Morphological classification and comparison of suboccipital muscle fiber characteristics

Abstract

In an attempt to clarify the function of the suboccipital muscles, we performed morphological observation of the suboccipital muscles for variations in the muscle belly and compared the morphology of their muscle fibers in terms of cross-sectional area by immunostaining with anti-myosin heavy chain antibodies. The cadavers of 25 Japanese individuals were used: 22 for morphological examinations and three for histological examinations. Among samples of the rectus capitis posterior major muscle (RCPma) and rectus capitis posterior minor muscle (RCPmi), 86.4% had a typical muscle appearance with a single belly, and 13.6% had an anomalous morphology. None of the samples of the obliquus capitis superior (OCS) or obliquus capitis inferior (OCI) muscles had an anomalous appearance. Measurement of cross-sectional area revealed that fast-twitch muscle fibers in the RCPma and OCI had a significantly greater cross-sectional area than those of the RCPmi and OCS. The cross-sectional area of intermediate muscle fibers was also significantly greater in the OCS than in the RCPma, RCPmi, and OCI. The cross-sectional area of slow-twitch muscle fibers was significantly greater in the OCS than in the RCPma, RCPmi, and OCI, and the RCPmi showed a significantly greater cross-sectional area for slow-twitch muscle fibers than did the RCPma, and OCI. Our findings indicate that the RCPmi and OCS exert a greater force than the RCPma and OCI, and act as anti-gravity agonist muscles of the head. Prolonged head extension in individuals with anomalous suboccipital muscle groups could result in dysfunction due to undue stress.

Upper cervical spine dysfunction and dizziness

“…These are four paired muscles (rectus capitis posterior major, rectus capitis posterior minor, obliquus capitis superior, and obliquus capitis inferior). Unilateral contraction of these muscles induces head rotation, and bilateral contraction causes head extension (Yamauchi et al, 2017). These muscles have a high muscle spindle density that not only allows flexible movement, but also act as specific sensory receptors (Kulkarni et al, 2001).…”

“…These muscles have a high muscle spindle density that not only allows flexible movement, but also act as specific sensory receptors (Kulkarni et al, 2001). Therefore, these muscles allow to control delicate movements in atlanto-occipital (C1-C0) and atlanto-axial (C1-C2) joint (Yamauchi et al, 2017). However, sustained and excessive stress in the cervical spine resulted from incorrect posture causes problems in these muscles.…”

“…However, sustained and excessive stress in the cervical spine resulted from incorrect posture causes problems in these muscles. (Yamauchi et al, 2017). McPartland et al (1997) reported that weakness of cervical muscle after whiplash is associated with chronic neck pain and poor balance.…”

Morphological Changes of the Suboccipital Musculature in Women with Myofascial Temporomandibular Pain: A Case-Control Study

“…Ultrasound imaging has gained relevance in recent years in the evaluation of cervical spine musculature. In fact, different studies reported the ability of ultrasound imaging to investigate deep neck extensors, such as the cervical multifidus [ 14 ] and suboccipital [ 15 ] muscles. No previous study has investigated cervical muscle morphology in individuals with TMD.…”

Suboccipital Muscles, Forward Head Posture, and Cervicogenic Dizziness

“…Agten et al [45] reported that the multifidus is a postural muscle that provides stability in the lumbar vertebral column because of its predominance of slow-twitch fibers. Yamauchi et al [49] observed that RCPmi and OCS have at least two-fold greater cross-sectional areas of slow-twitch fibers than fast-twitch fibers in human cadavers, and that OCI has a significantly larger cross-sectional area of fast-twitch fibers than other suboccipital muscles. Therefore, they suggested that the RCPmi and OCS may provide more force than the RCPma and OCI and act as antigravity agonist muscles of the head.…”