THE TRUNK and SPINAL COLUMN Chapter 12 Bones

THE TRUNK and SPINAL COLUMN Chapter 12

Bones of the Spinal Column 33 bones, 24 are flexible A. Cervical - 7 B. Thoracic - 12 C. Lumbar - 5 D. Sacrum - 5 (false vertebrae - fused together) E. Coccyx - 4 (false vertebrae - fused together) n LINK Click on picture

Landmarks of the Vertebrae

General Landmarks 1. Spinous process 3. Transverse process - tubercle of rib articulates 5. Body 6. Vertebral foramen

General Landmarks n Vertebral notch ¨ Superior ¨ Inferior

General Landmarks n Intervertebral foramen

Cervical Vertebrae

Cervical Vertebrae n n First 7 vertebrae Identified as C 1 – C 7 C 1 = Atlas C 2 = Axis

Atlas (C 1) 1. 2. Large vertebral foramen Transverse ligament Anterior Posterior

Axial (C 2) 1. Odontoid process or Dens

Thoracic (T 1 -T 12)

Lumbar (L 1 -L 5)

Note the differences: 1. Transverse process 2. Spinous process 3. Body

Sacrum

Intervertebral Disks

Actions of the Spinal Column Flexion n Extension n Lateral Flexion n Rotation n ¨ Same side ¨ Opposite side

Flexion Cervical flexion 1. Free in all three regions 2. Cervical and thoracic curves may be reduced to straight lines 3. Lumbar curve may be reversed in flexible subjects Lumbar flexion

Extension Cervical extension 1. Free in all three regions 2. Cervical and thorasic curves may be reduced to straight lines 3. Lumbar curve may be reversed in flexible subjects Lumbar extension

Cervical lateral flexion Lateral flexion 1. Free in cervical and lumbar regions 2. Limited in thorasic region by rib attachments 3. Accompanied by torsion Lumbar lateral flexion

Rotation Cervical rotation 1. Freest at top, least free at bottom 2. Accompanied by slight lateral flexion Lumbar rotation

Joints of the Spinal Column

Atlantooccipital joint n Articulation between the head and neck ¨ i. Atlas (C 1) ¨ ii. Occipital bone n n Acts as a hinge joint; flexion and extension No rotation at this joint

Atlantoaxial n n Articulation between C 1 and C 2 a. pivot joint - rotation is here b. the dens or ondontoid process fits into the inner, anterior portion of the vertebral foramen with the help of the transverse ligament.

Arthordial or gliding-type joints n Composed of the synovial joint between superior and inferior articulating surfaces

Cartilaginous or synarthrodial joints n Intervertebral disks i. nucleus pulposus - gel ¨ ii. annulus fibrosus - covering ¨ n n n Shape and thickness varies with location Make up approximately 25% of the column length Allow limited motion in all three planes

Defects of the Spine

Kyphosis - hunchback n Increase anterior concavity ( or curvature) of the thoracic curve

Lordosis - swayback n Increase posterior concavity of the lumbar region. ¨ it causes shortened back extensors ¨ it causes lengthened abdominal

Scoliois n n n Lateral curvatures or sideward deviations of the spine. Decreases the ability of the spin to support the body Distorts the body cavity and that crowds the organs Puts pressure on the nerves Causes: ¨ Imbalance of the deep back muscles and ligaments

Scoliois n Treatment ¨ Body cast ¨ Electrical stimulation of deep muscles ¨ Harrington Rod implant - ratchett effect

Sternum

Ribs 12 pairs n 7 pair are ‘true’ ribs n 5 pair are ‘false’ ribs n 3 pair attach indirectly to the sternum ¨ 2 pair are ‘floating ribs’ that don’t attach to the sternum ¨

Ribs