The atlantoaxial joint, between the atlas and axis, consists of three articulations. This moves the head up and down, as when shaking your head “yes.” This allows the skull to rock forward and backward, producing flexion and extension of the head. This articulation has a pronounced U-shaped curvature, oriented along the anterior-posterior axis. The atlanto-occipital joint is formed by the articulations between the superior articular processes of the atlas and the occipital condyles on the base of the skull. The articulations formed between the skull, the atlas (C1 vertebra), and the axis (C2 vertebra) differ from the articulations in other vertebral areas and play important roles in movement of the head. The lumbar region allows for considerable extension, flexion, and lateral flexion, but the orientation of the articular processes prohibits rotation. However, the flattened and vertically positioned thoracic articular processes allow for the greatest range of rotation within the vertebral column. In the thoracic region, the downward projecting and overlapping spinous processes, along with the attached thoracic cage, limit flexion, extension, and lateral flexion. This orientation provides the cervical vertebral column with extensive ranges of motion for flexion, extension, lateral flexion, and rotation. In the neck, the articular processes of cervical vertebrae are flattened and face upward or downward. The cervical and lumbar regions have the greatest ranges of motions. The orientation of the articular processes at these joints varies in different regions of the vertebral column and serves to determine the types of motions available in each vertebral region. ![]() These are plane joints that provide for only limited motions between the vertebrae. In addition to being held together by the intervertebral discs, adjacent vertebrae also articulate with each other at synovial joints formed between the superior and inferior articular processes called zygapophysial joints (facet joints). Anatomical names for most joints are derived from the names of the bones that articulate at that joint, although some joints, such as the elbow, hip, and knee joints are exceptions to this general naming scheme. This section will examine the anatomy of selected synovial joints of the body. In contrast, movements at the hip joint are restricted by strong ligaments, which reduce its range of motion but confer stability during standing and weight bearing. Thus, the ball-and-socket joint of the shoulder has little in the way of ligament support, which gives the shoulder an exceptionally large range of motion. However, the ligaments and muscles that support a joint may place restrictions on the total range of motion available. For example, a multiaxial ball-and-socket joint has much more mobility than a uniaxial hinge joint. The movements that are allowed are determined by the structural classification for each joint. ![]() Describe the structures that support and prevent excess movements at each jointĮach synovial joint of the body is specialised to perform certain movements.Discuss the movements available at each joint. ![]()
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