Osteology is the branch of science that deals with the study of bones. Bones are the living tissues because
1) They have blood vessels, lymphatic vessels and nerves.
2) They can grow.
3) They can repair themselves if damaged.
A long bone consists of the following parts:
1) Compact bone: It is a hard layer of bone that covers a spongy substance.
2) Spongy bone: It is composed of small bony plates arranged to form a porous or spongy structure.
3) Epiphysis: It means either extremity of a long bone.
4) Diphysis: It is the cylindrical shaft of a long bone.
5) Metaphysis: It is situated between epiphysis and diaphysis.
6) Periosteum: It is a fibrous membrane that covers the surface of bone except at the articular surface.
7) Endosteum: It is a membrane that lines the medullary cavity and various marrow spaces
8) Articular Cartilage: It is a thin layer of cartilage which covers the articular surface of the bone.
9) Medullary or Marrow Cavity: It is a hollow space in the middle of the long bone fiiied with either red or yellow marrow.
10) Bone marrow: It is soft and pulpy tissue which fills the marrow cavity of long bones and marrow spaces of all the bones. Articular cartilage, Proximal epiphysis Metaphysis Cancellous (spongy) bone Compact bone Medullary cavity Diaphysis Periosteum Endosteum Metaphysis Distal epiphysis- Articular cartilage.
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| Fig. 1.1: Structure of Bone |
COMPOSITION OF BONES :
Fresh or wet bone is composed of water (25%), ash or mineral matter (45%) and organic matter (30%). Dried bone consists of organic and inorganic matter in the ratio of 1: 2. The organic matter mainly consists of collagen (major), mucopolysaccharides, fatty acids, glycoproteins, and phospholipids (minor). The organic matter gives toughness and elasticity to the bone. The inorganic or mineral matter includes calcium, phosphorus, carbonates, citrates, sodium, potassium, magnesium, chlorides etc. The mineral matter gives hardness and rigidity to the bones. The chemical composition of bone in ox is as follows : : 33.30 % : 57.35 % : 3.85 % : 2.05 % : 3.45 % Gelatin/Organic matter Calcium phosphate Calcium carbonate Magnesium phosphate Sodium chloride & carbonates
FUNCTIONS OF BONES :
1. They give a definite shape to the body.
2. They offer support to the body.
3. They help in locomotion, defence and offence.
4. They protect vital organs such as the brain, lungs and heart.
5. They provide minerals like calcium and phosphorus to the body.
6. The bone marrow produces blood cells.
CLASSIFICATION OF BONES :
According to the gross appearance, the bones have been classified into six groups as long, short, flat, irregular, sesamoid and pneumatic.
1) Long bones:
1. These are greater in length than any other dimension.
2. They contain marrow/medullary cavities.
3. They are located mostly in the region of the limbs.
4. Functions: They aid in support, locomotion and prehension.
5. Examples are Humerus, Radius-ulna, Metacarpal, Femur, Tibia-fibula, Metatarsal, & Phalanges. The femur is the largest long bone. Elongated bones These are the diminutive forms of long bones. These are slender and long but are devoid of the medullary cavity. e.g. Ribs.
2) Short bones :
1. These are small bones of uniform dimensions.
2. There is no marrow cavity.
3. They are mainly found in joints between two large bones.
4. Function: They increase the mobility of the joints and distribute pressure.
5. Examples are Carpal and Tarsal bones.
3) Flat bones :
1. They are relatively thin and expanded in two dimensions.
2. Functions: They protect the vital organs and provide a large area for muscle attachment.
3. Examples are Scapula and Pelvic bones.
4) Irregular bones :
1. These are irregular in shape.
2. They are generally unpaired and located on the median plane.
3. Functions: They serve for protection, support and muscle attachment.
4. Examples are Vertebrae.
5) Pneumatic bones :
1. They contain air spaces or sinuses which communicate with the exterior.
2. The bones of birds are light in weight due to the presence of air säcs.
3. Examples are long bones of birds
6) Sesamoid bones :
1. These are small, sesame seed-like short bones.
2. These are placed between the bones and tendons.
3. Function: They work as pully to avoid friction.
4. Example is Patella, the largest sesamoid bone in the animal body.
SKELETON
Skeleton: It can be defined as a hard framework of the body which supports soft structures. The skeleton (Fig. 1.2) is divided into three parts a) Axial Skeleton: It is made up of bones of the skull, vertebral column, ribs and sternum. b) Appendicular Skeleton: It is made up of bones of the forelimb and hind limbs. c) Visceral Skeleton: It consists of bones developed in the substance of visceral or soft organs. e.g., Os cordis of Ox. Sacrum Lumbar Thoracic Scapula Cervical Coccygeal vertebrae DORSAL Pelvic bone Skull Anterior Mandible Femur Posterior Tibia Humerus Tarsal Radius & ulna VENTRAL Carpals Metacarpal Digit Metatarsal.
OSTEOLOGÍCAL TERMS :
Articular Projections:
Head:
Aspherical articular projection. : A more or less cylindrical articular projection. : A pully like articular structure. : A flat articular surface. Condyle Trochlea Facet Non-articular Projections:: Any prominence or projection on bonę. : A large, rounded non-articular projection. : A small rounded projection: A pointed projection: A sharp ridge: A cylindrical part of the bone to which the head is attached. Process Tuberosity Tubercle Spine Crest Neck Articular depressions: Glenoid cavity Cotyloid cavity: A shallow articular concavity. : A deep articular concavity. : An articular indentation. Notch Non-articular depressions:: A large, non-articular depression. : A small, non-articular depression. : A circumscribed hole in a bone. Fossa Fovea Foramen
(A) AXIAL SKELETON
It consists of bones of the skull, vertebral column, ribs, and sternum.
1) SKULL:
Parietal bone Cornual process It includes all the bones of the head and is described into facial and Zygomatic cranial bones. -Frontal bone The facial bones form the arch Orbit oral and nasal cavities and give shape Supraorbital foramen to the face.
The bones of the face are
2) Premaxilla
4) Pterygoid
6) Ventral Turbinates
8)Dorsal- Turbinates Lacrimal bone Malar bone
1) Maxilla
3) Palatine 5) Nasal
7)Malar
9) Lacrimal
10) Volmar
11) Hyoid these, the last three are single while others are paired bones. Maxilla Nasal bone Infraorbital foramen Premaxilla Palatine fissure
12) Mandible.
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| Skull of Ox |
The cranial bones form the cranium which lodges the brain. Bones of cranium include
1) Occipital
2) Sphenoid
3) Ethmoid
4) Interparietal
5) Parietal
6) Frontal single while others are paired bones.
7) Temporal bones. Out of these, the first three are unpaired or
2) VERTEBRAL COLUMN :
A series of vertebrae articulate together to form a long column of the axial skeleton in the body is called the vertebral column. The vertebral column consists of five types of vertebrae
1. Cervical vertebrae
2. Thoracic vertebrae: Neck: Withers and back: Loin: Croup
3. Lumbar vertebrae
4. Sacral vertebrae
5. Coccygeal vertebrae: Tail The vertebral formula for the ox is as - C, T, L. S, C, 15- 25 Typical Vertebra: A typical vertebra consists of a body, an arch and process. Body: It is a solid cylindrical mass which supports other structures of the bone. The anterior end is convex while the posterior end is the Supraspinous process concave.
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Lumbar vertebrae and Thoracic vertebrae
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Caudal Articular Arch :
It is a bony ring situated on the dorsal Cranial Articular aspect of the body. Processes: These are of 3 types i.e. articular, spinous and transverse. Articular processes Neural rings are two on each cranial and caudal aspect. The spinous process is single and is dorsal to the arch. The transverse processes are two in-process processes Transverse /process Body number and project outward from sides of Fig. 1.4 :
Typical Vertebra body.
1) Cervical Vertebrae :
They are seven in number as discussed below: Dorsal tubercle
i) Atlas: It is the first cervical vertebra. It comprises a larger neural ring and two wings. The cranial aspect of the body is highly concave to accommodate the occipital condyles of the skull. The caudal part bears a saddle-shaped Intervertebral Foramen Wing Articular facet Fovea dentist Ventral tubercle articular facet for axis.
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| Atlas of Ox |
ii) Axis: It is the second cervical vertebra. It is characterised by the presence of an odontoid process, two posterior articular processes and broad, thick spinous processes.
iii) Third, Fourth and Fifth Cervical Vertebrae: The typical cervical vertebrae i.e. iii, iv, & v have a long body, well developed articular processes, and short, tuberous spinous processes and a transverse process which is divided into upper and lower portions.
iv) Sixth Cervical Vertebra: In this, Neural articular and the spinous processes are well developed.
v) Seventh Cervical Vertebra: The body bears two facets at the caudal end for articulation with the heads of the first pair.
Typical cervical vertebra of ribs. The spinous process is flat and well developed. Odontoid Caudal Articular process Transverse process Intervertebral foramen Fig. 1.6: Axis Superior spine Caudal Articular process Cranial Articular ring process Body
2) Thoracic Vertebrae: They are 13 in number. The typical thoracic vertebra has a long spinous process, facets like the articular process and a short, thick but undivided transverse process.
3) Lumbar Vertebrae:
They are 6 in number. They are characterised by the presence of long, transverse processes, well developed articular processes and plate-like spinous processes. Superior spine Supraspinous process Caudal articular process Transverse process Cranial articular process Transverse process Cranial articular facet Body. Articular facet for the head of rib Fig. 1.8: Thoracic vertebra Fig. 1.9: Lumbar vertebra
4) Sacrum:
It is formed by the fusion Medial sacral crest and Neural ring of five sacral vertebrae in an ox. It is roughly triangular in outline and forms the roof of the pelvic cavity. Cranial articular The dorsal surface presents the process median sacral crest formed by the fusion of spinous processes. The ventral surface is concave. Body Lateral sacral crest Fig. 1.10: Sacrum of Ox 5) Coccygeal Vertebrae: There are 15 - 25 coccygeal vertebrae in ox. The first five vertebrae have neural rings, bodies and processes. They gradually reduce in size and the last few vertebrae possess only rod-shaped bodies with convex ends.
3) STERNUM:
It is a centrally placed, segmented, osteocartilaginous structure forming the floor of the thoracic cavity. It consists of seven sternal segments called sternebrae. It is divided into 3 parts viz. a) Presternum comprising the first sternal segment. b) Mesosternum (body of sternum) comprising of five middle segments. c) Xiphisternum comprising the last segment with xiphoid cartilage. The dorsal surface of the sternum is concave while the ventral surface is convex. The lateral border possesses 7 pairs of facets for attachment of costal cartilage.
4) RIBS:
These are elongated bones. They form the wall of the thoracic cavity. There are 13 pairs of ribs in cattle. The first 8 pairs of ribs are sternal and the rest 5 pairs are asternal. The shaft is curved and presents two surfaces and two borders. The lateral surface is convex, while the medial surface is concave. The proximal extremity consists of a head, neck and tubercle. The distal extremity is either articular or prolonged by the costal cartilage. Faucet for 1st rib 1st Sternębra Neck Articular facet- Head 2nd Sternebra Groove Cranial border Facet for costal cartilage Caudal border 7th Sternebra xiphoid cartilage Distal end.
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| Rib of Ox |
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