Recommendations for sensor locations in shoulder or neck muscles
Muscle

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Name
Trapezius
Subdivision
Trapezius Descendens (upper)
Muscle Anatomy
Origin
External occipital protuberance, medial 1/3 of superior nuchal line, ligamentum nuchae, and spinous process of 7th cervical vertebra.
Insertion
Lateral 13 of clavicle and acromion process of scapula.
Function
With the origin fixed: stabilisation (together with descending fibres) of the adduction of the scapula (performed chiefly by the transversal fibres).
Rotation of the scapula so the glenoid cavity faces cranially (performed together with the descending fibres with stabilisation by the transversal fibres).
In addition the descending fibres elevate the scapula. With the insertion fixed and acting unilaterally the descending fibres extend, laterally flex and rotate the head and joints of the cervical vertebrae so that the face turns towards the opposite side. With the insertion fixed and acting bilaterally the descending trapezius extends the head and neck.
Recommended sensor placement procedure
Starting posture
Erect sitting, with the arms hanging vertically.
Electrode size
Maximum size in the direction of the muscle fibers: 10 mm.
Electrode distance
20 mm
Electrode placement
- location
The electrodes need to be placed at 50% on the line from the acromion to the spine on vertebra C7.
- orientation
In the direction of the line between the acromion and the spine on vertebra C7.
- fixation on the skin
(Double sided) tape / rings.
- reference electrode
On the proc. spin. of C7 or on / around the wrist.
Clinical test
Elevate the acromial end of the clavicule and scapula; extend and rotate the head and neck toward the elevated shoulder with the face rotated in the opposite direction. Apply pressure against the shoulder in the direction of depression and against the head in the direction of flexion anterolaterally.
Remarks
The SENIAM guidelines include a separate sensor placement procedure for the trapezius ascendens and the trapezius transversalis muscle.