Chapter 6

The skeletal system*

Learning objectives


When you finish this chapter, you will be familiar with bone shapes, common types of bones, bone features, and clinically significant bones. You will not be asked to learn all the bones in the body, but you will be able to name most of them. Luckily the common domestic animal species generally have the same bones so you’ll have to learn them only once.


Terms to be identified


Bone shapes

Flat bones

Irregular bones

Sesamoid bones

Long bones

Short bones

Types of bone

Cancellous bone

Compact bone

General bone features

Articular surface

Condyle

Head

Facet

Foramen

Nutrient foramen

Fossa

Processes

Bones of the axial skeleton

Skull bones (external)

Frontal bones

Cornual process

Incisive bones

Interparietal bones

Lacrimal bones

Mandible

Ramus

Shaft

Maxillary bones

Nasal bones

Occipital bone

Foramen magnum

Occipital condyles

Parietal bones

Temporal bones

External acoustic meatus

Tympanic bullae

Zygomatic bones

Skull bones (internal)

Turbinates

Ribs

Costal cartilage

Costochondral junction

Head

Sternum

Manubrium (manubrium sterni)

Xiphoid (xiphoid process)

Vertebrae

Arch

Body

Processes

Articular processes

Spinous process

Transverse processes

Cervical vertebrae

Atlas

Axis

Thoracic vertebrae

Lumbar vertebrae

Sacral vertebrae (sacrum)

Coccygeal vertebrae

Bones of the appendicular skeleton

Thoracic limb

Scapula

Glenoid cavity

Neck

Spine

Humerus

Condyle

Epicondyles

Greater tubercle

Head

Neck

Olecranon fossa

Radius

Head

Neck

Styloid process

Ulna

Anconeal process

Coronoid processes

Olecranon process

Radial notch

Styloid process

Trochlear notch

Carpal bones (carpus)

Accessory carpal bone

Metacarpal bones

Cannon bone (hoofed animals)

Splint bones (horse)

Phalanges

Proximal sesamoid bones (hoofed animals)

Distal sesamoid bones (hoofed animals)

Pelvic limb

Pelvis

Acetabulum

Ilium

Ischium

Obturator foramen

Pubis

Femur

Condyles

Epicondyles

Greater trochanter

Head

Neck

Trochlea

Patella

Fabellae

Tibia

Condyles

Tibial crest

Tibial tuberosity

Medial malleolus

Fibula

Lateral malleolus

Tarsal bones (tarsus, hock)

Calcaneus

Metatarsal bones

Cannon bone (hoofed animals)

Splint bones (horse)

Phalanges

Proximal sesamoid bones (hoofed animals)

Distal sesamoid bones (hoofed animals)

Joints

Cartilaginous

Fibrous

Synovial

Clinical significance

Suppose you have been asked to take two radiographs of a patient’s left femur—a lateral (side-to-side) view and a cranial–caudal view. To take the shots, you need to know a few things:

Suppose you are doing a physical exam on a cat and as you palpate the hind legs, one leg seems to have a bump on a bone and the other leg doesn’t have the same bump on the same bone. Is the bone supposed to have the bump or not? What do you write on the physical exam sheet?

When you listen to heart and lung sounds in animals, you place the stethoscope at various places on the animals’ chests. Sometimes it’s next to the costochondral junction and other times it’s placed between the ribs more cranially or caudally. Specific sounds are heard at specific places. You will need to be able to locate these specific places by counting ribs and locating the area where the ribs attach to the cartilages that anchor them to the sternum.

Many other structures are named by which bones they are near. For example, the radial nerve is found by the radius bone in the front leg. The ulnar nerve is found by the ulna bone in the front leg. The femoral artery and vein run alongside the femur in the hind leg. If you know where the bone is located, you will have an easier time locating and identifying structures near it.

Bones have many physical characteristics. You will need to know their normal anatomy before you can detect abnormalities.

As you study the bones, feel them on live animals. Figure out which parts can be palpated on the outside of various animals’ bodies. Some things that are easily felt on a cat may be difficult or impossible to feel on a horse, and vice versa.

Introduction

The bones that make up an animal’s skeleton (1) support and (2) protect the soft tissues of the body, and (3) act as levers that the skeletal muscles use to move the body. They also (4) store minerals, particularly calcium.

• Bones providing support. The support function is often easy to visualize. The bones of the limbs support the rest of the body. Other bones perform their supporting roles more subtly. The ribs, for example, help maintain the size and shape of the thoracic (chest) cavity. They help prevent the lateral walls of the thorax from collapsing in response to gravity. The lumbar (abdominal) vertebrae support the weight of the abdominal organs by serving as the attachment sites for the slinglike abdominal muscles.

• Bones providing protection. The best examples of bones playing protective roles are the bones of the cranium (the portion of the skull that surrounds the brain) and the vertebrae that make up the spinal column. The very important brain and spinal cord are soft and fragile. If you held an animal’s brain in your hand, you could easily crush it between your fingers. The spinal cord has the same soft consistency. The bones of the cranium form a rigid case for the delicate brain. The arches of the vertebrae combine to form a bony canal (the spinal canal) that protects the fragile spinal cord. The individual joints between the vertebrae allow limited movement. These joints combine to allow the spine as a whole a considerable range of motion while still protecting the enclosed spinal column. Cats in particular give excellent demonstrations of spinal flexibility as they contort themselves.

• Bones as levers. The role of bones as levers is easy to visualize. The articular (joint) surfaces are the fulcrums for the levers, and the processes where the tendons attach muscles to bones are where the forces are applied. Note that the larger the process, generally the greater the force that can be applied there. Note also that, as a result of the body being sleek and compact, some bony levers have very poor mechanical advantage. This results in some muscles, such as the gluteals, having to be fairly large and powerful.

• Bones as storage sites. Bones act as reservoirs for important minerals, such as calcium. This storage capacity enables the body to deposit and withdraw vital minerals precisely as needed to maintain health.

As you examine skeletons and bones, try to imagine how the bones, joints, and muscles work together to make the body move. Look at the various bony processes and try to infer what the muscles attached to them would do when they contracted. That’s the kind of detective work paleontologists perform when they examine the fossilized bones of dinosaurs and other extinct beasts. They can make educated guesses about things such as muscle sizes, shapes, and strengths, body shapes, and even how the animal moved.

Medical word parts

The skeletal system

Types of bone

Virtually all bones are made up of two types of bone: cancellous bone, which is light and spongy; and compact bone, which is heavy and dense (Figures 6-1 and 6-2).

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FIGURE 6-1 Cancellous bone. A, The gross spongy appearance of cancellous bone in the distal end of a horse femur. B, A closer view that clearly shows the spicules of bone and the spaces between the spicules that once contained bone marrow.
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FIGURE 6-2 Compact bone. Compact bone forms the outside layer of all bones and the shafts of long bones such as this horse femur.

Bone shapes

Long bones

Long bones are so named because they are longer than they are wide (Figure 6-3). Most of the bones of the limbs are long bones. The two bones in Figure 6-3 are a feline femur (A) from the thigh area of the hind leg, and a canine humerus (B) from the upper front leg. The ends of long bones are called epiphyses. Each long bone has a proximal epiphysis and a distal epiphysis. The epiphyses are made of cancellous bone covered with a thin layer of compact bone. The long part of a long bone is the diaphysis. It is composed primarily of compact bone. Between the epiphyses and diaphysis, there are the areas where the bone grows longer in young animals. These growth plates are composed mainly of cartilage and are called the epiphyseal plates. The epiphyseal plates are the weakest part of the bone in young animals and are prone to fractures. Once an animal reaches its full size, the epiphyseal plates are replaced by solid bone through a process called ossification.

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FIGURE 6-3 A and B, Long bones.
Short bones

This equine carpus shows short bones that are shaped like cubes or marshmallows (Figure 6-4). They are composed of an inner core of cancellous bone covered by a thin layer of compact bone. Carpal and tarsal bones are the most common short bones in the body (Figure 6-5).

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FIGURE 6-4 Short bones in an equine skeleton.
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FIGURE 6-5 Short bones. Equine carpal bones.
Flat bones

Flat bones are mostly flat and thin (Figure 6-6, and see Figure 6-10). Their structure is like a “cancellous bone sandwich”—a central layer of cancellous bone covered on both sides by thin layers of compact bone. The pelvic bones and the scapula (shoulder blade) are prominent flat bones as are some of the skull bones (Figure 6-7).

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FIGURE 6-6 Flat bones. Pelvis from a bovine skeleton (dorsal view).
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FIGURE 6-7 Flat bone. Scapula from a canine skeleton (lateral view). Note the prominent spine facing toward us.
Irregular bones

Irregular bones are odd-shaped and don’t fit into any of the other three categories (Figures 6-8, 6-9, 6-10, and 6-11).

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FIGURE 6-8 Irregular bones in an equine skeleton.
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FIGURE 6-9 Irregular bone. Canine vertebra. Vertebrae don’t fit into the long bone, short bone, or flat bone categories.
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FIGURE 6-10 Flat bones and irregular bones. Canine skull bones. Some skull bones are flat bones (e.g., parietal bones, nasal bones), whereas others have very irregular shapes (e.g., maxillary bones, zygomatic bones).
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FIGURE 6-11 Irregular bones in a bovine skeleton. Sesamoid bones.

Common bone features (lumps, bumps, grooves, and holes)

Articular surfaces

Articular surfaces are smooth areas of compact bone that come in contact with smooth surfaces of another bone to form a joint. The articular surfaces are covered with hyaline cartilage (Figure 6-12).

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FIGURE 6-12 Canine stifle joint. The articular surfaces indicated are the hyaline cartilage covering the distal articular surface of the femur and the proximal articular surface of the tibia.
Condyles

A condyle is usually a large, round articular surface. The distal ends of the femur and humerus, and the occipital bone have the most prominent condyles (Figures 6-13 to 6-15).

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FIGURE 6-13 The condyles of the occipital bone in the canine skull. These articular surfaces are where the skull joins the spinal column. It connects the head to the neck. (This joint is the one your mother meant when she said you would lose your head if it wasn’t attached.)
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FIGURE 6-14 The condyles of the canine humerus. These surfaces along with the proximal articular surfaces of the radius and ulna form the elbow joint (caudal view).
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FIGURE 6-15 Condyles of the canine femur. These condyles meet the proximal end of the tibia to form the stifle joint (caudal view).
Head

The head of a bone is found at the proximal end of a long bone. It is mostly spherical in shape. The proximal ends of the femur, humerus, and ribs have heads (Figures 6-16 to 6-18). The head is usually joined to the rest of the bone by a narrowed region called the neck.

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FIGURE 6-16 Head of the canine femur. The head of the femur fits into a socket in the pelvis (the acetabulum) to form the hip joint. The neck is the narrow area between the head and the main part of the bone (cranial view).
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FIGURE 6-17 Head of the canine humerus. The head of the humerus joins the glenoid cavity of the scapula to form the shoulder joint. The neck, which is just lateral to the head, is not as pronounced as in the femur (caudal view).
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FIGURE 6-18 Head of a rib. The heads of the ribs articulate with the thoracic vertebrae of the spinal column.
Facet

A facet is a flat articular surface. It is found on carpal bones, tarsal bones, vertebrae, and some long bones, such as the radius and ulna (Figures 6-19 and 6-20).

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FIGURE 6-19 Articular facets on bovine thoracic vertebrae. The heads of ribs articulate with these articular facets (lateral view).
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FIGURE 6-20 Facet articular surfaces. Equine carpus. (Cranial view.)
Processes

Processes are the lumps and bumps on bones. Condyles and heads on long bones are considered processes, but they have a specific articular function so they are classified as articular surfaces. Most of the other processes on bones are places where the tendons of muscles attach to the bone. Larger processes are where more powerful muscles attach. Processes are given different names on different bones. Some of the names used are trochanter (femur), tubercle (humerus), tuber (ischium), crest (tibia), olecranon (ulna), spine (scapula), and wing (atlas) (Figures 6-21 to 6-27).

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FIGURE 6-21 Greater trochanter of the canine femur. (Cranial view.)
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FIGURE 6-22 Greater tubercle of the canine humerus. (Caudal view.)
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FIGURE 6-23 Tuber ischium of the bovine pelvis. (Ventral view.)
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FIGURE 6-24 Lateral (A) and cranial (B) views of the tibial crest of the equine tibia.
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FIGURE 6-25 Olecranon process of canine ulna. This is the “point” of the elbow where the powerful triceps brachii muscle attaches.
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FIGURE 6-26 Spine of the canine scapula. The spine runs along the lateral surface.
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FIGURE 6-27 Wings of the atlas (first cervical) vertebra.
Holes and depressed areas

A hole in a bone is called a foramen. Usually it is a passageway for blood vessels or nerves to enter and leave the bone (Figures 6-28 and 6-29).

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FIGURE 6-28 Nutrient foramen in an equine femur. Blood vessels supplying the interior of the bone enter and leave the femur through this hole.
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FIGURE 6-29 Obturator foramen in a canine pelvic bone (lateral view). This foramen doesn’t have anything large passing through it. It is there to make the pelvic bones lighter.

A fossa is a depressed, sunken area on the surface of a bone. Bone fossae are usually occupied by muscles or tendons (Figures 6-30 and 6-31).

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FIGURE 6-30 Fossae on canine scapula (lateral view). The supraspinous and infraspinous fossae on either side of the scapular spine are attachment sites for two shoulder muscles—the infraspinatus and supraspinatus muscles.
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FIGURE 6-31 Fossa on feline mandible (lateral view). The masseteric fossa on the lateral surface of the mandible is an attachment site for the large masseter jaw muscle.

The skeleton

Even though an animal has only one complete skeleton, we are going to divide it into two main parts (skeletons) for the purpose of studying the bones. The axial skeleton is made up of the bones located on or near the central cranial–caudal axis of the body—the skull, hyoid bone, spinal column, ribs, and sternum. The appendicular skeleton is made up of the main “appendages” of the body: the thoracic limbs and the pelvic limbs.

Axial skeleton

The axial skeleton is made up of the skull, hyoid bone, spinal column, ribs, and sternum. All the bones of the axial skeleton are located at or near the median plane of the animal’s body (Box 6-1 and Figure 6-32).

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FIGURE 6-32 Feline skeleton with the bones of the axial skeleton shaded red.
Skull

The skull is the most complex part of the skeleton. It is made up of bones that, with one exception, are united by jagged, immovable, fibrous joints called sutures. The only freely movable joint is the one between the mandible and the temporal bone. This joint is called the temporomandibular joint or TMJ.

The bones of the skull can be conveniently grouped into the bones of the cranium, which surround the brain, and the bones of the face. We will restrict our examinations to the external bones in each group, which are at least partly visible on the outside of the skull (Box 6-2). The names of these external skull bones are often used to describe locations on animals’ heads (e.g., left parietal region, right maxillary area) in medical records. The internal skull bones are hidden within the skull. The only internal bones we will cover are the nasal turbinates, which play important roles in the conditioning of inhaled air on its way to the lungs (Figures 6-33 to 6-38).

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FIGURE 6-33 The skull of a cat.
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FIGURE 6-34 Bovine skull.
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FIGURE 6-35 Dorsal view of a canine skull.
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FIGURE 6-36 Lateral view of a feline skull.
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FIGURE 6-37 Lateral view of an equine skull.
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FIGURE 6-38 Canine skull caudal view.
External bones of the cranium
Occipital bone
Interparietal bones
Parietal bones
Temporal bones
Frontal bones
External bones of the face
Incisive bones
Nasal bones
Maxillary bones
Lacrimal bones
Zygomatic bones

Note: The zygomatic arches are easily palpated on each side of an animal’s head just below and behind the eyes. They form the widest part of dog and cat skulls.

Mandible
Internal bones of the face
Turbinates
Hyoid bone

The hyoid bone (also known as the hyoid apparatus) attaches to the temporal bones and supports the base of the tongue, the pharynx, and the larynx. It is made up of several individual parts united by cartilage, but is usually referred to as a single bone (Figure 6-39).

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FIGURE 6-39 Skull radiograph showing hyoid bone.
Spinal column

The spinal column, also known as the vertebral column, is made up of a series of irregular bones called vertebrae that extend from the skull to the tip of the tail. A typical vertebra consists of a ventral body, a dorsal arch, and a group of processes. The body is the heaviest, most dense part of the bone. The bodies of adjacent vertebrae are separated by cartilaginous intervertebral discs. The arch dorsal to the vertebral body houses the spinal cord in the living animal. Three kinds of process are commonly found on vertebrae: a single spinous process that projects dorsally, two transverse processes that project laterally, and articular processes on the cranial and caudal ends of the vertebra (Figure 6-40).

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FIGURE 6-40 Basic anatomy of vertebra.

Vertebrae are grouped into five regions—cervical (neck region, abbreviated “C”), thoracic (chest region, abbreviated “T”), lumbar (abdominal region, abbreviated “L”), sacral (pelvic region, abbreviated “S”), and coccygeal (tail region, abbreviated “Cy”). Most vertebrae do not have specific names, but are identified by numbers within each region from cranial to caudal. A shorthand method of identifying vertebrae uses the abbreviation for the vertebral group followed by the number of the particular vertebra. For example vertebra C5 is the fifth cervical vertebra and T10 is the tenth thoracic vertebra (Box 6-3 and Figure 6-41).

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FIGURE 6-41 Feline vertebral column. The five sections of the vertebral column are shaded red. The sacral region is located primarily between the two halves of the pelvis and is only partially visible.

The first two cervical vertebrae are unusual in shape compared with the rest of the vertebrae, and they have specific names. The first cervical vertebra (C1) is called the atlas. It does not have a vertebral body, but consists of a bony ring that the spinal cord passes through and two large transverse processes called the “wings” of the atlas. The occipital bone of the skull forms a joint with the atlas—the atlantooccipital joint. The second cervical vertebra (C2) is called the axis. Its main characteristics are a large, bladelike spinous process and the peglike dens on its cranial end that tucks into the caudal end of the atlas to help form and stabilize the atlantoaxial (C1–C2) joint. The rest of the cervical vertebrae are fairly normal in appearance, and are just identified by number, like the rest of the vertebrae (Figure 6-42).

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FIGURE 6-42 Canine cervical vertebrae.

The number of thoracic vertebrae is usually equal to the numbers of pairs of ribs the animal has. The main characteristics of thoracic vertebrae are their tall spinous processes and their lateral articular facets, which form joints with the heads of the ribs.

The lumbar vertebrae are the most massive-looking vertebrae of the spinal column. They have to support the weight of the abdominal organs without the aid of the ribs, which help support the organs in the chest.

The sacral vertebrae are fused into a single solid structure called the sacrum. The sacrum forms a joint with the ilium of the pelvis—the sacroiliac joint.

The coccygeal vertebrae are the bones of the tail. At the cranial end, the first few coccygeal vertebrae look like small versions of normal vertebrae. They have bodies, arches, and processes. Further caudally, however, they gradually turn into simple little rods of bone.

Ribs

Ribs are flat bones that form the lateral sides of the thorax. They articulate with the thoracic vertebrae dorsally. The ventral part of a rib is composed of costal (rib) cartilage. Where the cartilaginous part meets the bony part is the costochondral junction. The costal cartilages join either the sternum or the costal cartilage of the ribs ahead of them (Figures 6-43 to 6-46).

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FIGURE 6-43 Feline skeleton with the ribs shaded red.
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FIGURE 6-44 Rabbit rib cage, sternum, and thoracic vertebrae. The point at which the bony part of the rib meets the cartilaginous part of the rib is the costochondral junction. Some of the costal cartilages join the sternum, and other costal cartilages attach to the costal cartilage of the rib in front.
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FIGURE 6-45 Rabbit ribs articulating dorsally with thoracic vertebrae.
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FIGURE 6-46 Canine rib. A, Caudal view of rib. B, Lateral view of rib articulating with vertebrae.
Sternum

The sternum (breastbone) is made up of bones called sternebrae. The first sternebra is named the manubrium (full name manubrium sterni). The last sternebra is named the xiphoid (full name xiphoid process). A piece of cartilage that extends off the caudal end of the xiphoid process is the xiphoid cartilage, which can be palpated at the caudal end of the sternum in most animals (Figure 6-47).

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FIGURE 6-47 Canine sternum and costal cartilages.

Appendicular skeleton

The appendicular skeleton is made up of the thoracic (front) and pelvic (hind) limb bones of the animal. They make up the main appendages of the body, hence the name (Box 6-4 and Figure 6-48).

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FIGURE 6-48 Feline skeleton with the bones of the appendicular skeleton shaded red.
Thoracic limb

The thoracic limb is the front leg. In most domestic animals it has no bony connection to the axial skeleton. Instead, the weight of the front part of the body is supported by a slinglike arrangement of muscles and tendons. From proximal to distal, the bones of the thoracic limb are the scapula, humerus, radius and ulna, carpal bones, metacarpal bones, and phalanges.

Scapula
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FIGURE 6-49 Canine scapula. (Lateral view.)
Humerus
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FIGURE 6-50 Bovine right humerus. (Caudal view.)
Ulna
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FIGURE 6-51 Canine left ulna. (Lateral view.)
Radius
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FIGURE 6-52 Canine left radius. (Cranial view.)
Carpal bones (carpus)
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FIGURE 6-53 Equine carpus. A, Cranial view. B, Caudal view.
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FIGURE 6-54 Distal limb bones of canine front leg.
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FIGURE 6-55 Distal limb bones of equine front leg.
Metacarpal bones
Phalanges
Pelvic limb

The pelvic limb is the hind leg. Unlike the thoracic limb, the pelvic limb is connected to the axial skeleton through the sacroiliac joint that unites the ilium of the pelvis with the sacrum of the spinal column. From proximal to distal, the bones of the pelvic limb are the pelvis, femur, tibia and fibula, tarsal bones, metatarsal bones, and phalanges.

Pelvis
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FIGURE 6-56 Canine pelvis. (Left lateral view.)
Femur
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FIGURE 6-57 Bovine left femur. A, Cranial view. B, Caudal view.
Patella
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FIGURE 6-58 Patella and fabellae. Radiograph of canine stifle.
Fabellae

• The medial and lateral fabellae (see Figure 6-58) are two small sesamoid bones in the proximal gastrocnemius (calf) muscle tendons of dogs and cats

• Located just proximal to (above) and caudal to (behind) the femoral condyles

Tibia
Fibula
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FIGURE 6-59 Canine left tibia and fibula. (Cranial view.)
Tarsal bones (tarsus, hock)
Metatarsal bones
Phalanges
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FIGURE 6-60 Equine left hind leg. This is the distal portion of the hind leg of a horse, from the distal part of the tibia to the distal phalanx.
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FIGURE 6-61 Feline (dorsal view) and canine (plantar view) hind feet.

Joints

Joints are where bones connect with each other. The three types of joint in the animal body are immovable fibrous joints, slightly movable cartilaginous joints, and freely movable synovial joints.

Fibrous joints
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FIGURE 6-62 Canine skull. The sutures that hold most of the skull bones together are examples of fibrous joints.

Cartilaginous joints
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FIGURE 6-63 Bovine pelvis. The two halves of the pelvis are joined together by the pelvic symphysis, a cartilaginous joint (ventral view).

Synovial joints
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FIGURE 6-64 Canine elbow joint. This is an example of a hinge joint.
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FIGURE 6-65 Equine carpus. This is an example of a gliding joint.
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FIGURE 6-66 Canine skull and first two cervical vertebrae. The joint between the atlas (C1) and axis (C2) cervical vertebrae is the only true pivot joint in the animal’s body.
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FIGURE 6-67 Canine hip joint. This is an example of a ball and socket joint. The ball is the head of the femur and the socket is the acetabulum in the pelvic bone.

Suggested in-class activities

Bone shapes and features

Bone shape and feature identification

Find bones that represent the various types of bone and the processes on them.

Supplies needed: disarticulated bones.

Bone shape and feature hunt

Students draw a shape or feature name out of a hat. They then must locate a bone on a skeleton that represents that shape or contains that feature. The student must also identify the bone.

OR

Students draw the name of a bone out of a hat. They must then locate the bone on the skeleton and identify the shape and what features the bone may possess.

Supplies needed: articulated skeleton.

The axial skeleton

Skull bone identification

Students examine various skulls from different species of animal, identifying the bones of the skull.

Supplies needed: various skulls.

Live animal palpation

Students palpate and identify the bones of the skull on live animals.

Supplies needed: live animals.

Skull bone hunt

Students draw the name of a skull bone out of a hat. They then must locate that bone on a live animal.

Supplies needed: live animals.

Vertebral process identification

Various vertebrae are set out. Students are to identify each vertebra by identifying the specific process types.

Supplies needed: vertebrae.

Axial assembly

Students assemble the bones of the axial skeleton in order.

Supplies needed: disarticulated skeleton.

Radiographic identification

Students identify bones of the axial skeleton on radiographs.

Supplies needed: radiographs.

Live animal palpation

Students palpate the bones of the axial skeleton on live animals.

Supplies needed: live animals.

The appendicular skeleton

Appendicular limb assembly

Students assemble, in order, both the thoracic and pelvic limbs.

Supplies needed: disarticulated skeleton.

Radiographic identification

Students identify bones of the appendicular skeleton on radiographs.

Supplies needed: radiographs.

Live animal palpation

Students palpate the bones of the appendicular skeleton on live animals.

Supplies needed: live animals.

Animals in motion

Each student is given a laminated drawing or photograph of an animal in motion. The student is to draw the location of the bones of the animal’s skeleton on the picture with an erasable marker. It is helpful to have live animals in the room for the students to position similar to their picture, then palpate for the bone locations and directions.

Supplies needed: laminated drawings and photographs of animals, erasable markers, and live animals.

Appendicular bone hunt

Students draw the name of a bone out of a hat. They then must locate that bone on an animal skeleton and/or a live animal.

Supplies needed: various animal skeletons and live animals.

Exercises

The skeletal system

The skeleton

Image

Joints

Critical and clinical thinking

Exercise 11

Defining Clinical Terms

Write the definition for each term.

1. Acetabulum_____________________________________

2. Articular process _________________________________

3. Articular surface _________________________________

4. Atlas ___________________________________________

5. Axis ___________________________________________

6. Calcaneus ______________________________________

7. Cancellous bone _________________________________

8. Cannon bone ___________________________________

9. Carpus _________________________________________

10. Cartilaginous joint ________________________________

11. Cervical vertebrae _______________________________

12. Coccygeal vertebrae _____________________________

13. Compact bone __________________________________

14. Condyle ________________________________________

15. Costal cartilage __________________________________

16. Costochondral junction ____________________________

17. Fibrous joint _____________________________________

18. Flat bones ______________________________________

19. Foramen ________________________________________

20. Foramen magnum ________________________________

21. Fossa __________________________________________

22. Irregular bones __________________________________

23. Joint ___________________________________________

24. Long bones _____________________________________

25. Lumbar vertebrae ________________________________

26. Manubrium sterni ________________________________

27. Metacarpals ____________________________________

28. Metatarsals _____________________________________

29. Obturator foramina _______________________________

30. Olecranon ______________________________________

31. Patella _________________________________________

32. Pelvis __________________________________________

33. Phalanges ______________________________________

34. Process _________________________________________

35. Sacral vertebrae _________________________________

36. Sesamoid bones _________________________________

37. Short bones _____________________________________

38. Spinous process _________________________________

39. Splint bones _____________________________________

40. Synovial joint ____________________________________

41. Tarsus __________________________________________

42. Thoracic vertebrae _______________________________

43. Transverse process _______________________________

44. Xiphoid process __________________________________

Exercise 12

Clinical Thinking Challenge

1. Name the four functions of bone.

2. ______________________ The ulna is an example of a/an _______ bone.

3. ______________________ A vertebra is an example of a/an _______ bone.

4. ______________________ The carpal bones are examples of _______ bones.

5. ______________________ The parietal bone in the skull is an example of a/an _______ bone.

6. ______________________ Name an example of a flat bone.

7. ______________________ Name an example of an irregular bone not found in the axial skeleton.

8. What bones make up the axial skeleton?

9. ______________________ The appendicular skeleton is made up of the _____ and ______.

10. ______________________ The bones of the front leg make up the _____ limb.

11. ______________________ The bones of the back leg make up the _____ limb.

12. ______________________ What attaches skeletal muscles to bones?

13. Explain where the epiphyseal plates are located in a long bone.

14. ______________________ What does the epiphyseal plate allow the bone to do?

15. ______________________ Another name for the epiphyseal plate is _______.

16. ______________________ The bones of the cranium and the bones of the face make up the _______.

17. ______________________ Skull bones that make up most of the upper jaw.

18. ______________________ Lower jaw.

19. ______________________ Skull bones that form the dorsolateral portion of the cranium.

20. ______________________ Bones of the “temple” area of the skull that also contain middle and inner ear structures.

21. ______________________ Bones of the “forehead” region of the skull.

22. ______________________ Bone that forms the “base” of the skull and articulates with the first cervical vertebra.

23. ______________________ Skull bones that form the “bridge of the nose.”

24. ______________________ Thin, scroll-like bones found inside the nasal cavity of the skull.

25. ______________________ ”Cheek bones” of the skull, made up of processes from the zygomatic and temporal bones.

26. ______________________ The tail vertebrae.

27. ______________________ The second cervical vertebra.

28. ______________________ Vertebrae that are the largest in size and also support the abdominal region.

29. ______________________ Fused vertebrae of the pelvic region.

30. ______________________ The first cervical vertebra, articulates with the skull.

31. ______________________ Vertebrae that articulate with the ribs.

32. ______________________ Vertebrae in the neck.

33. ______________________ What distinguishing processes does the atlas possess?

34. ______________________ What distinguishing process does the axis possess?

35. ______________________ The _______ joins the ribs to the sternum.

36. Name all the bones of the thoracic limb in order from proximal to distal.

37. ______________________ The socket portion of the shoulder joint.

38. ______________________ The main weight-bearing bone of the “lower arm.”

39. ______________________ These bones make up the joint that is the equivalent of our “wrist.”

40. ______________________ ”Finger” or digit bones.

41. ______________________ The long bone of the “forearm” that has a proximal process that is the point of the elbow.

42. ______________________ Shoulder blade.

43. ______________________ The “hand” bones.

44. ______________________ The long bone in the “upper arm.”

45. ______________________ The point of the elbow.

46. ______________________ What bone is partly or completely removed during feline declaw surgery?

47. Name all the bones of the pelvic limb from proximal to distal.

48. ______________________ The socket portion of the hip joint.

49. ______________________ The small long bone of the “lower leg.”

50. ______________________ These bones make up the “ankle” or “hock.”

51. ______________________ ”Toe” or digit bones.

52. ______________________ The large long bone of the “lower leg.”

53. ______________________ Part of the pelvic limb. Made up of three pairs of bones that are fused together.

54. ______________________ The “foot” bones.

55. ______________________ The long bone in the upper “thigh” region.

56. What three fused pairs of bones make up the pelvis?

57. What is the purpose of the obturator foramen?

58. ______________________and ______________________ What are the anatomic names of the two splint bones in the thoracic limb of a horse?

59. ______________________ The equivalent of our “heel” bone, the large process that forms the point of the hock.

60. ______________________ The name for a joint that allows free movement.

61. ______________________ The name for a joint that allows only a slight rocking movement.

62. ______________________ The name for a joint that does not allow any movement.