We palpate the 13th rib externally, then visualize this vertebra with forceps (hooking the forceps gently underneath the rib to watch which vertebra it is attached to - the T13 vertebra will move in response to movement of the rib). The 13th rib is the lowest rib in rats and is a floating rib (ie. does not connect to the sternum). When doing this be very careful to avoid puncturing the pleural space. Once landmarking at T13 has been made definitively we count up to T10 from T13. Good clearing of tissues on top of the vertebral processes will help with your landmarking.

Hi. In our lab we used to identify Th11 spinous process as most prominent one and count down from it. This method works for mice as well.

Hi.in our lab we use 13 rib to identify spines process for 13 thoracic vertebra.Then count upward to recognizeT10

We palpate the 13th rib externally, then visualize this vertebra with forceps (hooking the forceps gently underneath the rib to watch which vertebra it is attached to - the T13 vertebra will move in response to movement of the rib). The 13th rib is the lowest rib in rats and is a floating rib (ie. does not connect to the sternum). When doing this be very careful to avoid puncturing the pleural space. Once landmarking at T13 has been made definitively we count up to T10 from T13. Good clearing of tissues on top of the vertebral processes will help with your landmarking.

Hi we do as Michelle Rank has told you.In rat this way is useful to recognize T10.As mentinoed before, you have to recognize 13th rib in rat it moves under your light pressure because it is a floating rib.Then spiness process of 13th vertebra can be easily palpated as a landmark.By counting upward from 13th spiness process to 10th spines process .

Michelle's method is a good one. If you have the luxury of a C-arm then flouroscopy is great.

I also think the procedure proposed by Dr. Michelle Rank is precise

In addition to the above suggestions may be this article also useful to know some anatomical land marks for rat spinal cord lesion

De Medinaceli, L. (1986). An anatomical landmark for procedures on rat thoracic spinal cord. Exp. Neurol. 91, 404–408.

Purpose and Background for T9 contusion.

Adjust accordingly for T10.

A basic familiarity with general mouse and rat anatomy and physiology will facilitate greater ease when performing mouse laminectomies and will result in fewer surgical complications. It is a good idea to familiarize yourself with the anatomy of the vertebral column and watch the mouse laminectomy training video before your first surgery. Although it may seem tedious and repetitive, understanding and planning for the laminectomy will help you to think about each step of the process and will also help to prevent unnecessary trauma and/or death.

A clean laminectomy is only the first step in preparing a reliable and reproducible spinal cord contusion injury model. Below are a few general considerations to keep in mind.

- Refrain from damaging the muscle unnecessarily…it still needs to be sutured.

- Keep T8 and T10 cleared well enough and intact enough so that the person doing hits can clamp the mouse stably

- Avoid puncturing any sinuses or other vascular structures that may cause the animal to bleed out

- Always pay attention to depth of anesthesia and breathing

- Saline often helps to restore blood volume and maintain blood pressure in cases of extreme blood loss

- Rats that we operate on are fragile and everything should be done to minimize their suffering and decrease their recovery time

Materials.

_Pair of large forceps with teeth

_Ronguers

_microscissors

_Curette

_Small # 2 forceps

_Small #5 forceps

_Scalpel handle and 10 blade

_Betadine

_surgical spears

_gauze

_saline

_cotton-tipped swabs

_sterile underpad

Procedure.

1. Sterilize tools in hot bead sterilizer for 10 seconds.

2. Anesthetize rat, shave back and cover eyes with Vetlube

3. Prep skin with Betadine

4. Using a sterile 10 blade, make a skin incision from T6-T12 (incision length will vary, but it is a good idea to make the smallest incision that will still give the surgeon good visualization)

5. Locate and cut fat pad laterally (There is a large vein under fat pad, DO NOT accidentally cut the vein, otherwise the animal will bleed out).

6. Find T4 the largest process you can feel with finger and count back caudally to T9.

7. Superficially mark the location of T9 on the muscle with your scalpel.

8. Do a sharp incision into the muscle surrounding T9.

9. Carefully clean muscle away from vertebral column laterally and dorsally enough to visualize individual processes and clamp at T8 (you can do this with the scalpel, curette or with a surgical spear to a limited extent. Avoid puncturing sinuses or thoracic cavity)

10. Locate T4 spinous process and count back to T9 (use your finger to count. This is where it is particularly important to know the anatomical features of different vertebrae)

11. Clamp at T8 with large forceps and then with the ronguers remove the dorsal process of T9 (always pay attention to the direction of your ronguers. Point tip upward to avoid damaging cord under bone)

12. Use ronguers to clear away any bone that obscures the width of the spinal cord.

13. Soak up any excess blood or fluid from cord and clear any rough or jagged edges or stray pieces of bone from laminectomy site with #2 forceps.

14. Check to make sure that T10 can be clamped

We also have a video of our T9 laminectomy process which can be shared with qualified researchers (not posted online at ResearchGate)

identify the spinous process for 13 thoracic vertebra and subsequently count upward to recognize T10