Chapter 3 3 Functional Anatomy and Biomechanics Jean Lewis and Clare E. Milner C H A P T E R

Skeletal Anatomy 200 distinct bones Two types Cortical (compact): hard outer layer Trabecular (cancellous): lightweight, lattice-like structure for internal strength (continued)

Skeletal Anatomy (continued) Four classifications of bone Long bones (limbs, digits) (see figure 3.1) Short (tarsals, carpals) Flat (ribs, ilia) Irregular (ischium, pubis, vertebrae) Sesamoid bone: bones embedded in a tendon (patella)

Figure 3.1

Ossification of Bones Begins at diaphysis of long bones Epiphyseal plates: growth areas where cartilage is replaced by bone Additional cartilage is laid down to be replaced by bone during growth Most bones ossify sometime in the late teens Premature losing (shorter bones)

Figure 3.2

Planes and Axes of Movement Rotation is made about 1 or more of 3 axes Mediolateral axis (flexion and extension) Anteroposterior axis (abduction and adduction) Longitudinal (vertical) axis (internal and external rotation) Movement is seen in 1 of 3 cardinal planes Side view (sagittal plane) Front and back view (frontal, or coronal, plane) Top view (transverse plane)

Anatomical Position and Planes of Movement (figure 3.3)

Structure and Function of Joints Synarthrodial (immovable): cranial bones Amphiarthrodial (slight movement) Usually have a disc separating the bones Joints between the bodies of the vertebrae (continued)

Structure and Function of Joints (continued) Diarthrodial (freely moveable) Also called synovial Enclosed by an articular capsule, lined by synovial membrane Connective tissue connecting bone to bone

Factors Determining Direction and Range of Motion Shape of bone at articulating ends Length of ligaments

Specific Joint Movements Flexion Extension Abduction Adduction Internal rotation External rotation

Nontraditional Joint Movements (e.g., shoulder girdle) Elevation Depression Protraction Retraction Upward and downward rotation

Figure 3.4

Figure 3.5

Figure 3.6

Figure 3.7

Figure 3.8

Figure 3.9

Figure 3.10

Figure 3.11

Figure 3.12

Figure 3.13

Figure 3.14

Skeletal (Voluntary) Muscle Consists of muscle fibers and connective tissue Tendon is the passive part of the muscle Size and shape vary, depending on function of muscle

Figure 3.15

Forces That Cause Movement Muscle shortening Depends on force developed against resistance from other forces Gravity

Forces That Resist Movement Gravity Soft tissue restriction Exercise bands Hydraulic or air-pressure devices Resistance of training equipment Drag of air or water

Muscle Action Concentric Shortening Causes movement Eccentric Length increases under tension Slows movement Agonist Prime movers that cause joint movement Antagonist Muscles that lengthen during concentric action (continued)

Figure 3.16

Muscle Action (continued) Ballistic movements Resistance is minimal Burst of concentric action Isometric action Static (muscle exerts force equal in magnitude to opposing force) Little or no change in muscle length; no movements

Figure 3.17

Role of Muscles Cause movement Decelerate movement Stabilize or prevent movement Counter undesirable movement Guide movements

Figure 3.18

Figure 3.19

Figure 3.20

Figure 3.21

Figure 3.22

Figure 3.23

Figure 3.24

Figure 3.25

Figure 3.26

Figure 3.27