Lesson 18: Spine Joint Actions & Trunk Muscles

by Brent Brookbush DPT, PT, MS, PES, CES, CSCS, ACSM H/FS

The Spine - Number of Vertebrae, Curves, Joint Type and Actions

Color coated illustration of the spine, with vertebrae labeled from sacrum to cervical spine. General Anatomy of the Spine - By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body, invalid ID (See "Book" section below)Bartleby.com: Gray's Anatomy, Plate 111altered by User:Uwe Gille, Public Domain, https://commons.wikimedia.org/w/index.php?curid=1282158

The Spine

  • Cervical Vertebrae – The 7 vertebrae of the neck.

    • Lordotic Curvature
  • Thoracic Vertebrae – The 12 vertebrae with bony attachments to the 12 pair of ribs.

    • Kyphotic Curvature
  • Lumbar Vertebrae – The 5 vertebrae of the low back

    • Lordotic Curvature

Teaching Cues:  

  • Letter Association

    • Low back, Lumbar Spine, Lordotic Curve
  • Breakfast, Lunch and Dinner

    • 7am, 12noon & 5pm (7 cervical, 12 thoracic, and 5 lumbar vertebrae)

The facet (zygapophysial) joints: of the spine are "gliding joints", allowing a small amount of motion in various directions.  The large amount of movement we see from the spine is actually the summation of small amounts of motion at dozens of little joints.    See the activity below for more on what joint actions the spine can perform.

Trunk Muscles 

Study GuideQuick Reference - Trunk Muscles

Note: If you intend to do the activities below do not open the "Study Guide" - all the answers are already filled in.  The study guide is just a quick reference tool, similar to flash cards.  Great for last-minute prep' before an exam.

What joint do these muscles cross?

These muscles have attachments on the on the ribs, spine and pelvis, and will play a role in motion of the lumbar spine (a.k.a. trunk). Before we analyze each muscle, take a moment to