trapezius

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tra·pe·zi·us (mus·cle)

[TA]
extrinsic (thoracoappendicular) muscle of shoulder; origin, medial third of superior nuchal line, external occipital protuberance, ligamentum nuchae, spinous processes of seventh cervical and the thoracic vertebrae and corresponding supraspinous ligaments; insertion, lateral third of posterior surface of clavicle, anterior side of acromion, and upper and medial border of the spine of the scapula; action, when scapulae are fixed, portions of muscle can act independently: cervical portion elevates scapula, thoracic portion contributes to depression of scapula; upper and lowermost portions act simultaneously to rotate glenoid fossa superiorly; when the entire muscle and especially middle part contracts, the scapulae retract; draws head to one side or backward; nerve supply, motor by accessory, sensory by cervical plexus.
Synonym(s): musculus trapezius [TA], cowl muscle

trapezius

(trə-pē′zē-əs)
n. pl. trapezi·uses
Either of two large flat triangular muscles running from the base of the occiput to the middle of the back that support and make it possible to raise the head and shoulders.

trapezius

[trəpē′zē·əs]
Etymology: Gk, trapezion, small table
a large, flat, triangular superficial muscle of the shoulder and upper back. It arises from the occipital bone, the ligamentum nuchae, and the spinous processes of the seventh cervical and all the thoracic vertebrae. It acts to rotate the scapula upward; adduct, raise, or lower the shoulder; and retract the shoulder.
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Trapezius

tra·pe·zi·us mu·scle

(tră-pē'zē-ŭs mŭs'ĕl)
Origin, medial third of superior nuchal line, external occipital protuberance, ligamentum nuchae, spinous processes of seventh cervical and the thoracic vertebrae and corresponding supraspinous ligaments; insertion, lateral third of posterior surface of clavicle, anterior side of acromion, and upper and medial border of the spine of the scapula; action, when scapulae are fixed, portions of muscle can act independently: cervical portion elevates scapula, thoracic portion contributes to depression of scapula; upper and lowermost portions act simultaneously to rotate glenoid fossa superiorly; when the entire muscle and especially its middle part contracts, the scapulae retract; draws head to one side or backward; nerve supply, motor by accessory, sensory by cervical plexus.
Synonym(s): musculus trapezius [TA] , trapezius.
Figure 1: Efferent nerve pathways from the brainstem and spinal cord. Shown on the right: somatic, to skeletal muscles. Shown on the left: autonomic. B brain stem, C cervical, T thoracic, L lumbar, S sacral segments of the spinal cord. (Red shaded regions are those with no autonomic outflow.)

trapezius

large, triangular, superficial muscle on each side of the upper back, its origin extending in the midline from the base of the skull down to the spine of the lowest thoracic vertebra. From there its fibres converge towards the shoulder, and partly over it, round the side of the lower neck, to be inserted in a continuous line into the outer end of the clavicle and the spine of the scapula. The tone of the two muscles keeps the shoulders braced and they act with the scapular spine as a lever when lifting the arms at the shoulder. Figure 1.
References in periodicals archive ?
Here, we report four unusual cases of isolated accessory nerve palsy and paralysis of the trapezius muscle.
Muscle strength tests showed moderate weakness of all three segments of the right trapezius muscle (Figure 1a, b).
Recordings were made from all three segments of the trapezius muscle with a bar electrode with surface discs 2.
Needle EMG revealed abnormal spontaneous activity (positive sharp waves-PSW, fibrillation potentials) and markedly reduced recruitment of motor units from all segments of the trapezius muscle.
EMG examination of the upper segment of the trapezius muscle revealed reduced recruitment of motor units, increased polyphasia, and occurrence of mild PSWs and fibrillation potentials.
Medical examination revealed left shoulder drooping and atrophy of all segments of the trapezius muscle.
The amplitudes of CMAPs recorded from the upper and the lower segments of the right trapezius muscle were decreased.
Electrophysiological tests showed that the amplitudes of CMAPs from both upper and middle segments of the trapezius muscle were increased, but still lower than those in the right side.
Clinical parameters of the shoulder-girdle mechanism that can be measured are shoulder shrug weakness, limitations in shoulder-abduction and/or shoulder-flexion active range of motion, scapular winging at rest, and pain, typically in a characteristic location across the upper border of the trapezius muscle.
The trapezius muscle has upper, middle, and lower parts.
Innervation of the trapezius muscle by the intra-operative measurement of motor action potentials.
Utilization of intraoperative electroneurography to understand the innervation of the trapezius muscle.