The skeletal system Flashcards
The skeletal system Divided into
-Axial skeleton
Supports the head, neck, and trunk
-Appendicular skeleton
Supports the appendages or limbs
Attaches them to the rest of the body
-206 bones
Different types of bones
- Long bones
- Short bones
- Flat bones
- Irregular bones
- Sesamoid bones
Long bones
Body’s levers Allow movement e.g. in the limbs
Short bones
-Strong and compact
-bones Cube shaped
-Usually grouped in parts of the body where little movement is required
-Provide stability and some movement
Flat bones
- Protective bones with broad flat structures for muscle
attachment. E.g. protect brain, heart and pelvic organs
Irregular bones
- Bones with different characteristics
- Have complex shapes
- Do not fit in any other category
Sesamoid bones
- Bones within tendons
- Protect tendons from stress and wear
- Two main sesamoid bones
- Patella – kneecap
- Hyoid – sometimes classified as an irregular bone
Functions of the skeleton
- Supports the body
- Bones and their arrangement give the body its shape
- Allows and enables movement
- Protects delicate body organs
- Forms blood cells – red bone marrow
- Forms joints – movement
- Provides attachment for muscles which move the joints
- Provides a store of calcium salts and phosphorous
Bone composition
- Bones are living tissue
- Composed of osteoblasts and osteoclasts
- Tissue varies in density and compactness
- Many bones have a central cavity
- Contains marrow
- Source of most blood cells
- Site of fat storage
Bone cell types
Bone composition-compact
- Appears as a honeycomb under the microscope
- Haversian canals
- Passageways containing blood vessels, lymph
capillaries and nerves - The larger the canal the less dense and compact
the bones - Found in the outside of most bones and in the
shaft of long bones
Bone composition - cancellous
- Appears like a sponge
- Found at the ends of long bones and in irregular, flat
and sesamoid bones - Bone marrow only exists in cancellous bone
The axial skeleton
-Skull – cranium 8 bones; face 14 bones
-Hyoid – 1 bone
-Vertebral column – 33 vertebrae, some fused
-Sternum – 3 bones
-Ribs – 12 pairs
Skull bones
Vertebral column - spine
- The central part of the skeleton
- Supports the head
- Encloses the spinal chord
- Combines great strength with a moderate degree of
mobility - 33 vertebrae – irregular interlocking bones
- Some are fused = 26 individual bones
Vertebral column 5 different types of vertebrae
- Cervical – 7 bones in the neck
- Thoracic – 12 bones carrying the ribs in the centre of the body
- Lumbar – 5 bones in the lower back
- Sacral – 5 bones in the pelvis, fused to form the sacrum
- Coccygeal – 4 bones below the sacrum forming the coccyx
Thoracic cage
- Surrounds and protects the heart and lungs in
the thoracic cavity - Consists of the ribs, the sternum, and the thoracic vertebrae
- Twelve pairs - same in both males and females
- Ten of the twelve ribs connect to strips of hyaline cartilage on the anterior side of the body - costal cartilage
- Sternum has 3 parts
- Manubrium
- Body
- Xiphoid process
Thoracic cage
* Ribs 1-7 are called
* Ribs 8-12 are called
the true ribs.
* Connects to its own strip of costal cartilage, which in turn connects to the sternum.
the false ribs.
Appendicular skeleton
1-Arm – 1 humerus, 1 ulna, 1 radius
2-Wrist – 8 carpal bones
3-Hand – 5 metacarpal bones
4-Fingers – 14 phalanges in each hand, 2 in a thumb and 3 each in other fingers
5-Pelvic girdle – 2 innominate bones
6-Leg – 1 femur, 1 tibia, 1 fibula and 1 patella
7-Ankle and foot – 7 tarsals and 5 metatarsals
8-Toes – 14 phalanges in each foot, 2 in big toe and 3 in each other toe
Upper limb – arm and hand
Lower limb – leg and foot
- Talus joins the foot to the leg and is a principal part of
the ankle joint - Calcaneus (heel bone) projects backwards
- Navicular bone lies between the talus and
cuneiform bones (medial, intermediate, lateral)
