Final answer:
The groove extending the spinal cord's length posteriorly is the posterior median sulcus, separating the cord's right and left sides.
Step-by-step explanation:
The posterior median sulcus is a groove that extends the length of the spinal cord posteriorly. It is a midline feature of the posterior spinal cord that marks the separation between the right and left sides of the cord. The posterior median sulcus can be seen in a cross-section of a thoracic spinal cord segment.
The groove that extends the length of the spinal cord posteriorly is known as the posterior median sulcus. This midline feature marks the separation between the right and left sides of the cord. The posterior median sulcus is part of the spinal cavity, running the entire length of the trunk within the vertebral column. Additionally, the posterior median sulcus is essential in spinal cord anatomy as it relates to the arrangement of gray and white matter, as noted in the cross-section of the spinal cord.