Anatomy & Physiology

Anatomy & Physiology Study Guide

©2018 Achieve Page 102 9.6 Chapter Nine Review An introduction to articulations: • Articulations (joints) exist wherever two bones interconnect. Joints are categorized according to their range of motion or anatomical organization: • Immovable joints are synarthroses, slightlymovable joints are amphiarthroses, and joints that are freely movable are called diarthroses or synovial joints. • Alternatively, joints are classified structurally as bony, fibrous, cartilaginous, or synovial. • The four major types of synarthroses are a suture (skull bones bound together by dense connective tissue), a gomphosis (teeth bound to bony sockets by periodontal ligaments), a synchondrosis (two bones joined by a rigid cartilaginous bridge), and a synostosis (two bones completely fused). • The bony surfaces at diarthroses are enclosed within an articular capsule lined by a synovial membrane. • The two major types of amphiarthroses are a syndesmosis (bones connected by a ligament) and a symphysis (bones separated by fibrous cartilage). Synovial joints are freely movable articulations (diarthroses) containing synovial fluid: • The bony surfaces within a synovial joint are covered by articular cartilages and lubricated by synovial fluid. • Accessory synovial structures include menisci, or articular discs, fat pads, accessory ligaments, tendons and bursae. • A dislocation occurs when articulating surfaces are forced out of position. Anatomical and functional properties of synovial joints enable various skeletal movements: • The possible types of articular movements are linear motion (gliding), angular motion, and rotation. • Joints are called monaxial, biaxial, or triaxial, depending on the planes of movement they allow. • In gliding, two opposing surfaces slide past one another. • Important terms that describe angular motion are flexion, extension, hyperextension, abduction, adduction, and circumduction. • Rotational movement can be left or right, medial (internal) or lateral (external), or, in the bones of the forearm, pronation or supination. • Movements of the foot include inversion and eversion. The ankle undergoes flexion and extension, also known as dorsiflexion and plantar flexion, respectively. • Opposition is the thumb movement that enables us to grasp objects. • Protraction involves moving something anteriorly; retraction involves moving it posteriorly. Depression and elevation occur when we move a structure inferiorly and superiorly, respectively. Lateral flexion occurs when the vertebral column bends to one side. of 368