The role of sternocleidomastoid muscle in simulated low velocity rear-end impacts

Hernández, Ivonne A.; Fyfe, K.R.; Heo, Giseon; Major, Paul W.

doi:10.1007/s00586-005-0956-9

Cited by 9 publications

(4 citation statements)

References 20 publications

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“…Our peak head angles (4.8 ± 1.3 deg; range 1.8–8.3 deg) were well below those reported for Vibert's fore/aft perturbations (12.5 ± 8.7 deg; range 3.6–33.5 deg). Our lack of floppy responses was in keeping with other neuromuscular studies of seated perturbations with eyes open (Ono & Kanno, 1996; Castro et al 1997; Magnusson et al 1999; Brault et al 2000; Siegmund et al 2002, 2004; Blouin et al 2006 a ; Hernández et al 2006) and suggested that the floppy responses of some subjects could be related to the vision condition. This was confirmed in a follow‐up experiment wherein two subjects had larger, floppy‐like peak head angles in the eyes closed condition while exhibiting stiff responses in the eyes open condition (see two pairs of connected dots in Fig.…”

Section: Discussionsupporting

confidence: 91%

“…(2001, 2006) found that the head extension angles of their floppy subjects halved when they were asked to focus on an imaginary target either fixed in space or fixed to the sled on which they were seated. These findings suggest that an external reference frame – either imagined with eyes closed or present by default with eyes open – alters the neuromuscular and kinematic responses of the head and neck and explains the absence of floppy responses in not only our eyes‐open experiments, but also in previous studies conducted with eyes open (Ono & Kanno, 1996; Castro et al 1997; Magnusson et al 1999; Brault et al 2000; Siegmund et al 2002; 2004; Blouin et al 2006 a ; Hernández et al 2006).…”

Section: Discussionsupporting

confidence: 66%

“…(2001). Floppy responses have not been reported in other studies using seated human subjects (Ono & Kanno, 1996; Castro et al 1997; Magnusson et al 1999; Brault et al 2000; Kumar et al 2000, 2002; Siegmund et al 2002, 2004; Blouin et al 2006 a ; Hernández et al 2006) and therefore replication of this floppy behaviour is an important step in establishing jerk's role in whiplash injury. Second, we independently varied perturbation jerk and acceleration to investigate their effects on the neck muscles and head kinematics of seated subjects under conditions mimicking the onset of actual low‐speed vehicle collisions.…”

Section: Sled Pulse Characteristics Used In Previous Studies Of the Nmentioning

confidence: 87%

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Head and neck control varies with perturbation acceleration but not jerk: implications for whiplash injuries

Siegmund

Blouin

2009

The Journal of Physiology

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Recent studies have proposed that a high rate of acceleration onset, i.e. high jerk, during a low-speed vehicle collision increases the risk of whiplash injury by triggering inappropriate muscle responses and/or increasing peak head acceleration. Our goal was to test these proposed mechanisms at realistic jerk levels and then to determine how collision jerk affects the potential for whiplash injuries. Twenty-three seated volunteers (8 F, 15 M) were exposed to multiple experiments involving perturbations simulating the onset of a vehicle collision in eyes open and eyes closed conditions. In the first experiment, subjects experienced five forward and five rearward perturbations to look for the inappropriate muscle responses and 'floppy' head kinematics previously attributed to high jerk perturbations. In the second experiment, we independently varied the jerk (∼125 to 3 000 m s −3 ) and acceleration (∼0.65 to 2.6 g) of the perturbation to assess their effect on the electromyographic (EMG) responses of the sternocleidomastoid (SCM), scalene (SCAL) and cervical paraspinal (PARA) muscles and the kinematic responses of the head and neck. In the first experiment, we found neither inappropriate muscle responses nor floppy head kinematics when subjects had their eyes open, but observed two subjects with floppy head kinematics with eyes closed. In the second experiment, we found that about 70% of the variations in the SCM and SCAL responses and about 95% of the variations in head/neck kinematics were explained by changes in perturbation acceleration in both the eyes open and eyes closed conditions. Less than 2% of the variation in the muscle and kinematic responses was explained by changes in perturbation jerk and, where significant, response amplitudes diminished with increasing jerk. Based on these findings, collision jerk appears to have little or no role in the genesis of whiplash injuries in low-speed vehicle crashes.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 66%

Section: Sled Pulse Characteristics Used In Previous Studies Of the Nmentioning

confidence: 87%

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Head and neck control varies with perturbation acceleration but not jerk: implications for whiplash injuries

Siegmund

Blouin

2009

The Journal of Physiology

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“…Several injury mechanisms have been proposed for whiplash injuries, with neck muscles being both a potential site of injury and a potential contributor to other neck tissue injuries (40). Neck muscle activity begins about 50 -100 ms after vehicle acceleration onset (4,10,15,19,22,27,39,47), early enough to influence peak head and neck kinematics (4,39). Moreover, the time period over which the neck muscles are active overlaps the time period during which peak acceleration and displacement of the head and neck occur (10,34).…”

mentioning

confidence: 99%

The startle response during whiplash: a protective or harmful response?

Mang

Siegmund

Inglis

et al. 2012

Journal of Applied Physiology

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Whiplash injuries are common following rear-end collisions. During such collisions, initially relaxed occupants exhibit brisk, stereotypical muscle responses consisting of postural and startle responses that may contribute to the injury. Using prestimulus inhibition, we sought to determine if the startle response elicited during a rear-end collision contributes to head stabilization or represents a potentially harmful overreaction of the body. Three experiments were performed. In the first two experiments, two groups of 14 subjects were exposed to loud tones (124 dB) preceded by prestimulus tones at either four interstimulus intervals (100-1,000 ms) or five prestimulus intensities (80-124 dB). On the basis of the results of the first two experiments, 20 subjects were exposed to a simulated rear-end collision (peak sled acceleration = 2 g; speed change = 0.75 m/s) preceded by one of the following: no prestimulus tone, a weak tone (85 dB), or a loud tone (105 dB). The prestimulus tones were presented 250 ms before sled acceleration onset. The loud prestimulus tone decreased the amplitude of the sternocleidomastoid (16%) and cervical paraspinal (29%) muscles, and key peak kinematics: head retraction (17%), horizontal head acceleration (23%), and head angular acceleration in extension (23%). No changes in muscle amplitude or kinematics occurred for the weak prestimulus. The reduced muscle and kinematic responses observed with loud tones suggest that the startle response represents an overreaction that increases the kinematics in a way that potentially increases the forces and strains in the neck tissues. We propose that minimizing this overreaction during a car collision may decrease the risk of whiplash injuries.

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Effect of muscle activation on dynamic responses of neck of pilot during emergency ejection: a finite element study

Liu

et al. 2023

Med Biol Eng Comput

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The role of sternocleidomastoid muscle in simulated low velocity rear-end impacts

Cited by 9 publications

References 20 publications

Head and neck control varies with perturbation acceleration but not jerk: implications for whiplash injuries

Head and neck control varies with perturbation acceleration but not jerk: implications for whiplash injuries

The startle response during whiplash: a protective or harmful response?

Effect of muscle activation on dynamic responses of neck of pilot during emergency ejection: a finite element study

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