Anatomical characteristics of semispinalis capitis plane under ultrasound / 中华麻醉学杂志

ABSTRACT

Objective:To observe the anatomical characteristics of the semispinalis capitis plane (SCP) to provide a reference for clinically effective implementation of ultrasound-guided SCP block.Methods:Ultrasound scanning was performed in six certain districts of SCP in 30 healthy volunteers (60 sides). The key point was to examine and describe the anatomical characteristics of semispinalis capitis (SCA), deep space of SCA and structures within the space.Results:(1) Transverse scanning at the posterior arch of atlas revealed that the SCA was separated into medial and lateral head by an oblique thick septum; in the space between SCA and obliquus capitis inferior (SCA-OCI), the third occipital nerve (TON) and the greater occipital nerve (GON) were separated by a fascia.There was often a branch of occipital vein between them.The distance from TON to GON was (12.9±0.6) mm.(2) Transverse scanning at the lamina of axis revealed that the axial image of SCA and the structures in SCA-OCI space were similar to the results previously described in (1). The distance from TON to GON was (12.1±0.5) mm.(3) Sagittal scanning beside the spinous process of axis revealed that SCA was separated into superior and inferior belly by a septum which connected to the end of axis spinous process.(4) Sagittal scanning at the C 2, 3 facet joint revealed that in the space between OCI and C 2, 3 facet joint (OCI-C 2, 3) beneath SCA, there was no septum between TON and GON.The distance from TON to GON was (8.0±0.5) mm.(5) Transverse scanning at the lamina of C 4 revealed that in the space between SCA and semispinalis cervicis, the deep cervical artery and vein were observable except medial branch of C 4, and the characteristics of the short axis of the SCA belly were similar to the results previously described in (1). (6) Transverse scanning at the lamina of C 5 revealed that the view was similar to the results previously described in (5). The posterior branch of C 5 nerve was not found. Conclusions:SCP is rich in fascia, and blood vessels often pass through the deep surface space of SCA under ultrasound.The anatomical structure is complex, and there is individual variation.Grasping its ultrasonic anatomical characteristics is helpful in safely and effectively implementing ultrasound-guided SCP block.