Located between the neck and the low back, the middle back can be easy to ignore. People pay attention to this part of the spine when they’re trying to improve their posture, but it’s not a common source of complaints. Still, for some people, it can be a middle back misalignment that’s causing pain above or below the impacted area. Here’s more about your thoracic spine, its nerves, and the muscles that impact it.
Your Thoracic Vertebrae
There are 12 vertebrae that make up your thoracic spine. Directly above your T1 (the first thoracic vertebra) is your C7, the bottom vertebra of your neck. Below your T12 (the bottom thoracic vertebra) is your L1, the top lumbar vertebra. The health and placement of your cervical and lumbar vertebrae can greatly impact the health and function of your thoracic vertebrae.
Part of what makes the thoracic vertebrae different from the cervical and lumbar vertebrae is its relationship with the rib cage. Although we often think of the rib cage as a solid structure, it’s not. Instead, it is many pieces that are held together with muscles and other connective tissues.
The thoracic spine sort of works as an anchor and point of stability for the rib cage. There are facets on the sides of the vertebrae to articulate with the heads of the rib bones.
As with the cervical vertebrae, not all of the thoracic vertebrae look alike. Although the second through eighth thoracic vertebrae are similar, the first and ninth through twelfth have variations. (I’m not going to get into the specifics of each vertebra’s variations. If you want to read more about the thoracic deviations, click here.)
Below is a picture of what the second through eighth thoracic vertebrae look like.
Nerves from the Thoracic Spine
The nerves are named according to the vertebra that is directly above the nerve. For example, the T1 nerve is located directly below the T1 vertebra.
According to Spine-health.com, the thoracic nerves serve the following purposes:
- “T1 and T2 (top two thoracic nerves) feed into nerves that go into the top of the chest as well as into the arm and hand.
- T3, T4, and T5 feed into the chest wall and aid in breathing.
- T6, T7, and T8 can feed into the chest and/or down into the abdomen.
- T9, T10, T11, and T12 can feed into the abdomen and/or lower in the back.”
Now that we understand in a general way what these nerves do, let’s look at which muscles are controlled by these nerves. All of the vertebrae listed below will impact the erector spinae group, multifidus, and rotatores.
- T1: pectoralis major, anconeus, pronator quadratus, abductor digiti minimi of the hand, flexor digiti minimi brevis of the hand, lumbricals of the hand, dorsal interossei, and several other small muscles in the hand
- T2: serratus posterior superior
- T3: serratus posterior superior
- T4: serratus posterior superior
- T5: rectus abdominis, serratus posterior superior
- T6: rectus abdominis
- T7: rectus abdominis, internal oblique, external oblique
- T8: rectus abdominis, internal oblique, external oblique
- T9: rectus abdominis, internal oblique, external oblique, serratus posterior inferior
- T10: rectus abdominis, internal oblique, external oblique, serratus posterior inferior
- T11: rectus abdominis, internal oblique, external oblique, serratus posterior inferior
- T12: rectus abdominis, internal oblique, external oblique, serratus posterior inferior, quadratus lumborum, pyramidalis
Muscles that Impact the Thoracic Spine
- Erector Spinae: The erector spinae muscles run all along the spine. They help to move the spine into extension.
- Iliocostalis Lumborum: This muscle originates on the lower two thoracic and all of the lumbar vertebrae. The iliocostalis lumborum is another muscle that helps to extend the spine.
- Iliopsoas: The iliopsoas is actually a combination of three muscles that run from T12 and all of the lumbar vertebrae, join together, and insert on the upper part of the femur. This group is your main hip flexor.
- Latissimus Dorsi: This muscle originates on the lower six thoracic and all lumbar vertebrae. Even though it’s primarily used to move the humerus or rotate the scapula, it can still impact your low back.
- Multifidus: This muscle helps rotate and create side flexion for the spine. It is present from the cervical through the lumbar vertebrae.
- Rhomboids: Rhomboid major originates on the second through fifth thoracic vertebrae, and rhomboid minor originates on the bottom cervical and top thoracic vertebrae. These muscles retract and elevate the scapulas.
- Rotatores: The rotatores muscles help rotate the spine. They are present throughout the entire spine.
- Serratus Posterior: The origin of serratus posterior superior is C7 and the first three thoracic vertebrae. Serratus posterior inferior originates on the bottom two thoracic and top three lumbar vertebrae. These muscles primarily aid in respiration.
- Trapezius (Middle and Lower divisions): The middle trapezius originates on the first five thoracic vertebrae, and the lower trapezius originates on the sixth through twelfth thoracic vertebrae.
So, What Do I Do with this Information?
Now that you’re more aware of the vertebrae, nerves, and muscles that impact your thoracic spine; you might be able to better help yourself the next time you feel back pain. Try stretches, massage, and use tools like a lacrosse ball or The Orb to help you get into tight spots.
If you notice that you’re still having an odd sensation or intense pain, call your doctor. Your doctor can order all of the appropriate tests, medications, and therapy to get you the help you need.
Do you have more information to add about the thoracic spine? If you do, please share in the comments below.
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