LIF101 Anatomy

Lecture 3: The Spine and Rib Cage The Spine • A.K.A. vertebral column • Curved column of 24 vertebrae • Functions: – Supports the trunk and head – Surrounds and protects the spinal cord • Four-arch curve – 2 posterior curves – 2 anterior curves – Each curve represents a section of the spine.

Vertebra(e) • Bones that form the spinal column • Vertebra is singular, vertebrae is plural • Size and shape vary, depending on function and load • Three types of vertebrae – cervical (7) – thoracic (12) – lumbar (5) – also: sacrum and coccyx Parts of a vertebra

• Body • Vertebral foramen • 2 transverse processes • 1 spinous process Intervertebral disks

• Disk-shaped pads of cartilage between vertebrae • Serve as cushions/shock absorbers for spine • Allow ﬂexion, extension and some lateral movement • Flatten slightly throughout the day • No intervertebral disk between C1 and C2. Cervical Vertebrae

• Seven vertebrae in the neck • Smallest, lightest vertebrae, with most ﬂexible joints • Provide support and movement of head • C1 = atlas • C2 = axis • C7 = vertebra prominens (a clinical landmark)

Thoracic Vertebrae

• 12 total • Thoracic means “of the thorax” • Have costal facets, for articulation with ribs • Thoracic vertebrae are considered part of both the spine and the thorax.

Lumbar Vertebrae

• 5 total • Lumbar region, a.k.a. “small” of back • Largest, thickest vertebrae; they support the most weight • Also the least ﬂexible vertebrae

The Sacrum and Coccyx Sacrum

• 5 separate pieces of cartilage in infant • These pieces fuse to form one solid bone • Forms posterior wall of pelvis • Eight holes– each is a sacral foramen Coccyx

• A.K.A. tailbone • 4 separate pieces of cartilage in infant • These pieces fuse to form 1 solid bone

Rib Cage

• A.K.A. thoracic cage • Includes ribs, costal cartilage, thoracic vertebrae, and sternum • Protects contents of chest cavity and supports trunk muscles • Two types of joints – Costosternal joints – Costovertebral joints Ribs • 12 pairs of ribs – 7 true ribs – 5 false ribs (including 2 ﬂoating ribs) • Ribs move as a unit to accommodate breathing • Intercostal spaces (spaces between ribs) Sternum

• Lies in anterior midline of thorax • Three parts: – Manubrium (L. handle) – Body – Xiphoid process (L. sword) • Surface landmarks – Jugular notch – Sternal angle (2nd ribs attach here) Xiphoid Process

• Xiphoid means “sword-shaped” • May be bone or cartilage • Located at apex of thoracic arch • Clinical landmark: – Esophagus opens into stomach at this location – Heartburn occurs here. Rib Cage Surface Landmarks

• Jugular notch • Sternal angle • 2nd ribs • Thoracic arch • 10th ribs • Spinous processes of thoracic vertebrae • Some other ribs, depending on location, body position, and other tissues

Review of Spine and Rib Cage Surface Landmarks • Spinous processes of vertebrae (especially C7) • Jugular notch • Sternal angle • Second ribs • Tenth ribs • Other Ribs (false ribs typically easier to see.) • Thoracic arch • Location of xiphoid process • Sternal angle Spine and Rib Cage Quiz: Next Class! • Landmark Book: Pages 18–19 (bone landmarks only) • Diagrams (study these for labeling.) • Note packet • See course web page for relevant blog links. • Practice quiz PIN will be posted.