Unit Three Intervertebral Disc Flashcards
How many discs in the spine
23
How many discs in the cervical region
6
How many discs in thoracic region
12
How many discs in the lumbar region
5
Where are there no intervertebral discs in the spine
Occiput -C1, and C1-C2, sacrum and coccyx
What is replaced for disc in sacrum and coccyx
Fibrocartilage with no nucleus
What percentage of the intervertebral disc makes up the height of the spinal column
25%
Where are the discs the thickest
Lumbar
Where are the discs the thinnest
Upper thoracic
Where are the discs thicker ventrally
Cervical and lumbar
What makes up a symphysis joint
2 vertebrae plus the disc
A motion segment is
2 vertebrae plus the disc
What is the intervertebral disc attached to
Vertebral bodies, ALL, PLL, intra-articular, ligaments and ribs 2-9
What are the functions of the disc
Maintain the changeable space between vertebrae, aids in flexibility of spine, acts to properly assimilate compressive loads
The disc gives what type of stability to the vertebral column while the paravertebral muscles provide what type of stability to the spine
Intrinsic with disc and muscles are extrensic
What is considered the largest avascular structure in the human body
Disc
What are the three parts of the disc
Nucleus pulposis, annulus fibrosis, cartilaginous end-plate
The cartilaginous end plate is made up of
Hyaline cartilage
Intervertebral disc allows for what
Compressive, tensile and rotational motion
In between the two bodies contains
Intervertebral disc, end plate and apophyseal ring
The annulus fibrosis is where on the disc
Outer part
The annulus is able to sustain the forces of
Compression, torsion and flexion
Why is the annulus fibrosis able to sustain the forces of compression, torsion, and flexion
Due to the way the rings are located
What are sharpey’s fibers
Fibrous parts of the annulus fibrosis that attaches to the endplates of the vertebral bodies
Water content of the annulus fibrosis at birth is
78%
What is the water content of the annulus fibrosis by age 30
70%
In order for the disc to function properly is must have
High water content
If the disc becomes dehydrated, it loses the ability to
Support the axial load placed on it (loses hydrostatic pressure)
When the disc becomes dehydrated is causes a weight bearing shift which is
Shift from the nucleus, outward onto the annulus and the outer part of the vertebral body, and places more pressure on the Z joints
Weight bearing shift of dehydrated disc can result in
Pathological degenerative disc disease
What holes water in the disc
Proteoglycans, glycoaminoglycans (GAGs)
Function of proteoglycans in disc
Hold 500 times their own weight and gives disc hydrostatic pressure to support axial compression
Over night the height of the disc
Increases up to .5 to 1 inch due to non-axial loading
Diurnal change is
Exchange of water in and out of the disc
Diurnal change is only found in
Non-degenerated discs
How does water move in the disc during the day
Fluid moves out of the nucleus, through the annular rings and into the vertebral body
What happens to hydration of disc at night
Nucleus fills up with fluid and presses against the inner annular fibers and makes more tense and less flexible
Tears in the annular rings occur especially with
Coupled motion of flexion and torsion
How is the distribution of load in the disc
Nucleus distributes load equally throughout the annulus
In the severely degenerated disc, the nucleus has lost all its ability to Cushion the load and causes
Disc herniation
What nerve provides the outer 1/3 of the annular fibers have nociception
Sinuvertebral nerve
Since outer 1/3 of disc has nerve supply, what about other 2/3
No nerves so patient cant tell if damaged or not
How does disc received blood supply
Diffusion through the vertebral body endplates from network of vessels located centrally in endplate
What part of the disc has blood supply
Outer annular fibers
Since outer annulus fibers has blood supply that means
Outer 1/3 of annular fibers will heal/scar
Since inner 2/3 of annular fibers does not have blood supply what does that mean
Do not heal and remains a source of problems after being damaged
How do the rings (lamellae) progressively tear
From center outwards
How does a disc repair itself
From outward in
The nucleus pulposus is what percentage of water at birth
88%
By age 70, the water percentage of nucleus pulposis is what
69 to 70%
What part of the nucleus pulposis comes from the embryonic notochord
Center part of the nucleus
How long does the nucleus pulposis have a direct blood supply
Until age 8 then becomes avascular
Permanent dehydration of the nucleus pulposis occurs through
Aging process
Until what age is the nucleus pulposis disc fully hydrated
Age 40
By what age does the nucleus pulposis disc have reached their maximum state of dehydration
Age 60
The maximum state of dehydration of the nucleus pulposis causes
Decrease ROM and a slight narrowing of the IVF
What makes up about 40% of the total disc
Nucleus pulposus
Where is the nucleus pulposus best developed
Lumbar spine then cervical spine then the thoracic spine
Where is the nucleus pulposis placed in the cervical disc
Centrally
Where is the nucleus pulposis placed in the lumbar disc
Posterior
The composition of the nucleus polposus is
80% water and solid 20%
The solid portion of the nucleus pulposus is made up of
65% proteoglycans and 17% collagen 2 fibers, small amount of elastin
What are the cells located in the nucleus pulposis
Chondrocytes
The nucleus of the disc receives nutrition from
The blood that is inside the subchondral bone
The fluid that goes in and out of the disc goes to the
Subchondral bone
The nutrition is transferred from the subchondral bone to the fluid through what process
Diffusion
The nutrition then enters the fluid and is transported back into the nucleus where it is received is done by what process
Imbibition
What is imbibition
Absorption of a fluid by a solid body or gel
Is the cartilaginous vertebral end plate part of the bone or the vertebrae
No
How thick is the hyaline cartilage of the vertebral end plate
3 to 4 mm
The cartilaginous portion of the vertebral end plate is what with the annulus
Strongly interwoven into the annulus
Does the the permeability of the end plate increase or decrease with age
Decrease
The decrease in permeability of the disc is a major cause of
Disc degeneration
Decrease permeability of the disc causes
The nutrition from getting to the disc and metabolic waste products from leaving the disc
Is the very outer rim of the vertebral body covered by the end plate
No
What is the ring apophysis
The exposed peripheral area of the vertebral body
What is often the site for development of spur formation associated with the degeneration process
Ring apophysis
The vertebral end plate is part of what and not part of what
Part of the disc and not part of the vertebra
What does the nucleus pulposus look like
Thick, yellow gelatinous fluid
The nucleus pulposis makes up what percent of the total disc content
33 to 66%
Function of proteoglycans
Attract water molecules and help protect against shock
What are the two most common proteoglycans or GAGs
Glucosamine sulfate and chondriton sulfate
Are all discs the same in the spinal cord
No depends on length of vertebral body
What is in proteoglycans and GAGs that trap and hold water
Aggrecans
In the C spine the disc is larger
In the front than the back
The C region has what size disc
3 mm
The c spine disc contains what height of the body
2/5th
The T spine disc is larger
In the front than the back
What is the thickness of the disc in the T spine
5 mm
The disc in the T spine measures the height of the body to be3
1/5th
The L spine disc is larger
In the front than the back
The thickness of the disc is the L spine is
9 mm
The disc of the L spine measure the height of the vertebral body to be
1/3rd
What is an annular tear/ fissure
Separations between annular fibers, avulsion of fibers from their vertebral body insertions, or breaks through fibers that extend radially, transversely or concentrically, involving one or more layers of the annular lamellae
What are the three types of tears in a disc
Concentric tears, radial tears and transverse annular tears
What is a concentric tear
Separations of the tissue between the lamellae and allows fluid or mucoid material to accumulate here causing more pressure or separation
What are radial tears
Horizontal or obliquely horizontal tears that begin within the nucleus and progress outward toward the annular surface
Aka of transverse annular tears
Rim lesions
What are transverse annular tears
Tears of the very outer fibers of the disc (sharpey’s fibers) near the insertion into the ring apophysis
What are the meningeal branches of the spinal nerves
Number of small nerves that branch from the spinal nerve near the origin of the anterior and posterior rami, but before the rami communicantes branch
AKA of meningeal branches of the spinal nerves
Recurrent meningeal nerves, sinuvertebral nerves, or recurrent nerves of luschka
The size and severity of the disc herniation does not correlate to
The patients degree of pain, disability or suffering
Which type of contained herniation responds less favorably to surgery
Small contained herniations
In order for a disc to herniate, it’s structural components must first
Weaken
The structural components of a disc weaken as a result of
Disc degeneration
The degeneration of the disc begins as
The annulus becomes dried and more brittle allowing for the pressure of the nucleus to bulge out and tear the annulus fibers
What is desiccation
Annulus becomes dried
Most disc herniation occur at what age
30s or 40s when nucleus pulposus is still a gelatin like substance
With age the nucleus pulposus dries out and the risk of herniation is
Greatly reduced
After age 50 or 60, what is the cause of low back pain or leg pain
Osteoarthritic degeneration (spondylosis) or spinal stenosis
Diagnosis is based on
History, symptoms, and physical examinations
The majority of spinal disc herniation cases occur where in the spine
Lumbar region
The second most common site spinal disc herniation cases occur where in the spine
Cervical region
Cervical disc herniations most often occur where
C5/6 and C6/7
The herniations in the c spine can have symptoms that affect
Back of the skull, neck, shoulder girdle, scapula, shoulder, arm and hand
What nerve plexus are affected by the cervical disc herniation
Cervical plexus and brachial plexus
What disc herniations can mimic cervical disc herniations
Upper thoracic
What are the three main classifications of disc herniations
Bulge, herniation and sequestration
Aka protrusion herniation
Contained herniation or sub-ligamentous herniation
Aka of extrusion herniation
Non-contained herniation or trans-ligamentous herniation
Aka of sequestration
Free fragment
By convention, a herniation is a localized process involving less than what percent of the disc circumference
50% or 180 degrees
Definition of disc bulge
Disc in which the contours of the outer annulus extends in the horizontal plane beyond the edges of the disc space
A bulge of the disc involves what percentage of the circumference of the disc
More than 50%
Definition of the disc herniation
Focal incomplete extension of the contents of the nucleus pulposus through an incomplete tear of the annulus fibrosis in less than 50% of the circumference of the disc
Herniation has what percentage of disc circumference
Less than 50%
What are the two subclassifications of herniation
Protrusion and extrusion
Protrusion herniation
Disc material sticks backward into the canal
The disc protrusion looks
Less than its width
Extrusion disc herniation
Disc material sticks backward into the canal and then goes either upward or downward into the canal
Extrusion herniation appears
Longer than it is wide
What results in an anterior epidural mass
Extrusion of disc contents through complete tears of annulus fibrosus and the PLL
What are focal disc bulges
Less than 25% of the disc circumference is herniated
What is a broad based disc bulge
25 to 50% of the disc circumference is herniated
What is a contained herniation
The displaced portion of disc is covered by the outer annular fibers
What is uncontained herniation
The displaced portion of the disc protrudes through the outer annular fibers and into the spinal canal by itself
What is sequestration
An extruded disc in which a portion of the disc tissue has become displaced from the disc space of origin and lacks any continuity with the parent disc.
Herniated disc causes an inflammatory reaction that eventually
Reabsorbs most of the disc material
Is it better to have an uncontained disc herniation or contained one
Uncontained due to it being reabsorb more rapidly and completely
What is a good thing to do if patient has herniated disc
Walk
Bad thing to do if patient has herniated disc
Sitting
What is Knutsons vacuum disc phenomenon
Disc hardens due to decrease in water which makes it more easy to fracture. The fracture produces nitrogen gas formation and can be seen on X ray dark radiolucent line within disc
Aka of knutsons vacuum disc phenomenon
Phantom dis or vacuum defect or lucent cleft
Most common cervical disc herniation is at
C5/6
Mose common lumbar disc herniation is at
L4/5 and L5/S1
What is the most common cause of pain down the legs, along with low back pain, numbness and tingling in arms and other extremities
Disc herniation
Leaning to one side while having herniated disc is what type of mechanism
Voluntary or involuntary mechanism to alleviate nerve root irritation
What is lateral disc herniation posture
Patient will list or lean away from the side of sciatica because leaning into the side puts more pressure on the nerve root and causes more pain
What is medial disc herniation posture
Patient will lean into the side of sciatica because leaning away will pull the nerve root over the disc more and cause pain
What is central disc herniation posture
The patient tends to lean forward which open the joint and takes pressure off the spinal cord which the disc is pushing on
What disc herniation posture is most common
Lateral disc herniation
Which disc herniation posture is the least common
Central disc herniation
Leg raise test 0 to 35 degrees, if pain then
Muscle
Straight leg test 35 to 70 degrees
Tension now applied to sciatic nerve roots. The nerve tenses over the disc during this range
Straight leg raise 70 to 90 degrees
Pain at this level is probably joint pain as there is no further deformation of the nerve, nerve not pulled over disc, it relaxes at 70 degrees
If raise well leg (leg not with pain) and it hurts on the other leg side in low back then
Medial disc as it pulls opposite nerve root over disc
Positive straight leg raise is called
Lasegue sign
Finding of a negative straight leg raise sign is important in helping to
Rule out the possibility of a lower lumbar disc herniation
How to adjust lateral disc protrusion
Adjust with the disc protrusion (leg pain) up
How to adjust a medial disc protrusion
Adjust with the disc protrusion (leg pain) down
Adjusting medial and lateral disc protrusion with what
Side posture adjusting
Features of cauda equina syndrome
Bladder and bowel incontinence, perineal numbness, bilateral sciatica, lower limb weakness, crossed straight leg raising sign
What is a discetomy or microdiscectomy
Procedure that removes part of an intervertebral disc that is compressing the spinal cord or a nerve root
What is a laminectomy
Remove lamina
Purpose of laminectomy
Relieve spinal stenosis or nerve compression
Purpose of hemilameniectomy
Help alleviate the symptoms of an impinged or irritated nerve root in the spine
What is a hemilaminectomy
Remove one side of lamina
What are the two types of disc arthroplasty
Artificial disc replacement or total disc replacement
What is disc arthroplasty
Surgical procedure in which degenerated intervertebral discs in the spinal column are replaced with artificial devices in the lumbar or cervical spine
Disc arthroplasty used to treat
Chronic to severe low back pain and cervical pain resulting from degenerative disc disease, or for cases of cervical disc herniation
What is a kyphoplasty
Special material injected into fractured vertebral body which then hardens and stabilizes vertebra
What is dynamic stabilization surgery
Surgical technique designed to allow for some movement of the spine while maintaining enough stability to prevent too much movement
Anterior lumbar fusion is done where
On the front (anterior region) of the lower spine
Lumbar fusion is used when patients have symptoms of
Disc degeneration, disc herniation or spinal instability
Lumbar fusion is only indicated for
Recurrent lumbar disc herniations and not primary herniations
What is limbus bone
Disc herniation or migration of the nucleus through a secondary growth center in the anterior superior aspect of the body resulting in a non-union of the anterior superior portion of the body and leaving a free ossicle
What is schmorl’s node
Break in the vertebral end plate and body by the nucleus. A form of disc herniation. Remnants of notochord cells produce weakness in the cartilage end plates, which can lead to herniation of the nucleus pulposis
Schmorls node can lead to
DJD
What is intercalary bone
A free ossicle found between the annular fibers and the ALL, mainly in the cervical spine q
