This document summarizes anatomy and physiology of bone, muscle, and joints as well as skeletal disorders and congenital disorders present at birth. It discusses the structure and functions of the skeletal system including bones, cartilage, joints, and ligaments. It also describes muscle tissue types and functions. Finally, it outlines various congenital and acquired musculoskeletal diseases such as osteochondrodysplasia, dysostosis, traumatic injuries, nutritional diseases, developmental orthopedic bone diseases, and joint diseases including hip dysplasia.

1. Anatomy & physiology of bone,
muscle & joints
Skeletal disorder & congenital
disorders by birth
Submitted by: Dr. Kanwarpal Singh Dhillon
M.V.SC (Medicine)

2. Bone Tissue and The Skeletal System

3. The Skeletal System
• Functions of the Skeletal System
– Support against gravity
– Leverage for muscle action - movement
– Protection of soft internal organs
– Blood cell production
– Storage - calcium, phosphorous & fat

4. The Skeletal System
• The skeletal system includes:
– Bones
– Cartilages
– Joints
– Ligaments
– Other connective tissues

5. Structure of Typical Long Bone
• Diaphysis - tubular shaft forming the axis of
long bones.
– Composed of compact bone
– Central medullary cavity
– Contains bone marrow
• Epiphysis – expanded end of long bones.
– Composed mostly of spongy bone
– Joint surface is covered with articular (hyaline)
cartilage
– Epiphyseal lines separate the diaphysis from
the epiphyses
• Metaphysis – where epiphysis and diaphysis
meet

6. Bone - Remodeling/Homeostasis
• Homeostasis and Mineral Storage
– Bones store calcium
• Contain 99% of body calcium
• Store up to 2 kg calcium
• Hormones control storage/release
– PTH, calcitriol release bone calcium
– Calcitonin stores bone calcium
• Blood levels kept constant

7. General Structure of Synovial Joints
• Articular cartilage
– Ends of opposing bones are
covered with hyaline cartilage
– Absorbs compression
• Joint cavity (synovial cavity)
– Unique to synovial joints
– Cavity is a potential space that
holds a small amount of synovial
fluid

8. Muscle Function
• Movement
– Depends on type of muscle tissue
– Depends on location of muscle tissue
• Thermogenesis
• Protection
• Posture Maintenance
• Joint Stabilization

9. Muscle Tissue Characteristics
All muscle tissues share basic characteristics
1.Excitability
2.Contractility
3.Elasticity
4.Extensibility

10. Muscle Tissue Types
Skeletal
Cardiac
Smooth

11. (I) CONGENITAL MUSCULOSKELETAL
DISEASES
• Congenital disease of bone, cartilage ( joint
deformity), & muscle (congenital myopathy)
may be identifiable at birth or shorty
thereafter & often have an inherited etiology.

12. Retarded growth
• Reduced growth in terms of skeletal
development or body wt. when compared
with
– normal littermates
– or a failure to attain the weight & height
standards characteristic of a given breed.
• Many diseases may result in retarded growth.

13. • 6-month-old dwarf
German shepherd
dog

14. Osteochondrodysplasia
• Most patients with
osteoochondrodysplasia
have reduced skeletal
growth, characterized by
abnormal endochondral
and intramembranous
ossification.
• They have long trunks &
short legs.

15. Dysostosis
• Occur in the skull, axial & appendicular
skeleton.
• Characterized by overrepresentation or a
partial or complete absence of one or more
bone elements.

16. Radial hemimelia Polydactyly

17. Joint malformation
• Severe joint malformation are rarely diagnosed.
• May ranges from complete absence of joints to
bony fusion of skeletal elements.

18. Congenital myopathies
• It is group of primary, inherited diseases of
skeletal muscle identified within the first
weeks to months after birth.

19. (II) ACQUIRED MUSCLUOSKELETAL
DISEASES
• Do not have a primarily genetic etiology & are
not identifiable at birth.

20. Traumatic injuries (fractures)
• Approximately 40-50% of all dogs presented
to referral centers with traumatic injuries are
less than 1 year of age.
• Traumatic growth plate injuries have been
classified by Salter & Harris in an effort to
relate mechanisms, characterized by a
separation through the growth plate

21. • A type I growth plate injury is
characterized by a separation through
the growth plat.
• A type II injury is a combined growth
plate separation-metaphyseal
fracture.
• A type III injury is a combined growth
plate separation-epiphyseal fracture.
• A type IV injury is characterized by a
combination of a growth plate
separation with an epiphyseal &
metaphyseal fracture.
• Type V injuries are caused by
crushing of the growth plate, which
results in premature closure &
reduced bone length growth.

22. Limb deformities
• Limb deformities with abnormally
shaped bones may be caused by
dysostoses,
osteochondrodysplasias,
nutritonal diseases & growth plate
injuries.
• Clinically this results in shortened
bones or asymmetrical growth
plate with subsequent angular
deformity & rotational deformities
of the affected bone.

23. Nutritional diseases
• It includes nutritional secondary
hyperparathyroidism, hypovitaminosis D
(rickets), hypervitaminosis D, hypovitaminosis
A, hypervitaminosis A, hypovitaminosis E
Rickets

24. Developmental orthopedic bone
diseases (DODs)
• Craniomandibular osteopathy occurs in Terrier breeds.
• The bony formation along the mandible can be so
severe the affected dogs may not be able to prehend &
chew food.

25. • In young large or giant
breed dogs, diaphyseal
pain in one or multiple
bones may be an
indication of panosteitis.
• Hypertrophic
osteodystrophy is a
developmental disease
in immature, large, or
giant breed dogs in
which the metaphyseal
area of long bones
becomes swollen &

26. Joint disease
• Approximately 35% of dogs
younger than 1 yr of age
presented with a musculoskeletal
problems are diagnosed with an
arthropathy.
• Arthopathies may be classified as:
– Non inflammatory
– Inflammatory
• Infectious
• Non infectious
• About 95% of the arthopathies in
growing dogs are non-
inflammatory.
Canine polyarthropathy

27. Shoulder osteochondrosis
• Several breeds are
predisposed for
shoulder OC & 50-
70% heritability has
been estimated in
Labrador Retrivers.
Radiographic image of osteochondrosis
dissecans (OCD) lesions of the caudal
aspects of the humeral head

28. Elbow dysplasia
• Lameness localized to the
elbow of young growing dogs
with no history of trauma is
usually caused by the
syndrome called elbow
dysplasia.
• It includes ununinted
anconeal process, fragmented
medial coronoid process, OC
of the medial humeral
condyle, ununited medial
epicondyle & asynchronous
growth B/W radius & ulna.

29. Patellar luxation
• Medial patellar luxation occurs mainly in small
or miniature dog breeds.
• Lateral patellar luxation occurs mainly in large
dog breeds.

30. Hip dysplasia
• Canine hip dysplasia (CHD) is a developmental trait
primarily affecting medium & large breed dogs.
• It is characterized by faulty conformation & laxity of
the hip joint that usually affects both hips.
• Clinically, early synovitis & capsulitis caused by
subluxation is characterized by hindlimb lameness,
reduced exercise tolerance, reluctance to jump, a
“bunny hopping gait” & pain in hip joint.
• Affects all breeds of dogs, but more common in large
breeds.

32. REFERENCES…
• Small Animal Pediatrics by Michael E.
Peterson & Michelle Anne Kutzler
THANKS