Skeletal system Flashcards
Two types of skeletal systems
Axial, composed of the spine, head, and tail
Appendicular, all appendages
Dolichocephalic
long headed, ex. german shepard, collie,
Brachycephalic
Short wide skull, ex. pugs, boston terrier, boxer
Mesaticephalic
Moderate head, ex. beagles, terrier breads
Problems with brachycephalic breeds
defective teeth, difficulty breathing, shallow eye sockets, dystocia(difficult to give birth because of there large heads)
Spina bifida
Rare, a cleft or space in the dorsal part of the vertebral column
Hemi vertebrae
failure of the vertebrae body to ossify resulting in an improperly formed or shaped vertebrae
Different types of curvature of the spine and which way they curve?
Kyophis (Dorsal) Lordosis(ventral) Scoliosis( lateral)
os and oseo =bone
- Second hardest substance in the body (enamel is the hardest)
- Living, changing tissue
- Has the capacity for remodelling and repair in response to new stresses and _injury__
What is bone made of
Bone is made up of a few cells in a solid matrix
o Cells start out as osteoblast
o Produce a soft matrix made up of collagen fibers in ground substance
o Osteoblasts harden the matrix by adding crystalline calcium and phosphate salts in a process called ossification
Function of bone
Support, protection, leverage, storage, blood cell formation
Three main types of bone cells
Osteoclasts: cells that eat away or remove bone.
Osteoblasts: cells that form bone
Osteocytes: osteoblasts that have been trapped is ossified matrix
two types of bone
compact or cancellous
Compact bone
Dense, strong bone
Makes up the shaft of the long bones and the outer layer of the bones
Permeated by a microscopic framework of tunnels, channels, ad interconnecting networks, surrounded by a hard matrix
Bone is nourished and maintained through these tunnels
Function of bone: support
framework or scaffolding to support the animals and its organs
Function of bone:protection
surrounds ,supports, and protects delicate organs
Function of bone: Leverage
Levers to which the muscle attach allow animal to move its body
Function of bone: Storage
Particularly Calcium
Controlled by 2 hormones; Calcitonin(from the thyroid) that prevents the blood calcium level from going too high by placing calcium in bone and Parathyroid hormone(from the parathyroid glands) stops the blood calcium level from going too low bytaking calcium from bone
Function of bone: Blood cell formation
Site for hematopoiesis(production of blood cells)
Osteon or Haversian System
The functional and structural unit of compact bone
Contains one or two blood capillaries
Around each central haversian canal are concentric rings of matrix called lamellae (secreted by osteocytes)
There are small hollow cavities, called lacunae, between lamellae which contain the osteocytes
Osteocytes in the lacunae have many protoplasmic processes that extend outwards in a spider-like manner through a series of minute hollow tunnels called canaliculi
There is basically a continuous network of communicating canals (canaliculi) that join the central canal to the lacunae and adjacent lacunae to each other
Groups of osteons lie in a parallel arrangement.
Adjacent lamellae are separated with demarcation lines called cement lines
Perforating (Volkmann’s) canals penetrate the bone and connect the central (Haversian) canals of adjacent osteons
Cancellous bone
Lies adjacent to compact bone and is continuous with it.
No distinct line of demarcation between the two regions
Less organized histologically than compact bone
Primary feature is the trabeculae or spicules, which are a series of branching, overlapping plates of matrix
These plates are organized to produce large, interconnecting, cave like spaces which function in storage and as pockets to hold the
hematopoietic of the bone marrow
Spicules function to reduce the weight of the bone without compromising strength.
Arranged to provide support against the forces pulling on the bone
Spicules are randomly punctuated by lacunae (osteocyte-holding spaces) and blood vessels which provide lots of nourishment to nearby osteocytes
Bone shapes
Long, short, flat irregular
Long bones
Greater in one dimension than the other (i.e. Longer than wide)
Function as levers, support and sites for muscle attachment
Important for locomotion
Include most bones of the limbs
Parts of long bone
Epiphyses, diaphysis, epiphyseal, periosteum, endosteum, articular cartilage
Epiphyses
enlarged end of the long bone
Primarily made of cancellous/spongy bone
Diaphysis
Shaft of long bones
Primarily compact bone
Epiphyseal(growth) plate
Area between epiphyses and diaphysis
Layer of dividing cartillage still exists here in young growing bones allowing the bone to increase in length
Allows the bone to increase in length
When the animal has reached its full size the epiphyseal plate completely ossifies (turns to bone)
Until ossification these regions are the weakest
Periosteum
A tough, fibrous membrane which lines the outer surface of bone (except at the articular surfaces)
Adhreres tightly to the outer layer of compact bone
Anchored by bundles of collagen fibers that perforate and become embedded in the outer lamellae
Composed of outer layer of fibrous connective tissue and an inner osteogenic layer, which is a source of new born forming cells and provides access to blood vessels
Very important for: healing, growth in diameter of bone
Endosteum
Similar to the periosteum, but lines the inner surface of the bone
Also contains osteoblasts, is a source of new bone and assists in healing
Articular Cartilage
Smooth layer of hyaline cartilage covering the articular surface of the epiphysis
Reduces friction and wear in joints
Short bones
Cuboid shaped and contain no marrow cavity, just spongy bone in centre
Function – absorbs concussion or shock
Examples – tarsus, carpus
Flat bones
Thin and flat
Function- to protect vital organs and act as attachments for large muscle groups
Examples – ribs, scapula, pelvis, cranial bones
Irregular bones
Any bones that don’t fit into any of the above three categories
Sesamoid bones
Shaped like sesame seeds (hence the name)
Embedded in tendons and function to to reduce friction and/or change the course of a tendon
Example: patella (or knee cap) and fabellae (behind the stifle in dogs and cats)
Common bone features
Articular surface; condyles, head, facet, processes, foreman, and fossa
Condyles
Large and round
Seen mainly in the femeur, humorous and occipital bone of the skull
Head
Single spherical portion located at the __proximal epiphysis, femur and ribs_
Example: the ‘ball’ of the ‘ball and socket joints’
United with the shaft of the bone by a narrow region called the neck
Facet
Flat, allowing for rocking or twisting motion
Seen in carpal/tarsal bones, vertebrae and long bones such as the radius/ulna
Processes
- A general term that includes all bumps and projections on the bone
Processes that have a non-articulating function tend to have rough, irregular surfaces
Are usually the site of muscle or tendon attachmnet
Example: the spine of the scapula
As a rule of thumb, the larger the process the more powerful the muscular pull on that area of the bone
Processes go by many names such as:
Trochanter, at the femur
Tubercle, at the humerus
Spine, at the scapula
Even just “process”, such as in the spinous process of the vertebrae
Foramen
A hole in the bone through which nerve or blood vessels passes
Exception is the obturator foramen at the pelvis
Largest foramen of the body and exists to decresses the weight of the pelvic bone
Fossa
a depression or sunken area on the surface of a bone
muscles or tendons usually occupy this area