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BIOL 1117 Lecture Notes - Synovial Joint, Cartilaginous Joint, Hyaline Cartilage

6 pages86 viewsFall 2013

Department
Biology
Course Code
BIOL 1117
Professor
Christopher Richardson

Page:
of 6
L15-Joints
10/9/13
Joints (Articulations)
ojoint (articulation): any point where two bones meet; degree of mobility
of bones at the meeting point or joint can vary widely
oKinesiology: the study of musculoskeletal movement
a branch of biomechanics: focuses on a broad variety of
movements and mechanical processes in the body, including the
physics of blood circulation, respiration, and hearing
Joints and Their Classification
ojoint name: typically derived from the names of the bones involved
glenohumeral joint (where the humerus meets the glenoid cavity),
radioulnar joint (where radius meets the ulna), atlanto-occipital
joint (where atlas vertebrate meets the occipital condyle)
ofour major joint categories:
fibrous joints
cartilaginous joints
bony joints
synovial joints
oJoints are classified by how the adjacent bones are connected to each other
including the differences in degree of mobility or movement of the bones
Fibrous Joints (Synarthrosis)
ofibrous joint: adjacent bones are connected by collagen fibers that emerge
from one bone and penetrate into the other
othree kinds of fibrous joints
sutures
gomphoses
syndesmoses
Fibrous Joint – Sutures
osutures – immovable or slightly movable fibrous joints that closely bind
the bones of the skull to each other
Fibrous Joint – Gomphoses
ogomphosis – attachment of a tooth to its socket
Fibrous Joint-Syndesmosis
osyndesmosis – a fibrous joint with two bones bound by long collagenous
fibers which give the bones more mobility than other fibrous joints.
odegree of mobility varies
oThe joint between the distal ends of the tibia and fibula is less movable
than the joint between the radius and ulna shafts which is more movable,
which allows for supination to pronation of the forearm
Cartilaginous Joints (amphiarthrosis)
ocartilaginous joint: two bones are connected by cartilage
otwo types of cartilaginous joints
Synchondroses is a joint with the bones bound by hyaline
cartilage; for ex, the temporary joint between the epiphysis and
diaphysis of long bone of a child
Symphyses is a joint with the bones connected by fibrocartilage;
for ex, the joint between two vertebral bodies which are joined by
cartilaginous discs
Bony Joint (Synostosis)
obony joint: an immovable joint formed when the gap between two bones
ossify, and they become in effect, a single bone
ofibrous or cartilaginous joints can ossify.
oHumans are born with right and left frontal and mandibular bones which
soon fuse after birth into one frontal bone and one mandible
oIn older humans, cranial sutures can ossify with age as the suture
disappears with suture line left behind
oThe epiphyses and diaphysis of long bones are joined by cartilage joints
which become bony joints when the epiphyseal plate ossifies
Synovial Joint (Diarthrosis)
osynovial joint: joint in which two bones are separated by a space called a
joint cavity
omost are freely movable
omost structurally complex type of joint
omost likely to develop painful dysfunction
omost important joints for physical and occupational therapists, athletic
coaches, nurses, and fitness trainers
Synovial Joint: General Anatomy
oarticular cartilage: layer of hyaline cartilage that covers the facing
surfaces of two bones
ojoint (articular) cavity: a narrow space that separates articular surfaces
osynovial fluid: slippery lubricant in joint cavity
nourishes articular cartilage and removes waste
viscous, slippery texture also makes the movement of synovial
joints almost friction free
ojoint (articular) capsule: connective tissue that encloses the cavity
outer fibrous capsule: continuous with periosteum of connecting
bones
inner synovial membrane: contains mainly fibroblast-like cells
that secrete synovial fluid and it has macrophages that remove
debris from the cavity
oaccessory structures associated with synovial joints
tendon: a strip or sheet of tough collagenous connective tissue that
attaches muscle to bone; most important structure for stabilizing a
joint.
Remember, outer layer of periosteum of bone provides strong
attachment and good continuity between bone, tendon and muscle.
ligament: similar tissue that attaches one bone to another
bursa: a fibrous sac filled with synovial fluid, located between
adjacent muscles, where tendon passes over bone, or between bone
and skin
Bursa cushions muscles, helps tendons slide more easily
over joints; also modify the direction of tendons pull on the
muscle
tendon sheaths: elongated cylindrical bursae wrapped around a
tendon
Joints and Lever Systems
olever – any elongated, rigid object that rotates around a fixed point called
a fulcrum
olong bones act as levers to enhance the speed or power of limb movements
orotation occurs when an effort applied overcomes resistance (load) with
output force at some other point
resistance arm and effort arm are described relative to fulcrum
Lever Systems
oIn skeletal anatomy, the fulcrum is the joint; the effort applied is applied
by a muscle and the resistance can be an object, the limb itself, or tension
in an opposing muscle
oThe effort is the input force at the point of the effort which generates the
output force through the lever to oppose the resistance force or to act on an
object
Mechanical Advantage
oadvantage conferred by a lever can be of two kinds:
to exert more force against a resisting object than the input force
applied to the lever
to move the resisting object farther or faster than the effort arm is
moved
a single lever cannot confer both advantages
Thus, a single lever cannot simultaneously both move an object
faster and exert more output force on the same object

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