skeletal system Flashcards
What is included in the skeletal system?
Bones and joints
functions of the skeletal system
- provides shape and form to body
- provides support for the body
- protects soft vital organs
- provides attachment for muscles
- production of blood cells in bone marrow
- provides a store for minerals
what is the structure of bone
Bone is dense connective tissue that is composed of two parts:
- bone matrix of collagen and osteocytes that provide resilience and elasticity
- mineral matter which gives hardness and rigidity
Features of long bones
- longer rather than wider
- includes many bones of the limbs
- usually joint to another bone and involved with joint movement
- provides strength and flexibility to limbs
- acts as a scaffold for muscle origin and insertion
- marrow cavities produce blood cells
Name the different parts of the structure of a long bone
- diaphysis
- epiphysis
- epiphyseal plate or line
- cortex
- periosteum
- endosteum
- medullary cavity
- articular cartilage
- nutrient foramen
What are short bones
usually bones of approximately the same length, width and thickness
what are irregular bones
bones which possess irregular projections and large areas for muscle attachments
what do flat bones serve and what bones does it include
flat bones serve as a protective surface and provide large areas for muscle attachment and it includes the scapular, sternum and the ribs
why do flat bones serve as a protective surface
because they consist for 2 hard layers of compact bone
what are sesamoid bones
small bones situated within tendons
what are visceral bones
bones that sit within organs
In the long bone, what is the diaphysis?
the long shaft of the bone
In the long bone, What is the epiphysis
two ends of the bones which have bony material called spongy bone or cancellous bone which contains red marrow
In the long bone, what is the epiphyseal plate or line (growth plate)
the gap or line between the diaphysis and epiphyses.
what is the cortex
the cortex is made up of hard dense compact bone and gives bone its strength
in the long bone, what is the periosteum
the periosteum is thin fibrous connective tissue covering the outer surface of the bone. it’s rich in nerves and blood vessels and essential for growth, repair and nutrition of the bone.
in the long bone what is the endosteum
the endosteum is fibrous membrane lining on the inside of the marrow cavity
in the long bone, what does the medullary cavity contain?
it contains bone marrow, red marrow in young animals and yellow marrow in mature animals
what is red and yellow marrow
red marrow produces blood cells and yellow marrow is fat storage
in the long bone, what is the articular cavity
it is a thin layer of hyaline cartilage which covers the ends of the bone
in the long bone, what is the nutrient foramen?
it is a small hole in the bone that allow entry of blood vessels into the interior of the bone so it can receive its blood supply
the skeleton is predominantly made of what in young animals?
cartilage
As an animal grows, the amount of bone present increases and the cartilage is replaced with bone, what is this process called?
endochondal assification
Remaining cartilage is gradually replaced by what?
osteocytes, bone matrix and calcium
In young animals, where does growth occur?
near the ends of the bones from a cartilage structure called the epiphyseal plate
What happens to the epiphyseal/growth plate when the animal matures?
becomes bony and growth no longer occurs
what are osteocytes
mature bone cells
what are osteoblasts?
immature (young) bone cells which can make and lay down new bone matrix
what are osteoclasts
cells which break down and remodel bone
osteoblasts become what once matured?
osteoclasts
What is the cranium
the bony casing enclosing the brain.
what is the mandible
lower jaw with teeth
what is the maxilla
the upper jaw with teeth, contains nasal cavity, sinuses and hard palate
what is dolichocephalic
long narrow head
what is mesocephalic
medium sized head
what is brachycephalic
short wide head
what is the vertebral column?
a series of stacked spinal bones called vertebrae forming a flexible column, with a skull at one end and tail at the other.
what are vertebrae
- irregular shaped bones with projections and processes
- provide a ring of bone forming a tunnel
- this tunnel forms a protective canal protecting the spinal cord
the canal protecting the spinal cord is called what?
the vertebral canal
features of intervertebral discs
- lie between vertebral bodies
- act as shock absorber and allows movement between bones
- made of a ring of dense fibrous connective tissue with a soft middle
what is a prolapsed disc?
a prolapsed (slipped) disc involves dorsal protrusion of disc material into the overlying vertebral canal
name the parts of the spine
- cervical vertebrae
- thoracic vertebrae
- lumbar vertebrae
- sacral vertebrae
- coccygeal vertebrae
where is the cervical vertebrae
the neck region, 7 in a dog
where is the thoracic vertebrae
- over the chest cavity
- each one has an attached pair of ribs
- 13 thoracic vertebrae in a dog
what are the ribs attached to
- dorsally attached to thoracic vertebrae which move during breathing
- ribs are attached ventrally either to the sternum or ribs in front by cartilage
where is the lumbar vertebrae
lower back region over abdominal cavity. 7 in a dog
what is the sacral vertebrae
the bones that connect the spine to the pelvis right at the base of the tail. 3 in dogs that are fused
what is the coccygeal vertebrae
the vertebrae that makes up the tail bones. can be up to 20 in a dog but varies
what are the bones compromising the forelimb
- scapular (shoulder blade)
- humerus
- radius and ulna
- carpal bones
- metacarpal bones
- phalanges or digits: P1, P2,P3
where’s the scapular located
sits against the rib cage
what is the humerus
the bone of the upper aspect of the forelimb.
- proximally joins with the scapula
- distally adjoins the radius and ulna bones to form the elbow
what is the radius and ulna
- two bones are positioned next to each other
- shorter radius sits more cranial to the ulna (forms the forearm)
- distally the radius and ulna adjoin the bones of the carpus (wrist)
what are the carpal bones
- a collection of short bones positioned to form the carpal joint.
- distally join metacarpals
what are phalanges
- bones of the toes or digits
- 3 bones for each digit but varies in animals
what are the bones compromising the hind limb?
- femur
- patella
- tibia and fibula
- tarsal bones
- metatarsal bones
- phalanges or digits
- pelvis
features of the pelvis
- attaches to hind limbs to spine
- consists of 3 bones which fused together when animals stop growing
- pelvis attaches to sacral vertebrae and femur joins pelvis
what is the femur
- the bone of the upper aspect of the hindlimb
- proximally adjoins the pelvis to form hip
- distally joins tibia and fibula bones to form stifle (knee)
features of the tibia and fibula
- two bones positioned next to each other
- shin in humans
- fibula is located laterally and smaller than tibia
- distally tibia and fibula adjoin the bones of the tarsus
what are tarsal bones
- short bones position to form the tarsus joint
- distally joint the metatarsus
what are metatarsal bones
- the hindlimb equivalent of the metacarpal bones
joints are classified into 3 groups, what are they
- fibrous joints (immobile)
- cartilaginous joints (slightly moveable)
- synovial joints ( highly moveable)
features of cartilage
- a dense clear connective tissue
- found primarily in joints, at ends of bones.
- consists of chondrocytes, collagen and many elastic fibres but no calcium
- tough and rigid but with some give.
- does not have good blood supply and has poor ability to heal if damaged
what are the three types of cartilage
- hyaline articular cartilage
- fibrocartilage
- elastic cartilage
features of hyaline articular cartilage
- forms the articular surfaces at the ends of bones
- smooth, shiny and white
- functions to cushion bones, acts as shock absorber
- allows smooth movements and prevents bones rubbing on each other
- very thin and poor blood supply
features of fibrocartilage
- stronger than hyaline
- found in the intervertebral discs
- the shock absorber in the stifle joint
features of elastic cartilage
- contains more elastic fibres than others, so very flexible
what does the synovial joints consist of
- articular cartilage
- joint capsule
- synovial fluid
- synovial membrane
- ligaments
what is the joint capsule
- surrounds whole joint
- made up of an outer fibrous protective capsule and inner smooth synovial membrane
features of synovial membrane
- lines the joint cavity and secretes joint fluid
features of synovial fluid
- viscous (thick) consistency
- reduces friction
- shock absorption
- nutrition for articular cartilage
features of ligaments
- tough fibrous connective tissue
- may be located on inside or outside of joint capsule
- bind and hold bones together, providing stability for joints.
- prevent excessive movements of the bones
joints in the forelimb
- shoulder
- elbow
- carpus
- paw
joints in the hindlimb
- hip
- stifle
- tarsus or hock
- paw
what is the purpose of ball and socket joints
- allow for movement
what for hinge joints allow for
- only allow flexion & extension
define flexion
- bending of a joint
- grind angle of bones together
define extension
- straightening of a joint
- increasing angle between bones
define abduction
- moving limb away from midline
define adduction
- moving limb towards midline
some notable differences of a bird skeleton
- hollow bones that reduce weight of the skeleton
- elongated bones in the forelimb to support the wings
- extended enlarged sternum used to attach major flight muscles
- spinal vertebrae in lower back are fused to provide rigid structure that will support flight
- pelvis is fused to the spine
