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Cervical-1
Cervical anatomy & biomechanics
Question | Answer |
---|---|
Craniovertebral Region | - Occipute, atlas, axis & supporting ligs - 25% of vertical height - Injuries here can involve brain, brainstem, spinal cord |
C-S region (vertebrae #s) | C3-C7 |
Facet alignment: C-S | - 45 degrees from frontal & horizontal planes - Allows Flex/Ext - Coupling (SB & Rot) always ipsilat |
Facet alignment: T-S | - 20 to 30 degrees off frontal plane - Allows for side Flex & Rot (less for Flex/Ext) - T10-12: aligns more in sagittal plane allows more flex/ext - Varied coupling |
Facet alignment: L-S | ◦ L-shaped facets ◦ Ideal for Flex/Ext ◦ Resist Rot |
C-S variations bc of diff needs and stresses | - 1st C&T, 5th L, & sacral vert have adaptations needed to join to adjacent structures ◦ Transitional vert: CT, TL, L-S junction (qualities common in 2 regions) - Incr size from cephalad to cauda = need for incr WB - C1 described as a washer |
Typical vs Atypical C vert | - Typical C3-C6 - Atypical C1,C2,C7 |
Articular facets are oriented __________ and permit a ______ ROM. | obliquely, large |
Facet jt: classification & capsular pattern | - Synovial plane jt (diarthrodial) - C,T,L: Side Flex & Rot equally limited, Ext |
OA jt: classification & capsular pattern | - True synovial, with fibroadipose meniscoid. Nearly in horizontal plane - Ext & Rot equally limited (?) |
Ligamentum Nuchae: | -Not really a lig -Powerful anti-shear mechanism due to fiber arrangement -C-S: it's an extension of supraspinous lig -Attachment for post neck mms -Elastic component -> passively assist in head control and return energy to the system |
Cruciate ligs | maintain stability at the occipital-C1-C2 articulations |
Transverse lig | has a thin layer of articular cartilage for dens |
Alar ligs | - Limit Flex & axial Rot of C1 on C2 - Runs sup & laterally attaches med to occipital condyle - Taut in Rot, contralat taut in SB, & resists distraction |
C1 - Atlas | - Meant to transmit forces occiput to rest of spine - No body - No SP -> incr in potential for craniovertebral Ext - Acts as washer: no ms attachment, less lig attachment - Glides contralat with Rot, ipsilat with SB of head |
OA jt | -Nearly horiz, few mm mvt -Kidney shape concave facet for convex occ condyle -Only 1 glide: diagonal -Flex/Ext: Ant roll, post glide (B condyles) ◦ SB/Rot: always contralat coupling. With R Rot, R condyle glides post & L ant, and L SB (never alone) ◦ |
AA jt | - Dens pivots on post arch Atlas - Lat facets are biconvex (C1/C2), tilt with Flex/Ext, inf glide of C1 on C2 with Rot |
Mvt range of nodding motion | 10-30 degrees |
Rot biomechanics | - AA ROM in ipsilat Rot = 45 (32–47) - AA Rot contributes ~55% of total ROM of C region. - Dysfunction of 1st vert will present as significant loss of C Rot - With R Rot, R condyle of C1 glides post & inf, L condyle glides ant & inf (Both inf) |
Lower Cervical Biomechanics | -C IV disc is unique - Clefts in disc develop into Unncovertebral joints (U-Joints) -Both translation and sagittal plane Rot occur in lower C region -C2-6 ipsilat coupling of SB&Rot -Flex: B upslide -Ext: B down slide -R SB: R down slide & L upslide |
OA jt ROMs (Flex, SB, Axial Rot) | - Flex: 15-20 degrees - SB: 9 degees to B sides - Axial Rot of 0 (8 degrees if forced) |
AA jt ROMs (Flex, Ext-limited, SB) | -With Rot, ipsilat condyle slides post, contralat condyle moves ant. Both slide inf along convex surface telescoping head downward -Flex variable. ~10 degrees -Ext limited by ant arch of C1 -Flex limited by tectoral membrane -SB is ~5 degrees |
Rotexion biomechanics | - OA contralat coupled - AA ipsilat coupled - C2/3 ipsilat coupled |
Latexion biomechanics | - OA contralat coupled - AA contralat coupled - C2/3 ipsilat coupled |