Axial Skeleton Flashcards
Ligamentum Flavum
Limits and “softens” end range intervertebral flexion
Supraspinous and interspinous ligaments
Limit Flexion
Intertransverse Ligaments
Limits contralateral lateral flexion and forward flexion
Anterior longitudinal Ligament
limits extension or excessive lordosis in the cervical and lumbar regions; reinforces the anterior sides of the intervertebral discs
Posterior Longitudinal ligament
Limits flexion; reinforces the posterior sides of the intervertebral discs
Capsules of the apophyseal joints
Strengthen the apophyseal joints
Cervical Spine Coupled Motion Rule
C2-C7: Ipsilateral coupling
Thoracic Spine Coupled Motion Rule
T1 & T2 follow cervical rule
T3-T7 have contralateral coupling
T8-T12 follow lumbar rule
Lumbar Spine Coupled Motion Rule
When extended (Contralateral coupling)
When flexed (Ipsilateral coupling)
Role of Annulus Fibrosus
contains Nucleus Pulposus and provides resistance to tension. Enhances spines rotational stability
Role of Nucleus Pulposus
provides spine with shock absorption during movement.
Anterior Pelvic Tilt
Extends the lumbar spine and increases lordosis. This action tends to shift the nucleus pulposus anteriorly and reduces the diameter of the intervertebral foramen.
Posterior Pelvic Tilt
Flexes the lumbar spine and decreases the lordosis. This action tends to shift the nucleus pulposus posteriorly and increases the diameter of the intervertebral foramen.
Thoracic spine close packed position
extension
Transverse and Spinous Processes
provide mechanical outriggers, or levers, that increase the mechanical leverage of muscles and ligaments.
Apophyseal joints
primarily responsible for guiding intervertebral motion, much as railroad tracks guide the direction of a train.
Interbody joints
primary function of these joints is to absorb and distribute loads across the vertebral column
Atlanto-Occipital Joint
provides independent movement of the cranium relative to the atlas (C1). Two Degrees of freedom.
Transverse ligament of the atlas
essential to the horizontal plane stability of the atlanto-axial articulation, without it, the atlas can slip anteriorly and damage the spinal cord.
Tectorial membrane
the ligament likely provides generalized multidirectional stability to the craniocervical junction.
Alar Ligaments
also known as ”check ligaments”, ability to resist, or check, axial rotation of the head-and-atlas relative to the dens. It is relatively loose in the anatomical position but becomes increasingly taut during axial rotation.
Atlanto-Axial Joint
two articular components: a median joint and a pair of laterally positioned apophyseal joints.
Allows 2 degrees of freedom, horizontal rotation and flexion/extension.
Thoracic Spine Flexion
30-40 degrees
Thoracic spine extension
15-20 degrees
thoracic spine rotation
25-35 degrees
Thoracic spine lateral flexion
25-30 degrees
Sacroiliac Joint
Auricular surfaces (sacrum, ilium), transfer forces between LE and thorax, very little motion
Anterior SI ligament
thickening of the anterior and inferior regions of the capsule, stabilizer of the SI joint.
Interosseous Ligament
strongest ligament of the SI joint.
Short and long posterior SI ligament
Stability, prevent forward tilting of the sacral promontory.
Sacrospinous Ligament
assist in pelvic stability. The ligament works with the sacrotuberous ligament to prevent rotation of the illum past the sacrum
Sacrotuberous Ligament
assists in pelvic stability, prevents the sacrum from tipping forward when downward pressure is applied to the spine.
Nutation
Sacrum rotates anteriorly relative to ilium
Nutated = close packed SIJ
Counternutation
Sacrum rotates posteriorly relative to ilium
Function of the sacroiliac joint
(1) a stress relief mechanism within the pelvic ring and (2) a stable means for load transfer between the axial skeleton and lower limbs.
Dorsal Nerve Root
contain primarily ”incoming” (afferent) dendrites, with the cell body of the neuron located in an adjacent dorsal root ganglion.
Ventral Nerve Root
contains primarily “outgoing” (efferent) axons that supply motor commands to muscles and other effector organs associated with the autonomic nervous system.
Dorsal Ramus
forms nerves that innervate, in general, the muscles, joints, and skin of the posterior trunk and neck.
Ventral Ramus
forms nerves that innervate, in general, the muscles, joints, and skin of the anterior-lateral trunk and neck, and the extremities.
Trapezius Action
Descending part elevates scapula, ascending part depresses scapula, middle retracts scapula. Descending and ascending parts act together to rotate the glenoid cavity superiorly
Latissimus Dorsi Action
Extends, adducts, and internally rotates the humerus
Levator Scapulae Action
elevate scap, rotates glenoid cavity inferiorly by rotating scapula
Rhomboids
Retracts the scap, rotates glenoid cavity inferiorly
Serratus Posterior Superior and Inferior Action
Proprioceptive, superior muscle elevates ribs while the inferior portion depresses the ribs.
Serratus Anterior
protracts the scapula
Erector Spinae Muscles
extends spine, laterally flexes
Semispinalis Muscles
Extension and contralateral rotation of the head, cervical, and thoracic regions
Scalenes muscle action (anterior, middle, posterior)
Anterior and middle portions elevates first rib and bends neck, posterior portion elevates 2nd rib and bends neck
Longus Colli action
Resists lordosis (ant fibers), vertical stabilizer (lat fibers)
Longus capitis
Flexes head
Rectus capitis anterior
flexes head at AO
Rectus capitis lateralis
flexes head laterally to same side at AO
Sternocleidomastoid
Bilaterally: mid/lower cervical flexion, slight upper cervical extension
Unilaterally: Contralateral rotation, ipsilateral lat-flexion
Rectus capitis posterior major action
extends and rotates head to same side
Rectus capitis posterior minor action
Extends head
Obliquus capitis inferior action
rotates atlas to turn face to same side
Obliquus capitis superior action
extends and bends head laterally
Quadratus Lumborum action
Extensor bilaterally and lateral flexor unilaterally
