The integrated roles of longus colli and sternocleidomastoid muscles: An electromyographic study

Abstract

Using bipolar fine-wire electrodes, we examined the right and left longus colli (LC ) and sternocleidomastoideus ( StM) muscles electromyographically in ten healthy young adults. Action potentials were recorded on FM magnetic tape and each experiment was also videotaped. The head-neck motions were recorded using a special neck goniometer. The muscles were studied in sitting, supine, prone and lateral positions, both during free movements and against resistance. There was complete inactivity in both muscles in relaxed sitting, normal breathing, deep expiration, and wet and dry swallowing. There was very marked synchronous EMG activity of the LC and StM muscles during resisted forward flexion, marked activity during neck flexion against head weight in the supine position, and during resisted right and left side-bending. Variable activity was found in both muscles during deep breathing, coughing, forceful blowing, loading on top of the head, resisted backward extension, neck holding against head weight in the prone position and in twisting movements downwards and upwards. During free flexion-extension movements, LC and StM act synchronously. During free lateral bending they work homolaterally, but during free rotation to the right, the right LC works with the left StM and vice versa.

Neural Substrates for Head Movements in Humans: A Functional Magnetic Resonance Imaging Study

“…Because the presence or absence of actual movements could not be verified visually during scanning, compliance with isometric tasks during practice and scanning was confirmed by surface electromyography (EMG) of the sternocleidomastoid and the extensor carpi ulnaris muscles bilaterally. The sternocleidomastoid is an agonist in contralateral horizontal rotation of the head and it is active during contralateral isometric head rotation (Vitti et al, 1973). The extensor carpi ulnaris is involved in wrist extension and is active in ipsilateral isometric wrist extension (Divekar and John, 2013).…”

“…Anatomic 3D images were processed, coregistered with the functional data, and transformed into Talairach space (Talairach and Tournoux, 1988). For group analyses, the data were spatially smoothed with an isotropic Gaussian kernel (full-width half-maximum 4 mm) (White et al, 2001) and normalized across runs and subjects with the percent signal change transformation. BOLD signal time courses were obtained by averaging individual data points across blocks of the same type and then averaging across participants.…”

Muscle Functional MRI as an Imaging Tool to Evaluate Muscle Activity

“…Accordingly, mfMRI has gained popularity in studies evaluating muscle function, including deep paraspinal muscles 9,10,15,20,25,42 that were previously difficult to achieve and not without some risk with invasive EMG. 26,27,34,46,60 …”

Do longus capitis and colli really stabilise the cervical spine? A study of their fascicular anatomy and peak force capabilities

“…It is an apparent contradiction that the longus muscles are capable of only small peak forces, yet are considered important during voluntary movement in biomechanical (Winters and Peles, 1990), EMG (Conley et al, 1995, Falla et al, 2003, Fountain et al, 1966, Vitti et al, 1973, and histological study (Boyd-Clark et al, 2001, Cornwall and Kennedy, 2015, Miller et al, 2016. This may be explained by the mechanics of the upright position: the head-neck complex behaves like a well-balanced inverted pendulum, with the centre of mass of the head lying anterior to the neck (Winters and Peles, 1990).…”

“…How this flexion force might affect the individual motion segments is not clear. Fundamental electromyographic (EMG) studies of longus colli function indicate it is inactive at rest, and most active during voluntary movements (Fountain et al, 1966, Vitti et al, 1973, findings which are generally supported by more modern methods (Conley et al, 1995, Falla et al, 2003.…”