic, vagus, and cutaneous cervical nerves, course through the region. The posterior triangle of the neck forms from thesternocleidomastoid anteriorly, trapezius posteriorly, and clavicle as the base. The levator scapulae form part of the floor along with the splenius, scalenus, and anterior scalene muscles.

The location of the levator scapulae in the posterior triangle of the neck is pivotal whenperforming a cervical paravertebral block of the brachial or cervical plexuses utilizinga posterior approach. In the posterior approach to the brachial or cervical plexuses, a muscle-sparing needle trajectory is optimal to decrease pain and soft tissue injury associated with the procedure. The needle insertion can be between the levator scapula and trapezius muscles.[5][33]

Medial Angle

The angle at the medial border, or spinovertebral angle, represents the insertion site of the levator scapulae. Research has noted that the right spinovertebral angle is greaterthan the left, and alteration of the angle may result inlevator scapulae pathology from a directional change of the insertion site, possibly manifesting as neck stiffness.[3]

Review Questions

Figure

Neck Muscles. This lateral-view illustration showsthe trapezius, sternocleidomastoideus, sternohyoideus, omohyoideus belly, scalenus anterior and medius, levator scapulae, splenius, mylohyoideus,thyrohyoideus, digastricus, and stylohyoideus (more...)

Figure

Muscles connecting the upper extremity to the vertebral column, Occipital Bone, Superior Nuchal Line, Sternocleidomastoid, Ligamentum Nuchae, Splenius Capitis of Cervicis, Levator Scapula (highlighted), Rhomboideus Minor and Major, Spine of Scapula, Trapezius, (more...)

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: Disclosure: James Henry declares no relevant financial relationships with ineligible companies.
: Disclosure: Sunil Munakomi declares no relevant financial relationships with ineligible companies.