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
Shoulder girdle
- Two scapulae + two clavicles
- Bones form an incomplete ring articulating with the
manubrium
Pelvic girdle
- Formed by 2 large innominate bones
- Meet in front of the symphysis pubis
- Articulate with the sacrum to form a ring of bone
- The innominate bones + pelvis and coccyx forms
the pelvis - Surrounds pelvic cavity
- Female pelvis is wider and shallower than male
- Each innominate bone consists of:
- Ilium
- Ischium
- pubis
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)
typs Joints
- 3 types
- Freely moveable - synovial joints
- Slightly moveable – cartilaginous joints
- Fixed – fibrous joints
Freely moveable – synovial joints
- Varied degrees of movement
- All contain
- Hyaline (articular) cartilage
- Joint capsule
- Synovial membrane
- Synovial fluid
- Some have
- Bursae
- Fat pads
- ligaments
Synovial
joint types
Ball and socket
Gliding
Hinge
Saddle
Pivot
Ellipsoidal
Ball and socket
- Most moveable
- Allow flexion, extension, adduction, abduction
rotation and circumduction - E.g. shoulder and hip
Gliding/Plane
- Bones glide over each other
- Least moveable of joints
Hinge joint
- Movement in 1 direction only
- Flexion and extension
Saddle joint
Movement around 2 axes
* Allows flexion, extension, adduction, abduction,
circumduction
Pivot joint
- Movement around one axis only and a rotary
movement
Ellipsoidal/condyloid joint
- Functions similarly to the ball and socket joint but
is unable to rotate 360 degrees
Slightly moveable - Cartilaginous
joints
- Moves by compression of the cartilage
- Pad of white fibrocartilage between the joints
Fixed/fibrous joint
- No movement
- Fibrous tissue between the ends of the bones
Postural deformities
- Spine has 2 natural curves
- Inward curve in lower back
- Slight outward curve in the upper back
- Spine’s curves become exaggerated
- Causes
- Congenital – present at birth, inherited
- Environmental – sitting, standing incorrectly etc.
- Traumatic - accidents
Fractures A breakage of the bone due to disease or injury
* 6 main types
- 6 main types
- Simple
- Compound
- Comminuted
- Greenstick
- Impacted
- Complicated
Simple/closed fracture
- Bone has broken in one
place - No tissue damage around
fracture
Compound/open fracture
- Broken bone pierces the skin
- May communicate with the surface of the skin through an open wound
Comminuted fracture
- A bone broken in several places
Greenstick fracture
- More common in soft flexible bones especially children
- Incomplete fracture of long bone
Impacted fracture
- A bone which has been broken and then one end is driven into the other
Complicated fracture
- Broken bone which damages
tissue/organs around it
Diseases and disorders
Arthritis
Gout
Osteoporosis
Slipped
disc
Stress
Arthritis
- An inflammation of the joints
- Can be acute or chronic
- Acute – heat, redness and visible inflammation of the
affected joints accompanied by severe pain - Chronic – loss of cartilage, deposition of bone tissue
around the joint margins =less pain and inflammation - Monoarticular arthritis = inflammation of 1 joint
- Polyarthritis = inflammation of many
Rheumatoarthritis
Type of polyarthritis Caused by an autoimmune disease that attacks synovial membranes Acute and chronic phases with varying degrees of damage and deformity
Osteo-arthritis
Injury of joint or associated with ageing process
Chronic arthritis of the degenerative type
Cartilage of joint breaks down Usually affects weight bearing joints like knees, feet and back
Gout
- A form of arthritis often affecting the big toe
- More common in men
- Caused by deposition of uric acid crystals in the
joint capsule and cartilage - Attacks of acute gouty arthritis
- Chronic destruction of joints
Osteoporosis
- Brittle bone disease
- Caused by calcium deficiency/accelerated bone loss
- Porosity and brittleness of bones
Slipped disc
- Weakening or tearing of one of the intervertebral discs
- Disc bulges or sticks out
- May press on spinal Stressnerve causing pain
Stress
- When stressed muscle tension increases
- Causes poor posture, stiff joints and problems with spinal vertebrae
