Animal Skeletal System (Osteology)

The animal skeletal system consists of bones, cartilage, tendons, and ligaments. They form the central framework of the animal’s body.

From this article, you will learn the detailed topics of animal skeletal anatomy with other helpful guides.

Quick overview: bones are the principal components of the animal skeletal system that form the hard framework known as the skeleton. The skeleton of the animals is divided into two major parts – axial and appendicular skeletons.

So, it would help if you focused on studying the bones (osteology) from animal skeletons. Let’s get the proper guide and learn the features of every bone from the animals’ axial and appendicular skeletons.

Animal skeletal system

It is mandatory to know every single bone from the animal skeletal system. Let’s learn and identify all the bones from the animal skeleton –

Now, let’s see the key features or learning objectives of the skeletal system of the animals.

Learning objective of the skeletal system:

• Define and able to identify all the essential osteological terminology,
• Describe the functions of the animal bones and skeleton,
• Be able to use the standard terminology to describe the different features of the animal’s bones,
• Be able to classify all the bones according to their gross appearances,
• Know the name and identify the bones from the axial skeleton of the animals,
• Know the name and identify the bones from the appendicular skeleton of the animals,
• Identification of the modification of the limb bones from the domestic and wild animals,
• Differentiate the bones among various animal species,
• Know the ideal structure of the long bone of an animal and
• Understand the intra-cartilaginous and intramembranous ossification of the animal’s bones,

What is veterinary osteology?

The study of bones that make up the skeleton of an animal is veterinary osteology. Thus, the bones become the major component of the skeleton of animals.

Besides the formation of the animal skeleton, bones have the following functions: –

• They act as the levers for the muscles,
• These bones provide the hard framework and protect the visceral organs of animals and
• They help to manufacture the cells and also act as a reservoir of mineral salts,

The number of bones in various animals is different. You will find the complete guide on the number of bones I have already explained in other articles.

Table 1 shows the helpful article that provides the ideal guide to knowing the number of bones from different animals –

What are the different types of skeletons in animals?

The skeleton provides the basis for the external structure and appearance of most vertebrae animals. All mammals share the basic body plan with similarities in the skeletal structure.

The animal skeleton consists of bones, cartilage, and ligaments. There are two different types of skeletons in the animal body –

• The axial skeleton of an animal: – it consists of the bones of the animal skull, vertebral column, ribs, and sternum,
• Appendicular skeleton of an animal: – it consists of the bones of the front and hind limbs of the skeleton,

The bones (except vertebrae) from most of the animal’s skeleton are bilaterally symmetrical. Only the vertebrae are the unpaired and irregular bones of the animal’s skeleton.

You will find the complete guide on the skeletons of various animals here on Anatomy Learner. I have already described the various animal’s skeletons with diagrams.

Table 2 shows the full guide on the skeleton of various animals –

The main functions of the animal skeleton are –

• It is responsible for the maintenance of the shape of the animal body,
• The skeleton of an animal gives protection to the visceral organs and provides attachment to the muscles and
• It provides the flexibility and as well as the locomotion of the animal body,

Skeletons of animals with names

Before going to describe the features of the bones from the animal skeleton, you might know the following –

• Type of the bone based on their external appearance,
• Structures of the long bone of an animal,
• Typical process of animal bone formation and
• Various osteological terminology that describe the features of the animal bones,

The bones of the animal skeletal system are divided into various categories based on size, shape, and structure. Long, short, irregular, flat, pneumatic, sesamoid, visceral, and modified long bones are the most common categories of the animal’s bones.

The long bone of an animal presents three parts: diaphysis, epiphysis, and metaphysis. You will find the hard and dense compact substance at the bone’s external aspect. Again, this compact substance of the animal bone surrounds the spongy substance.

The diaphysis of an animal’s long bone is the part that is ossified from the primary ossification center.

All the topics mentioned above from the animal bones are described in detail by the anatomy learner. Here in Table 3, I have mentioned the complete guide to these topics of animal bones –

Bones from the axial skeleton of animals

The bones from the animal’s axial skeleton consist of the following –

• Bones of the skull: – includes the paired and unpaired bones. It may also divide into 7 cranial and 9 facial bones.
• Different features of the animal mandible: – ramus, body, and processes,
• Vertebral bones: – includes the cervical, thoracic, lumbar, sacral, and caudal vertebrae.
• Ribs and sternum of the animal: – the number of the ribs varies from species to species. But there is only one sternum in the vertebrate animal. The segment of the sternum is variable in different animal species.

The diagram shows the bones from the axial skeleton of the animals. You will find little variation in the features of these axial bones among the horse, dog, and ox.

The bones of most of the vertebrate skull may be grouped as follows –

Cranial bones of the animal skull:

• Occipital bone – single,
• Interparietal bone – paired,
• Parietal bone – paired,
• Sphenoid bone – single,
• Ethmoid bone – single,
• Frontal bone – paired, and
• Temporal bone – paired,

Facial bones of the animal skull:

• Lacrimal bone – paired,
• Malar bone – paired,
• Maxilla bone – paired,
• Pre-maxilla bone – paired,
• Palatine bone – paired,
• Nasal bone – paired,
• Nasal bone – paired,
• Pterygoid bone – paired,
• Turbinate bone – paired, and
• Vomar bone – single,

You will find the detailed guide on the skull bones of different animals in Table 4 –

The guide mentioned above might help you to learn the typical osteological features of the animal’s skulls. You might also know the typical features of the animal mandible bones. Let’s see the article to get an overview of the animal mandibles –

• Dog mandibular anatomy – canine mandibular body and ramus with the diagram and
• Cow jaw bone anatomy – identification along with the teeth,

Animal vertebral column bones

First, let’s know what the animal vertebral column is. It is the series of vertebral bones that articulate all together to form a long column along the axial skeleton.

Based on shape, size, and location, the vertebral column of an animal divides into 5 segments –

• Cervical vertebrae of the animal (neck),
• Thoracic vertebral bones of the animal (thorax),
• Lumbar vertebral bones (loin),
• Sacral vertebral bones (pelvic region), and
• Caudal or coccygeal vertebral bones (tail bones),

The vertebral formula of any particular animal consists of the following –

• The letter symbol for each region of the spine and
• The number of the vertebrae in that particular region of the specific animals,

You will see a great variation in the number of vertebrae in various animals. The number of vertebrae in common domestic animals is shown in Table 5 –

Again, the below-mentioned article might help you to know the details of counting the animal’s vertebrae –

• How many vertebrae does a cat have?
• How many thoracic vertebrae does a normal dog have?

To describe the osteological features of a particular vertebra, you might know its typical features. Here, the diagram shows the common features of the animal’s typical vertebra.

Animal cervical vertebrae

Most animals possess seven cervical vertebrae in their spine or vertebral column. The typical features of the animal’s cervical vertebrae are –

The first (atlas) and second (axis) cervical vertebrae of an animal are highly modified in their structure,

The third, fourth, and fifth (3rd to 5th) cervical vertebrae of the animal show the common features of the typical vertebrae,

The sixth cervical vertebrae of most of animals show the quadrilateral plate on its lower part of the transverse process,

Animal’s seventh cervical vertebra possesses two facets on its caudal aspect of the body for articulation with the first pair of ribs,

Here, the Table 6 shows a detailed guide for the cervical vertebrae from different animals –

Other vertebral bones of the animals

First, let’s see the identifying features of the other vertebral bones (except cervical) –

Thoracic vertebrae: they possess the longer spinous process and additional intervertebral foramen,

Animal lumbar vertebrae: – they have the long, flattened transverse process and quadrilateral spinous process,

Sacral vertebrae: – they are variable in number in different animals (3 – 5). These sacral vertebral bones of the animals fuse to form a single sacrum.

Caudal vertebrae: – they are also variable in the animals and have incomplete bones that form the tail.

Now, let’s find the perfect guide on animals’ thoracic, lumbar, sacral, and caudal vertebrae. Here, Table 7 provides the complete guide for these animal’s vertebrae –

Animal sternum and ribs

The sternum and ribs are also part of the axial skeleton of the

animal skeletal system. Here, the sternum of the animal is the long osseo-cartilaginous structure. This structure is located at the midline of the floor of the animal’s thoracic cavity.

Again, the ribs are paired, curved, modified long bones of the axial skeleton of the animal. You will find three types of ribs (asternal, sternal, and floating) in the axial skeleton of the animals.

The number of ribs varies with the animals and forms the thoracic cage. The below-mentioned guide provides the osteological features and counting of the ribs from different animals (Table 8) –

Appendicular skeleton of the animal skeletal system

In this article section, you get a detailed guide on the appendicular skeleton bones. First, let’s identify the bones from the appendicular skeleton of the animals –

Bones of the animal forelimb:

• Scapula of the animal: form the shoulder girdle or region,
• Humerus bone of the animal: form the brachium or arm region,
• Radius and ulna bones: form the antebrachium or forearm of the limb and
• Tarsal, metatarsal, and phalanges: form the manus region of the forelimb of an animals,

The number of bones in manus varies in different animals. So, it is important to learn the osteological features of these bones from particular animals.

Bones of the animal hindlimb:

• Hip bones (ilium, ischium, and pubis): form the pelvic girdle of the animal,
• Femur of the animal: forms the thigh region of the animal,
• Tibial and fibula bones: form the leg region of the animals and
• Tarsal, metatarsal, and phalanges: They form the manus region of the animal’s hind legs. Again, the number of bones of the pes region varies in different animals.

Notes on forelimb bones of the animals

The first bone of the forelimb of an animal is the scapula. It is a triangular bone in most domesticated animals located at the cranio-lateral aspect of the thorax.

Here, the diagram identifies the important osteological features of the forelimb bones of the animals. But, you might learn the details of these bones’ osteological features from other articles for anatomy learners.

The surfaces, borders, and spine with the acromion process are the most identifying features of the scapula. But, you will find the little differences of the scapula bones among the horses, dogs, and cows.

Let’s find the detailed guide on the forelimb bones of different animals from Table 9 –

The humerus is the long bone of the animal’s forelimb that forms the arm. It possesses a body with four surfaces: proximal and distal extremities.

The special feature of the body is the presence of a musculospiral groove. Again, the features of the head and distal extremities (olecranon and radial fossa) are essential osteological features of the humerus.

The radius (cranial and larger) and ulna (caudolateral and small) are the fused bones in animals? They possess different important osteological features, like the olecranon and anconeal processes.

Animal manus bones

The carpals of an animal’s forelimb are the short bones that are arranged into two rows. These bones are located between the radius and ulna bone above and the metacarpals below.

The cow possesses six carpal bones in its carpus, whereas the horse has seven carpals. The proximal row of the cow carpal possesses four carpals, and the distal row consists of two carpals.

Again, the proximal row of horse carpus has 4 carpals. However, the distal row of the horse carpus has 3 carpals.

There are two large and two small metacarpal bones in the cow’s manus. But, the horse manus has only one metacarpal bone.

The animal metacarpal bone has a shaft and two extremities (proximal and distal). The shaft of the animal metacarpal bone is cylindrical and possesses two distinct surfaces – dorsal and palmar.

The dorsal longitudinal groove on the metacarpals of a cow indicates the function of two bones. Three phalanges (proximal, middle, and distal) form the digit of the animals.

The number of digits varies among the horses, dogs, and cows.

Notes on hindlimb bones of the animal

The animal’s right and left hip bones form the bony pelvis or pelvic girdle. Each animal hip consists of the ilium, ischium, and pubis bones.

The ilium of an animal is the flat triangular bone located at the craniolateral aspect of the hip. Tuber sacral and tuber coxae are the clinically important osteological features of the animal ilium bone.

Animal ischium is the roughly quadrilateral plate of bone of the hip. It forms the ischial tuberosity, ischial arch, and obturator foramen of the hip.

The animal’s pubis is also the triangular bone located at the craniaomedial aspect of the hip. It forms the floor of the pelvic cavity of the animal. Again, the cranial part of the pubis bone possesses the iliopubic eminence where the pre-pubic tendon inserts.

These are very short descriptions of animal hips. But, you need to know more about the animal hip with the proper diagram.

Let’s find the perfect guide on the different bones of the animal hindlimb from Table 10 –

You will also find other guides on the different bones from the animal skeleton. Reading them from the particular animal’s anatomy learning section will be better.

Animal thigh and leg bone

The femur is the animal thigh bone, which is the largest and most cylindrical bone of the skeleton. It is also known as the round bone in the animal, as its body is cylindrical in the middle.

The animal femur bone possesses the shaft and two extremities (proximal and distal). The most important osteological feature from the proximal extremity of the animal femur is the head with fovea capitis.

Again, the distal extremity of the animal femur possesses the cranial trochlea and caudal condyle. The body of the animal femur has the supracondylar fossa.

Most of the animals have the rough triangular patella that is placed in front of the trochlea of the femur.

The animal tibia is the massive and strong bone of the skeleton. It also possesses the shaft and two extremities like the other long bones of the body.

Formally, this bone forms the leg region of the animal. Thus, it is also called the leg bone of the animals.

The tibial crest and spine are essential features of the animal tibia bone. Again, the caudal surface of the animal tibial bone shows the popliteal ridges and lines.

The fibula of the animal varies in its structure in different animals. It is a highly rudimentary bone in the ox that attaches to the lateral aspect of the tibial bone.

Pes bone of the animal skeleton

The tarsal, metatarsal, and phalanges of the hindlimbs of animals form it. You will find the animal tarsal between the tibia and metatarsal bones.

There are also variations in the number of the animal tarsals. You will find five tarsal bones in the ox. However, the horse has six tarsal bones.

These animal’s tarsal bones are arranged into three rows. There are differences in the arrangement of the tarsal bones between the horses and cows.

Here, the diagram shows the arrangement of the tarsal bones of the horses and cows.

You will find two metatarsal bones in the ox, whereas the horse has only one. The third and fourth metatarsals fused to form a single large metatarsal.

There is another small metatarsal bone in the ox at the medial aspect of the third metatarsal.

By their external appearance, you may easily differentiate the metatarsal from the metacarpal bones. The metatarsals are the four-sided bones in the cow that possess four surfaces.

Again, the longitudinal groove of the cow’s metatarsal is deeper and wider than the metacarpal. However, the phalanges of the animal’s hindlimb almost possess similar osteological features.

Conclusion

So, this article provides complete guides on the bones of the animal skeletal system. You might learn the bones from the axial and appendicular skeleton of the animal with real samples.

Besides these guides, you will find more animal bone information from other articles. So, let’s find them from the anatomy learner and complete your animal skeletal system learning.

WRITTEN BY

Sonnet Poddar

Hi, I am Sonnet (veterinarian; I Completed my DVM – DOCTOR OF VETERINARY MEDICINE and have a good Knowledge of VETERINARY ANATOMY) from AnatomyLearner.com. I love sharing essential and informative veterinary anatomy topics with the new learner. I tried my best to provide a perfect guide with possible explanations, labeled images, and videos to learn gross veterinary anatomy and histology of animal’s organs.