The Skeletal
System
Mrs. Higgins, LVT
Locust Trace Agriscience Center
Veterinary Assistant Program
Functions
• External structure and appearance for most
vertebrate animals
Vital organs
• Provide protection of ______________
(take a guess)
• Give rigidity and form to the body
• Act as levers
Calcium
Phosphorus
• Store minerals _______________
and _______________
• Form the cellular elements of blood
What am I made of?
• The skeletal system is made of various forms of
connective tissue
o They all work together to provide structure and movement
• Consists of:
o
o
o
o
Bone
Joints
Cartilage
Ligaments/Tendons
Terminology
Osteoblasts
Osteoclasts
Bone
• Oste/o ____________
• Oste/o __________
Immature
• -blasts ____________
Break
• -clasts ___________
• Immature bone cells
that produce bony
tissue, become
osteocytes
• Eat away bony tissue
from medullary cavity
Terminology
• Parts of the bone
o
o
o
o
o
o
Diaphysis
• Shaft of the long bone
Epiphysis
• Either end of the long bone
Epiphyseal Cartilage
• Layer of cartilage within the
metaphysis of an immature bone
that separates the diaphysis from
the epiphysis. Location of growth
Metaphysis
• In a mature bone; flared area by
the epiphysis
Periosteum
• Fibrous membrane that covers the
surface of the bone
Medullary Cavity
• “marrow cavity”; In young animals,
filled with red marrow
(hematopoietic tissue)
Bone Marrow
• Hematopoietic
o Hemat/o- blood
o -poietic: pertaining to formations
• Forms blood cells (red cells and white cells)
• In adult animals, red marrow is replaced by yellow
marrow. This is mostly fat cells, serves as fat storage
area.
Cartilage
• A form of connective tissue
• More elastic and flexible than bone
• Articular cartilage
o Covers the joint surfaces of the bone
• Meniscus
o Curved fibrous cartilage found in some joints
o Acts as cushion from force
o Example….. Stifle/knee
Cartilage
Joints
• Also called articulations
• Form the connection between bones
• Different types depending on degree of movement
1. Fibrous
2. Cartilaginous
3. Synovial
• There are many within each category above, but
we will cover a few from each
Fibrous Joints
• No joint
cavity, no
movement
• Example
o Suture joint:
between bones
of the skull.
Suture joints often
completely ossify
in maturity
Cartilaginous Joints
• Bones are united
by cartilage with
no joint cavity
• Limited
movement
• Example
o Symphyses joints: joined
by flattened disks of
fibrocartilage as found
between the pelvic
bones (birth canal) or
between vertebrae
Synovial Joints
• Moveable joints
• Examples
o Ellipsoid Joint: when a row of small bones fit against a long bone (carpus
or tarsus)
o Spheroid Joint: “ball and socket”; movement in nearly any direction.
Spherical head of one bone fits into the depression of another bone.
(Example is….. ______________________)
Hip joint
o Hinge joints: allows for movement in one direction. Example
Knee
or stifle
__________________
o Pivot joint: movement occurs around one axis. Example
Atlas/axis joint of neck
___________________________
Synovial Joints
Ellipsoid
Synovial Joint
Spheroid (ball and socket)
Synovial Joins
Hinge Joint
Synovial Joint
Pivot Joint
Terms of Movement
• Adduction
o Movement towards midline
• Abduction
o Movement away from midline
• Flexion
o Closure of a joint angle
o Reducing angle
• Extension
o Straightening of joint
o Increasing the angle
• Hyperflexion
o When a joint is flexed or extended too far
Movement Terms
Tendons
• Connective tissue that attaches muscle to bone.
Ligament
• Connective
tissue that
attaches
bone to bone
The Skeleton
The Skeleton
• Broken into two parts
• Axial Skeleton: the central skeleton consisting of the
skull, vertebral column, and ribs
• Appendicular skeleton: Limbs/Appendages
(thoracic limbs and pelvic limbs)
**Most of the skeletal system will be the same for
different species of animals…. However, there will be
differences in the feet/legs and the vertebral column
of each animal. Why??
Vertebral Column
• Made up of many individual vertebra (singular)
or vertebrae (plural)
• Numbered from head to tail and grouped into
sections
o
o
o
o
o
Cervical
Thoracic
Lumbar
Sacral
Coccygeal
• Two of the vertebra have names
o C1: atlas
o C2: axis
Thoracic Limbs
• The forequarters carry up to 70% of the body weight
of animals
• Consists of
o
o
o
o
o
o
o
Scapula
Humerus
Radius
Ulna
Carpal bones
Metacarpal bones
Phalanges
Pelvic Limbs
• Carry less weight (about 30%) but are heavily
muscled
• Consist of
o
o
o
o
o
o
o
o
Pelvis
Femur
Patella
Tibia
Fibula
Tarsal Bones
Metatarsal bones
Phalanges
*Sesmoid bone: small bone held in place by tendon
(patella)
Let’s Label!!
Do you see the
differences?
Cattle
Dog
Horse
Swine
Different numbers of metacarpal bones and phalanges present
Horse Lower Leg
• P1 or long pastern or
proximal phalanx
• P2 or short pastern or
middle phalanx
• P3 or coffin bone or
distal phalanx
**The horse industry uses
long and short pastern
and coffin bone
Great Interactive Websites
• http://www2.ca.uky.edu/agripedia/agmania/intera
ctive/
• http://www.real3danatomy.com/bones/dogskeleton-3d.html
• http://www.vet.osu.edu/assets/flash/education/out
reach/games/skeleton/skeleton.html