Uncinate Process
Description[edit | edit source]
The uncinate process of the vertebrae are associated with the uncovertebral joints, also known as the joint of Luschka, and are a unique feature of the cervical spine [1].
The uncinate process refers to a hook-shaped process, or bony protuberances, located on the lateral or posterolateral margins of the superior endplates of the cervical vertebral bodies, most commonly found at the levels of C3-C7 [2]. They are positioned on each side of the associated intervertebral discs, lateral and anterior to the intervertebral foramina (IVF) [3].
In the upper cervical spine, the uncinate processes are positioned in a more anterior position in relation to the lower cervical spine, where they are positioned slightly more posterior [2].
Articulations[edit | edit source]
There are a total of four articulations that make up the uncovertebral joints, which are formed between the superolateral margins of the uncinate processes and the inferolateral portion of the vertebral body above [2].
Function[edit | edit source]
Generally speaking, the uncovertebral joints follow the movements of the cervical spine, contributing to both the mobility and stability of the spinal motion segments. Specifically, the uncovervebral joints play a role in the following:
- Limiting lateral flexion, which plays a role in preserving the integrity of the ipsilateral IVF [1].
- Maintains the position of the intervertebral disc during axial rotation [1].
Anatomical Variation[edit | edit source]
- Uncinate processes are subject to variation and may be absent on the vertebral body of C7. On occasion, they may extend down to the level of T1 and T2 [4].
Clinical Significance[edit | edit source]
The uncovertebral joints are a common site for osteoarthritic changes [1]. These hypertrophic and arthritic changes typically have no specific cause but rather are believed to be related to the dehydration and shrinkage of the intervertebral disc, leading to increased load and contact between the vertebra above and the uncinate process below. Additionally, it had been reported that the chondrocytes ability to regenerate decreases which overtime leads to thinning of the articular cartilage of the joint. This deformation of the articular cartilage is the earliest change in osteoarthritis. This thinning of the articular cartilage results in increased exposure of the subchondral bone, making the bone susceptible to chronic mechanical injuries, commonly resulting in the growth of bone spurs which are also known as osteophytes.
These osteoarthritic changes often begin in the fourth decade of life and progress to involve more uncovertebral joints and become more distorted with age [1].
The osteoarthritc changes to these uncovertebral joints preferentially appear in the lower cervical spine secondary to the relatively higher loads and stress experienced at these levels [1].
The growth of these osteophytes from the uncinaete processes project laterally and can therefore impinge on anatomical structures in the area. Some structures that have been reported to be affected include the spinal nerve root, vertebral arter, radicular (medullary( artery, cervical spinal cord, and cervical sympathetic trunk [1].
Intervertebral Foramen Stenosis
Vertebral Artery Compression
References[edit | edit source]
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Hartman J. Anatomy and clinical significance of the uncinate process and uncovertebral joint: a comprehensive review. Clinical Anatomy. 2014 Apr;27(3):431-40.
- ↑ 2.0 2.1 2.2 Moore KL, Dalley AF. Clinically oriented anatomy. Wolters kluwer india Pvt Ltd; 2018 Jul 12.
- ↑ Vaskovis J. Uncovertebral joints [internet]. Anatomy, spine and back, spine. Kenhub; 2020 [cited 2020Sep26]. Available from: https://www.kenhub.com/en/library/anatomy/uncovertebral-joints
- ↑ Tubbs RS, Rompala OJ, Verma K, Mortazavi MM, Benninger B, Loukas M, Chambers MR. Analysis of the uncinate processes of the cervical spine: an anatomical study. Journal of Neurosurgery: Spine. 2012 Apr 1;16(4):402-7.
