Human Spine
Spinal Column (33 verebrae)

• 7 cervical
• Atlas = C1 (sagittal "yes" with occipital)
• Occipito-atlantal joint
• Atlanto-axial joint
• Intervertebral joints are gliding (plane) joints
• Axis = C2 (rotation around dens process)

• 12 thoracic
• 5 lumbar
• 5 sacral (fused = sacrum)
• 4 coccygeal (fused = coccyx)

• Body - weight bearing portion
• Pedicle - attached to body
• Lamina - attached to spinous process
• Vertebral foramen - hole for spinal cord
• Articular process - where vertebrae articulate
• Spinous process -  lumps seen posteriorly

• separates first 24 vertebra
• annulus fibrosus (thick ring)
• nucleus pulposus (watery and substance filled center)
• how affected by aging?

Thorax (ribs and sternum)

• 12 pair of ribs
• 7 true (attach directly to sternum)
• 5 false
• 3 indirectly attach to sternum
• 2 are floating (no anterior attachment)
• Sternum
• Manubrium
• jugular notch (superior manubrium - articulation with clavicles)
• sternal angle (inferior manubrium - equivalent to 2nd rib)
• Body
• Xiphoid process

• Sternocleidomastoid
• Origin - manubrium and medial clavicle
• Insertion - mastoid process
• Action - flexion of head and neck, rotation, and lateral flexion
• Palpation - anterolateral side of neck
• Rectus capitis anterior, Rectus capitis lateralis, Longus capitis, Longus colli, 8 pair of hyoid muscles

• Splenius capitis (O- vertebral processes, I - occipital bone), Semispinalis capitis, Splenius cervicis, Rectus capitis posterior major and minor, Obliquus capitis superior and inferior

• Sternocleidomastoid, levator scapulae, scalenus anterior, cervical flexors, cervical extensors

• Erector Spinae Muscles
• Spinalis (closest to spine)
• Longissimus (middle)
• Iliocostalis (lateral)
• Many others including semispinalis (capitis, cercicis, thoracis), multifidi, rotatores, interspinales, intertranversarii, levatores, costatum

• Rectus Abdominis (parallel to midline)
• Origin - crest of pubis
• Insertion - cartilage 5,6,7 ribs and xiphoiud process
• Internal Obliques (high medial to low lateral)
• Origin - external surface of lower 8 ribs
• Insertion - linea alba
• External Obliques (high lateral to low medial)
• Origin - linea alba and lower 4 ribs
• insertion - iliac crest, lumbordorsal fascia

Chapter 9 Key Terms:

annulus fibrosus (280)	thick, fibrocartilaginous ring that forms the exterior of the intervertebral disc
flexion relaxation phenomenon (298)	when the spine is in full flexion, the spinal extensor muscles relax and the flexion torque is supported by the spinal ligaments
intraabdominal pressure (299)	pressure inside the abdominal cavity; believed to help stiffen the lumbar spine against buckling
kyphosis (284)	extreme thoracic curvature
ligamentum flavum (283)	yellow ligament that connects the laminae of adjacent vertebrae; distinguished by its elasticity
lordosis (284)	extreme lumbar curvature
motion segment (277)	two adjacent vertebrae and the associated soft tissues; the functional unit of the spine
nucleus pulposus (280)	colloidal gel with a high fluid content, located inside the annulus fibrosus of the intervertebral disc
prestress (283)	stress on the spine created by tension in the resting ligaments
primary spinal curves (283)	curves that are present at birth
scoliosis (284)	lateral spinal curvature
secondary spinal curves (283)	curves that do not develop until the weight of the body begins to be supported in sitting and standing positions
spondylolisthesis (303)	complete bilateral fracture of the pars interarticularis, resulting in anterior slippage of vertebra
spondylolysis (303)	presence of a fracture in the pars interarticularis of the vertebral neural arch