A pedicle is a short, thick piece of bone that connects the front part of a vertebra (the body) to the back part (the arch). Every vertebra in your spine has two pedicles, one on each side, and together they form the sidewalls of the bony tunnel that houses your spinal cord. The term comes up most often in spinal imaging, back pain diagnoses, and spine surgery, though it has a separate meaning in reconstructive surgery as well.
Where Pedicles Sit in the Spine
Picture a single vertebra from above. The large, rounded front section is the vertebral body, which bears most of your weight. Projecting backward from either side of that body are two stubby columns of bone: the pedicles. They meet a pair of flat plates called laminae, and together these four structures form a bony ring called the vertebral arch. The open space inside that ring is the vertebral foramen, and when all your vertebrae stack up, those individual openings line up into the spinal canal, the protected corridor your spinal cord runs through.
Pedicles do more than just bridge two parts of bone. They form the medial (inner) border of the intervertebral foramen, the small window on each side of the spine where spinal nerves branch off and exit. They also contribute to the articular facets, the smooth joint surfaces where one vertebra connects to the next. So pedicles play a direct role in both protecting the spinal cord and guiding nerve roots safely out of the spine.
How Pedicle Size Varies by Spinal Region
Not all pedicles are the same size. In the cervical spine (the neck), pedicle height stays relatively constant from one vertebra to the next. Moving down into the thoracic spine (mid-back), pedicle height gradually increases, peaking around T12 at the bottom of the ribcage. In the lumbar spine (lower back), the height decreases again. Pedicle width follows a different pattern: the upper thoracic vertebrae tend to have the narrowest pedicles, while the lumbar vertebrae have wider ones.
These size differences matter clinically. A narrower pedicle leaves less room for surgical hardware and less margin for error during screw placement. A shorter pedicle reduces the space available in the spinal canal, which is one reason the thoracic spine is a common site for spinal stenosis in certain conditions. In achondroplasia, for example, the pedicles fuse to the vertebral body prematurely, producing shortened pedicles and a narrower canal that can compress the spinal cord.
Why Surgeons Anchor Hardware to the Pedicle
The pedicle is the strongest part of a vertebra that a surgeon can reach from the back of the spine. That strength makes it the ideal anchor point for pedicle screws, which are threaded through the pedicle and into the vertebral body to stabilize the spine. Pedicle screw fixation was first used to treat thoracolumbar fractures and has since expanded to address a wide range of spinal problems: tumors, infections, spondylolisthesis (where one vertebra slips forward over another), scoliosis, and kyphosis.
The advantage of going through the pedicle is that the screw grips bone in three dimensions, providing rigid fixation across a small number of vertebrae without locking down extra segments above or below. This means less of the spine needs to be immobilized, preserving more of your natural range of motion. Screws placed through the pedicle can also be used to apply corrective forces, pulling a curved or rotated spine back toward a more normal alignment. For patients, the practical result is that pedicle screw systems often eliminate the need for an external brace after surgery.
Pedicle Problems: Fractures and Narrowing
The pedicle itself rarely fractures in isolation, but the nearby pars interarticularis, a thin bridge of bone just behind the pedicle, is a well-known weak point. Stress fractures there (called spondylolysis) are common in adolescents who play sports involving repeated extension of the lower back, like gymnastics, football, and weightlifting. Some people are also born with thinner bone in this area, making them more vulnerable even without heavy athletic demands.
Symptoms of a pars fracture typically include lower back pain that worsens with activity, limited range of motion, and sometimes muscle spasms. If the fracture allows a vertebra to slip forward, the condition progresses to spondylolisthesis. Diagnosis usually starts with X-rays taken from multiple angles, followed by CT scans for a detailed look at the bone or MRI to catch injuries before they show up on plain X-rays.
On imaging, pedicles are visible as round, oval shapes on a standard front-to-back spinal X-ray. Radiologists sometimes describe them as “owl eyes” because the two pedicles look like a pair of eyes staring back at you. When one pedicle is missing or destroyed, typically by a tumor, only one “eye” remains. This is called the winking owl sign and prompts further investigation.
Pedicle in Reconstructive Surgery
Outside of spinal anatomy, the word pedicle appears in reconstructive surgery. A pedicle flap is a section of tissue, including skin, fat, and muscle, that is moved from one part of the body to another while staying connected to its original blood supply. The tissue passes through a tunnel under the skin to reach its new location. This technique is commonly used in breast reconstruction after mastectomy, with tissue borrowed from the back or abdomen to rebuild the breast mound. Because the flap keeps its own blood vessels, it has a reliable oxygen supply from the start, which improves healing compared to fully detached grafts.
Pedicle vs. Pedicel in Botany
In plant anatomy, the similar-sounding term pedicel refers to the small stalk that attaches an individual flower to the main stem of a flower cluster. It is not the same as a peduncle, which is the main stalk supporting an entire group of flowers. The two terms are often confused, but if you encountered “pedicle” in a medical context, the spinal or surgical definition is almost certainly the one that applies.