Bio 201 chapter 9 lecture
- 1. 6/10/2014 1 Joint Classifications FibrousJoints CartilaginousJoints Synovial Joints Types of Movements at Synovial Joints Types of Synovial Joints FactorsAffectingContact and Range of Motion at Synovial Joints The structural classification of joints Fibrous joints (bones held together by dense collagen fibers) Cartilaginous joints (bones held together by cartilage) Synovial joints (bones held together by ligaments) The functional classification of joints Synarthrosis (an immovable joint) Amphiarthrosis (a slightly movable joint) Diarthrosis (a freely movable joint)
- 2. 6/10/2014 2 Lack a synovial cavity The articulating bones are held very closely together by dense irregular connective tissue Fibrous joints permit little or no movement Three types of fibrous joints Sutures Syndesmoses Gomphoses Sutures Occur only between bones of the skull Syndesmoses Permits slight movement Interosseous membrane ▪ Between the tibia and fibulain the leg Gomphoses Immovable joint Joint in which a cone-shaped peg fits into a socket Articulations of the teeth with the sockets of the maxillae and mandible Lacks a synovial cavity Allows little or no movement Joint is tightly connected by cartilage Two types of cartilaginous joints Synchondroses Symphyses
- 3. 6/10/2014 3 Synchondroses Connecting tissue is hyaline cartilage Epiphyseal (growth) plate Symphyses Slightly movable joint Ends of the articulating bones are covered with hyaline cartilage, but a disc of fibrocartilage connects the bones Pubic symphysis Between the anterior surfaces of the hip bones Intervertebral joints between the vertebrae Synovial cavity allows a joint to be freely movable Ligaments hold bones together in a synovial joint Articular Capsule A sleeve-likecapsule encloses the synovial cavity The articular capsule is composed of two layers ▪ an outer fibrous capsule ▪ an inner synovial membrane Synovial Fluid The synovial membrane secretes synovial fluid Functions to reduce friction by: ▪ lubricating the joint ▪ absorbing shocks ▪ supplying oxygen and nutrients to the cartilage ▪ removing carbon dioxide and metabolic wastes from the cartilage
- 4. 6/10/2014 4 Accessory Ligaments and Articular Discs Collateral ligaments of the knee joint Anterior and posterior cruciate ligaments of the knee joint Menisci ▪ Pads of cartilage lie between the articular surfaces of the bones ▪ Allow bones of different shapes to fit together more tightly Nerve and Blood Supply Nerve endings convey information about pain from the joint to the spinal cord and brain Nerve endings respond to the degree of movement and stretch at a joint Arterial branches from several different arteries merge around a joint before penetrating the articular capsule Bursae andTendon Sheaths Bursae ▪ Sac-like structures containing fluid similar to synovial fluid ▪ Located between tendons, ligaments and bones ▪ Cushion the movement of these body parts Tendon sheaths ▪ Wrap around tendons ▪ Reduce friction at joints
- 5. 6/10/2014 5 Specific terminology is used to designate the movements that occur at joints Movements are grouped into four main categories: 1) Gliding 2)Angular movements 3) Rotation 4) Special movements Gliding Simple movement back-and-forth and from side-to-side There is no significant alteration of the angle between the bones Limited in range Intercarpal joints Angular Movements Increase or a decrease in the angle between articulating bones Angular movements include ▪ Flexion ▪ Extension ▪ Lateral flexion ▪ Hyperextension ▪ Abduction ▪ Adduction ▪ Circumduction Flexion Decrease in the angle between articulating bones Bending the trunk forward Extension Increase in the angle between articulating bones Flexion and extension are opposite movements Lateral flexion Movement of the trunk sideways to the right or left at the waist Hyperextension Continuation of extension beyond the normal extension Bending the trunk backward Abduction Movement of a bone away from the midline Moving the humerus laterally at the shoulder joint Adduction Movement of a bone toward the midline Movement that returns body parts to normal position from abduction
- 6. 6/10/2014 6 Circumduction Movement of a body part in a circle Moving the humerus in a circle at the shoulder joint Rotation A bone revolves around its own longitudinal axis Turning the head from side to side as when you shake your head “no” Special Movements Elevation Depression Protraction Retraction Inversion Eversion Dorsiflexion Plantar flexion Supination Pronation Opposition
- 7. 6/10/2014 7 Synovial joints are classified based on type of movement Planar Hinge Pivot Condyloid Saddle Ball-and-socket PlanarJoints Primarily permit back-and-forth and side-to-side movements Intercarpal joints Hinge Joints Produce an opening and closing motion like that of a hinged door Permit only flexion and extension Knee and elbow Pivot Joints Surface of one bone articulates with a ring formed partly by another bone Joints that enable the palms to turn anteriorly and posteriorly CondyloidJoints The projection of one bone fits into the oval-shaped depression of another bone Wrist
- 8. 6/10/2014 8 SaddleJoints Articular surface of one bone is saddle-shaped, and the articular surface of the other bone fits into the “saddle” Thumb Ball-and-SocketJoints Ball-like surface of one bone fitting into a cuplike depression of another bone Shoulder and hip Range of motion (ROM) Refers to the range, measured in degrees of a circle, through which the bones of a joint can be moved Factors contribute to keeping the articular surfaces in contact and affect range of motion: Structure or shape of the articulating bones ▪ Shape of bones determines how closely they fit together Strength and tension of the joint ligaments ▪ Ligaments are tense when the joint is in certain positions ▪ Tense ligaments restrict the range of motion Arrangement and tension of the muscles ▪ Muscle tension reinforces the restraint placed on a joint by its ligaments , and thus restricts movement Contact of soft parts ▪ The point at which one body surface contacts another may limit mobility ▪ Movement be restricted by the presence of adipose tissue Hormones ▪ Flexibilitymay also be affected by hormones ▪ Relaxin increases the flexibilityof the pubic symphysis and loosens the ligaments between the sacrum and hip bone toward the end of pregnancy Disuse ▪ Movement may be restricted if a joint has not been used for an extended period
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