T1 is the first thoracic vertebra, transitional between the cervical and thoracic spine. Its body is larger than C7 and has complete (not hemi-) costal facets for the first rib articulation. The T1 transverse process is large and projects posterolaterally to articulate with the first rib. T1 contributes to the brachial plexus via its ventral ramus (C8-T1 lower trunk).
| Articulations |
|
|---|---|
| Landmarks |
|
| Ossification | Three primary centres, one for the body and two for the vertebral arch, fusing by age 6, with ring apophyses fusing by age 25. |
T1 compression or injury (Klumpke pattern) affects the lower brachial plexus, producing intrinsic hand weakness and Horner syndrome (ptosis, miosis, anhidrosis) from sympathetic chain involvement. T1 is the reference level for thoracic spinal surgery, the prominent C7 spinous process (vertebra prominens) identifies the C7-T1 junction. T1 corpectomy for pathological fracture or tumour at this level requires posterior stabilisation due to the transition zone mechanical demands.
Injuries at the C7-T1 junction are easily missed on plain films because the shoulders obscure the view, so CT is often needed.
The T1 spinous process can be avulsed by muscular pull or flexion in the same way as C7.
This website uses cookies to enhance your experience. Some are essential for site functionality, while others help us analyze and improve your usage experience. Please review your options and make your choice.
If you are under 16 years old, please ensure that you have received consent from your parent or guardian for any non-essential cookies.
Your privacy is important to us. You can adjust your cookie settings at any time. For more information about how we use data, please read our privacy policy. You may change your preferences at any time by clicking on the settings button below.
Note that if you choose to disable some types of cookies, it may impact your experience of the site and the services we are able to offer.
Some required resources have been blocked, which can affect third-party services and may cause the site to not function properly.
This website uses cookies to enhance your browsing experience and ensure the site functions properly. By continuing to use this site, you acknowledge and accept our use of cookies.
