[Relation between neck accessory inspiratory muscle electromyographic activity and lung volume]

Area of Science:

• Respiratory Physiology
• Electromyography (EMG)
• Muscle Activity

Context:

• The relationship between lung volume and respiratory muscle EMG activity is not fully understood.
• Previous research indicated a link between lung volume and scalene muscle EMG.
• Neck accessory muscles play a role in respiration, particularly at higher lung volumes.

Purpose:

• To define the relationship between changing lung volume and the EMG activity of neck accessory inspiratory muscles.
• To quantify the onset and maximal EMG activity of scalene, sternocleidomastoid, and trapezius muscles during inspiration.
• To determine the lung volume dependency of EMG activity in these muscles.

Summary:

• Scalene (SCLN), sternocleidomastoid (STERNO), and trapezius (TRAPEZ) muscles' EMG activity was measured during inspiration in healthy subjects using ultrasound-guided fine wire electrodes.
• The relationship between EMG and lung volume followed exponential curves for SCLN, but not for STERNO or TRAPEZ.
• SCLN demonstrated the earliest onset and highest activity at total lung capacity, indicating it is the most active neck accessory inspiratory muscle, followed by STERNO, and then TRAPEZ.

Impact:

• This study clarifies the distinct roles and activation patterns of neck accessory muscles during breathing.
• Findings highlight the lung volume dependency of EMG activity in these muscles.
• Provides crucial data for understanding respiratory mechanics and potential dysfunction in respiratory disorders.