1.2 Osteology and Arthrology of the Neck Flashcards
What is the upper cervical spine?
C0-C1 through C1-C2
What is the lower cervical spine?
C2-3 through C6-C7
What are the joints of the vertebral bodies?
- Interbody joints
- Uncovertebral joints
What are the joints of the vertebral arches?
Zygophphyseal joints
What are the joints of the upper cervical spine?
- Atlanto-occipital joint (C0-C1)
- Atlanto-axial joints (C1-C2)
Joint type for interbody joints
- Symphysis
- Secondary cartilaginous joint
Function of interbody joint
- Weight bearing
- Shock absorbing
Articulating surfaces
- Inferior and superior vertebral bodies
- Connected by IV discs and ligaments
Parts of the IV disc
- Annulus fibrosus
- Nucleus pulposus
Annulus fibrosus
- Made up of concentric rings
- Insert onto the epiphyseal rims of vertebral bodies
Nucleus pulposus
- 85% water at birth
- Acts as a semifluid fulcrum
- Dehydrates with age
Movements of the interbody joint
- Flexion
- Extension
- Lateral flexion
- Rotation
Ligaments for the interbody joints
- Anterior longitudinal ligament
- Posterior longitudinal ligament
Anterior longitudinal ligament
Resists extension
Where does the ALL attach?
Connects w/ anterolateral aspects of vertebral bodies and IV discs
Posterior longitudinal ligament
Resists flexion
Where does the PLL attach?
Attaches mostly to the IV discs on posterior side of vertebrae
How does the PLL compare to the ALL?
More narrow and weaker compared to ALL
How innervated is the PLL?
Well innervated w/ nociceptors
Where are the uncovertebral joints found?
- B/t the uncinate processes of the C3-C6 vertebrae
- Lateral and posterolateral margins of IV discs
Describe what is unique about the articulating surfaces of the uncovertebral joints?
- Covered cartilage
- Enclose a fluid-filled cavity
What is the clinical significance of the uncovertebral joints?
Frequent site of bone spurs, causing neck pain
What type of joints are the zygapophyseal joints?
Synovial plane
What are the articulating surfaces of the zygapophyseal joints?
Superior and inferior articular facets of the articular processes
Describe the orientation of the articular facets in zygapophyseal joints
- Superior face anterior/inferior
- Inferior face posterior superior
Describe the joint capsule for the zygapophyseal joints
Loose
Movements of the zygapophyseal joints
Flexion, extension, lateral flexion, and rotation
Why are the zygapophyseal joints in the cervical spine so free?
- IV discs are thick relative to vertebral bodies
- Facet joint articular surfaces are large
- Joint planes are nearly horizontal
- Joint capsules in facet joints are loose
- Neck is slender, less surrounding soft tissue bulk
Where do the innervation of the zygopophyseal joints come from?
Articular branches coming from medial branches of posterior rami
What are the ligaments of the zygopophyseal joints?
- Ligamentum flavum
- Interspinous ligament
- Nuchal ligament
Where is the ligamentum flavum found?
Binds lamina from above to below
Function of ligamentum flavum
- Resist separation of the vertebral laminae through abrupt flexion
- Preserve posture
- Assist with straightening the column after flexing
Where are the interspinous ligaments found?
- Connects interspinous processes
- Articulates with superior and inferior aspects of spinous process
What is the nuchal ligament?
Strong median ligament of neck
What is the nuchal ligament made of?
Fibro-elastic tissue
What are the attachments for the nuchal ligament
- Supraspinous ligament merges superiorly w/ nuchal ligament
- External occipital protuberance and posterior border of foramen magnum
- Spinous process of cervical vertebrae
Function of nuchal ligament
Substitutes for muscular attachments for spinous processes of C3-C5 (they’re way small)
Atlanto-occipital joint (CO-1) type
Synovial condyloid
Articulating surfaces of atlanto-occipital joint
Lateral masses of C1 (atlas) and occipital condyles
Describe the joint capsule of atlanto-occipital joint
Thin and loose
Movements of the atlanto-occipital joints
- Nodding the head (flexion and extension), like the “yes” movement
- Little lateral flexion and rotation
Ligaments of the atlanto-occipital joints
- Anterior atlanto-occipital membrane
- Posterior atlanto-occipital membrane
Attachments of anterior atlanto-occipital membrane
From anterior arch of C1 to anterior margin of foramen magnum
Attachments posterior atlanto-occipital membrane
From posterior arch of C1 to posterior margin of foramen magnum
What are the atlanto-axial joints (C1-2)
- Lateral atlanto-axial
- Median atlanto-axial joint
Lateral atlanto-axial joint type
Synovial plane
Articulations of Lateral atlanto-axial joint
- Lateral masses of C1
- Superior facets of C2
Capsule of Lateral atlanto-axial joints
-
Movements of atlanto-axial joints
Rotation of head, “no” movement
Median atlanto-axial joint Type
Synovial pivot
Articulating surfaces of Median atlanto-axial joint
- Dens of C2
- Anterior arch and transverse ligament of C1
Capsule of Median atlanto-axial joint
-
Movements of Median atlanto-axial joint
Rotation of head, “no” movement
How is the dens of C2 held in place anteriorly?
Anterior arch of atlas
How is the dens of C2 held in place posteriorly?
Transverse ligament of the atlas
Ligaments of the atlanto-axial joint
- Cruciate ligaments
- Alar ligaments
- Tectorial membrane
Cruciate ligaments of the atlanto-axial joint
- Transverse ligament
- Longitudinal bands
Transverse ligament of the atlas attachments
B/t tubercles on medial aspect of lateral masses of C1
Attachment for superior longitudinal band
From transverse ligament to occipital bone
Attachment for inferior longitudinal band
From transverse ligament to body of C2
How does the strength of the longitudinal bands compare to the transverse ligament?
Weaker
Where do the alar ligaments attach?
From sides of the dens to lateral margins of foramen magnum
Function of the alar ligaments
“Check ligaments”, preventing excessive rotation
What is the tectorial membrane
Strong superior continuation of PLL
Where does the tectorial membrane attach?
Across median atlanto-axial joint through foramen magnum to central floor of cranial cavity
Describe the course of the tectorial membrane
From body of C2 to internal surface of occipital bone
What does the tectorial membrane cover?
Covers alar and transverse ll. of atlas
What is an often MOI for fracture and dislocation of atlas?
Vertical forces like hitting bottom of pool in a dive
What does the fracture and dislocation of the atlas do?
Compresses lateral masses b/t occipital condyles and axis
What happens if the force of the atlas fracture/dislocation is sufficient?
- Rupture transverse ligament
- AKA Jefferson fracture
What happens to the spinal cord with a fracture/dislocation of the atlas?
Does not mean there will be a spinal cord injury, but more likely if the transverse ligament is injured
When does a vertebral dislocation occur?
If force is insufficient for frature
Describe the effect of a vertebral dislocation on the spinal cord
Slight dislocations can occur in cervical spine w/o injury to spinal cord b/c of large central canal
What ligament is most directly impacted with hyperextension of the neck?
- AKA whiplash
- ALL may be severely stretched/torn
What happens with a rupture of the transverse ligament of atlas?
Dens is set free, results in atlanto-axial subluxation
What could happen if there is complete dislocation of the atlanto-axial joint?
- Dens may be driven into upper cervical region of spinal cord, causing quadriplegia
- If into the medulla of brainstem → death
Which is weaker, the alar or transverse ligament?
alar ligament
What causes the rupture of the alar ligament?
Flexion + rotation may tear one or both
What is the effect of an alar ligament rupture?
Increased ROM of 30% to opposite side
