What are the structural features of the skeleton of the vertebrate depicted. Axial skeleton in animals

What are the functions of the musculoskeletal system?

The musculoskeletal system performs the functions of support, maintaining a certain shape, protecting organs from damage, and movement.

Why does the body need a musculoskeletal system?

The musculoskeletal system is necessary for the body to sustain life. It is responsible for keeping fit and protecting the body. The most important role of the musculoskeletal system is movement. Movement helps the body in choosing habitats, searching for food and shelter. All functions of this system are vital for living organisms.

Questions

1. What underlies the evolutionary changes in the musculoskeletal system?

Changes in the musculoskeletal system had to fully ensure all the evolutionary changes in the body. Evolution has changed the appearance of animals. In order to survive, it was necessary to actively search for food, better hide or defend against enemies, and move faster.

2. What animals have an external skeleton?

The external skeleton is characteristic of arthropods.

3. Which vertebrates do not have a bone skeleton?

The lancelet and cartilaginous fish do not have a bone skeleton.

4. What does the similar plan of the structure of the skeletons of different vertebrates indicate?

A similar plan of the structure of the skeletons of different vertebrates speaks of the unity of the origin of living organisms and confirms the evolutionary theory.

5. What conclusion can be drawn, having become acquainted with the general functions of the musculoskeletal system in all animal organisms?

The musculoskeletal system in all animal organisms performs three main functions - supporting, protective, motor.

6. What changes in the structure of protozoa led to an increase in the speed of their movement?

The first supporting structure of animals - the cell membrane allowed the body to increase the speed of movement due to flagella and cilia (outgrowths on the shell)

Tasks

Prove that the complication of the skeleton of amphibians is associated with a change in the habitat.

The skeleton of amphibians, like other vertebrates, consists of the following sections: the skeleton of the head, trunk, limb belts and free limbs. Amphibians have significantly fewer bones compared to fish: many bones fuse together, cartilage is preserved in some places. The skeleton is lighter than that of fish, which is important for terrestrial existence. A wide flat skull and upper jaws are a single formation. The lower jaw is very mobile. The skull is movably attached to the spine, which plays an important role in terrestrial food production. There are more sections in the spine of amphibians than those of fish. It consists of the cervical (one vertebra), trunk (seven vertebrae), sacral (one vertebra) and tail sections. The tail section of a frog consists of one tail bone, while in tailed amphibians it consists of separate vertebrae. The skeleton of the free limbs of amphibians, unlike fish, is complex. The skeleton of the forelimb consists of the shoulder, forearm, wrist, metacarpus and phalanges of the fingers; hind limb - thigh, lower leg, tarsus, metatarsus and phalanges of fingers. The complex structure of the limbs allows amphibians to move both in the aquatic and in the terrestrial environment.

Skeleton(from the Greek "skeleton" - dried) are referred to as structures of various structure and origin, ensuring the preservation of the shape of the animal's body, as well as support and protection for internal organs. In addition, to the individual components of the skeleton are attached muscles, providing the movement of the animal - so the skeleton is an important functional unit of the musculoskeletal system. Vertebrates, unlike most invertebrates, have endoskeleton- i.e. their supporting structures are located not on the surface, but in the deep parts of the body.

The prototype of the vertebrate skeleton - as well as the only skeletal structure in the lower chordates - is chord, a dense strand of cells of mesodermal origin, stretching along the dorsal (dorsal) side through the entire body, from head to tail. In higher chordates - vertebrates- the notochord is preserved only at the embryonic stage of development, being replaced in the adult state by cartilage and bone tissues, which are formed in ontogeny from mesenchyme, i.e. germinal connective tissue of predominantly mesodermal origin. Initially, skeletal elements are formed from cartilage; however, nowadays the cartilaginous skeleton is observed only in the lower groups of vertebrates ( lampreys, mixins, cartilaginous fish and some others). In higher vertebrates, cartilaginous structures are observed mainly in the embryonic stage of development and in childhood; in the adult state, their skeleton is built mostly from bones.

Anatomically, the skeleton of vertebrates is formed by many elements that have a different structure, shape, origin and location in the animal body. Between themselves, these skeletal elements (cartilage or bones) are connected either immobile ( synarthrosis) or mobile ( joints) joints; the latter option ensures the movement of body parts relative to each other and the entire body of the animal in the surrounding space. With all the diversity, skeletal elements in different groups of vertebrates can be combined into several departments.

Integumentary skeleton

The integumentary skeleton is a collection of bone elements located in the skin of an animal; these elements are initially formed from bone tissue and do not have a cartilaginous stage of development. The skin of modern vertebrates usually does not contain any bone elements in its composition, however, in many extinct forms, the body was partially or completely enclosed in a bone shell; in addition, some bones have an integumentary origin skulls and limb belts.

Modern lampreys and mykishnas do not have any bony shell, however, many ancient aquatic vertebrates (for example, armored fish) were fully encased in powerful armor; The vast majority of modern fish also have a protective layer over the skin of bony scales of various shapes and structures, while elements of the gill cover are also referred to as integumentary bones.

Terrestrial four-legged vertebrates also initially had a complete bone cover of plates and scales, later some of its components became part of the skull, jaws, limb girdles, while others were lost. The skin of these vertebrates, however, retained the ability to form bone, so that some of their representatives again acquired protective scales or plates - for example, abdominal ribs crocodiles, shell turtles and armadillos.

Internal skeleton

bird skeleton

Spine

vertebral column, formed by a set vertebrae, is the most important element of the so-called axial skeleton, historically formed around the notochord, although the notochord itself in the adult state is reduced, remaining only in fish, primitive amphibian and reptiles, being strongly compressed inside the vertebrae and expanding between them; in most terrestrial vertebrates, the remnants of the notochord are only gelatinous formations in intervertebral discs. Individual vertebrae have different structures in different groups of vertebrates; in addition, within the same organism, the vertebrae are also heterogeneous, which makes it possible to distinguish several sections of the spine. The spine of fish is most simply arranged - only the trunk and tail sections are clearly distinguished in it; in the course of further evolution, separation of the thoracic, cervical, lumbar and sacral regions occurred; each group of vertebrates has its own special set of spine sections.

The axial skeleton includes ribs, which first appear in cartilaginous fish and are elongated cartilaginous or bone formations that serve mainly for attaching muscles; different groups of vertebrates have ribs of various shapes, sizes and origins connected to the vertebrae of one or more sections of the spine. On the ventral (abdominal) side, the ribs can join sternum, thus forming chest.

Scull

head skeleton - scull- is a very complex formation, consisting of many cartilaginous or bone elements of different structure and origin: here there is a combination of both internal and integumentary bones fused with them. In general terms, four components can be distinguished in the composition of the vertebrate skull:

brain box- in fact, this is a continuation of the axial skeleton, which is formed along the back, lower and lateral sides of the brain from the internal and partially integumentary bones. The occipital region, in this case, contains large foramen magnum through which the spinal cord passes, and condyles to connect with the first vertebra.
skull roof- bone elements covering the brain from above, in front and from the sides, as well as forming the structures of the nose, eye sockets, temporal region, upper jaw, and formed exclusively by integumentary bones.
palatine complex- elements that form the primary and secondary palate and are formed by the internal and integumentary bones.
visceral skeleton- cartilaginous or bone elements, initially formed around the oral cavity and pharynx, and originating from the mesenchyme of endodermal origin. In the lower chordates, gill arches, the anterior ones being converted into jaws ; in higher ones, they are supplemented by the integumentary bones of the lower jaw and the hyoid region, while the remains of the former gill arches are transformed into the bones of the middle ear or into cartilages that do not belong to the skeleton itself larynx.

Skeleton of limb girdle

Limb belts- These are cartilaginous or bone formations designed to connect the actual limbs to the body. According to the limbs, allocate shoulder girdle, or the belt of the forelimbs, and pelvic girdle or hind limb belt. The composition and structure of the limb girdle varies in different groups of vertebrates, but some general patterns are observed.

shoulder girdle consists of two parts - integumentary and internal origin. Cover covers collarbone and some other bones that provide a connection between the forelimb and the spine, and in fish also with the skull. The internal bones of the shoulder girdle are present in higher vertebrates. spatula- a bone that is directly connected to the forelimb and serves to attach muscles.
pelvic girdle- a purely endoskeletal formation that serves to attach the muscles of the hind limb. In fish, the pelvic girdle is a simple element that has nothing to do with the axial skeleton; in terrestrial vertebrates, on the contrary, it is attached to the spine and consists of clearly distinguished three pairs of bones.

limb skeleton

Loose limbs vertebrates that serve as a means of transportation have some variations in different groups. So, ray-finned fish possess paired fins(thoracic and abdominal), built on the principle of folds; these limbs practically do not have an internal skeleton, supported by rays of integumentary origin. Fins of the Ancients lobe-finned fish, on the contrary, demonstrate a typical three-segment structure, in which the segment closest to the body is formed by a single element, the middle segment by two elements, and the distal segment by many small bones arranged in the form of a blade. Terrestrial vertebrates inherit a similar pattern, with only five rays remaining in the third (distal) segment in the general case - this is how a typical five-fingered limb is formed, consisting of shoulder, forearms and brushes(for the front) either from hips, shins and feet(for back).

The concept of " phylogenesis”(from the Greek phyle - “genus, tribe” and genesis - “birth, origin”) was introduced in 1866 by the German biologist Ernst Haeckel to denote the historical development of organisms in the process of evolution.

Consider how the spine developed and improved from the simplest organisms to humans. It is necessary to distinguish between the external and internal skeleton.

Exterior skeleton performs a protective function. It is inherent in lower vertebrates and is located on the body in the form of scales or shells (tortoise, armadillo). In higher vertebrates, the external skeleton disappears, but its individual elements remain, changing their purpose and location, becoming the integumentary bones of the skull. Located already under the skin, they are connected with the internal skeleton.

Internal skeleton performs mainly a supporting function. In the course of development, under the influence of a biomechanical load, it constantly changes. In invertebrates, it looks like partitions to which muscles are attached.

In primitive chordates (lancelets), along with partitions, an axis appears - a chord (cell cord), dressed in connective tissue membranes. In fish, the spine is relatively simple and consists of two sections (trunk and tail). Their soft cartilaginous spine is more functional than that of chordates; the spinal cord is located in the vertebral canal. The skeleton of fish is more perfect, allowing for faster and more precise movements with a smaller mass.

With the transition to a terrestrial way of life, a new part of the skeleton is formed - the skeleton of the limbs. And if in amphibians the skeleton is made of coarse fibrous bone tissue, then in more highly organized terrestrial animals it is already built from lamellar bone tissue, consisting of bone plates containing ordered collagen fibers.

The internal skeleton of vertebrates passes through three stages of development in phylogenesis: connective tissue (membranous), cartilaginous and bone.

Mammal skeleton (left) and fish (right)

The deciphering of the lancelet genome, completed in 2008, confirmed the proximity of the lancelets to the common ancestor of vertebrates. According to the latest scientific data, lancelets are relatives of vertebrates, although the most distant.

The mammalian spine consists of the cervical, thoracic, lumbar, sacral, and caudal sections. Its characteristic feature is the platycelial (having flat surfaces) shape of the vertebrae, between which cartilaginous intervertebral discs are located. The upper arches are well defined.

In the cervical region, all mammals have 7 vertebrae, the length of which depends on the length of the neck. The only exceptions are two animals: the manatee has 6 of these vertebrae, and different species of sloths have 8 to 10. The giraffe has very long cervical vertebrae, while cetaceans that do not have a cervical interception, on the contrary, are extremely short.

The ribs are attached to the vertebrae of the thoracic region, forming the chest. The sternum closing it is flat and only in bats and in representatives of burrowing species with powerful forelimbs (for example, moles) has a small crest (keel), to which the pectoral muscles are attached. In the thoracic region there are 9-24 (usually 12-15) vertebrae, the last 2-5 bear false ribs that do not reach the sternum.

In the lumbar region from 2 to 9 vertebrae; rudimentary ribs merge with their large transverse processes. The sacral region is formed by 4-10 fused vertebrae, of which only the first two are truly sacral, and the rest are caudal. The number of free tail vertebrae ranges from 3 (in the gibbon) to 49 (in the long-tailed pangolin).

The mobility of individual vertebrae depends on lifestyle. So, in small running and climbing animals, it is high along the entire length of the spine, so their body can bend in different directions and even curl up into a ball. The thoracic and lumbar vertebrae are less mobile in large, rapidly moving animals. In mammals moving on their hind legs (kangaroos, jerboas, jumpers), the largest vertebrae are located at the base of the tail and sacrum, and then their size consistently decreases. In ungulates, on the contrary, the vertebrae and especially their spinous processes are larger in the anterior part of the thoracic region, where the powerful muscles of the neck and partly of the forelimbs are attached to them.

In birds, the forelimbs (wings) are adapted for flying, and the hind limbs for moving on the ground. A peculiar feature of the skeleton is the pneumaticity of the bones: they are lighter because they contain air. The bones of birds are also quite fragile, as they are rich in lime salts, and therefore the strength of the skeleton is largely achieved by the fusion of many bones.

The skeletons of different animals are different from each other. Their structure largely depends on the habitat and lifestyle of a particular organism. What do animal skeletons have in common? What differences exist? How is the human skeleton different from the structure of other mammals?

The skeleton is the body's support

The hard and elastic structure of bones, cartilage and ligaments in the human and animal body is called the skeleton. Together with muscles and tendons, it forms the musculoskeletal system, thanks to which living beings can move in space.

It mainly includes bones and cartilage. In the most mobile part, they are connected by joints and tendons, forming a single whole. The solid "skeleton" of the body does not always consist of bone and cartilage tissue, sometimes it is formed by chitin, keratin, or even limestone.

Bones are an amazing part of the body. They are very strong and rigid, able to withstand huge loads, but at the same time remain light. In a young body, the bones are elastic, and over time become more fragile and brittle.

The skeleton of animals is a kind of "pantry" of minerals. If the body experiences a lack of them, then the balance of the necessary elements is replenished from the bones. Bones consist of water, fat, organic substances (polysaccharides, collagen), as well as salts of calcium, sodium, phosphorus, and magnesium. The exact chemical composition depends on the nutrition of a particular organism.

Meaning of the skeleton

The body of people and animals is a shell, inside of which there are internal organs. This shell is shaped by the skeleton. Muscles and tendons are attached directly to it, contracting, they bend the joints, making movement. So, we can lift a leg, turn our head, sit down or hold something with our hand.

In addition, the skeleton of animals and humans serves as protection for soft tissues and organs. For example, the ribs hide the lungs and heart under them, covering them from blows (of course, if the blows are not too powerful). The skull prevents damage to the rather fragile brain.

Some bones contain one of the most important organs - the bone marrow. In humans, it is involved in the processes of hematopoiesis, forming red blood cells. It also forms leukocytes - white blood cells that are responsible for the body's immunity.

How and when did the skeleton originate?

The skeleton of animals and the entire musculoskeletal system arose due to evolution. According to the generally accepted version, the first organisms that appeared on Earth did not have such complex adaptations. For a long time, soft-bodied amoebic creatures existed on our planet.

Then in the atmosphere and hydrosphere of the planet there was ten times less oxygen. At some point, the share of gas began to increase, starting, as scientists suggest, a chain reaction of changes. Thus, the amount of calcites and aragonites increased in the mineral composition of the ocean. They, in turn, accumulated in living organisms, forming solid or elastic structures.

The earliest organisms that possessed a skeleton were found in limestone strata in Namibia, Siberia, Spain and other regions. They inhabited the world's oceans about 560 million years ago. In their structure, the organisms resembled sponges with a cylindrical body. Long rays (up to 40 cm) of calcium carbonate departed radially from them, which played the role of a skeleton.

Varieties of skeletons

There are three types of skeleton: external, internal and liquid. The external or exoskeleton is not hidden under the cover of skin or other tissues, but completely or partially covers the body of the animal from the outside. What animals have an external skeleton? It is possessed by arachnids, insects, crustaceans, and some vertebrates.

Like armor, it performs mainly a protective function, and sometimes it can serve as a refuge for a living organism (tortoise or snail shell). Such a skeleton has a significant drawback. It does not grow with the owner, which is why the animal is forced to periodically shed it and grow a new cover. For some period, the body loses its usual protection and becomes vulnerable.

The endoskeleton is the internal skeleton of animals. It is covered in meat and leather. It has a more complex structure, performs many functions and grows simultaneously with the whole body. The endoskeleton is divided into an axial part (spine, skull, chest) and an additional or peripheral part (limbs and bones of the belts).

The liquid or hydrostatic skeleton is the least common. It is possessed by jellyfish, worms, sea anemones, etc. It is a muscular wall filled with liquid. Fluid pressure maintains the body's shape. When the muscles contract, the pressure changes, which sets the body in motion.

What animals do not have a skeleton?

In the usual sense, the skeleton is precisely the internal frame of the body, the totality of bones and cartilage that form the skull, limbs, and spine. However, there are a number of organisms that do not possess these parts, some of which do not even have a specific shape. But does that mean they don't have a skeleton at all?

Jean Baptiste Lamarck once united them into a large group of invertebrates, but apart from the absence of a spine, nothing else unites these animals. It is now known that even unicellular organisms have a skeleton.

For example, in radiolarians, it consists of chitin, silicon or strontium sulfate and is located inside the cell. Corals can have a hydrostatic skeleton, an internal protein, or an external calcareous skeleton. In worms, jellyfish and some molluscs, it is hydrostatic.

In a number of molluscs, it has the shape of a shell. In different species, its structure is different. As a rule, it includes three layers, consisting of the protein conchiolin and calcium carbonate. Shells are bivalve (mussels, oysters) and spiral with curls, and sometimes carbonate needles and spikes.

arthropods

The type of arthropods also belongs to invertebrates. This is the most numerous which combines crustaceans, arachnids, insects, centipedes. Their body is symmetrical, has paired limbs and is divided into segments.

By structure, the skeleton of animals is external. It covers the entire body in the form of a cuticle containing chitin. The cuticle is a hard shell that protects each segment of the animal. Its dense areas are sclerites, interconnected by more mobile and flexible membranes.

In insects, the cuticle is strong and thick, consisting of three layers. On the surface, it forms hairs (chaetae), spikes, bristles and various outgrowths. In arachnids, the cuticle is relatively thin and contains a dermal layer and basement membranes underneath. In addition to protection, it protects animals from moisture loss.

Land crabs and wood lice do not have a dense outer layer that retains moisture in the body. Only the way of life saves them from drying out - animals constantly strive for places with high humidity.

Skeleton of chordates

Chord - an internal axial skeletal formation, a longitudinal strand of the bone frame of the body. It is present in chordates, of which there are more than 40,000 species. These include invertebrates, in which the notochord is present for a certain period in one of the stages of development.

In the lower representatives of the group (lancelets, cyclostomes and certain species of fish), the notochord is preserved throughout life. In lancelets, it is located between the intestines and the neural tube. It consists of transverse muscle plates, which are surrounded by a shell and are interconnected by outgrowths. Contracting and relaxing, it works like a hydrostatic skeleton.

In cyclostomes, the notochord is more solid and has rudiments of vertebrae. They do not have paired limbs, jaws. The skeleton is formed only by connective and cartilaginous tissue. Of these, the skull, rays of the fins and the openwork lattice of the gills of the animal are formed. The tongue of cyclostomes also has a skeleton; at the top of the organ there is a tooth with which the animal bores its prey.

Vertebrates

In the higher representatives of the chordates, the axial cord turns into a spine - the supporting element of the internal skeleton. It is a flexible column consisting of bones (vertebrae) that are connected by discs and cartilage. As a rule, it is divided into departments.

The structure of the skeletons of vertebrates is much more complicated than that of other chordates and, moreover, of invertebrates. All representatives of the group are characterized by the presence of an internal frame. With the development of the nervous system and brain, they formed a bone cranium. And the appearance of the spine provided better protection for the spinal cord and nerves.

Paired and unpaired limbs depart from the spine. Unpaired are tails and fins, paired are divided into belts (upper and lower) and the skeleton of free limbs (fins or five-fingered limbs).

Fish

In these vertebrates, the skeleton consists of two sections: the trunk and tail. Sharks, rays and chimeras do not have bone tissue. Their skeleton is made up of flexible cartilage, which over time accumulates lime and becomes harder.

The rest of the fish have a bony skeleton. Cartilaginous layers are located between the vertebrae. In the anterior part, lateral processes extend from them, passing into the ribs. The skull of fish, unlike land animals, has more than forty movable elements.

The pharynx is surrounded by a semicircle from 3 to 7 between which there are gill slits. On the outside, they form gills. All fish have them, only in some they are formed by cartilaginous tissue, while in others - by bone.

The radial bones of the fins connected by a membrane depart from the spine. Paired fins - pectoral and ventral, unpaired - anal, dorsal, caudal. Their number and type vary.

Amphibians and reptiles

In amphibians, the cervical and sacral regions appear, which range from 7 to 200 vertebrae. Some amphibians have a tail section, some do not have a tail, but there are paired limbs. They move by jumping, so the hind limbs are elongated.

Tailless species lack ribs. The mobility of the head is provided by the cervical vertebra, which is attached to the back of the head. Shoulders, forearms and hands appear in the thoracic region. The pelvis contains the iliac, pubic, and ischial bones. And the hind limbs have a lower leg, thigh, foot.

The skeleton of reptiles also has these parts, becoming more complicated with the fifth section of the spine - the lumbar. They have 50 to 435 vertebrae. The skull is more ossified. The tail section is necessarily present, its vertebrae decrease towards the end.

Turtles have an exoskeleton in the form of a strong shell of keratin and an inner layer of bone. The jaws of turtles are devoid of teeth. Snakes do not have a sternum, shoulder and pelvic girdle, and the ribs are attached along the entire length of the spine, except for the tail section. Their jaws are very movably connected to swallow large prey.

Birds

Features of the skeleton of birds are largely related to their ability to fly, some species have adaptations for running, diving, climbing branches and vertical surfaces. Birds have five sections of the spine. Parts of the cervical region are movably connected, in other regions the vertebrae are often fused.

Their bones are light and some are partially filled with air. The neck of birds is elongated (10-15 vertebrae). Their skull is complete, without seams, in front of it has a beak. The shape and length of the beak are very different and are associated with the way animals feed.

The main adaptation for flight is a bone outgrowth in the lower part of the sternum, to which the pectoral muscles are attached. The keel is developed in flying birds and penguins. In the structure of the skeleton of vertebrates associated with flight or digging (moles and bats), it is also present. It is not in ostriches, the owl parrot.

The forelimbs of birds are wings. They consist of a thick and strong humerus, a curved ulna, and a thin radius. Some of the bones in the hand are fused together. In all but ostriches, the pelvic pubic bones do not fuse together. So birds can lay large eggs.

mammals

Now there are about 5,500 species of mammals, including humans. In all representatives of the class, the internal skeleton is divided into five sections and includes the skull, vertebral column, chest, belts of the upper and lower extremities. Armadillos have an exoskeleton in the form of a shell of several scutes.

The skull of mammals is larger, there is a zygomatic bone, a secondary bony palate and a paired tympanic bone, which is not present in other animals. The upper belt, mainly includes the shoulder blades, collarbones, shoulder, forearm and hand (from the wrist, metacarpus, fingers with phalanges). The lower belt consists of the thigh, lower leg, foot with tarsus, metatarsus and fingers. The greatest differences within the class are seen precisely in the limb girdles.

Dogs and equids do not have shoulder blades and clavicles. In seals, the shoulder and femur are hidden inside the body, and the five-fingered limbs are connected by a membrane and look like flippers. Bats fly like birds. Their fingers (except one) are greatly elongated and connected by a membrane of skin, forming a wing.

How is a person different?

The human skeleton has the same sections as other mammals. In structure, it is most similar to a chimpanzee. But, unlike them, human legs are much longer than arms. The whole body is oriented vertically, the head does not protrude forward, as in animals.

The share of the skull in the structure is much larger than that of monkeys. The jaw apparatus, on the contrary, is smaller and shorter, the fangs are reduced, the teeth are covered with protective enamel. A person has a chin, the skull is rounded, does not have continuous superciliary arches.

We don't have a tail. Its underdeveloped variant is represented by a coccyx of 4-5 vertebrae. Unlike mammals, the chest is not flattened on both sides, but expanded. The thumb is opposed to the rest, the hand is movably connected to the wrist.

During veterinary-sanitary or forensic examinations, the doctor has to determine the type of animal by the carcass, corpse, their parts or individual bones. Often the decisive factor is the presence or absence of some detail or form feature on them. Knowledge of the comparative anatomical features of the structure of bones allows us to confidently draw a conclusion about the type of animal.

NECK VERTEBRAE - vertebrae cervicales.

Atlant - atlas - the first cervical vertebra (Fig. 22).

In cattle, the transverse processes (wings of the atlas) are flat, massive, set horizontally, their caudolateral acute angle is drawn back, and the dorsal arch is wide. On the wing there is an intervertebral and wing foramen, there is no transverse one.

In sheep, the caudal margin of the dorsal arch has a deeper, gentle notch, and there are also only two openings on the wing.

Rice. 22. Atlas cows (I), sheep III), goats (III), horses (IV), pigs (V), dogs (VI)

In goats, the lateral edges of the wings are slightly rounded, and the caudal notch of the dorsal arch is deeper and narrower than in sheep and cattle, and there is also no transverse foramen.

In horses, on significantly developed thinner obliquely located wings, in addition to the alar and intervertebral foramina, there is a transverse foramen. The caudal edge of the dorsal arch has a deep, gentle notch.

In pigs, all cervical vertebrae are very short. Atlas has massive narrow wings with thickened rounded edges. The wing has all three openings, but the transverse one can be seen only along the caudal margin of the wings of the atlas, where it forms a small channel.

In dogs, the atlas has widely spaced lamellar wings with a deep triangular notch along its caudal margin. There is both an intervertebral and a transverse foramen, but instead of a wing hole, there is a wing notch - incisure alaris.

The axis, or epistrophy, is axis s. epistropheus - the second cervical vertebra (Fig. 23).

Rice. 23. Axis (epistrophy) of a cow (1), sheep (II), goat (III), horse (IV), pig (V), dog (VI)

Rice. 24. Cervical vertebrae (middle) cow* (O, horses (II), pigs (III), dogs (IV)

In cattle, the axial vertebra (epistrophy) is massive. The odontoid process is lamellar, semi-cylindrical. The crest of the axial vertebra is thickened along the dorsal margin, and the caudal articular processes protrude independently at its base.

In horses, the axial vertebra is long, the odontoid process is wide, flattened, the crest of the axial vertebra bifurcates in the caudal part, and the articular surfaces of the caudal articular processes lie on the ventral side of this bifurcation.

In pigs, the epistrophy is short, the odontoid process in the form of a wedge has a conical shape, the crest is high (rises in the caudal part).

In dogs, the axial vertebra is long, with a long wedge-shaped odontoid process, the ridge is large, lamellar, protrudes forward and hangs over the odontoid process.

Typical cervical vertebrae - vertebrae cervicales - third, fourth and fifth (Fig. 24).

In cattle, typical cervical vertebrae are shorter than in horses, and the fossa and head are well defined. In the bifurcated transverse process, its cranioventral part (costal process) is large, lamellar, drawn down, the caudodorsal branch is directed laterally. The spinous processes are rounded, well-defined and directed cranially.

Horses have long vertebrae with a well-defined head, vertebral fossa, and ventral crest. The transverse process is bifurcated along the sagittal plane, both parts of the process are approximately equal in size. There are no spinous processes (scallops in their place).

The upper vertebrae are short, the head and fossa are flat. The costal processes from below are wide, oval-rounded, drawn down, and the caudodorsal plate is directed laterally. There are spinous processes. Very characteristic of the cervical vertebrae of pigs is an additional cranial intervertebral foramen.

In dogs, typical cervical vertebrae are longer than in pigs, but the head and fossa are also flat. The plates of the transverse costal process are almost identical and bifurcate along one sagittal plane (as in a horse). Instead of spinous processes, there are low scallops.

Sixth and seventh cervical vertebrae.

In cattle, on the sixth cervical vertebra, the ventrally strong plate of the costal process is drawn out in a square shape, on the body of the seventh there is a pair of caudal costal facets, the transverse process is not bifurcated. The lamellar spinous process is high. There is no transverse opening, like a horse and a pig.

In horses, the sixth vertebra has three small plates on the transverse process, the seventh is massive, does not have a transverse opening, resembles the first thoracic vertebra of a horse in shape, but has only one pair of caudal costal facets and a low spinous process on the body.

Rice. 25. Thoracic vertebrae of cow (I), horse (II), pig (III), dog (IV)

In pigs, the sixth vertebra has a ventrally drawn wide, powerful plate of the transverse process of an oval shape; on the seventh, the intervertebral foramina are double and the spinous process is high, lamellar, set vertically.

In dogs, the sixth vertebra has a wide plate of the costal process slanted from front to back and downwards; on the seventh, the spinous process is set perpendicularly, has a styloid shape, and the caudal costal facets may be absent.

Thoracic vertebrae - vertebrae thoracicae (Fig. 25).

Cattle have 13 vertebrae. In the region of the withers, the spinous processes are wide, lamellar, caudally inclined. Instead of a caudal vertebral notch, there may be an intervertebral foramen. The diaphragmatic vertebra is the 13th with a steep spinous process.

Horses have 18-19 vertebrae. In the region of the withers, the 3rd, 4th and 5th spinous processes have club-shaped thickenings. The articular processes (except for the 1st) have the appearance of small contiguous articular surfaces. The diaphragmatic vertebra is the 15th (sometimes the 14th or 16th).

Pigs have 14-15 vertebrae, maybe 16. The spinous processes are wide, lamellar, vertically set. At the base of the transverse processes, there are lateral foramens that run from top to bottom (dorsoventrally). There are no ventral ridges. Diaphragmatic vertebra - 11th.

Dogs have 13 vertebrae, rarely 12. The spinous processes at the base of the withers are curved and directed caudally. The first spinous process is the highest; on the latter, ventrally from the caudal articular processes, there are accessory and mastoid processes. Diaphragmatic vertebra - 11th.

Lumbar vertebrae - vertebrae lumbales (Fig. 26).

Cattle have 6 vertebrae. They have a long, slightly narrowed body in the middle part. ventral crest. The transverse costal (transverse) processes are located dorsally (horizontally), long, lamellar, with pointed jagged edges and ends bent to the cranial side. The articular processes are powerful, widely spaced, with strongly concave or convex articular surfaces.

Horses have 6 vertebrae. Their bodies are shorter than in cattle, the transverse costal processes are thickened, especially the last two or three, on which flat articular surfaces are located along the cranial and caudal edges (in old horses they often synostose). The caudal surface of the transverse costal process of the sixth vertebra is articulated with the cranial margin of the sacral wing. Normally, there is never synostosis here. The articular processes are triangular in shape, less powerful, more closely spaced, with flatter articular surfaces.

Rice. 26. Lumbar vertebrae of cow (I), horse (I), pig (III), dog (IV)

Pigs have 7, sometimes 6-8 vertebrae. The bodies are long. The transverse costal processes are horizontally arranged, lamellar, slightly curved, have lateral notches at the base of the caudal margin, and lateral foramina closer to the sacrum. The articular processes, like those of ruminants, are powerful, widely spaced, strongly concave or convex, but, unlike ruminants, they have mastoid processes that make them more massive.

Dogs have 7 vertebrae. The transverse costal processes are lamellar, directed cranioventrally. Articular processes have flat articular, slightly inclined surfaces. The accessory and mastoid (on the cranial) processes are strongly pronounced on the articular processes.

The sacrum - os sacrum (Fig. 27).

In cattle, 5 vertebrae have fused. They have massive quadrangular wings, located almost on a horizontal plane, with a slightly raised cranial margin. The spinous processes are fused, forming a powerful dorsal crest with a thickened edge. The ventral (or pelvic) sacral openings are extensive. Complete synostosis of the vertebral bodies and arches normally occurs by 3-3.5 years.

In horses, 5 fused vertebrae have horizontally arranged triangular wings With two articular surfaces - ear-shaped, dorsal for connection with the wing of the ilium of the pelvis and cranial for connection with the transverse costal process of the sixth lumbar vertebra. The spinous processes grow together only at the base.

Pigs have 4 vertebrae fused. The wings are rounded, set on the sagittal plane, the articular (ear-shaped) surface is on their lateral side. There are no spinous processes. Inter-arc holes are visible between the arcs. Normally, synostosis occurs by 1.5-2 years.

In dogs, 3 vertebrae are fused. The wings are rounded, set, as in a pig, in the sagittal plane with a laterally located articular surface. At the 2nd and 3rd vertebrae, the spinous processes are fused. Synostosis is normal by 6-8 months.

Tail vertebrae - vertebrae caudales s. coccygeae (Fig. 28),

Cattle have 18-20 vertebrae. Long, on the dorsal side of the first vertebrae, rudiments of arches are visible, and on the ventral (on the first 9-10) paired hemal processes, which can form hemal arches on the 3rd-5th vertebrae. "The transverse processes are wide, lamellar, ventrally curved.

Figure 27. The sacral bone of a cow (1), sheep (I), goat (III), horse (IV), pig (V), dog (VI)

Horses have 18-20 vertebrae. They are short, massive, retain arches without spinous processes, only on the first three vertebrae are the transverse processes flat and wide, disappearing on the last vertebrae.

Pigs have 20-23 vertebrae. They are long, arcuate with spinous processes, inclined caudally, preserved on the first five or six vertebrae, which are flatter, then become cylindrical. The transverse processes are wide.

Rice. 28. Tail vertebrae of cow (I), horse (II), pig (III), dog (IV)

Dogs have 20-23 vertebrae. On the first five or six vertebrae, arches, cranial and caudal articular processes are preserved. The transverse processes are large, long, drawn caudoventrally.

Ribs - costae (Fig. 29, 30).

Cattle have 13 pairs of ribs. They have a long neck. The first ribs are the most powerful and the shortest and straightest. Medium lamellar, widening downwards considerably. They have a thinner caudal margin. The posterior ones are more convex, curved, with the head and tubercle of the ribs closer together. The last rib is short, thinning downwards, and may be hanging. It is palpable in the upper third of the costal arch.

Synostosis of the head and tubercle of the rib with the body in young animals does not occur simultaneously and goes from front to back. The head and tubercle of the first rib are the first to fuse with the body. The articular surface of the tubercle is saddle-shaped. The sternal ends of the ribs (from the 2nd to the 10th) have articular surfaces for connection with the costal cartilages, which have articular surfaces at both ends. Sternal ribs 8 pairs.

Horses have 18-19 pairs of ribs. Most of them are of uniform size along the entire length, the first ventrally is significantly expanded, up to the tenth the curvature and length of the ribs increase, then begin to decrease. The widest and lamellar first 6-7 ribs. Unlike ruminants, their caudal margins are thicker and their necks are shorter. The tenth rib is almost four-sided. Sternal ribs 8 pairs.

Pigs often have 14, maybe 12 and up to 17 pairs of ribs. They are narrow, from the first to the third or fourth, the width increases slightly. They have articular surfaces for connection with costal cartilage. In adults, the sternal ends are narrowed; in piglets, they are slightly expanded. Rib tubercles have small flat statutory facets, rib bodies have an indistinct spiral turn. Sternal ribs 7 (6 or 8) pairs.

Dogs have 13 pairs of ribs. They are arched, especially in the middle part. Their length increases to the seventh rib, width - to the third or fourth, and curvature - to the eighth rib. Facet ribs on tubercles convex, sternal ribs 9 pairs.

Breast bone - sternum (Fig. 31).

In cattle, it is powerful, flat. The handle is rounded, raised, does not protrude beyond the first ribs, is connected to the body by a joint. The body expands caudally. On the xiphoid process there is a significant plate of xiphoid cartilage. Along the edges of 7 pairs of articular costal fossae.

In horses, it is laterally compressed. It has a significant cartilaginous addition on the ventral edge, forming a ventral ridge, which protrudes on the handle, rounding off, and is called a falcon. In adult animals, the handle fuses with the body. Cartilage without xiphoid process. Along the dorsal edge of the sternum there are 8 pairs of articular costal fossae.

Rice. 29. Cow ribs (I), horse (II)

Rice. 30. Vertebral end of horse ribs

Rice. 31. Breast bone of a cow (I). sheep (II), goats (III), horses (IV), pigs (V), dogs (VI)

In pigs, as in cattle, it is flat, connected to the handle with a joint. The handle, unlike ruminants, in the form of a rounded wedge protrudes ahead of the first pairs of ribs. The xiphoid cartilage is elongated. On the sides b (7-8) pairs of articular costal fossae.

In dogs, it is in the form of a round, well-shaped stick. The handle protrudes in front of the first ribs with a small tubercle. The xiphoid cartilage is rounded, on the sides there are 9 pairs of articular costal fossae.

Thorax - thorax.

In cattle, it is very voluminous, laterally compressed in the anterior part, has a triangular outlet. Behind the shoulder blades it greatly expands caudally.

In horses, it is in the form of a cone, long, slightly compressed from the sides, especially in the area of attachment of the shoulder girdle.

In pigs, it is long, laterally compressed, height and width vary in different breeds.

In dogs of a cone-shaped shape with steep sides, the inlet is rounded, the intercostal spaces - spatia intercostalia are large and wide.

Questions for self-examination

1. What is the significance of the apparatus of movement in the life of the organism?

2. What functions does the skeleton perform in the body in mammals and birds?

3. What stages of development in phylo- and ontogenesis does the internal and external skeleton of vertebrates go through?

4. What changes occur in the bones with an increase in static load (with limited motor activity)?

5. How is a bone built as an organ and what are the differences in its structure in young growing organisms?

6. What departments is the vertebral column divided into in terrestrial vertebrates and how many vertebrae are in each department in mammals?

7. In which part of the axial skeleton is there a complete bone segment?

8. What are the main parts of the vertebra and what parts are located on each part?

9. In what parts of the spinal column did the vertebrae undergo reduction?

10. By what signs will you distinguish the vertebrae of each department of the spinal column and by what signs will you determine the specific features of the vertebrae of each department?

11. What are the characteristic features of the structure of the atlas and axial vertebra (epistrophy) in domestic animals? What is the difference between the atlas of pigs and the axial vertebra of ruminants?

12. By what sign can the thoracic vertebrae be distinguished from the rest of the vertebrae of the spinal column?

13. By what signs can the sacrum of cattle, horses, pigs and dogs be distinguished?

14. What are the main features of the structure of a typical cervical vertebra in ruminants, pigs / horses and dogs.

15. What is the most characteristic feature of the lumbar vertebrae? How do they differ in ruminants, pigs, horses and dogs?

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