ANSC 300 Bones, Joints, & Synovial Fluid

Skeletal System

• is more important for more than just movement

• framework and levers

• protection

• mineral storage

• fat storage

• production of blood cells

All Skeletons Have Generally ______ Bones.

the same

Axial Skeleton

• skull, vertebrae, bones attached to the vertebrae, ribs, ventral connections of the ribs, and the sternum

Appendicular Skeleton

• front (thoracic) and hind (pelvic) limbs, pectoral girdle (shoulder), and pelvic girdle (pelvis)

• Pectoral Girdle: scapula, clavicle, coracoid

• Pelvis Girdle: os coxae (ilium, ischium, pubis)

5 Types of Bone Found in the Body

Short Bones

• carpals, tarsals

Flat Bones

• skull, pelvis, ribs, sternum

Irregular Bones

• vertebrae, some facial

Sesamoid Bones

• patella, prox. and distal sesamoids

Long Bones

• limbs mostly

Skull

• made up of multiple bones

• Neurocranium (brain): upper and posterior

• Viscerocranium (facial structures): lower and anterior part

Vertebrae

• includes spinous and transverse processes, and vertebral foramen

• thoracic vertebrae, lumbar vertebrae, sacral vertebrae, & caudal vertebrae

Intervertebral Disc

• is a cushion of cartilage between vertebrae that permits limited movement

• Nucleus Puplosus: soft interior of the disc

• Anulus Fibrosus: collar that supports the periphery of the disc

• What Happens with a Herniated Disc?

  • when the nucleus pulposus ruptures through the annulus fibrosus

Vertebral Formulas for Different Species

CERVICAL:

• Horse, Ox, Sheep, Goat, Pig, Dog: 7

• Chicken: 14

THORACIC:

• Horse: 18

• Ox, Sheep, Goat, Dog: 13

• Pig: 14-15

• Chicken: 7

LUMBAR:

• Horse, Ox: 6

• Sheep, Pig: 6-7

• Goat, Dog: 7

• Chicken: 14

SACRAL

• Horse, Ox: 5

• Sheep, Goat, Pig: 4

• Dog: 3

CAUDAL:

• Horse: 15-20

• Ox: 18-20

• Sheep: 16-18

• Goat: 12

• Pig, Dog: 20-23

• Chicken: 6

Pelvis

• ilium, ischium, and pubis

• Pelvis: os coxae

• Tuber coxae & Tuber ischiadicum: hooks and pins

• Acetabulum: femur articulation cavity

Thoracic Limb

A. Scapula

B. Shoulder

C. Humerus

D. Elbow

E. Radius

F. Carpus

G. Metacarpus

H. Phalanges (or phalanx)

Pelvic Limb

A. Ilium

B. Pubis

C. Femur

D. Patella

E. Stifle?

F. Tibia

G. Tarsus (hook)

H. Metatarsus

I. Pastern Joint

The Radius is _____ to the Metacarpus

proximal

The Skull is ______ to the Os Coxae

cranial

The Phalanges are _____ to the Femur

distal

The Lumbar Vertebrae is ______ to the Cervical Vertebrae

cotal

Long Bone

Layers (top to bottom):

• Epiphysis

• Metaphysis

• Diaphysis

• Metaphysis

• Epiphysis

Compact Region: appears to be solid

Spongy Region (aka cancellous bone): appears to be spongy, contains trabeculae (spicules) of mineralized tissue (regions between the trabeculae are filled with bone marrow)

Periosteum: composed of outer fibrous layer and inner cell-rich layer containing osteoblasts, covers bone exterior

Endosteum: lines the inner surface of bones, specifically the medullary cavity and covers the trabeculae of spongy bone

Epiphysis

extremity of the long bone

Metaphysis

expanded or flared part of the bones at the ends of the diaphysis

Diaphysis

cylindrical shaft between the epiphyses

Physis

epiphyseal plate

Bone Composition

• composed of water, minerals, and organic matter

• calcium and phosphorus are important

• Wet Weight: 25% / 45% / 30%

• Dry Weight: 0% / 70% / 30%

Types of Cells Found in Bone

• Osteoprogenitor Cells: stem cell

• Osteoblast: forms bone matrix

• Osteocyte: maintains bone tissue

• Osteoclast: derived from blood-producing stem cells (monocytes)

Haversian Systems

• contain a canal surrounded by layers of bone

• bone vessels are contained in:

  • haversian canals

  • volkmann canals

• osteocytes communicate via canaliculi

  • How Do They Communicate?

    • the interstitial fluid diffuses through the canalicular network from the blood vessels in the canals for maintenance of the osteocytes; facilitation of fluid transport may be caused by periodic contraction of the osteocytes

Long Bone Growth

• is mainly in length

• part of growth and development

• Ossification: bone formation

  • endochondral

  • intramembranous

• Epiphyseal Plate is the key for long bones

Diametrical Growth

• is important throughout life

• What Bone Cells are Key for this Process?

  • osteoblasts and osteoclasts

• Why is this Important through Life (and Not Just Growth)?

  • it helps maintain bone strength, adaptability, and health

Four Zones of a Epiphyseal Plate

Epiphyseal Bone

1. Reserve Cartilage → youngest

2. Proliferation

3. Hypertropy

4. Calcified Matrix → oldest

Trabeculae

Long Bone Structure

1. Epiphysis

2. Diaphysis

3. Epiphysis

4. Medullary Cavity

5. Endosteum

6. Periosteum

7. Epiphyseal Plate

8. Articular Cartilage

9. Spongy Bone

Joints

• are the movable union between two bones

• are named for the bones that are articulating

• the “yes” and “no” joints are two key joints of the vertebral column

• simple vs. compound

• Classification: 2 Ways

• Structure:

  • fibrous

  • cartilaginous

  • synovial

• Function:

  • immovable

  • slightly moveable

  • freely moveable

Synovial Joints

• allow one surface to glide over another

• contain a capsule filled with fluid

• joint capsule is a 2-layered structure

• ligaments are key to joint formation

• synovial fluid lubricates and nourishes articular cartilage

• What is Hyaluronic Acid?

  • found in the skin, eyes, and joints that maintains hydration and tissue structure

Key Joints

Knee: radiocarpal, middle carpal, carpometacarpal

Fetlock: metacarpophalangeal (MP)

*Pastern: proximal interphalangeal (PP)

*Coffin: distal interphalangeal (DIP)

Hock: tibiofibular, intertarsal (proximal + distal), tarsalmetatarsal

Fetlock: metatarsophalangeal (MP)

*Pastern: proximal interphalangeal (PIP)

*Coffin: distal interphalangeal (DIP)

The “Yes” and “No” Joints are Two Key Joints of the Vertebral Column

“Yes” Joint: Alanto-Occipital Joint

“No” Joint: Alanto-Axial Joint