Human Anatomy Skeletal System: Vertebral Column/Thoracic Cage

Vertebral Column

26 bones, 33 vertebrate some fused

7 cervical (neck) - concave posteriorly curve. Secondary

12 thoracic (chest) - convex posteriorly curve. Primary

5 lumbar (lower back) - concave posteriorl curve. Secondary

5 sacral fused into sacrum - convex posteriorly curve. Primary

4 coccygeal fused into coccyx

Surrounds and protects spinal cord, attachment of ribs and back and chest muscles.

Curves make it more springy

Intervertebral discs

separate individual vertebrae

Nucleus pulposus - gelatinous absorb compressive stress

Annulus fibrosus - outer ligament and inner fibrocartilage. Limit expansion of pulposus. Bind vertebrate to resist tension. Collagen fibers withstand twisting.

absorb shock and compression

can herniate (compression causing nucleus pulposus to protrude and squish nerves/cord) but do not slip (move left/right)

Typical vertebrae

Laminae - complete arch from transverse to spinous process. Posterior.

Pedicle - form side of vetrebral arch. Anterior.

Body - bears weight

Spinous Process - posterior. Attach ligament and muscle to stabilize column.

Transverse process - attach muscle and ligament. Lateral.

Transverse foramen - vertebral artery and veins pass through.

Vertebral foramen - house spinal cord and nerves

Superior articular facet - join vertebrae to more superior ones.

Inferior articular facet - join vertebrae to more inferior ones.

Vertebral notch - u-shaped borders on pedicle. Form intervertebral foramina when vertebrae are stacked.

Intervertebral foramina - hole that spinal nerves pass through.

Atlas

C1

Holds globe

Articulates superiorly w/ occipital condyles on skull to move head up and down.

Articulates inferiorly w/ axis

No body or spinous process

No intervertebral disc

ANterior and posterior arch and tubercle

Axis

C2

Dens (Odontoid process) to act as pivot for skull “no”

Cradled in anterior arch of atlas

Thoracic Vertebrae

Giraffe

Spinous process points inferiorly

Attach ribs

Better for rotation of spine

Lumbar vertebrae

Moose.

Weight-bearing, receives the most stress

Sacrum

Posterior part of pelvis

Forms sacroiliac joint

Coccyx

Tailbone

slight support to pelvic organs. mainly useless

Thoracic Cage

Thoracic vertebrae, ribs, costal cartilage, sternum

Protective cage around heart, lungs, etc.

Support shoulder girdles and upper limbs.

Attachment of back, neck, shoulder, chest muscles and ligaments.

Intercostal spaces hold intercostal ligaments to lift cage while breathing.

Sternum

Flat bone

Manubrium - articulates w/ clavicles, 1st & 2nd ribs

Body - articulates w/ 2nd to 7th ribs

Xiphoid process - hyaline cartilage that fully ossifies at age 40.

Sternal angle - horizontal ridge where manubrium articulates w/ body. Fibrocartilage hinge joint. Allows body to move anteriorly when inhaling. In line w/ disc between 4th and 5th thoracic vertebrate. Lies at level of 2nd rib

Ribs

1-7 = true. Own cartilage

8-10/12 = false. Join cartilage w/ 7 or no cartilage

11,12 = floating. No cartilage

Inferior borders have costal grooves where nerves and vessels are housed.