2. WHAT WE WILL COVER
• Skeletal system: cartilage and bones.
• Classification of bones and joints
3. SKELETAL SYSTEM
• The skeletal system is divided into two
functional parts. This is the Axial skeleton
and the appendicular skeleton.
• 1. axial skeleton = consists of the bones of
the head, neck, and trunk. The head refers
to the cranium or skull, the neck refers to
the hyoid bone and cervical vertebrae and
the trunk is the ribs, sternum, vertebrae
and sacrum.
• 2. appendicular skeleton = consists of the
bones of the limbs, including those
forming the pectoral (shoulder) and pelvic
girdles.
4. CARTILAGE AND BONES
• The skeleton is composed of
cartilages and bones. Cartilage is
a resilient, semirigid form of
connective tissue that forms
parts of the skeleton where
more flexibility is required – for
instance; the costal cartilages
attach the ribs to the sternum.
• Blood vessels do not enter the
cartilage, but its cells obtain
oxygen and nutrients by
diffusion.
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5. CARTILAGE AND BONES CONTINUED…
• A fibrous connective tissue covering surrounds each skeletal element like a sleeve,
except where articular cartilage occurs. Around the bones it is called the periosteum,
and around cartilage it is called the perichondrium. Their functions are laying down
more cartilage or bone – especially during fracture healing.
• There are two types of bones, these are compact bones and spongy bones. They are
distinguished by the amount of solid matter and by the number and size of the spaces
they contain. Compact bones are present in the outer layer of long bones, they are
dense and sold and provide strength and protection. Spongy bones are present in the
middle of long bones and have a porous structure, they make. Bones lighter so that
muscles can move them more easily.
6. CLASSIFICATION OF BONES
• 1. long bones = are tubular or a cylinder like shape, however, keep in mind it
describes the shape not the size (humerus, ulna and radius in the arm) (femur,
tibia and fibula of legs) (metacarpals and phalanges of fingers) (metatarsals,
phalanges in toes).
• 2. short bones = are cuboidal and found only in the tarsus (ankle) and carpus
(wrist). Mostly equal in length, width and thickness.
• 3. flat bones = usually serve protective functions. It is typically thin but also
curved. (flat bones of the cranium skull) (the scapula – shoulder blades) (the
sternum – breastbone) and the ribs. Flat bones serve as points of attachment for
muscles and often protect internal organs.
• 4. irregular bones = have various shapes other than long, short or flat (bones of
the face or the vertebrae).
• 5. sesamoid bones = usually small and round (shaped like a sesame seed)
develop in certain tendons, and are found where tendons cross the ends of long
bones in the limb; they protect the tendons from compressive forces and often
change the angle of the tendons as they pass to their attachments (e.g. the
patella or knee-cap)
7. CLASSIFICATION OF JOINTS
• 1. Synovial joints = the articulating bones of
synovial joints are united by a joint capsule
composed of an outer fibrous layer and lined
by a serous synovial membrane. The joint
cavity of a synovial joint (e.g. the knee) Is a
potential space that contains a small amount of
lubricating synovial fluid, secreted by the
synovial membrane.
2. fibrous joints = The articulating bones of a
fibrous joint is united by fibrous tissue. The
amount of movement that happens at a
fibrous joint depends on the length of the
fibers that unite the articulating bones. These
bones are close together, either interlocking
along a wavy line or overlapping. A
syndesmosis type of fibrous joint unites the
bones with a sheet of fibrous tissue, either a
ligament or a fibrous membrane.
Consequently, this type of joint is partially
movable. The interosseous membrane in the
forearm is a sheet of fibrous tissue that joins
the radius and ulna in a syndesmosis.
3. Cartilaginous joints = The articulating
structures of cartilaginous joints are
united by hyaline cartilage or
fibrocartilage. In primary cartilaginous
joints, or synchondroses, the bones are
united by hyaline cartilage, and this
allows slight bending during early life.
Primary cartilaginous joints are usually
temporary unions, such as those
present during the development of a
long bone. Secondary cartilaginous
joints, or symphyses, are strong,
slightly movable joints united by
fibrocartilage. The fibrocartilaginous
intervertebral discs between the
vertebrae consist of binding connective
tissue that joins the vertebrae together.
