Lecture 2 - Skeletons Flashcards
Why have a skeleton?
Support
Muscle attachment
Protection for organs
Permit transmission of force
Hydrostatic skeleton
A fluid skeleton in many soft-bodied invertebrates, including annelids, that allows an organism to change shape but not volume.
Pressure generated by muscles
Exoskeletons
thick, hard outer coverings that protect and support animals’ bodies
Endoskeleton
internal skeleton or supporting framework in an animal
Vertebrate skeletons are generally made of?
Cartilage and bone
What makes up the axial skeleton?
skull, vertebral column, ribs, sternum
What makes up the appendicular skeleton?
Pectoral girdle, arm and hand, pelvic girdle, leg and foot
Cartilage skeleton
Cells surrounded by a gel matrix
Bone
Dynamic tissue that continually repairs and remodels itself.
Connective tissue hardened by calcium phosphate
What is bone made up of?
made up of bone tissue, marrow, cartilage and periosteum
Compact bone
Hard, dense bone tissue that is beneath the outer membrane of a bone
Cylinders of tissue around blood vessels
Spongy bone
A layer of bone tissue having many small spaces and found just inside the layer of compact bone.
Formed by trabeculae
Strong but light
Diaphysis
Cylinder of compact bone
Endosteum cells resorb and deposit
Epiphyses
Spongy bone covered with compact bone and cartilage
Where do bones grow?
Bones grow between the ends of the diaphysis and the epiphysis
How does bone grow?
The ends grow first, then the shaft extends
Bone grows by filling in parts
Bone matrix
rigid framework of bone that consists of tough protein fibers and mineral crystals
bone restoration
Through the crystallization of ions from plasma and deposited in the bone
Osteoblasts produce collagen fibers that become encrusted with minerals
How can bone restoration be reversed?
Can be reversed by low pH and acid phosphate - can lead to osteoporosis
How does a bone grow?
The bone first begins as Endochondrial (bone as cartilage)
Then increases in length at ends
Where does the bone increase in width?
Increase in width at periphery with centre dissolved
How does bone respond to forces?
The growth of certain bones will continue to grow during life in response to what is needed.
E.g., a tennis played having very strong bones in it’s right arm
Wolff’s Law
A bone grows or remodels in response to forces or demands placed upon it
Simple wolff’s law
Stressed bone is strengthened, unstressed bone is reabsorbed
Bone Marrow
A soft tissue inside the bone that produces blood cells
Red marrow
Mesh of fibres that produces blood cells
Fatty yellow marrow
Stores fat
Types of joints
Fibrous
Cartilaginous
Bony
Synovial
Fibrous joint
Collagen between bones e.g., sutures of the skull
Immovable and usually strong
Cartilaginous joints
allow only slight movement and consist of bones connected entirely by cartilage e.g., sternum
Most flexible joint
Bony joints
- bones fused by osseous tissue
e. g., mandibles in childhood
Synovial joints
bones separated by fluid-filled joint cavity e.g., knee, elbow
Tendon attaches muscle to bone, ligament attached bone to bone
Synovial joints strength
The strongest joints
Examples of Synovial joints
Ball and socket e.g., shoulder Hinge e.g., knee, elbow Pivot e.g., radius and ulna Saddle e.g., base of thumb Condyloid e.g., fingers Gliding e.g., wrist
Ball and socket joint
-smooth hemispherical head fits within a cuplike depression
-extensive movement, et less stable (dislocation; shoulder)
Multiaxial joint
Hinge joint
convex surface of one bone fits into the concave surface of another
Monoaxial joint
Pivot joints
One bone has a projection that is held in place by a ringlike ligament of another bone
The first bone rotates on its longitudinal axis relative to the other
Monoaxial joint
Condyloid (ellipsoid) joints
Oval convex surface on one bone fits into a similarly shaped depression on the next. e.g., fingers
Biaxial joints
Gliding (plane) joint
Two flat surfaces that slide over each other to allow movement
Non-axial joint
Saddle joints
Two planes of movement, with a small amount of rotation
Similar to ellipsoid joint
