Lumbar Spine Anatomy

Question 1

The human spine

Answer 1

The human spine is made of 24 vertebra. The vertebra stack on top of one another to create the spinal column. The spinal column gives the body its main upright support. From the side the spine forms 3 curves. The neck, called the cervical spine curves lightly inward. The mid-back or thoracic spine curves outward.

Question 2

Lordosis

Answer 2

The inward curve of the lower back

Question 3

What makes up the lower lumbar spine?

Answer 3

The lower 5 vertebra often referred to as l1 - l5

Question 4

What does the L5 connect to?

Answer 4

The L5 connects to the Sacrum, the triangular bone at the base of the spine that fits between the two pelvic bones.

Question 5

Sacroiliac Joints (SI Joints)

Answer 5

The joints that connect the Sacrum to the Pelvis

Question 6

Vertebral Body

Answer 6

Each vertebra is formed by a round block of bone called the vertebral body

Question 7

How do lumbar vertebral bodies compare to the vertebral bodies of other parts of the spine?

Answer 7

The lumbar vertebral bodies are taller and bulkier partly because because the lumbar spine has to sustain pressure from the body weight and from daily actions like lifting and carrying and twisting

Question 8

What connects to the back of the vertebral body?

Answer 8

A bony ring. When the vertebra are stacked they create a hollow tube called the spinal canal. This boney tube surrounds the spinal cord as it passes through the spine.

Question 9

What do the spinal column protect?

Answer 9

Just as the skull protects the brain, the bones of the spinal column protect the spinal cord.

Question 10

How far does the spinal cord extend?

Answer 10

From the brain to the L2 vertebra

Question 11

What happens to the spinal cord below the L2 vertebra?

Answer 11

The spinal cord splits into a bundle of nerves that goes to the lower limbs and pelvic organs

Question 12

Cauda Equina

Answer 12

The latin term for the bundle of nerves below the L2 vertebra meaning horse’s tail

Question 13

What does the spinal cord do as it travels from the brain to the base of the spine?

Answer 13

It sends out nerves on the side of each vertebra called nerve roots

Question 14

What do the nerve roots do

Answer 14

They join with the rest of the nerves to create the body’s electrical system.

Question 15

What makes up a spinal segment

Answer 15

Two vertebra, intervertebral disc between, two nerve roots that leave the spinal cord at that level and two facet joints that link each level of the spinal column

Question 16

What makes up the intervertebral disc?

Answer 16

The intervertebral disc is made up of two parts: the center is called the nucleus pulposus is spongy and acts as a shock absorber to cushion the force between each vertebra. The nucleus is surrounded by a series of strong ligimentous rings called Annulus Fibrosus

Question 17

What are ligaments made of?

Answer 17

Strong connective tissue that connects one bone to another

Question 18

What is the Annulus Fibrosus

Answer 18

A special ligament that connects two vertebra together

Question 19

Facet Joints

Answer 19

Between the vertebra in each spinal segment are two facet joints. They are located on the back of the spinal column.

Question 20

How do facet joints connect vertebral bodies?

Answer 20

A small boney knob that sticks out from the vertebral body at the back of the spine. Where these knobs meet create a synovial joint that connects the two vertebra.

Question 21

synovial joint

Answer 21

most moveable and widespread joint throughout the body

Question 22

How do the facet joints move in the lumbar spine?

Answer 22

The facet joints move together in a sliding motion as you bend forward and backward

Question 23

Articular Cartilage

Answer 23

The surfaces of the facet joints are covered by articular cartilage. It’s a smooth rubbery material that covers the ends of most joints. It allows the bone ends to move together smoothly without friction

Question 24

Neural Foramen

Answer 24

As the nerves leave the spinal cord they pass through a small boney tunnel called a neural foramen

Question 25

Lumbar Ligaments

Answer 25

The lumbar spine is supported by a complex set of ligaments and muscles. The ligaments are arranged in layers and run in multiple directions where they connect the bones of the spine to the sacrum and pelvis.

Question 26

Lumbar Muscles

Answer 26

The muscles of the lower back are also arranged in layers.

Question 27

Superficial (top) muscle layer

Answer 27

Those closest to the surface are covered by a thick tissue called fascia (fasha)

Question 28

Middle muscle layer

Answer 28

Runs up and down over the middle layer, chest and lower back. They blend in the lumbar spine to form a thick tendon that binds the bones of the lower back, sacrum and pelvis

Question 29

Deep muscle layer

Answer 29

Runs along the back surface of the spine. These muscles connect the lumbar vertebra to the sacrum and pelvis. They coordinate movement with the muscles of the abdomen to hold the spine steady during activities

Question 30

Lumbar Vertebra Long

Answer 30

The lumbar vertebrae consist of five individual cylindrical bones that form the spine in the lower back. These vertebrae carry all of the upper body’s weight while providing flexibility and movement to the trunk region. They also protect the delicate spinal cord and nerves within their vertebral canal.

Found along the body’s midline in the lumbar (lower back) region, the lumbar vertebrae make up the region of the spine inferior to the thoracic vertebrae in the thorax and superior to the sacrum and coccyx in the pelvis The lumbar vertebrae are stacked to form a continuous column in order from superior (L1 or first lumbar vertebra) to inferior (L5 or fifth lumbar vertebra). Together they create the concave lumbar curvature in the lower back.

Connecting each vertebra to its neighboring vertebra is an intervertebral disk made of tough fibrocartilage with a jelly-like center. The outer layer of the intervertebral disk, the annulus fibrosus, holds the vertebrae together and provides strength and flexibility to the back during movement. The jelly-like nucleus pulposus acts as a shock absorber to resist the strain and pressure exerted on the lower back.

The lumbar vertebrae are the some of the largest and heaviest vertebrae in the spine, second in size only to the sacrum. A cylinder of bone known as the vertebral body makes up the majority of the lumbar vertebrae’s mass and bears most of the body’s weight. Posteriorly the body is connected to a thin ring of bone known as the arch. The arch surrounds the hollow vertebral foramen and connects the body to the bony processes on the posterior of the vertebra. The vertebral foramen is a large, triangular opening in the center of the vertebra that provides space for the spinal cord, cauda equina, and meninges as they pass through the lower back.

Extending from the vertebral arch are several bony processes that are involved in muscle attachment and movement of the lower back. The spinous process extends from the posterior end of the arch as a thin rectangle of bone. It serves as a connection point for the muscles of the back and pelvis, such as the psoas major and interspinales. On the left and right lateral sides of each vertebra are the short, triangular transverse processes. The transverse processes form important connection points for many muscles, including the rotatores and multifidus muscles that extend and rotate the trunk.

Unlike the cervical vertebrae in the neck, the lumbar vertebrae lack the transverse foramina in the transverse processes, and also lack facets to either side of the body. The fifth lumbar vertebra is distinct from the L1-4 vertebrae in being much larger on its front side than in the back. Its spinous process, on the other hand, is smaller than in the other lumbar vertebrae with a wide, four-sided shape that comes to a rough edge and a thick notch.