lan10:joints and muscular

• The bones of the skeleton are attached to one another at joints, or articulations.
• The bones of the skeleton are rigid, movement can occur only at the joints.
• The joints of the body may be classified in two ways -- according to their function and according to their structure.
• levator scapulae - elevates the scapula; pronator teres - turns palm posteriorly; adductor longus - adducts the thigh
• The functional classification of joints is based on the amount of movement that can occur at the joint.
• There are three basic types of joints based on functional activity: synarthroses or immovable joints; amphiarthroses or slightly movable joints; and diarthroses or freely movable joints.
• The structural classification of joints relies on the type of connective tissue which binds the articulating surfaces together and on the presence or absence of a joint cavity.
• There are three structural categories of joints: fibrous joints; cartilaginous joints; and synovial joints.
• In fibrous joints, the articulating bones are firmly bound together by dense fibrous connective tissue.
• These joints are very strong and permit little or no movement.
• A joint cavity is not present in fibrous joints.
• Two major types of joints in this structural division are: sutures and syndesmoses.
• In cartilaginous joints, the articulating bones are bound to each other by cartilage.
• These joints lack a joint cavity and permit little or no movement.
• Two major types of joints in this structural division are: synchondroses and symphyses.
• Most joints in the body are synovial joints.
• The movement of a synovial joint is limited only by ligaments, muscles, tendons, or adjoining bones.
• Synovial joints are characterized as diarthroses, or freely movable joints.
• The articulating bones are separated by a fluid filled joint cavity in synovial joints.
• Articular cartilage (hyaline) covers the surface of the articulating bones in synovial joints.
• Several ligaments support the shoulder joint, including the large coracohumeral ligament between the coracoid process of the scapula and humeral head, which is a thickening of the superior part of the articular capsule.
• The joint between the lateral end of the clavicle and the acromion process of the scapula is a synovial planar joint stabilized by the acromioclavicular ligament and the coracoclavicular ligament.
• The “superstabilizer” tendon of the biceps muscle secures the head of the humerus against the glenoid cavity.
• The flat superior surface of the tibia which is the largest weight-bearing surface in the body, is deepened by two crescent-shaped fibrocartilage pads called the medial and lateral menisci.
• The coracoacromial ligament extends in between the coracoid process and acromion.
• The knee joint is stabilized medially and laterally by the very strong medial tibial collateral ligament and lateral fibular collateral ligament, which extend from the femur to the tibia and fibula, respectively.
• The menisci are attached only at their outer margins and frequently become damaged or torn loose in athletic injuries.
• The glenohumeral ligaments are three thickenings of the anterior part of articular capsule that extend from the glenoid cavity to the lesser tubercle and neck of the humerus and are often indistinct providing only minimal strength.
• The synovial cavity of the knee has a complex shape with at least a dozen bursae associated with this joint.
• Additional stability is added to the knee joint by the presence of the anterior and posterior cruciate ligaments which extend diagonally from the superior surface of the tibia to the distal end of the femur, between the condyles.
• Four bursae are associated with the shoulder joint, which flattened fibrous sacs lined with a synovial membrane and contain synovial fluid to help decrease friction on the shoulder where tendons and muscles cross the joint capsule.
• The knee joint is a modified synovial hinge joint classified as a synovial planar joint because its movements are limited to extension, flexion and some rotation by the surrounding ligaments.
• The glenoid cavity in relation to the large size of the head of the humerus is stabilized by muscles (rotator cuff muscles) whose tendons fuse with the articular capsule to hold the humerus in place.
• The joint cavity in synovial joints is enclosed by an articular capsule, consisting of an outer layer, the fibrous capsule, and an inner layer, formed by the synovial membrane.
• The synovial membrane secretes synovial fluid, which fills the synovial cavity, lubricates the joint, and provides nourishment for the articular cartilage in synovial joints.
• Synovial joints are reinforced and strengthened by band-like ligaments composed of dense regular connective tissue.
• Synovial joints can be divided into six categories according to the shape of the articulating surfaces and the type of movement allowed.
• Number of divisions in the origin of the muscle – if biceps, triceps or quadriceps is part of the name, two, three or four origins/heads occur.
• Skeletal muscles in the body seldom act independently; instead they are arranged in groups which perform specific functions to produce movement at a joint.
• Muscle location – indicates a structure located close by the muscle.