Rectus capitis lateralis muscle revisited: a histological study using human fetuses.

Background: Rectus capitis lateralis muscle (RCLM) is located at the border between the ventral and dorsal muscle groups, but the nerve topographical anatomy around the muscle is obscure.

Materials And Methods: We observed the RCLM in histological sections of 12 midterm and 10 near-term fetal heads (9-18 and 26-40 weeks of gestational age).

Results: At midterm, the RCLM wrapped around the inferiorly protruding inferolateral corner of the cartilaginous occipital bone.

Fetal development and growth of the human erector spinae with special reference to attachments on the surface aponeurosis.

Purpose: The longissimus (LO) and iliocostalis (IC) of adults consist of myofibers extending from the superolateral to the inferomedial side of the back and, because of the same course, they are fused in the thoracolumbar region. The LO also has a medial attachment to the long myofibers of the transversospinalis (TS) showing a course from the superomedial to the inferolateral side. However, there is apparently no information regarding when and how these similar longitudinal muscles differentiate from a cluster of dorsomedial myotome cells.