Upper Cervical Spine Anatomy & Biomechanics Flashcards
anatomy of OA Joint
-concave articular facets for the articulation with the convex occipital condyles
anatomy of AA joint
-inferior articular facets (convex) articulate with the axis (C2)
other name for C1
atlas
other name for C2
axis
anatomy of atlas (C1)
-lacks a body; consists of an anterior & posterior arch connected by a lateral mass
AA joint anatomy
-superior articular facets (convex) articulate with inferior articular facets of C1 (convex) - stabilized by ligaments
How are the inferior articular facets shaped?
-as rest of the C-spine (45 degrees to the horizontal)
primary motions at OA joint
-flexion/extension motion (“yes joint”)
primary motions at AA joint
-rotation
Innervation of anterior & posterior suboccipital muscles, dura of posterior cranial fossa, the AO joint, the AA joint, the C2-3 facet joints, all ligaments, SCM, upper trap, & the vertebral arteries?
- dorsal & ventral rami of C1-C3
- pain can arise from any of these structures
transverse foramen
- foramen for the vertebral artery which lies anterior to the gutter
- present from C1-C6
- subject to degenerative changes
What anatomical structure(s) provide the primary stabilization for the UCS region?
-ligaments (atlas to occiput, transverse ligament, alar ligaments)
transverse ligament
- atlas to axis
- passes behind dens, stabilizing dens in contact with the atlas, controlling ant-post movement at the AA joint
If the transverse ligament were cut what would happen?
-the atlas displaces forward 7 mm
alar ligaments
- run from lateral margins of the foramen magnum to the tip of the odontoid
- very thick, strong ligaments
What happens to the dens if the alar ligaments were to rupture?
-the dens would fracture
tectorial membrane
-continuation of the PLL
apical ligament
-runs from odontoid to the anterior margin of the foramen magnum
rectus capitis posterior major attachment
-C2 spinous process to lateral aspect of nuchal line
rectus capitis posterior major function
-bilaterally extends the head; unilaterally produces ipsilateral side flexion & rotation
rectus capitis posterior minor attachment
-C1 to medial aspect of nuchal line
rectus capitis posterior minor function
-extension of head & minor contribution to ipsilateral side-flexion
superior oblique attachment
-C1 transverse process to lateral aspect of nuchal line
superior oblique function
-bilaterally extends head, unilaterally produces ipsilateral side-flexion & contralateral rotation
inferior oblique attachment
-C2 spinous process to C1 transverse process
inferior oblique function
-produces ipsilateral rotation
rectus capitis anterior attachment
-muscle runs deep to the longus capitis from the lateral mass of the C1 to the base of the occiput
rectus capitis anterior function
-produces flexion of the head & minimum assistance with rotation
rectus capitis laterals attachment
-from superior surface of the C1 transverse process to the inferior surface of the jugular process of the occiput
rectus capitis lateralis function
-ipsilateral side flexion of the head
deep cervical flexors (longus colli) attachment
-from TP (1-5) & articular processes of C4-C7 to mastoid process
deep cervical flexors (longus colli) function
-neck flexion
UCS forward bend/retraction biomechanics?
- convex occipital condyles roll anterior & glide posteriorly on concave atlas
- atlas tilts around its axis (atlas glides forward & tilts anteriorly), ultimately causing C2 to glide forward on C3
OA biomechanics in forward bend/retraction?
-occiput flexes on atlas about 15 degrees
AA biomechanics in forward bend/retraction?
-minimal flexion - atlas tilts anteriorly, separating atlas from dens about 3 mm
UCS biomechanics of backward bend/protraction?
- convex occipital condyles roll posterior & glide anteriorly on concave atlas
- atlas tilts around its axis (atlas glides backward & then tilts posteriorly), ultimately causes C2 to glide backwards on C3
OA biomechanics in backward bend/protraction?
-occiput extends on atlas about 25 degrees
AA biomechanics in backward bend/protraction?
-minimal extension - atlas tilts posteriorly & slides up dens very slightly
Osteokinematics of UCS during rotation (R rotation)?
- occiput rotates right creating tension on both alar ligaments which rotates C2 to the R. Occiput sidebends (L) due to convex-concave rule.
- atlas rotates (R) with occiput but sideglides (L) in response to the (L) sidebending of occiput & the wedge shape of the lateral bodies of the atlas
Rotation arthrokinematics of OA joint (using R rotation as example)?
-(R) & (L) occipital condyles (L) roll & (R) glide
Rotation arthrokinematics of AA joint (using R rotation as example)?
-(R) atlas posterior glide on axis (L) atlas anterior glide on axis
UCS osteokinematics of side bending?
- occiput sidebends (R) creating tension in the (L) alar ligament which rotates C2 to the right
- (R) sidebending at occiput induces (L) rotation of the atlas due to the convex-concave rule however due to the wedge shape of the atlas, it side glides slightly to the (R)
OA arthrokinematics in side bending?
-(R) occipital condyle posterior rotation & anterior glide (L) occipital condyle anterior rotation & posterior glide
AA arthrokinematics in side bending?
-(R) atlas anterior glide on axis (L) atlas posterior glide on axis
Coupled movement with rotation?
- cervical R rotation results in R rotation & L side bending at occiput & C1
- all vertebrae from C2 down are rotated R & sidebent R; opposite occurs to the L
Coupled movements in sidebending?
-occiput & C1 move together; cervical R side bending results in R side bending & R rotation from C2 down; occiput & C1 will rotate to the L
