Describe the types of joints and their associated movements Flashcards
Describe the shoulder joint
The shoulder joint/glenohumeral joint: is the most movable synovial joint and so fairly weak, resulting the most frequent dislocation of joints. Stability is sacrificed for mobility. It is a ball and socket diarthrosis joint, with articulation of the head of the humerus with the glenoid cavity of the scapula.
The somewhat oversized articular capsule allows for the extensive range of motion. The bones of the pectoral girdle provide some stability to the joint but most come from the surrounding skeletal muscles and their associated tendons and ligagments.
The glenoid labrum of the shoulder joint functions to deepen the cavity of the glenoid fossa.
What are the 3 main types of joints
Synarthroses (immovable joints): here the bony edges are very close and may interlock. They are extremely strong joints and occur between bones where movement must be prevented. There are four major types:
Sutures: Found only in the skull, where edges of bone are interlocked and bound with dense connective tissue.
Gomphoses: the bolting together of teeth to the bony sockets in the maxillary bone and mandible. Held together with a periodontal ligament.
Synchondroses: is a rigid cartilaginous bridge between two articulating bones. seen at the first pair of ribs and the sternum.
Synotoses: totally rigid, immovable joint create when two separate bones fuse together and the boundary between them disappear. The metopic suture of the frontal bone and the epiphyseal lines of mature bones are synostoses.
Amphiarthroses (slightly movable joints): permits some movement not as much as a freely movable joint so is stronger. Articulating bones are conntected via collagen fibers or cartilage. There are two main types:
Syndesmosis: bones are connected by ligaments. E.g. the distal articulation between the between the tibia and fibula.
Symphysis: articulating bones are separated by a wedge or pad of fibrocartilage. E.g. between the vertebrae and the two pubic bones.
Diathroses (freely movable joints): or synovial joints permit the widest range of motion. A synovial joint is surrounded by a fibrous articular capsule, and a synovial membrane that lines the walls of the articular cavity. The synovial fluid that fills the cavity originated from the areolar tissue of the synovial membrane . Synovial joints are typically found at the ends of long bones e.g. the upper and lower limbs.
Articular cartilage: articular surfaces do not come into contact with each other as there is articular cartilage covering the faces of the bones at the joint. Provides a slick and smooth surface to reduce friction. The opposing articular cartilage do not touch as there is synovial fluid in-between them. When damaged the matrix begins to break down, the exposed surface will have a rough feltwork of bristly collagen fibers, which increases friction at the joint and disrupts movement.
Synovial fluid: main function of synovial fluid is for lubrication (reducing friction and aiding movement), nutrient distribution (circulating removal of waste and provides nutrients), Shock absorption (distributes compression more evenly across the joint).
The more stable a joint the more restricted its range of motion.
What are the different types of synovial joints
Planar/gliding: have flattened or slightly curved faces
Hinge: permit angular articulation in a single plane
Pivot: are monoaxial and permit only rotation
Ball and socket: the round head of one bone rests in the cup shaped depression of another bone. Aloows triaxial articulation (circumduction, rotation, all angular movement).
Saddle/ sellaris : have saddle shaped articular faces. Each faces in concave on one axis and convex on the other. The opposing faces nest together. Allows angular articulation as well as circumduction but permits rotation.
Ellipsoidal/ condyloid: has an oval articular faces that nestles into a depression in the opposing surface. Allowing angular motion in two planes along the oval or across.
Describe the different types of movement/articulation
Glinding/linear: Nonaxial/multiaxial. This type of joint allows gliding of two opposing surfaces paced each other. They can move in any direction but this movement is slight and rotation is generally prevented by the capsule and associated ligaments. Gliding occurs between carpal and tarsal bones and between the clavicles and sternum.
Angular: monoaxial/biaxial/triaxial. Angular movement involves flexion, extension, hyperextension, abduction, adduction and circumduction.
Flexion and extension: Movement on the anterior/posterior plane. Decreasing and increasing the angle between articulation point respectively. Extension beyond the anatomical position is called hyperextension. This can occur in the spine and the neck but is prevented in joints such as the knees or elbow by ligaments, bony processes or soft tissues.
Abduction away from the longitudinal axis of the body. Adduction is towards the body. This type of movement always refers to the appendicular skeleton not the axial seleton.
Rotation: this could be of the head or rotation of the limbs medial or lateral to the longitudinal axis of the body.
Special movements:
Flexion, extension, hyperextension, abduction, adduction, circumduction.
Head rotation right and left, lateral flexion side ways movement in the vertebral column pronounced in the cervical and thoracic regions
Medial internal rotation, lateral external rotation of the arm
Supernation and pronation of the forearm
Movements of the ankle: inversion, eversion, dorsiflexion, plantar flexion (ankle extension).
Opposition of the fingers in the hand.
Movements of the mandible: retraction, projection, depression, elevation.
Describe the knee joint
The Meniscus (also known as cartilage) is a fibrocartilage in the knee that has a very unique shape, design and purpose. The purpose of the meniscus is act as a shock absorber and space filler between the bones of the knee. The menisci are of a “C” shape which corresponds and is contoured to the surface of the femur.
