Anatomy of the Spine Ligaments, Bones, & Disc

By a href="https://www.joionline.net/content-writers/">Tim Wall, ATC

Anatomy of the Spine or Back

Please watch this video on why Back Pain Can’t Wait.

The spine is made up of numerous structures which support the body.  Our goal of this article is to give you all of the information you need if you have back pain.  We want to help you get back to the activities that you love without back pain.  Let’s start with the structures that are in your back:

• bones
• nerves
• muscles
• tendons
• ligaments.

There are over 25 bones called vertebrae which are stacked on top of each other to make up the spine.  It starts in the pelvis and ends at the head.  These bones provide the basic structure and support of your back.

 Anatomy of the Spine

 

Spine Anatomy

The vertebrae are separated by a cushion called the intervertebral disk.  The disc is kind of like a jelly donut. The outer portion is made of thick connective tissue and attaches to the body of the vertebrae.  An injury to the disk can be very painful.

 

It is called the annulus fibrosis.  The inner portion is a thick gel material called the nucleus pulposus.  To learn more about spinal disks, please watch this educational video about disks.

There is a joint on each side of the vertebrae at each level.  These are called facet joints.  Facet joints provide stability but allow movement of the vertebrae on each other.

MRI Image of Lumbar Disc

In the center of the vertebrae there is a large hole called the vertebral foramen. The spinal cord is housed within the foramen of the vertebrae.  It begins at the base of the skull at the bottom of the brain and runs down to the L2 level.  Nerves branch off of the spinal cord between every vertebra.

The muscle anatomy of the back Includes many small muscles that control the small movements at each spinal level.  There is also large muscle that control posture and movement of the spine as a unit.  Many other large muscle attach to the spine which control extremity and trunk movements.

The lower back muscles fall into two main categories: deep muscles and superficial muscles. The deep muscles, like the multifidus and transversospinalis muscles, are in charge of stabilizing the spine and maintaining proper alignment. The superficial muscles, like the erector spinae and quadratus lumborum, assist in movement and provide strength.

To learn more about the spine, please watch this video about the Anatomy of the Spine.

What are the Five Parts of the Spine?

The spine can be divided into 5 parts.  They include:

• Cervical: the neck
• Thoracic: the chest and anything with a rib attached to it
• Lumbar: the low back
• Sacrum: the part that sits between the pelvic bones in the back
• Coccyx: the pointy part at the bottom

The lumbar spine is the body’s foundation, supporting our weight, enabling us to stand, walk, and perform various activities. It also protects the spinal cord, which transmits signals between the brain and the rest of the body. The complex structure of the lumbar spine allows for a balance of stability and flexibility, ensuring proper movement while minimizing injury risk.

Image of the components of the spine

What Does C3 Spine Control?

C3 is a key level in the spine because injuries to the spinal cord at or above this level can impair the ability to breath.  This is because the Phrenic nerve branches off of the C1, 2, and 3 spinal levels. The phrenic nerve is the nerve which controls the Diaphragm muscle which draws air into the lungs during breathing.

What Part of the Spine Controls the Arms?

The quick answer is that most of the nerves that supply the arms come from the neck.  Nerves exit the neck from C3 to T1 and join together to give nerve supply to the arms. An injury to the neck or a disk issue between the vertebrae in the neck can cause problems in the arms. These problems may include weakness, loss of sensation, or pain. Problems in the neck can also cause pain under the shoulder blades.

What Part of the Spine Controls the Legs?

The quick answer is that the lower part of the spine controls the legs.  The nerves that exit the spinal cord in the lower portion travel through the spaces between the lumbar and sacral segments. They join to form the lumbosacral plexus, which is a network of nerves.

Ligaments of the Low Back

Ligaments are tough, fibrous tissues that connect bones and stabilize joints. In the lower back, ligaments play a pivotal role in supporting the spine and preventing excessive movement. The ligaments of the lumbar spine include the anterior and posterior longitudinal ligaments, ligamentum flavum, and interspinous and supraspinous ligaments.

Low Back Nerves

The nerves separate in the low back and pelvic regions into several large nerves. These include the:

• Femoral Nerve
• Obturator Nerve
• Sciatic Nerve

The sciatic nerve is more well known because it is the most frequently involved in back pain.  A patient will describe a pain or tingling going down the back of their leg.  To learn more about what you can do about sciatica, please read this article.

Typical Triggers of Lower Back Pain

Lower back pain can be triggered by a range of factors, from muscle strains and sprains to degenerative conditions and herniated discs. Recognizing the common causes of lower back pain can help you identify the root issues and seek appropriate treatment.

Muscle strains and sprains in the lower back are a frequent pain source. These injuries can occur from lifting heavy objects, sudden movements, or poor posture. When the muscles or ligaments in the lower back are stretched or torn, it can result in acute or chronic pain.

Degenerative conditions, such as arthritis or spinal stenosis, can also affect the lower back. As we get older, the discs between our vertebrae may deteriorate, leading to reduced cushioning and increased friction. This can cause pain, stiffness, and limited mobility in the lower back.

Herniated discs are another common cause of lower back pain. When a spine disc ruptures or bulges, it can put pressure on nearby nerves, causing pain, numbness, or tingling sensations. The lower back is a common area for herniated discs to occur, and the pain can be debilitating.

If you are experiencing lower back pain, it is essential to consult with a healthcare professional for an accurate diagnosis and appropriate treatment plan. They can help pinpoint the root cause of your pain and recommend therapies, exercises, or medications to alleviate your symptoms.

Preventing and Managing Lower Back Pain

Lower back pain is a common problem that can significantly impact your daily life. Luckily, there are various preventive measures and management techniques that can help alleviate discomfort and foster a healthy lower back.

An effective strategy is to incorporate exercises and stretches that target your lower back muscles. Strengthening these muscles can provide spine support and stability, reducing the risk of pain and injury. Beneficial exercises include bridges, bird dogs, and pelvic tilts. Moreover, stretching exercises like the cat-camel stretch and knee-to-chest stretch can help improve flexibility and relieve tension in the lower back.

Single Knee to Chest

Keeping proper posture and body mechanics is another critical aspect of preventing lower back pain. Whether standing or sitting, it’s crucial to keep your spine aligned and avoid slouching. Use ergonomic chairs and adjustable desks that support good posture. Avoid sitting or standing in the same position for extended periods and take regular breaks to stretch and move around.

Workplace ergonomics play a vital role in preventing lower back pain. Ensure that your workstation is set up correctly, with your chair at the right height and proper lumbar support. Use a footrest if needed and position your computer monitor at eye level to avoid straining your neck and back.

JOI and JOI Rehab Can Help!

If you have back or neck problems, you need to have a thorough examination.  With expert surgeons, physical therapists and physical medicine physicians, JOI can help you get back to the activities of daily living.  We hope that this article has helped you understand a little more about the back and spine.  

For physical therapy appointments, please call 904-858-7045. To schedule an appointment with an Orthopedic Spine Specialist, please call 904-JOI-2000, schedule online or click the link below.