Bones make good fossils.

Chapter 6

1) Bones make good fossils. While the soft tissue of a once living organism will decay and fall away over time, bone tissue will, under the right conditions, undergo a process of mineralization, effectively turning the bone to stone. A well-preserved fossil skeleton can give us a good sense of the size and shape of an organism, just as your skeleton helps to define your size and shape. Unlike a fossil skeleton, however, your skeleton is a structure of living tissue that grows, repairs, and renews itself. The bones within it are dynamic and complex organs that serve a number of important functions, including some necessary to maintain homeostasis.

2)functions of the skeletal system into 2 groups (physical and metabolic)

Physical function

· Support – holds your vital organs in place when playing sport. The vertebral column holds the body upright.

· Movement – muscle are attached to bones, which are jointed. When the muscles contract the bones move.

· Shape – gives shape to the body and makes you tall or short.

Metabolic function

· Protection – the cranium and ribs protect the brain and vital organs in the chest.

· Blood production – red blood cells (to carry oxygen) and white blood cells (to protect against infection) are produced in the bone marrow of some bones.

3)3 types of bone cells and their functions

· Osteoblasts -secrete matrix (mineral salts and collagen) holds everything together form new tissue

· Osteoclasts -bone remodeling, healing, release calcium into blood

· Osteocyte -mature bone cells trapped in their own matrix deeper in compact bone

4)Sketch and label of a typical long bone


Bone type

Function and description

Example of bones in this category

Long bones

are longer than they are wide, i.e. length > diameter.

They consist of a shaft – which is the main (long) part and variable number of endings (extremities), depending on the joints formed at one or both ends of the long bone. Long bones are usually somewhat curved – contributing to their mechanical strength.





Short bones

can be approximately cube-shaped, i.e. length is similar to width / depth / diameter.

The most obvious examples are the carpal (of the hands / wrists) and the tarsal (of the feet / ankles) bones.





Flat bones

have a thin shape and, in some cases, provide mechanical protection to soft tissues beneath or enclosed by the flat bone e.g. cranial bones that protect the brain. Flat bones also have extensive surfaces for muscle attachments e.g. scapulae (shoulder) bones.




7 types of synovial joints;

· Planar joints have bones with articulating surfaces that are flat or slightly curved. These joints allow for gliding movements; therefore, the joints are sometimes referred to as gliding joints. The range of motion is limited and does not involve rotation. Planar joints are found in the carpal bones in the hand and the tarsal bones of the foot, as well as between vertebrae.

· In hinge joints, the slightly-rounded end of one bone fits into the slightly-hollow end of the other bone. In this way, one bone moves while the other remains stationary, similar to the hinge of a door. The elbow is an example of a hinge joint. The knee is sometimes classified as a modified hinge joint.

· Pivot joints consist of the rounded end of one bone fitting into a ring formed by the other bone. This structure allows rotational movement, as the rounded bone moves around its own axis. An example of a pivot joint is the joint of the first and second vertebrae of the neck that allows the head to move back and forth. The joint of the wrist that allows the palm of the hand to be turned up and down is also a pivot joint.

· Condyloid Joints – consist of an oval-shaped end of one bone fitting into a similarly oval-shaped hollow of another bone. This is also sometimes called an ellipsoidal joint. This type of joint allows angular movement along two axes, as seen in the joints of the wrist and fingers, which can move both side to side and up and down.

· Saddle Joints-Each bone in a saddle joint resembles a saddle, with concave and convex portions that fit together. Saddle joints allow angular movements similar to condyloid joints, but with a greater range of motion. An example of a saddle joint is the thumb joint, which can move back and forth and up and down; it can move more freely than the wrist or fingers.

· Ball-and-socket joints possess a rounded, ball-like end of one bone fitting into a cup-like socket of another bone. This organization allows the greatest range of motion, as all movement types are possible in all directions. Examples of ball-and-socket joints are the shoulder and hip joints.

9)Sketch and label the major components of a synovial joint

10) ​Point out and/or identify the following joints:

Related image


Flexion – occurs when the angle between the bones decreases. Moving the forearm upward at the elbow or moving the wrist to move the hand toward the forearm are examples of flexion.

Extension – angular movement in which the angle between the bones of a joint increases.

Adduction – is the movement of a bone toward the midline of the body.

Abduction -occurs when a bone moves away from the midline of the body

Rotation – is the movement of a bone as it rotates around its longitudinal axis.

Pronation – the action of rotating the forearm so that the palm of the hand is turned down or back

Supination – the action of rotating the forearm so that the palm of the hand is turned up or forward