Module A
The Skeletal System and its Articulations
 

Page 22: Questions # 1, 3, 4, 5, 6 [answers in bold print]

1.    Using the skeleton shown in Figure A.9, identify by name the bones important to human movement analysis.  (Exclude individual bones of the skull, the hand , and the bones distal to the calcaneus in the foot.)

        sternoclavicular         sternum            clavicle
        shoulder                     scapula             humerus
        elbow                          humerus           ulna
        radiounlnar                radius                ulna
        wrist                           ulna-radius        carpals

3.    Discuss potential damaging effects on young musculoskeletal structures with excessive weight training.

Micro tears in susceptible tissues, as well as the risk of strong muscle contractions pulling away its tendinous attachment to the bone, are hazards inherent in intense weight training programs.

4.    Define and cite an example in human movement of compression, tension, torsion, and shear forces

Vertebrae compress the intervertebral discs upon takeoff and landing during running and jumping; the articular ligaments of the elbow are put on tension upon lifting a heavy suitcase; transverse rotation of the thorax causes torsion on the intervertebral disks during a softball batting swing; the fifth lumbar vertebra tending to slide forward and downward exerts a shear force on the sacrum.

5.    Define the properties of stability and mobility of an articulation.

A joint's stability is its ability to absorb shock and withstand motion without injury.  A joint's mobility is the ease with which it is allowed to move before being restricted by surrounding structures.

6.    List four limiting factors to the range of motion of an articulation and cite an example in the human body.

Factors limiting the ROM of an articulation are bony contact (closing the jaw), musculotendinous inflexibility (inability to extend knee with hip flexed), contacting muscle tissues (squatting till the hamstring muscles contact the gastrocnemius), restrictive clothing (running wearing tight pants).