Skeletal System Flashcards
How many bones are there in the human body?
206
What are the 2 main groups of bones?
- Axial - forms the long axis of the body and includes bones of the skull, vertebral column and rib cage
- Appendicular - bones of the limbs and the pectoral and pelvic girdles
What are the 2 types of bone tissue?
- Compact bone - dense, smooth, homogenous
2. Spongy bone - needle-like pieces of bone called trabeculae and lots of open space
What is the function of trabeculae?
To allow the bone to resist stress
What are the 4 types of bone?
- Long bone
- Short bone
- Flat bone
- Irregular bone
Give 2 characteristics of long bones
- Longer than they are wide
- Very strong - good for support and movement
What are the 3 parts of a long bone?
- Epiphysis - wide area on each end filled with spongy bone that produces RBC
- Diaphysis - long cylindrical middle filled with compact bone that takes the brunt of the force that the bone supports
- Metaphysis - between epiphysis and diaphysis, transfers load and stress from joints and is important in bone growth
Give 2 examples of long bones
- Femur
2. Humerus
Give 3 characteristics of short bones
- Usually cube shaped
- Contain spongy bone with an outer layer of compact bone
- Provide support and stability
Give 2 examples of short bones
- Talus
2. Trapezium
Give 4 characteristics of flat bones
- Thin bone with a high SA
- Usually curved
- Protect organs and are an attachment site for muscle
- Made up of compact bone on the surface and spongy bone in the middle
Give 2 examples of flat bones
- Sternum
2. Parietal
Give 2 characteristics of irregular bones
- Contain spongy bone with an outer layer of compact bone
- Shape of the bone is specific to its function
Give 2 examples of irregular bones
- Vertebrae
2. Pubis
What is the function of ligaments?
To connect bones to each other
What is the function of tendons?
- To connect muscle to bone
- To provide durability and conserve space
What are the 3 types of bone cells?
- Osteoblasts
- Osteocytes
- Osteoclasts
What are the 3 main functions of osteoblasts?
- Form bones
- Create collagen fibres
- Create an extracellular matrix to absorb minerals from the blood and deposit them in the matrix
What is the function of osteocytes?
- Mature osteoblasts
- Exchange nutrients and waste products with the blood stream to keep bone tissue alive
What is the main functions of osteoclasts?
- Break down bone cells by breaking down the extracellular matrix and releasing the products into the bloodstream
- This maintains homeostasis and defines the shape of the bone
What are the individual units of bone called?
Osteons
Describe the structure of osteons
- Rings called lamellae (concentric layers)
- Spaces called lacunae (contain osteocytes)
- Central (Haversian) canal (contains blood vessels, lymph vessels and neurones)
- Aligned in the same way as the force applied to the bone
Describe the structure of the Haversian canal
- Each canal is connected by a Volkmann’s canal
- The central canal connects osteons to each other
What are the bones formed from?
- Long, short and irregular bones are formed from hyaline cartilage
- Flat bones are formed from fibrous tissue
What is the name of the process in which bones develop and grow?
Osteogenesis
When does Osteogenesis begin and when is it complete?
- Begins before birth
- Completed in 21st year of life
What is ossification?
The formation of bone using hyaline cartilage as a model
Describe the process of ossification
- Formation of the bone collar around a hyaline cartilage model
- Cavitation of hyaline cartilage (the cartilage matrix deteriorates)
- Invasion of internal cavities by the periosteal bud (blood vessel) and spongy bone formation occurs
- Formation of the medullary cavity, appearance of secondary ossification centres in the epiphyses
- Ossification of the epiphyses; when completed, the hyaline cartilage remains only in the epiphyseal plates and articular cartilages
Name 3 factors that affect bone growth
- Hormones
- Diet
- Exercise
How do hormones affect bone growth?
- Responsible for regulation of bone growth
- Deficiency/ excess results in abnormal bones (e.g. gigantism)
How does diet affect bone growth?
- Bones need calcium and vitamin A, C and D
- Sunlight provides vitamin D which is responsible for the work of osteoblasts fixing calcium to bones
- Green vegetables provide calcium
Why do pregnant women receive free dental care?
The foetus needs calcium for bone growth and if the mother is deficient in calcium, the calcium from her teeth will be used
How does exercise affect bone growth?
Stimulates bone thickening
What are the 4 stages of bone repair?
- Haematoma formation
- Fibrocartilage callus formation
- Bony callus formation
- Bone remodelling
How does haematoma formation occur?
- Blood vessels are ruptured when the bone breaks
- A haematoma forms as a blood-filled swelling or bruise
How does fibrocartilage callus formation occur?
- New capillaries form in the blood clot and dead tissue is disposed of by phagocytes
- Connective tissue cells form internal and external masses of repair tissue called the fibrocartilage callus
- This originates from the endosteum and periosteum and contains cartilage matrix, bone matrix and collagen fibres
How does bony callus formation occur?
As more osteoblasts and osteoclasts migrate to the area and multiply, the fibrocartilage callus is replaces with a bony callus made of spongy bone
How does bone remodelling occur?
Over the next few weeks to months, the bony callus is remodelled in response to the mechanical stresses placed on it to form a strong patch at the fracture site
What are the 5 main functions of bones?
- Support - bones form an internal framework that supports weight and organs
- Protection - bones surround and protect the body’s organs
- Movement - bones are used as levers by muscles to allow the body to move
- Storage
- Haematopoiesis - blood cell formation which occurs in the bone marrow
What is stored in bones?
- Fat - bone marrow
- Phosphorous - in the bone itself
- Calcium - as salt and Ca ions
What are calcium ions needed for?
- Nerve impulse transmission
- Muscle contraction
- Blood clotting
What is the skeleton of an embryo mainly made up of?
Hyaline cartilage
What would happen if a drug was given that blocks ACh?
It would prevent muscle contraction
What are the 2 main components of the skull?
- Cranium
- Facial bones
What is the function of the cranium?
To protect the brain and provide points of attachment for the head and neck muscles
What are the 4 functions of the facial bones?
- Provide the framework for the face
- Contain cavities for special sense organs
- Provide opening for air and food passage
- Secure the teeth and anchor the facial muscles
What type of bone is the skull mostly made up of?
Flat bone
How many bones make up the vertebral column in an adult and a foetus/infant?
Adult - 26
Foetus - 33
What type of bone are the vertebrae?
Irregular
What are the 3 main functions of the vertebral column?
- Protects the spinal cord
- Gives axial support to the trunk
- Provides attachment points for ribs and muscles of the back and neck
How many bones are the sacrum and coccyx made up of?
Sacrum = 5 fused vertebral bones Coccyx = 4 fused vertebral bones
What are the 3 types of vertebrae and how many of each bone are there?
- Cervical vertebrae (7)
- Thoracic vertebrae (12)
- Lumbar vertebrae (5)
What are the 3 structural classes of joints?
- Fibrous
- Cartilaginous
- Synovial
What are the structural characteristics of each type of joint?
Fibrous = bone ends/ parts united by collagenic fibres Cartilaginous = bone ends/ parts united by cartilage Synovial = bone ends/ parts covered with articular cartilage and enclosed within an articular capsule lined with a synovial membrane
What are the 3 types of Fibrous joint?
- Suture (short fibres - mobile)
- Syndesmosis (longer fibres - slightly mobile)
- Gomphosis (periodontal ligament - immobile)
What are the 2 types of Cartilaginous joint?
- Synchondrosis (hyaline cartilage - immobile)
2. Symphysis (fibrocartilage - slightly mobile)
Give 3 examples of cartilaginous joints
- Epiphyseal plates
- Intervertebral discs
- Symphysis pubis
What are the 6 types of Synovial joint?
- Plane
- Hinge
- Pivot
- Condylar
- Saddle
- Ball and Socket
Give 2 examples of synovial joints
- Shoulder (multiaxial)
2. Elbow (uniaxial)
What are the 3 functional classes of joints?
- Synarthoses (immovable)
- Amphiarthroses (slightly movable)
- Diarthroses (freely movable)
What are the 4 distinguishing features of synovial joints?
- Articular cartilage (covers the end of bones, forming joints)
- Articular capsule (encloses the joint surface)
- Joint cavity (contains lubricating synovial fluid)
- Reinforcing Ligaments (reinforces fibrous layer of the capsule)
What are the 3 factors that influence the stability of a synovial joint?
- Shape of the articular surface
- Presence of strong reinforcing ligaments
- Tone of surrounding muscles
Describe the hip joint
- Articular surfaces deep and secure
- Capsule heavily reinforced by ligaments and muscle tendons
- Extremely stable
Describe Rotation and give the name and type of joint involved
- Turning of the bone around its own axis
- Atlantoaxial joint
- Pivot
Describe Lateral and Medial Rotation and give the name and type of joint involved
- Turning of the bone around its own axis
- Hip joint
- Ball and socket
Describe Circumduction and give the name and type of joint involved
- Moving a limb so that is describes a cone in space
- Shoulder joint
- Ball and socket
Describe Abduction and give the name and type of joint involved
- Movement of the limb away from the midline of the body
- Shoulder joint
- Ball and socket
Describe Adduction and give the name and type of joint involved
- Movement of the limb towards the midline of the body
- Shoulder joint
- Ball and socket
Describe Flexion and give the name and type of joint involved
- Movement that decreases the angle of the joint and brings articulating bones closer together
- Knee joint
- Hinge
Describe Extension and give the name and type of joint involved
- Movement that increases the angle of the articulating bones
- Knee Joint
- Hinge
Describe Dorsiflexion and Plantar Flexion (of the foot) and give the name and type of joint involved
- Up and down movements of the foot
- Lifting foot towards shin = dorsiflexion
- Depressing foot (pointing toes) = plantar flexion
- Ankle joint
- Condyloid
Describe Inversion and Eversion and give the name and type of joint involved
- Special movement of the foot
- Inversion = sole of foot turns medially
- Eversion = sole faces laterally
- Ankle joint
- Condyloid
Describe Supination and give the name and type of joint involved
- Rotating forearm laterally so the palm of the hand faces anteriorly or posteriorly
- Proximal radioulnar joint
- Pivot
Describe Pronation and give the name and type of joint involved
- Rotating forearm medially so the palm of the hand faces posteriorly or inferiorly
- Proximal radioulnar joint
- Pivot
Describe Opposition and give the name and type of joint involved
- Action taken when you touch your thumb to the tips of other fingers on the same hand
- Carpometacarpal joint
- Saddle
