The document summarizes key aspects of the locomotor system and skeleton. It describes the skeleton's main functions of providing shape, support, protection and movement. The skeleton is divided into the axial skeleton of the skull, vertebral column, ribs and sternum, and the appendicular skeleton of the limbs. Typical long bones have a shaft, ends, and growth plate. Bones are classified based on shape and composition. Key markings and structures of bones are also defined.

1. Locomotor System – I
Skeleton (BONES AND Cartilage)
ANATOMY-I (ANAT-02101) Crd Hr 3(1-2)
LECTURE 2
BY
SULTAN ALI
DVM (SAU, TANDOJAM)
MPHIL (UVAS, LAHORE)

2. Learning outcomes
At the end of this lecture students will be expected to know about:
Components of locomotor system .
The skeleton, its divisions, Major bones of the body and regional locations.
Classification, properties, structure and functions of bones.
The structure of a typical long bone (Epiphysis, Metaphysis, Diaphysis-Medullary
cavity, Periosteum, Endosteum)

3. (Complex organ system)

4. SKELETON
The framework of hard structures of the body which provide a specific shape, support and
protection to the soft tissues of the animals.
FUNCTIONS:
 Foundation or proper shape.
 Support and furnishes attachment to the soft tissues.
 Provide protection to delicate tissues/organs.
 Help in locomotion, act as a levers.
 Pneumatic types of bones (fowl/birds) helps in flight.
 Metabolic support. Hematopoiesis and mineral reservoir.
It consist of mainly the:
 Bones.
 Supplemented by cartilage
in many places.
 The binding tissue called
the ligament and
 The joints.

5. SKELETAL SYSTEM
Appendicular skeleton:
includes the bones of the thoracic girdle and forelimbs and the pelvic girdle and hind limbs.
Axial skeleton:
consists of the bones of the skull, hyoid apparatus, vertebral column, ribs, and sternum.
Segments of vertebral column:
Cervical. Thoracic. Lumbar. Sacral. and Caudal. (formerly coccygeal).
vertebral formula.
Dog: C7 T13 L7 S3 Cd20.
Heterotopic or visceral skeleton:
Certain bones of soft organs e.g. os penis and os cardis.

6. Skeleton of dog
Divisions of Skeleton
(1)Axial:
vertebral column, ribs,
sternum and skull
(2)Appendicular:
bones of the limbs
(3) Splanchnic:
bones developed in the
substance of viscera /
soft tissues

7. Factors causing variation in the number of
bones of skeleton:
Age, Fusion during growth of skeletal elements.
Individual variations : within normal range
Bones come in different shape, size and
strength
•These differences are determined by
genetic determination & static and dynamic
influences.
•Muscle or tendon attachments on bones
cause the development of processes,
tubercles, crests, spines, roughened
surfaces, depressions or notches.
•Blood vessels, nerves or organs contour the
surface of bone (groove)

10. Regional location of bones and joints:
Coracoid
*Dorsal as well as palmar sesamoid bones.
JOINTS
SHOULDER
ELBOW
KNEE
FETLOCK
PASTERN
COFFIN
JOINTS
HIP
STIFYL
HOCK
FETLOCK
PASTERN
COFFIN
P1
P2
P3

11. Classification of bones on the basis of shape / appearance:
Bone: The hard semi rigid calcified connective tissue
forming the skeleton.
Five general divisions:
 Long Bones.
 Short Bones and,
 Sesamoid bones.
(are characteristic of the limbs)
 Flat Bones.
 Irregular bones.
(are characteristic of the skull and vertebral column)
CHEMICAL COMPOSITION
Dried bone consists of organic and inorganic
matter in the ratio of 1 : 2
Organic Ground Substance: Collagen fibers.
Contributing flexibility and tensile strength
Bone mineral: Calcium phosphate (85-90 %)
Calcium carbonate (8-10 %), Magnesium
phosphate (1.5 %) and calcium fluoride (0.3 %)
Contributing stiffness and compressive
strength
PHYSICAL PROPERTIES OF BONE
Fresh dead bone is yellowish-white in color
Macerated or boiled and bleached is bright white
Tensile strength nearly twice that of oak

13. Characterized by:
a body/shaft -Diaphysis
a proximal and distal ends/extremities -Epiphyses
and the growth plate -Metaphysis
•Diaphysis encloses the central marrow
or medullary cavity.
•Epiphysis consist of core of spongy
bone covered by compact bone and
Articular cartilage (hyaline cartilage)
•Shaft is lined by periosteum and
endosteum on the outside and inside
respectively.
Long bones:
Typical in limbs
Main weight bearing
Ends are enlarged

14. Structure of a typical long bone:
Medullary cavity: the space in shafts
of long bones in the adult are filled
largely with yellow bone marrow chiefly
fat, in fetus and the newborn, red bone
marrow functions in forming red blood
cells.
Periosteum: the fibrous layer of
connective tissue covers the non
articular surfaces of all bones in the
fresh state.
aid in growth, repair, nutrition &
attachment for ligaments and tendons.
Endosteum: is lines the large
medullary cavities similar to periosteum
but thinner.
Perichondrium: The connective tissue
covering of cartilage does not differ
histologically from periosteum.

16. Vessels and Nerves of Bone
• Nutrient foramen and canals
• Long bones and many flat and irregular bones have a conspicuous
• Nutrient (medullary) artery and vein
• Lymph vessels are present in the periosteum as
perivascular sheaths
• and probably also as unaccompanied vessels within the bone
marrow.
• Nerves in bone are principally sensory

17. Short bones - vary greatly in shape : cylindrical, cuboid
or spheroid (six surfaces) to irregularly compressed rods
(one flat) articular surface.
Bears weight, helps in joints movement
They are occupied by a three-dimensional lattice of
spongy bone with intervening haemoreticular tissue.
Include the bones of the carpus, tarsus and spine
Sesamoid bones
Seasame (seed in Greek), found in Freely moving joints.
develop in the capsules of some joints or in tendons Chief
function is to protect tendons, where greatest friction is
developed.
Largest bone is patella

18. • Flat bones protect the soft organs , serve for muscle
attachment.
• consists of two layers of solid bone (tabulae) with spongy bone
(diploe) or air-filled cavities (sinus) between them.
• Include the scapula and skull bones
• Some of the flat bones of the skull are pneumatized.
Irregular bones
• Jutting processes are the characteristic features
• Muscular and ligamentous attachments; some articulation.
• Vertebral column, some bones of the skull, and the os coxae.
Pneumatic bones:
contain air-spaces or sinuses within the compact substance
instead of spongy bone and marrow.

19. COMPACT BONE/Lamellar/Cortical bone:
Collagen fibres arranged in parallel and concentric
Haversian Lamellae Outer and Inner circumferential
lamellae covered by periosteum and endosteum,
respectively Composed of cylindrical units Osteons
(Haversian system)
OSTEON
•A central vascular channel (Haversian canal)
surrounded by Haversian Lamellae
•Bone cells are located between the lamellae
•The Haversian or nutrient canals communicate with the
marrow cavity and the external surface via transverse
channels, Volkmann canals
•Forms the outer layer of the whole of long, short,
irregular and flat bones
•Forms the shaft of the long bones

21. SPONGY BONE/Cancellous / Trabecular bone :
•Consists of delicate intercrossing bony plates and
spicules
•The intervals (marrow spaces) between the plates are
occupied by marrow and lined by endosteum
•Forms the bulk of short/irregular bones and of the
extremities and inner aspect of shafts of long bones,
diploe of flat bones
PNEUMATIC BONES contain air-spaces or sinuses
within the compact substance instead of spongy bone and
marrow.

25. MARKING ON THE BONES/ BONY CONTOURS OF A BONE.
Tuberosity:
A large usually rounded roughened projection which is non articular.
Tubercle:
A small rounded projection.
Trochanter:
A large blunt projection found only on the femur
Trochlea:
Pulley shaped articular projection/structure

26. Marking on the bones
Condyles:
A large articular prominence, usually smooth and convex at the end of the
long bones e.g. condyles of humerus and femur.
Epicondyle:
A prominence just above the condyles usually roughened.
 Spine:
A sharp thin elongated process e.g. scapula
Crest:
Prominent or well developed linear sharp ridge on the bone e.g. humerus,
tibia.
Line: Less prominent or faint ridge

28. Marking on the bones
Foramen:
An opening in the bone (for blood vessel and nerve).
Canal:
Long foramen which has a second opening.
Fissure:
A narrow cleft like opening between bones
Groove:
Small narrow furrow accommodating vessels, nerve or tendon.
Sinus:
A large air cavity with in a bone
• Head. Neck, Fovea
• Notch: Depression on the edge of bone
• Facet. A smooth flat surface.
 Mostly covered by hyaline cartilage