4

In the previous post, we looked at how the poll functions as a gateway through the ventral fascial system, linking posture, nervous system regulation, and front-end function. The dorsal system expands that picture by showing how tension or support at the poll is transmitted through the spine and into the rest of the body.

The Deep Dorsal Line (DDL) travels from the tail to the poll and acts as a deep stabilizer of the vertebral column. Rather than creating big movement, it helps the spine organize itself efficiently, segment by segment.

The DDL begins in the tail musculature, travels along the spinous processes of the vertebrae, and continues through the nuchal ligament to the poll. Through the dorsal intervertebral membranes, it has an indirect relationship with the dura mater via the myodural bridge. Because of this connection, tension patterns along the spine can influence not only posture, but also neurological comfort and coordination.

When the DDL is placed under excessive or prolonged tension (such as with chronic over-flexion or riding consistently behind the vertical) it can lose its ability to stabilize without bracing. Over time, this may contribute to persistent neck or back pain and a shift in balance toward the forehand, as the spine becomes less able to support the body evenly.

Overlaying this deeper stabilizing system is the Superficial Dorsal Line (SDL), a more global myofascial chain responsible for transmitting force through the body. The SDL originates at the third phalanx of the hind hooves, travels up the back of the limbs through the hamstrings (including the biceps femoris and semitendinosus), continues along the longissimus dorsi, and extends up the neck to the skull.

Functionally, the SDL supports extension of the back while coordinating flexion and engagement of the hind limbs. It plays a major role in linking hind-end propulsion to the spine and poll.

When this line becomes chronically contracted, we often see patterns such as a hollow or rigid back, reluctance to engage, or generalized back pain. Chronic tension along the SDL can also contribute to conditions like kissing spine, where excessive extension reduces space between the dorsal spinous processes.

Hoof balance influences this system as well. A negative plantar angle can place added stress on the SDL from the ground up, reinforcing tension patterns that travel through the hind limbs, spine, and ultimately toward the poll.

Training approaches that encourage length through the neck and topline, rather than holding or compressing posture, can help reduce excessive tension along the SDL. When the horse is allowed to find length through the topline, the dorsal lines are better able to transmit force without bracing.

Together, these fascial lines, along with the lateral and spiral lines, create multiple pathways connecting the poll to the pelvis. This is why dysfunction, inflammation, or sustained tension in the upper cervical region can echo throughout the entire body.

In the final post of this series, we’ll look at what this means for training choices, equipment use, and how we support the horse’s development over time.