ANSC 300 - Ch. 9 - Bones, Joints, & Synovial Fluids

Besides movement, what is the skeletal system used for?

Framework and levers

Protection

Mineral storage

Fat storage

Production of blood cells

What is the makeup of calcium and phosphorus in the body?

Calcium - 99%

Phosphorus - 85%

Where do adult mammals have fat storage?

Medullary cavity (yellow marrow)

Where are blood cells produced?

Red marrow

Directional terms

Cranial (towards head) → Caudal (towards tail)

Dorsal (towards back) → Ventral (towards belly)

Proximal (towards center of body) → Distal (towards limbs)

Axial skeleton

Includes skull, ribs, sternum, and vertebrae

Appendicular skeleton

Includes limbs and pelvic girdle

Short bones

Carpals and tarsals

Flat bones

Skull, pelvis, ribs, sternum

Skull and pelvis are made up of multiple bones

Irregular bones

Vertebrae, some facial

Sesamoid bones

Patella, proximal and distal sesamoids

Found in limbs embedded along or within tendons of legs

Long bones

Mostly limbs

Difference between skull and cranium

Cranium is the upper part where the brain is

Skull is the entire thing

Neurocranium vs. viscerocranium

Neurocranium is bone surrounding the brain

Viscerocranium is area along the jaw

Vertebrae

Features include spinous and transverse processes, and vertebral foramen

Where does the spinal cord lay?

In the vertebral foramen

Intervertebral disc

“Cushion” of cartilage between vertebrae

Nucleus pulposus - cushion part

Anulus fibrosus - gives structure and shape

Herniated disc

Occurs with a hole in the anulus fibrosus region, losing that cushioning and causing pain for the animal

Order of vertebrae from head to tail

Cervical, thoracic, lumbar, sacral, caudal

What is the only animal that doesn’t have 7 cervical vertebrae?

Chickens - they have 14

Thoracic vertebrae

Average number is 13, while horses have 18 and chickens have 7

Lumbar vertebrae

Average number is 6-7, while chickens have 14 due to them being combined with sacral vertebrae to create lumbosacral vertebrae

Sacral vertebrae

Horse and Ox: 5

Sheep, goat, pig: 4

Dog: 3

Chicken: None (combined to make lumbosacral vertebrae)

Caudal vertebrae

Most domestic animals have around 20, while goats only have 12 and chickens have 6

Pectoral girdle

Scapula, clavicle, coracoid

Some species don’t have clavicles or coracoids

Pelvic girdle

Os coxae (ilium, ischium, pubis)

Tuber coxae and tuber ischiadicum

Hooks and pins

Acetabulum

Femur articulation cavity

Label the picture of the thoracic limb

A. Scapula

B. Shoulder joint

C. Humerus

D. Elbow joint

E. Radius

F. Carpal (knee joint)

G. Metacarpal (cannon)

H. Digits

Label the picture of the pelvic limb

A. Os coxae

B. Hip joint

C. Femur

D. Patella

E. Stifle

F. Tibia

G. Tarsals/Hock joint

H. Metatarsals

I. Digits

Distal limbs

Located from the cannon and down

Names are the same, but some species have more bones left than others and the structure may vary depending on the species.

Compact

Solid layer around the bone; “eggshell” of the bone

Spongy

Found on the ends of bones, thin layer on medullary cavity; where red marrow is located; technical term is trabeculae

Epiphysis

Widened end of bone

Diaphysis

Long shaft of bone; approx. where medullary cavity is

Metaphysis

Connection between epiphysis and diaphysis

Physis

Epiphyseal (growth) plate

Endosteum

Inner lining of medullary cavity

Periosteum

Outer layer of bone tissue

What covers the bone exterior?

Articular cartilage covers the ends of the bone (smooth to the touch)

Periosteum covers the shaft of the bone (rough to the touch)

Label the parts of the bone

1. Epiphysis

2. Diaphysis

3. Epiphysis

4. Medullary cavity

5. Endosteum

6. Periosteum

7. Physis

8. Metaphysis

9. Spongy bone

Wet weight of water, minerals and organic matter in bone

25%

45%

30%

Dry weight of water, minerals, and organic matter in bone

0%

70%

30%

Percentage of calcium and phosphorus in bone

Calcium: 37%

Phosphorus: 18.5%

What is the dietary significance of calcium and phosphorus?

It needs to be a 2:1 ratio

Osteoprogenitor cells

Stem cells (bone producing)

Osteoblast

Forms bone matrix

Osteocyte

Maintains bone tissue

Osteoclast

Resorbs bone (breaks them down)

Derived from blood-producing stem cells (monocytes)

Where are blood vessels contained?

Haversian and Volkmann canals

Haversian canals

Goes up and down shaft of bone; contains components of lymphatic system

Volkmann canals

Go across the shaft of the bone

How do osteocytes communicate?

Through canaliculi, gap junctions and hormones

Endochondral ossification

Most of the ossification of the body; starting material is cartilage

Intramembranous ossification

Starting material is fibrous material; flat bones use this

What bone cells are key for diametrical growth?

Osteoclasts help form the medullary cavity

Osteoblasts form everything else

Why is diametrical growth important all throughout life and not just growth?

Breaking bones, exercise or lack thereof, lack of movement, nutrition (lack of calcium)

Simple joints

Two bones

Compound bones

2+ bones

Fibrous joint structure

Tend to be considered immovable

Ex: Skull

Cartilagenous joint structure

Tend to be slightly moveable

Ex: Vertebrae

Synovial joint structure

Tend to be freely moveable

Ex: Legs

Synovial joints

Contain a capsule filled with fluid

Fluid lubricates and nourishes articular cartilage

Hyaluronic acid: component of synovial fluid; aids in the viscous consistency of it; most effective as a joint injection

Yes joint

Atlas joint; Atlanto-occipital joint; Creates nodding motion

No joint

Axis joint; Atlanto-axial joint; Joint between atlas and axis