Background: A forward head posture (FHP) is one of the most common types of poor head posture in patients with neck disorder. A prolonged FHP might increase pressure on the posterior cranio-cervical structure and exhibit reduced performance on a cranio-cervical flexion test (CCFT). CCFT is included to activate deep cervical flexor muscles and inhibit excessive activation of superficial cervical flexor muscles. Therefore, the selective activation of deep cervical flexors is needed for effective exercise for FHP.
Objects: The purpose of this study was to compare muscle thickness between longus colli (Lco) and sternocleidomastoid (SCM) using ultrasonography in subjects with FHP depending on head support.
Methods: This was a cross-sectional, case-control research design study. The ultrasonographic images of Lco and SCM were taken in 17 subjects with FHP during the 5 phases of the CCFT with and without a head support. Towel was used for supporting head to make the neutral head position in supine. Changes in muscle thickness during the test were calculated to infer muscle activation. Data were analyzed using repeated measures of two-way analysis of variance with the significance level of .05.
Results: When subjects performed the CCFT with head support, there was a significant difference in muscle thickness of Lco and SCM (p<.05). According to a post hoc paired t-test, change of thickness of Lco was greater at all phases, and change of thickness of SCM muscle was less at phase 4 and 5 in condition with head support (p<.01) compared to condition without head support (p<.01).
Conclusion: The result of this study suggest that applying head support for neutral head position during CCFT could be a useful method for activating Lco muscle without excessive activation of SCM muscle.

Ⅰ. 서론
 Ⅱ. 연구방법
  1. 연구대상
  2. 실험기기 및 도구
  3. 실험방법
  4. 분석방법
 Ⅲ. 결과
  1. 머리받침 적용과 단계에 따른 긴목근의 근두께변화량 비교
  2. 머리받침 적용과 단계에 따른 목빗근의 근두께변화량 비교
 Ⅳ. 고찰
 Ⅴ. 결론
 References

• 박준상(서울 척병원 재활센터) | Jun-sang Park
• 송시정(서울 척병원 재활센터, 연세대학교 대학원 물리치료학과) | Si-jeong Song
• 정희석(서울 척병원 재활센터, 연세대학교 대학원 물리치료학과) | Hee-seok Jung
• 권오윤(연세대학교 보건과학대학 물리치료학과, 연세대학교 보건환경대학원 인간공학치료학과) | Oh-yun Kwon Corresponding Author