• Physical Therapy Rehabilitation Science
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• 제6권1호
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• pp.33-38
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• 2017

Objective: This study tried to examine the muscle activity of the neck and trunk according to head posture changes during use of laptops. Design: Cross-sectional study. Methods: This study included nineteen young men and women. All subjects maintained each posture while practice typing on laptops for ten minutes with a 5-minute break between each posture. For the neutral head posture, the subjects practiced typing while pulling their chins down towards the Adam's apple and were able to look at their knees while having their external auditory meatus, acromion, and greater trochanter vertical to the ground. For the natural head posture, they practiced typing while balancing their posture between extension and flexion of the cervical vertebrae by themselves without any guidelines. While a forward head posture was created by having their heads face the front horizontal to the rope hanging from the ceiling, they practiced typing with their external auditory meatus located in the place which was 5 cm in front of the vertical plane. The subjects used general word process but practiced typing with accuracy and high speed. Muscle activities were randomly measured using surface electromyography according to each postures. Results: The research result had found that muscle activity with the natural head posture was more significantly reduced than that of the forward head posture in the sternocleidomastoid muscle, upper trapezius, cervical vertebral spinae, and thoracic vertebrae spinae muscles (p<0.05) and that the neutral head posture was more significantly reduced than that of forward head posture in the upper trapezius, cervical vertebral spinae, and thoracic vertebrae spinae muscle activity (p<0.05) with significant increases in lumbar spinae muscle activity (p<0.05). Also, muscle activity with the neutral head posture significantly increased more in the sternocleidomastoid muscle and lumbar spinae than that of the natural posture (p<0.05). Conclusions: Our study results suggest that in order to prevent musculoskeletal pain, the neutral head posture with use of laptops is effective in reducing load to the shoulders and vitalizing the postural muscles.

• The Journal of Korean Physical Therapy
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• 제25권4호
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• pp.217-223
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• 2013

Purpose: This study was to investigate whether the two different head postures, natural and ideal head posture, affect head/shoulder posture and muscle activity. Methods: Thirty healthy subjects with the forward head and round shoulder posture were participated in this study. This study utilized a within-subjects design with subjects being positioned into two sitting positions: natural head posture (NHP) and ideal head posture (IHP). Forward head angle (FHA) and forward shoulder angle (FSA) of each subject were measured for assessing the head/shoulder posture and muscle activities of upper trapezius (UT), lower trapezius (LT), and serratus anterior (SA) during the forward overhead reaching. Results: There were significant increases in both FHA and FSA after taking IHP, which showed greater angles than in taking NHP. In change of muscle activities, there were significant decreases in both LT and SA after taking IHP, which showed lower activities than in taking a NHP, whereas there was no significant change in UT. Conclusion: These findings demonstrate that postural alterations associated with forward head and rounded shoulder postures could alter scapular kinetics and muscle activity during the forward overhead reaching.

• 대한치과교정학회지
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• 제30권5호
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• pp.543-552
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• 2000

본 연구는 natural head posture(NHP)를 이용하여 정모 두부 방사선 규격사진 촬영시 재현도를 알아보기 위하여 시행되었다. 두개 안면부의 기형이 없는 25세 전후의 성인 남녀 30명을 대상으로 통상적인 방법(술자 유도법)과 NHP에서 Head Posture Aligner를 이용한 방법(HPA법)으로 정모 두부 방사선 사진을 각기 2주 간격으로 촬영한 후 5개의 고경 계측항목과 9개의 폭경 계측항목을 선정하여 t 검정으로 각 계측항목의 재현도를 비교하는 한편, 정모와 측모 두부 방사선 사진으로3차원 상을 합성시 오차의 요인이 되는 두부의 상하회전 정도 차이를 촬영 방법별로 비교 분석하여 다음과 같은 결과를 얻었다. 1. 시간 간격을 두고 술자 유도법으로 2회 촬영한 정모 두부 방사선 사진의 계측치는 모든 고경 계측항목에서 서로 차이를 나타내어 낮은 재현도를 보였다. 2. 시간 간격을 두고 HPA법으로 2회 촬영한 정모 두부 방사선 사진의 계측치는 모든 고경 계측항목에서 통계적으로 유의한 차이를 나타내지 않아 재현도가 높음을 보였다. 3. 폭경 계측항목의 경우 2회 계측치의 차이를 통하여 살펴 본 재현도에서 술자유도법과HPA방법간에 두드러진 차이를 보이지 않았다. 4. 정모 및 측모 두부 방사선사진으로 3차원상을 합성하기 위한 수직적 두부 위치 보정각을 계산한 결과, 술자 유도법의 경우 $2.5^{\circ}$인 반면, HPA법은 $0.8^{\circ}$로 작게 나타났다. 이상의 결과는 정모 두부 방사선 규격 사진 촬영시 두부 위치의 재현도를 증가시키기 위하여 HPA의 사용이 필요함을 시사하였다.

• 대한치과교정학회지
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• 제35권5호
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• pp.341-350
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• 2005

두부방사선규격사진에서는 매 촬영 시마다 두부의 수직적 회전 정도를 일정하게 유지하기 위하여 두부자세의 재현이 필요하다 본 연구는 유도방법에 따른 자연두부자세의 수직적 두부회전 정도의 차이를 비교하고 각 두부자세의 재현성을 평가하기 위하여 시행되었다 20대 성인 남녀 30명을 연구대상으로 하여 head posture aligner를 이용한 방법(HPA법)과 self balance posture를 이용한 방법(SBP법)으로 자연두부자세를 유도하여 측모 및 정모두부방사선규격사진을 각각 한 달 간격으로 촬영한 후, 측모두부방사선규격사진 상에서 유도 방법에 따른 수직적 두부회전 정도의 차이를 비교하는 한편, 측모 및 정모두부방사선규격사진에서 시간 간격을 두고 동일 방법으로 유도하여 촬영한 두 사진 상의 동일 계측항목 간 차이를 비교함으로써 각 두부자세의 유도방법에 대한 재현성을 평가하였다 연구결과 SBP법으로 유도한 자연두부자세는 HPA법에 의해 유도된 자연두부자세보다 평균 $2.79^{\circ}$ 고개를 숙인 자세로 나타났다. 또한 HPA법 또는 SBP법을 이용하여 시간 간격을 두고 각각 2회 촬영한 측모두부방사선규격사진과 정모두부방사선규격사진 상의 계측치는 모든 계측항목에서 통계적으로 유의한 차이를 보이지 않는 것으로 나타났다. 본 연구 결과는 HPA법과 SBP법으로 유도한 자연두부자세가 모두 재현성이 있음을 나타내는 것으로 두부방사선규격사진 촬영 시 재현성을 높이기 위하여 HPA법과 더불어 SBP법도 임상적으로 사용될 수 있음을 시사하였다.

• Journal of Oral Medicine and Pain
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• 제20권2호
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• pp.361-376
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• 1995

The purpose of this study was to investigate the relationship between the head and neck postre and the cervical curvature, especially in forward head postrue(FHP). Sixty patients with craniomandibular disorders and thirty dental students without any signs and symptoms of craniomandibular disordres participated in this study as patient groups and sa control group, respectively. The author evaluated the head and neck posture of all subjects by plumb line and CROM( Cervical Ragne of Motion), and had taken cephaograph in natural head position. On the cephalograph the angle of cervical inclination formed by true horizntal plane and 4th cervical vertebra(C4) and the radius of cervical curvature from C1 to C5 were measured. A specially designed ruler was used for measuring cervical curvature. Occlusal contac number and force with T-scan system, electromygraphic activity of cervical muscles with Bio-EMG, and distance of freeway space with Bio-ECN were recorded, respectively. The collected data were processed by SAS/STAT progrm. The obtained results were as follows : 1. In subjects with longer radius which was less cervical curvature, head positioned more anteriorly than subjects with smaller radius, and they showed slightly straight cervical vertebra. 2. Between the patients and the control group, there were no differences in cervical curvature, in forward head position by plumb line and in CROM. But the patient group had a greater cervical inclination than the control group had. 3. There were positive correlation between cervical curvature and forward head position by plumbline,between forward head position y plumb line and that by CROM in patient group. The cervical inclination, however, had negative correlation with cervical curvature, and with forward head postion by plumb line, respectively. 4. In case of showing more cervical curvature and more forward head position by plumb line the head position was defined as forward head posture. In patient group, subjects without forward head posture showed greater posterior teeth contact force than subjects with forward head posture, but in control group, there were no difference between the two subjects. 5. There were higher electromyographic activity in almost all muscles and smaller freeway space in induced forward head posture than those in natural head position in subjects without forward head posture. In conclusion, head position of patients with craniomandibular disorders were not more anterior than that of normal control person, but they had tendency to head extension. From the result of this study, forward head posture could be defined as posterior rotation of upper cervical segment with a straight lower cercial segment due to loss of normal lordosis.

• Journal of Oral Medicine and Pain
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• 제24권2호
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• pp.189-206
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• 1999

This study was performed to investigate the factors affecting muscle activity and cephalometric variables according to change of head postures. For this study, 150 patients with temporomandibular disorders and 80 dental students without any signs and symptoms of temporomandibular disorders were selected as the patients group and as the normal group, respectively. Head position to body-midline in frontal plane and upper quarter posture to body plumb line in sagittal plane were observed clinically and electromyographic(EMG) activity of anterior temporalis, masseter, sternocleidomastoideus, and trapezius on clenching were recorded with $BioEMG^{(R)}$ in four head postures, which were natural head posture(NHP), forward head posture(FHP), $20^{\circ}$ upward head posture(UHP), and $20^{\circ}$ downward head posture(DHP). Cephaloradiographs were also taken in the same head postures as in EMG taking, but that was taken only in NHP for the patient group. Cephalometric variables measured were SN angle, CVT angle, atlas inclination angle, occlusal plane angle, Me-C2 angle, pharyngeal width, occiput~axis distance, area of pharyngeal space, and cervical curvature. The data were analyzed by SAS statistical program. The results of this study were as follows : 1. Between the patient and the normal group, there were significant difference in distance from plumb line to acromion, eye-tragus angle, electromyographic activity of the four muscles, and cephalometric variables of linear measurement. 2. There was no consistent pattern of correlation between upper quarter posture, EMG activity and cephalometric variables in any case without relation to cervical curvature and head position in frontal plane. 3. Sternocleidomastoid muscle only showed variation of electromyographic activty with changes of head postures, but all the muscles did show correlation with head postures. 4. All the cephalometric variables measured in this study showed difference of mean value by head posture, and CVT angle, pharyngeal width, occiput-atlas distance, and area of pharyngeal space showed correlation between these variables with change from NHP to FHP, and from NHP to UHP.

• Journal of Oral Medicine and Pain
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• 제21권1호
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• pp.55-65
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• 1996

This study was performed to investigate the effects of head posture and occlusal splint on the vertical dimension in mandibular rest position and swallowing. Thirty health dental students ware selected lot this study and BioEGNⓡ(Bioresearch Inc., USA) was used for measuring interocclusal distance during rest - swallowing - rest - tapping movement. This swallowing movements were observed in both normal head posture(NHP) and forward head posture (FHP). Thickness of occlusal splint was about 2mm at posterior molar area and even tooth contact were achieved on light biting. The four mandibular positions at which interocclusal distance measured were swallowing position, after swallowing position in which interocclusal distance was maximum, rest position follows swallowing, and tapping position after rest. Changes of distance in each position were measured for three mandibular planes, that is, sagittal, frontal, and horizontal plane, respectively. The results obtained were as follows : 1. In normal head posture, the mandible was raised 1.03mm without splint, and 0.77mm with splint on swallowing, and there was no significant difference between the two. In horizontal plane, however, mandible was displaced more anteriorly in both swallowing position and tapping position with splint. 2. In forward head posture, the mandible was less raised with splint on swallowing, but features in horizontal plane were almost same as those in normal head posture. 3. In natural dentition, significant difference between NHP and FHP were observed in horizontal plane trajectory for swallowing and tapping position. But the difference for same positions were observed in frontal trajectory with splint. 4. Total amount of mandibular movement of two groups classified with sagittal interocclusal distance of swallowing position generally showed significant difference between the higher and the lower height group in head posture without splint. 5. Correlationship among total amount of mandibular movement for three mandibular planes were observed between sagittal plane and horizontal plane, and between sagittal plane and frontal plane in head posture without splint.

• 대한치과교정학회지
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• 제25권2호
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• pp.129-142
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• 1995

본 연구는 한국성인의 두경부자세와 두개안면형태를 두개내 및 두개외 기준선에 대하여 알아보고 그 상관성을 평가하여 향후 진단시 보조적 자료로 사용하고자하여 시행되었다. 양호한 안모와 1급 구치관계를 지닌 성인 남, 녀 각 25명씩 총 50명에 대하여 natural head position 측모 두부 X-선 계측사진을 촬영하여 투사도를 그린후 posterior nasal spine을 지나는 true vertical line과 sella를 지나는 true horizontal line을 기준으로하여 자세변수 및 형태변수를 계측, 계산하였다. SPSS통계처리 프로그램을 이용하여 남녀평균, 표준편차를 구하고 student t-test로 유의차를 검정한후 자세변수와 형태변수간의 상관관계를 보았으며, 또한 자세변수를 이용하여 두경부자세의 재현성을 평가하여 다음과같은 결과를 얻었다. 1. 한국성인에서의 두경부자세변수와 두개안면형태변수의 평균과 표준편차를 얻었다. 2. 한국성인은 OPT/CVT간 각에 있어서 $3.55{\pm}2.58^{\circ}$의 경추 전방만곡을 보였다. 3. 자세변수와 형태변수의 상관관계에서는 두경부자세와 안면의 수직적인 비율, 안면돌출도, 하악골의 회전이 높은 상관성을 보였다. 4. 두경부자세와 상하악간 관계, 전후방적 악골비율의 상관관계는 미약하였다. 5. Natural head position에서의 head positioning error는 $1.65^{\circ}$로 SN line의 개인간 변이도 $3.31^{\circ}$ 보다 작았다. 다른 자세변수도 head positioning error가 각 변수들의 개인간 변이도보다 작았다.

• Journal of Oral Medicine and Pain
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• 제21권2호
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• pp.393-405
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• 1996

This study was performed to investigate the effects of changes of head posture and cervical spine shape on the mandibular resting or clenching electromyographic(EMG) activity in anterior temporalis(TA), masseter(MM), sternocleidomastoid muscle(SCM) and trapezius insertion(TI). 30 patients with Temporomandibular Disorders(TMDs) participated in this study. EMG activity($\mu$V) at rest and clenching was observed in four head postures, namely natural head posture(NHP), forward head posture(FHP), upward head posture(UHP), and downward head posture(DHP). For taking in upward or downward head posture head was inclined 10$^{\circ}$ upward or downward and CROM$^\textregistered$(cervical-range-of motion, Performance attainment Inc., USA) was used to maintain same posture during the procedure, and BioEMG$^\textregistered$ (Bioelectromyograph, Bioresearch Inc., USA) was used to record EMG activity in the above four muscles at eight locations on both sides. The recorded EMG activity($\mu\textrm{V}$) were compared and analyzed by cervical spine shape such as the head position from plum line, cervical curvature, and cervical inclination. Head position from plum line was measured in vertical plate calibrated with cm scale, comical curvature by radius was measured with adjustable curved ruler, and cervical inclination by cervical vertebrae tangent(CVT)was measured in lateral cephalograph. The results obtained were as follows : 1. Mean value of head position from plum line, cervical curvature, and cervical inclination were 4.8cm, 26.7cm, and 86.6$^{\circ}$, respectively, And There were no correlationship among these items. 2. For resting EMG activity by head posture, the value in anterior temporalis was higher at FHP than at DHP, the value in masseter was higher at FHP than at NHP, and DHP, the value in sternocleidomastoid muscle was higher at UHP than at NHP, and the value in trapezius insertion was higher at FHP and DHP than, NHP and UHP. The clenching EMG activity, however, did not show any difference by head posture. 3. Comparison of resting and clenching EMG activity between higher and lower groups by head position from plum line, cervical curvature, and cervical inclination did not show any significant difference. From this result, the author concluded that the cervical spine shape had not significantly affected to EMG activity in usual patients with TMDs.

• Journal of Oral Medicine and Pain
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• 제21권1호
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• pp.89-101
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• 1996

This study was performed to investigate influence of the changes of head posture on resting electromyographic (EMG) activity in anterior temporalis, masseter, sternocleidomastoid muscle and trapezius, and on status of occlusal contacts. For this study twenty-nine patients with temporomandibular disorders(TMD) and thirty dental students without any masticatory symptoms were selected as patients group and control group, respectively. EMG activity($\mu$V) at rest was observed in four kind of head postures such as natural or normal head posture(NHP), forward head posture(FHP), upward head posture(UHP), downward head posture(DHP), and in NHP and FHP, EMG activity with flat occlusal splint was also checked. BioEMG$^\textregistered$(Bioelectromyograph, Bioresearch Inc., USA) was used to record EMG activity in the above four muscles with eight locations on both sides. The author used T-Scan$^\textregistered$(Tekscan Co., USA) system to investigate the changes of oclusal contats on clenching in the four head postures about number, force, time(duration) and total left-right statistis(TLR, occlusal stability crossing left-right dental arch on clenching). For taking in upward or downward head posture, head was inclined $10^{\circ}$ upward or downward and CROM$^\textregistered$ (cervical-range-of motion, Performance attainment Inc., USA) was used to maintain same posture during the procedure. The results obtained were as follows : 1. For resting EMG activity, anterior temporalis did not show any difference by change of head posture, but masseter and sternocleidomastoid muscle showed higher value of EMG activity in FHP and UHP, and trapezius showed higher value of EMG activity in FHP and DHP. 2. EMG activity of trapezius was higher than that of any other muscles in NHP, FHP, and DHP, but in UHP, the activity was the lowest reversely. 3. Patients group showed higher EMG activity than control group did in all the muscles in NHP. And significant difference between the two groups were also observed in anterior temporalis in FHP, in sternocleidomastoid muscle in UHP, and in sterno-cleidomastoid muscle and trapezius in DHP with higher activity in patients group. 4. There was no change of EMG activity in NHp with splint, but EMG activity in anterior temporalis and masseter was decreased in FHP with splint. 5. In general, status of occlusal contacts was not changed with head posture in all subjects, and difference between patients group and control group was only noted for number and force of tooth contact in UHP and DHP with more value in control group. 6. Correlationship between EMG activity and number ad force of tooth contacts was shown negatively with regard to masseter in NHP, and trapezius in UHP and DHP.