The right & left trapezius together form a trapezium (Diamond shape) that covers the upper half of the back.

ORIGIN:

Upper fibres of the trapezius- C7 spinous process, External occipital protuberance, medial third of the superior nuchal line of the occipital bone & ligamentum nuchae.

Middle fibres of the trapezius- C7 spinous process, T1,T2 & T3 spinous process, corresponding supraspinous ligaments.

Lower fibres of the trapezius- T4-T12 spinous process & corresponding supraspinous ligaments.

INSERTION:

Upper fibres of the trapezius- after originating, the fibres run downward & laterally to insert into posterior border of the lateral one-third of the clavicle.

Middle fibres of the trapezius- medial border of the acromion & superior lip of the posterior border (crest) of the spine of the scapula.

Lower fibres of the trapezius- after originating, the fibres run upward & laterally to converge near scapula & end in aponeurosis overdeltoid tubercle(apex of triangular surface) at the medial end of the spine with the bursa intervening.

INNERVATION:  Spinal accessory nerve & Proprioceptive fibres from vental rami of C3 & C4.

BLOOD SUPPLY: Superficial branch of transverse cervical artery or superficial cervical artery

ACTIONS:

Trapezius causes movement at the spine as well as at the scapula. It produces movement at scapula when the spinal origins are stable and it produces movement at the spine when scapula is stable. Its main function is to stabilize and move the scapula. For the movement at the head and neck it needs to keep the scapular attachment stable.
Trapezius produces actions either by contracting bilaterally or unilaterally. Its fibres also have different actions as they run in different directions. However during the functional movements, each of these fibres needs to work in coordination to produce a smooth action.

Palpation:

Upper Trapezius: The upper trap may be palpated from the base of the skull to the base of the neck and across the top of the shoulder girdle.

Position : Lying  in prone, gently squeeze the most superficial layer of muscle at the upper cervical spine. Ask the patient to  lift their head – you  feel the density of this layer quickly increase as the upper trap contracts – follow those same fibers down across the top of the scapula.

Gently elevate and relax their shoulder girdle as you palpate may help you trace the fibers from the base of the neck to lateral clavicle .

Note: if you feel too deep when palpating the traps at the cervical spine you will be palpating the splenii. These muscles are easy to identify, they feel like two near-vertical bars or cylinders of muscle. They course up and down the back of the neck, they  do not course over the shoulder girdle.

• Middle Trapezius:

prone postion , palpate the spine of the scapula. Move your hand medial to the spine of the scapula; asking your patient  to retraction which lead to pop the middle trapezius into your fingers. Remember these are superficial fibers.

• Lower Trapezius:

Prone position , Palpate the lateral border of the very superficial lower trap with your partner in prone . You may be able to get your fingers underneath the lower trap and gently lift it from underlying musculature.

If you are facing  a difficulty in palpating lower trapezius then do lower trapezius manual muscle test (MMT)) – this should result in a strong contraction of muscle. Make sure to palpate the border of the lower trapezius all the way to its origin on the spinous process of T12.

Integrated Function:

• Stabilization: AC Joint reinforcement of the acromioclavicular ligament, stabilization of the scapula .

• Eccentrically Decelerates: the trapezius muscle may eccentrically decelerate protraction and upward rotation. In addition to that ,the lower trap may eccentrically decelerate elevation and anterior tipping, and the upper trap may decelerate depression and posterior tipping.

 

Scapular movements:-

Upper fibres elevate the scapula: as in shrugging the shoulder
Middle fibres retract the scapula.
Lower fibres along with upper fibres rotate the scapula around the sternoclavicular joint so that the acromion & inferior angles move up & medial border moves down (Upward rotation of scapula).

Spinal movements:-

When the scapulae are stable, trapezius on both the sides co-contract together to produce neck extension.
When it contracts unilaterally, it causes ipsilateral lateral flexion and contralateral rotation of the neck.

Synergists:

Upper fibres act with the levator scapulae during scapular elevation
Middle fibres act with the rhomboids to retract the scapula
Lower fibres along with upper fibres & serratus anterior rotate the scapula forwards round the chest wall (protraction/ internal rotation) thus playing an important role in abduction of the shoulder beyond 90°.
Antagonists:
Lattisimus dorsi depresses the shoulder which is opposite to the elevation action of the upper trapezius.
Levator scapula & Rhomboids rotate the scapula downwards- opposite to the action of upper & lower fibres of trapezius.

Upper fibres & lower fibres of trapezius work along with the serratus anterior in order to produce a smooth overhead shoulder motion- flexion and abduction.  This happens as a result of inferior pulling of medial border of scapula by lower fibres of trapezius, elevation movement by upper trapezius and lateral & forward movement by the serratus anterior. It is found on EMG analysis that Trapezius activity rises linearly to 180° in abduction while serratus anterior activity rises in flexion.

 

Fascial integration:

The trapezius muscle is connected to the bone by a thin fibrous lamina and firmly adherent to the skin at its occipital origin. In the middle the muscle is connected by a broad semi-elliptical aponeurosis to spinous process of C6-T3 and forms a tendinous ellipse with the opposite muscle.

The superficial & deep epimysia are continuous with an investing layer of deep cervical fascia, which is the most superficial part of deep cervical fascia that encircles the whole neck.

It surrounds the neck like a collar and splits around the sternocleidomastoid muscle and the trapezius muscle.
It is attached posteriorly to ligamentum nuchae, anteriorly to hyoid bone, superiorly to external occipital protuberance, superior nuchal line, mastoid process, external acoustic meatus, lower margin of zygomatic arch & body of mandible from angle of mandible to symphysis menti and inferiorly to spine & acromial process, upper surface of clavicle & suprasternal notch of manubrium sterni.

When the fascia is traced forward from ligamentum nuchae, it splits and encloses trapezius, reunites and forms roof of posterior triangle of neck and again splits to enclose sternocleidomastoid and reunites again to forms roof of anterior triangle of neck.

Superiorly it splits to enclose submandibular gland and parotid gland & inferiorly it splits to enclose suprasternal space and supraclavicular space.

The Myofascial line- the Superficial Back Arm Line begins with the wide sweep of the trapezius’s axial attachments, from the occipital ridge through the spinous process of T12. These fibres converge toward the spine of scapula, the acromion of the scapula and lateral third of the clavicle.

In fact, the specific connections here are interesting: the thoracic fibers of the trapezius link roughly with the posterior fibers of the deltoid; the cervical fibers of trapezius link with the middle deltoid; and the occipital fibers of trapezius link to the anterior deltoid.

 

Postural dysfunction:

Upper body posture significantly affects the recruitment of the musculature of shoulder as well as neck region causing some muscles to undergo tightness and some to undergo lengthening resulting into altered biomechanical alignment consequently leading to pain and dysfunction. Similarly shoulder and neck pathologies or trauma may lead to disturbed head, neck and shoulder posture leading to abnormalities & pain.

Poor head and shoulder posture mainly constitutes of forward head posture, poking chin, forward shoulder posture or round back (increased kyphosis). Each of these postures has altered kinetics as well as kinematics.
Thigpen et al, conducted a study on the effect of head and shoulder posture on shoulder and neck biomechanics and found that forward head and forward shoulder posture significantly affects muscle recruitment leading to overuse and overloading of some muscles and inhibited use of some muscles causing altered scapular kinematics.

Trapezius is a large muscle of neck and upper back. Inflammation in any of the bands (Mostly upper) of the muscles fibres is called trapezitis. Constant loading on the muscle can result to stress and strain leading to inflammation and spasm of the muscle, myofascial pain & facet joints locking.

Working in one posture say for example lifting head while working on a computer with improper ergonomic care, reading a book or texting on mobile phones(TEXT NECK) with constant cervical flexion, driving with poked chin or watching television for prolonged period of time can overload the trapezius muscle resulting into protective spasm and thereby inflammation.

Consequently the muscle may undergo tightness and shortening thereby affecting anterior and posterior neck & shoulder musculature. If this isn’t treated at proper time there will be altered neck and scapular kinematics and kinetics leading to upper crossed syndrome.

Upper crossed syndrome is a condition where muscles on one diagonal at a joint become tight and hypertonic whereas on the other diagonal are weak and lengthened.
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Persistent poor upper body posture with repetitive overuse of Trapezius, weak & lengthened lower trapezius, rhomboids, deep neck flexors and serratus anterior puts stress on trapezius to remain contracted. Prolonged contraction causes local ischemic changes in the muscle leading to development of fibrous nodules and thereby triggers points.

 

 

 


Trapezius is also one of the key muscles controlling the position of scapula. Serratus anterior works in coordination with the trapezius and produces smooth arm movements. If any of the 2 muscles is weak or paralyzed, it will result into dynamic winging and affect scapulo-humeral rhythm.

 

When the trapezius is intact & serratus anterior is paralyzed, the scapula elevates & moves medially, with the inferior angle rotating medially. As a result active abduction of arm can occur through its full range but it will be weakened. However flexion will be both diminished in strength and limited in range to 130° or 140° of flexion. Along with this there will be unopposed action to scapular retraction produced by trapezius, and scapular upward rotation will be limited to 20°.

When the serratus anterior is intact & trapezius is paralyzed, the scapula depresses & moves laterally, with inferior angle rotating laterally. As a result, active abduction of the arm is both weakened & limited in range to 0-75°, with the remaining range occurring exclusively on gleno-humeral joint. However flexion will be weakened but range won’t be limited.

CASE STUDY :   A 25 year old right hand dominant male computer engineer 

History :

1)   Pain (VAS=7.6) & discomfort over nape of the neck – 5 days especially in evening or night,

2) Difficulty in flexing the neck and working on computer for long hours. His job profile consists of working on computers for 6-8 hours at a stretch. His chair is ergonomically designed which is good for the low back but the eyes and computer screen are not in one level making him to work constantly in forward head posture. This results into constant stress over the neck musculature.

On observation : 

Swelling  over the right shoulder blade area with neck bit side flexed on right side with scapula in elevation.

On palpation :

There was spasm of right upper fibres of trapezius, with jump sign positive suggestive of development of trigger points. There was grade 1 tenderness over C7 spinous process and right side C6-C7 facet joint.

On examination:

  1.  ROM of cervical flexion (0°- 30°), left lateral flexion (0°- 20°) and right rotation (0°-25°).
  2. There was weakness of right middle & lower fibres of trapezius, rhomboids Grade 4/5 with pain over shoulder blade area, serratus anterior grade 4/5.
  3.  Other muscles on right as well left side were normal and Shoulder ROM was full & pain free.
  4.  Short muscles : Right Upper trapezius, levator scapula
  5. Upper limb sensations and radial pulses were normal. CCFT score was 70/100 suggestive of moderate deep neck flexors endurance. NDI score was 52%.

Provisional diagnosis : Upper cross syndrome with facet arthropathy

Treatment : 
1) MFR  over right upper trapezius.

2) MET for upper trapezius- Reciprocal inhibition,

3) strengthening of middle and lower fibres of trapezius, rhomboids, serratus anterior, and endurance training of    deep neck flexors.

4) Active ROM exercises for neck. With visual biofeedback he was instructed to correct the forward head posture and was advised for chin tucks even at job.

5) Maitland mobilization over facet joint C6-C7.

6) Ergonomic advice

At the end of 1 week there was improvement of VAS score to 4/10 and increase in ROM of around 10° for every limited ROM.

References:

1)  Norkins C, Levangie P. “Joint structure & function.” 4th ed.
2)  Myers T. “Anatomy Trains. Myofascial meridians for movement and manual therapists.” Churchill Livingston.              Second edition.
3) Thigpen CA et al. Head and shoulder posture affect scapular mechanics and muscle activity in overhead tasks. J           Electromyogr Kinesiol (2010)
4) David Magee. “Orthopaedic physical assessment”. 5th ed.
5) Kisner & Colby. Therapeutic exercise. 5th ed.

6)  Trapezius (Image)- Wikipedia
7) www.King of the gym.com (Image)