Lumbar Vertebrae, Sacrum, and Coccyx

Lumbar vertebrae are vertebrae of the ___

abdomen

How many lumbar vertebrae are there?

5

How do lumbar vertebrae compare in size to other vertebrae?

they are the largest

What type of curve do lumbar vertebrae have?

lordotic (secondary; convex anteriorly, concave posteriorly)

Explain the shape and size of the body of lumbar vertebrae

• large, bean shaped

• increases in size from the 1st to the 5th

• superior and inferior surfaces are slightly concave

• sides are concave

Explain the projection of the transverse processes of each lumbar vertebrae

L1-L3: directed laterally

L4-L5: inclined slightly superiorly

Explain the location and size of the pedicles of the lumbar vertebrae

• projected posteriorly off of the body

• contain the inferior and superior vertebral notches

• large, thick, and blunt

• horizontal projection posteriorly

Explain the location of the lamina of the lumbar vertebrae

posterior to the pedicles and transverse processes

What is the pars interarticularis?

part of the lamina between the superior and inferior processes (found only on lumbar vertebrae)

only visualized in an oblique

What is the part of the lamina between the superior and inferior processes on lumbar vertebrae?

pars interarticularis

Explain spina bifida

no fusion of posterior lamina (spinal cord is not fully surrounded)

can occur anywhere in the spine (usually L-spine)

What are the 3 types of spina bifida?

• spina bifida occulta

  • less severe

• meningocele

  • linings of spinal cord protrude through the defect

• myelomeningocele

  • the spinal cord itself protrudes through the defect

  • usually paralyzing

Explain what is special about the 5th lumbar vertebrae

• the body is deeper in the front than in the back so it can articulate with the sacrum (gives it a wedge shape)

• spinous process is blunt and short

• transverse processes are thick

What is the largest amphiarthrodial, cartilaginous, symphysis joint? (also the most moveable joint in the vertebral column)

lumbosacral joint

Explain the lumbosacral joint space image

• performed as a supplement lateral

• interiliac line

• 5-7^o caudal angle (depending on interiliac line)

Explain spondylolysis

• fracture or defect in the pars interarticularis of a lumbar vertebra

• can result in spondylolisthesis

Explain spondylolisthesis

forward displacement of a vertebra over an adjacent one (L4-L5, L5-S1)

The inferior articulating process of the 5th lumbar spine articulates with the ___

superior articulating process of the sacrum

The articulating processes of the lumbar spine sit at a ___ degree angle to MSP

30-50^o

How are zygapophyseal joints visualized on an x-ray?

45^o oblique

When are scotty dogs demonstrated?

30-50^o oblique

AP = side down

PA = side up

Explain the parts of the Scotty Dog

• ear - superior articulating process

• eye - pedicle

• nose - transverse process

• neck - pars interarticularis

• body - lamina

• (front) leg - inferior articular process

The inferior and superior notches of the lumbar vertebrae lie at a ___ degree angle to MSP

90^o

How are intervertebral foramina visualized on an x-ray?

in a lateral position

Explain the curve of the sacrum

concave anterior, convex posterior (primary curve)

What makes up the sacrum? How is it labeled?

5 fused false vertebrae segments

labeled as 1st sacral segment, 2nd sacral segment, etc.

The sacral segments are separated by ___

transverse lines

Which vertebra is at the level of ASIS?

2nd sacral segment

Explain the location of the base and apex of sacrum

base: superior part

apex: inferior part

Explain the difference between male and female sacrum

male is longer

female has more of a curve (inferiorly)

Explain the 1st sacral segment

• resembles vertebra of the lumbar region

• last intervertebral joint

• last pair of intervertebral foramina

What are the superior articulating processes of the sacrum?

processes that articulate with the inferior articulating process of L5

The superior articulating processes of the sternum and the inferior articulating processes of L5 form the ___

last pair of zygapophyseal joints

What is the sacral promontory?

the prominent ridge at the upper anterior margin of the base of the sacrum

Explain the ala of the sacrum

large wing-like masses lateral to the sacral base

The auricular/articular surface of the sacrum articulates with the ___ to form the ___

iliac bones of the pelvis; forms the SI joints

When are the SI joints seen on an x-ray?

25-30 degree obliques

Where is the sacral canal located?

What is the function of the sacral canal?

directly posterior to the sacral segment bodies;

transmits sacral nerves

What are the sacral foramina?

• foramen located on the anterior and posterior walls of the sacral canal

• 4 anterior pairs

• 4 posterior pairs

• (16 total)

The sacral foramina are connected on the anterior side by ___

transverse lines

What are the sacral cornua?

two processes that project inferiorly from the posterior aspect of the last sacral segment to join the coccyx

What is the classification of the sacrococcygeal joint?

cartilaginous, amphiarthrodial, symphysis

The coccyx is made up of ___

4 fused bones

Where are the base and apex of the coccyx located?

base is superior

apex is inferior

What are the coccygeal cornua?

superior projections off of the posterior lateral aspect of the 1st coccygeal segment (joins the sacral cornua)