BIOL1008 Chapter Notes - Chapter 2: Hyaline Cartilage, Synovial Fluid, Synovial Membrane
7 Jun 2018
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MODULE 2.1. MUSCLES AND JOINTS
2.1.1. Movements about Joints
Angular movements increase or decrease the angle between two adjoining bones in a single
plane (refer to Figure 1, an image of the different types of movement).
Movements and Joints
- Flexion: the bending of a joint, usually reducing the angle that two movable articulated
bones make with each other e.g. elbow/knee/neck (atlas and skull)
- Extension: opposite of flexion – increasing the angle between the bones, usually to a
8 degrees aiu e.g. elbow/knee/neck (atlas and skull)
- Abduction: movement of bone or limb away from median plane of body e.g.
hip/shoulder/metacarpo-phalangeal joints
- Adduction: opposition of abduction – involving approach to median plane of body, or
in the case of the extremities, to the axis of a limb e.g. hip/shoulder/metacarpo-
phalangeal joints
Rotational movements are the movement of a bone around a central axis without any
displacement of that axis. If the anterior surface of a bone such as the humerus moves inward
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(i.e. the lateral aspect is brought towards the anterior position) it is called inward (medial)
rotation. When the anterior surface turns outward it is outward (lateral) rotation.
Rotations
- Medial rotation: pivoting of a body part around its axis in the medial or inward
direction e.g. shoulder/hip/head/vertebra
- Lateral rotation: pivoting of a body part around its axis in the lateral or outward
direction e.g. shoulder/hip/head/vertebra
In circumduction the joint movement delineates a cone. It involves abduction, adduction,
flexion, extension and some rotation. Circumduction happens in hip and shoulder.
2.1.2. Types of Joints
Definition of joint
- A joint is a junction (articulation) between two or more bones
- A fibrous or fixed joint is an immovable joint in which bones are held together by
connective tissue
- Fibrous joints are found where it is important to have joints which do not allow any
movement so that bones can be connected to form rigid, supporting structures
- Example of fibrous joint: between bones of the skull, between teeth and jaws
- A cartilaginous joint allows limited movement. The bones are held together by
interposed cartilage fastened to the bones by connective tissue
- Sites in the body where there are cartilaginous joints: between adjacent
vertebrae/between coxal bones/ribs and sternum
- A synovial joint is a freely moveable joint in which bones are bound together by
ligaments and connective tissue forming a fluid-filled joint cavity. In the joint cavity,
ends of bones are covered in articular cartilage. An outer articular capsule helps to
maintain bone alignment while an elastic synovial membrane secretes and contains
the lubricating synovial fluid
2.1.3. How Muscles Move Joints
Across all joints, muscles are arranged in antagonistic pairs. The contraction of each pair
member results in opposing movements of the joint.
- Which two antagonistic muscles are located on the upper arm? Biceps, triceps
- Which muscle is on the front (anterior surface) of the arm? Biceps
- Which muscle is on the back (posterior surface) of the arm? Triceps
2.1.4. Structure of Synovial Joints
Hinge joint – allows movement in one plane only, e.g. extension and flexion.
- Which bones are involved in the joint of the elbow? Humerus, ulna and radius
- With what structures on the skull does the atlas articulate? Occipital condyles
- What body movement does this joint allow? Nodding of the head
- Name other hinge joints and the bones involved:
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