Bone System

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* The bone and skeletal system

* Basic features of the skeleton

* Bone

* Composition and structure of bones

* Types of bones

* Key features of the bones

* Joints

* The human skeleton

* Disease and injury of the skeletal system

* References

* Conclusion

* Attachments


The following work aims at studying the skeletal system, its components and functions. The skeleton consists of a set of bones is the frame or body support and also serves as protection. The skeleton is the passive part of the locomotor system

The skeletal system consists of a set of solid structures basically consist of bone, called bone.

The bones serve three main functions: to provide support to the body, constitute the moving segments of the lever system configured with the joints and muscles, providing protection to internal organs and tissues. Other important functions of the bones are involved in the metabolism of various minerals such as calcium or phosphorus, and the formation of blood, a process that is involved within the bone marrow of some bones. The human skeleton has about 208 bones. This figure is not constant because some people have some small bones, known as supernumeraries, which are located in the head or fingers. A baby can have up to three hundred bones and born with some separated to facilitate the birth.

The bones are of various shapes and sizes: large, flat, short, spongy and compact. Each bone has a special role in the system. Bones are not flat structures, they have bumps and rough parts.

To study the human skeleton are taken into account 4 regions: the head (skull and face), trunk (spine, ribs, sternum, scapula and clavicle), upper extremities (shoulder, arm, forearm and hand) and last but not least the lower extremities (hips, thighs, legs and feet).

The skeletal system

The skeletal system and the skeleton:

The skeletal system consists of a set of solid structures basically consist of bone, called bone.

An internal skeleton is rigid or rigid structures inside the body, moving through the muscular system. If such structures are mineralized or ossified, as in humans and other mammals, they are called bones. Another component of the skeletal system are the cartilage, which complement the structure. In humans, for example, nose and ears are supported by cartilage. Some agencies have an internal skeleton composed entirely of cartilage, not bone calcified, as in the case of sharks. The bones and other rigid structures are connected by ligaments and muscle attached to the system via tendons.

The human skeleton is a highly questionable form of power as the differences between the parties leading to confrontation coquitlicos bones. With the exception of the hyoid bone, which is separated from the skeleton, all bones are articulated to form a continuum, supported by additional connective structures such as ligaments, tendons and cartilage.

The skeleton of an adult human has about 206 bones, not counting the teeth, bones, sutures or wormians (supernumerary skull) and sesamoid bones.

The organized set of skeletal bones, or organs, forms the skeletal system, which concurs with other organ systems (nervous system, joint and muscular system) to form the musculoskeletal system.

The skeleton is a structure characteristic of vertebrates. In biology, the skeleton is quite rigid or rigid structure that gives support and provides the basic morphology of the body, some facial cartilages (nasal, auricular, etc.) Should also be considered part of the skeleton.

Basic functions of the skeleton:

Bones play important roles among which we can mention the following.

1) Role of support. The skeleton is a framework which supports and fixing other parts of the body, but especially the ligaments, tendons and muscles, which in turn held in place by the other muscles of the body.

2) Locomotion. The bones are passive motion, but in combination with muscles allow movement, and which serve as a support and fixing.

3) Protection. In many cases the bones protect the delicate organs such as in the case of the skull bones, which provide excellent protection for the brain, spine and ribs protect the heart and lungs, the orbital cavities protect the eyes, the temporal bone houses the ear, and vertebral column protects the spinal cord.

4) Hematopoiesis. In the red marrow of long bones produce red blood cells and fewer lymphocytes and monocytes.*


* The bone is a strong body, hard and resistant as part of the endoskeleton of vertebrates. Is mainly composed of bone tissue, a specialized type of connective tissue consisting of cells, and calcified extracellular components. Bone also has covered the connective tissue (periosteum) and cartilage (articular facet), vessels, nerves, and some contain hematopoietic and adipose tissue (bone marrow).

The bones have various forms and serve several functions. With a complex internal structure but very functional morphology determines the bones are plastic, lightweight but very tough and hard.

The complete set of parts organized bone (bone) forms the skeleton or skeletal system. Each piece plays a particular role and set in relation to the parts next to which is articulated.

The surface of the bone presents extensions, bumps and tubers, which are inserted joint ligaments and tendons of the muscles, and a variety of irregularities such as grooves, pores and depressions that run and penetrate the blood vessels and nerves.


Composition and structure of bones:

The bones are soft structures beige color resistant mineral compounds and organic.

The minerals give hardness and strength to bones and are

Calcium phosphate 85 per 100.

Calcium carbonate per 100 9

Calcium fluoride 4 by 100

Phosphate 2 mg per 100

Ossein is the organic substance and is more than 1 / 3 of the material forming bone and the bone gives it elasticity and resilience.

The bone mineral are inert components or remain fixed but are constantly exchanged and replaced with organic components in a process known as remodeling.

Its formation and maintenance is regulated by hormones and food intake, which provide vital vitamins to function properly.

Bone structure:

If you make a longitudinal cut in the long bone can observe the following structures:

* The periosteum and conjunctiva thin membrane that covers the whole bone.

* The compact tissue, extending from the ends or epiphyses and becomes thicker in the center or shaft,

* The spongy tissue, which is located in the epiphysis and the bone marrow is

* The spinal canal, which is occupied by the bone marrow. In the red bone marrow are the erythroblasts, which originated the red blood cells, so this structure is the main hematopoietic organ.

As for the microscopic structure of bone consists of bone cells or osteoblasts and substance. In cross-section observed Haversian canals, around which are arranged in concentric layers of lamellae.



Types of bones

Depending on their size and shape, we can distinguish three types of bone: long bone, flat and short.

* The long bones, such as limbs, are cylindrical and elongated. Have a central body or shaft and finger ends or epiphyses, which are part of a joint. The area where the shaft joins the bone ends is known as the metaphysis. They consist of a crust, a layer of compact bone tissue several millimeters thick, and is what gives strength to the bone, and an inner zone called medullary cavity. The crust is lined on the outside with a sheet of connective tissue and bone called endosteum. The marrow cavity of the bone ends is filled with spongy bone tissue, little dense. In the central regions of the bones, the cavity contains a distinct tissue, including bone marrow.

* The flat bones such as skull, sternum, ribs or hip bones, are thin, flat and wide. Have an outer layer of compact bone tissue, and are filled with spongy bone.

* The short bones such as vertebrae, carpal bones of the hands and tarsus of the feet are small and have a cubic or cylindrical. Like the flat bones, have an outer layer of compact bone tissue, bone tissue filled.

The bone is not completely solid but has small gaps between their components, forming small channels along which the blood vessels responsible for nutrient exchange. Depending on the size of these spaces, the bone is classified as compact or spongy.

* A combination of a central canal, the concentric lamellae that surround it and the lacunae, canaliculi and osteocytes in them including called osteon or Haversian system. The remaining sheets between plates are called interstitial osteons.

* Compact Bone: is most of the diaphysis of long bones and the outside of all bones of the body. Compact bone provides protection and support. Has a structure of layers or concentric rings around central canals called Haversian canals extending longitudinally. Haversian canals are connected to other channels called Volkmann canals that perforate the periosteum. Both channels are used by blood vessels, lymphatics, and nerves to extend the bone. Between the concentric lamellae of mineralized matrix or lacunae are small holes where the osteocytes. For these cells to exchange nutrients with the interstitial fluid, each lacuna has a number of canaliculi through which extend extensions of the osteocytes. The canaliculi are connected together and eventually to the Havers channels.

* Cancellous bone: a difference of compact bone, cancellous bone does not contain osteons, but interstitial blades are irregularly arranged forming a partition or plates called trabeculae. These walls form a spongy structure, leaving voids that are filled with red bone marrow. Within the trabeculae are the osteocytes lie in lacunae with canaliculi radiating from them. In this case, blood vessels penetrate directly into the cancellous bone and allow the exchange of nutrients to the osteocytes.

The spongy bone is the main constituent of the epiphysis of long bones and the interior of most bones.

* It is a very consistent fabric, resistant to shock, pressure and tension but also elastic, protects vital organs like heart, lungs, brain. Also allow movement in parts of the body to perform work or activities by setting the displacement of the individual. Originating form the locomotor or skeletal bone structure and is lined with muscles depending on their location. It is also a calcium deposit mobilized, hematopoietic organ (home to the bone, forming the reports of blood components). Saving as a reservoir of calcium and phosphorus in the body.


Main functions of bones:



Articulation is called the union of two or more bones together. The joint function is to provide mobility and stability to the bone segments that relate to them.

Types of joint:

According to the range of motion that allow three types of joint.

* Fixed or synarthrosis joints do not allow hardly any movement to the bone segments involved, they contact each other directly. This occurs in the joints between the bones of the skull, whose main function is to protect the organs found inside.

* The semi-mobile joints or amphiarthrosis, can be articulated slightly, and the bony segments that form are surrounded by a thin layer of cartilage or fibrocartilage. Such is the case of the joints of the vertebral bodies, which allow only small movements. Nonetheless, when aggregated movements of all joints of the spine, it can describe the large movements of flexion, extension or rotation.

* Finally moving or synovial joints, are those that offer a greater range of motion, in them, the bone ends that are linked to each other have different structures that facilitate the sliding of one over the other and while ensuring stability the joint. Most of the joints of the extremities are of this type.

The human body has many types of movable joints. The hip and shoulder joints are field-cavity type, which allow free movement in all directions. The elbows, knees and fingers are hinge joints, so that mobility is only possible in a plane. Pivot joints that allow rotation only, are characteristic of the first two vertebrae, is also the joint that allows rotation of the head from side to side. Sliding joints where bony surfaces move apart very short distances are observed between different bones of the wrist and ankle

The articular cartilage

The articular cartilage is a layer of cartilage and variable thickness, lining the bone ends that are within the joints. Its function is to prevent wear and friction of the bone ends, allow them to fit better and absorb, transmit and distribute the forces of gravity and muscle pull that converge in the joints.

The size and shape of the articular cartilage varies considerably. Articular cartilage are the most voluminous of the knees and hips, which must withstand a greater force of gravity: its thickness in these joints, you can reach 4mm.

The most important property of articular cartilage is the elasticity, ie the ability to return to its previous condition after being subjected to heavy pressure. This elasticity is due to that, when pressed, the articular cartilage expels water from its own tissue into the joint cavity and when this pressure ceases, absorb water again.

The joint capsule and joint fluid

The joint capsule or synovium is a double cover that cushions the joints mobile and used to provide stability. The joint capsules are more bulky knees, projecting into the joint or lateral meniscus notches.

The outer layer of the joint capsule or fibrous membrane, is a rugged and expandable mantle that is strongly attached to the bones, just outside the joint. The inner layer, or synovial membrane, thinner and elastic lines the joint on the inside and is attached by its ends, the articular cartilage. Its main function is to produce and secrete into the joint cavity joint fluid, also has many defensive cells.

Joint fluid or synovium is a yellow viscous liquid that occupies the inside of the joint cavity. Its function is to lubricate and reduce friction between the bone ends and nourish the articular cartilage. It also has defensive cells.


The human skeleton.

To study the human skeleton are considered three regions: head, trunk and extremities.

* Bones of the head

To study the bones, which are 22, can be considered two parts: the skull and face.

* Bones of the skull.

The skull bones protective roles for the brain include the following: a front that forms the front and helps form the eye sockets, one located in the occipital region of the skull post-inferior, two temporary located on either side the skull at ear level, two parietal on each side of the head above the top of the storms, a sphenoid bone is forming the anterior skull base and ethmoid located between the frontal and sphenoid .

* Bones of the face:

The region of the face consists of 14 bones that help to form cavities. All facial bones are fused to the skull, except the lower jaw is articulated to the skull by a movable joint. These bones are:

Two passages that form the base of the nose.

Forming the two malar cheeks of the face.

Unguis tear or two that are located in the eyeballs and have a tear trough where are the tears.

Two found inferior turbinate in the nasal passages.

Two palatine bones forming the palate with the maxillae and help form the nasal cavity, and orbits bosa.

Two maxillae contribute to form the eye sockets, nostrils and the roof of the mouth. At its lower edge which houses alveoli have teeth.

The lower jaw that forms the lower jaw. Alveoli which house has the teeth and movement.

Finally, the vomer which is part of the nasal septum.

* Bones of the trunk

The trunk is made up of 58 bones for study considered the following parts: the vertebral column, ribs and sternum.

* The spine:

The spine is the axis of the body and is located in the posterior midline of the body. It extends from the base of the skull to the coccyx region. It consists of 33 vertebrae that are joined by cartilage disks spine is made up of the cervical, thoracic, lumbar, sacral and coccygeal.

* Ribs

Long bones are arched and plans are articulated with the vertebral column behind and in front to the sternum. There are twelve pairs of which the first seven ribs are true, they are directly attached to the sternum. The next three are the false ribs because they do not meet the chest bone but cartilage of the ribs true. The last two pairs are called floating ribs because its leading edge is free.

* The sternum

It is a flat bone located forward in the midline of the body. The sternum support both clavicles and the first ten pairs of ribs.

* Bones of the upper extremities:

The upper extremities have the function taking objects and serve as a defense. To study the bones of the upper limbs can be distinguished: the shoulder, arm, forearm and hand.

* Bones of shoulder

The shoulder is formed by the clavicle and scapula. The set of bones of men known by the name of girdle.

The clavicle is an S-shaped bone that is located in the upper chest region axle articulates with the sternum and scapula.

The scapula is a flat bone located behind the ribcage

* Bones of the arm.

This consists of a single bone, the humerus.

The humerus is a long bone that articulates with the scapula and the head of the radio.

* Bones of forearm

It consists of two bones: the cube located in and the radio out.

The ulna is longer than the radius and forms the soco-

The radius is shorter than the ulna and slightly curved. The radio can turn on the ulna, which allows the hand movements, ie, turn it down and in and out and up.

* Bones of the hand:

The hand has 27 bones and is equipped with high mobility and agility. In hand we can distinguish 3 regions:

1) The carpus, consists of eight small bones arranged in two rows. The first is tied to the forearm and is formed by: scaphoid, semilunar, pyramidal, pisiform. The second is articulated with the bones of the palm and consists of: trapezium, trapezoid, more and hooked.

2) The pastern along the palm of the hand and consists of five metacarpal bones, one for each finger.

3) The fingers are formed by three bones each, phalanx, and falangeta falangina, except the thumb which has only phalanx and falangeta.

* Bones of the lower extremities.

To study the bones of the lower limbs are divided into four regions: hip or pelvic girdle, thigh, leg and foot.

* Bones of the hip or pelvic girdle.

The hip fixation serves the lower extremities and is composed of two large bones, the iliac or innominate from the welding of three bones: the ilium, pubis and esquion.

* Thigh bone

It consists of a single bone, the femur, which runs from the hip to the knee, articulates with the acetabulum of the ilium.

* Bones of the leg

Consists of two long bones: the tibia, to the inner side and the fibula to the outside, the patella, which is part of the knee joint, is therefore between the thigh and leg and prevents leg bend forward.

* Bones of the foot.

The foot bones are divided into three groups: tarsus, metatarsus and toes.

The tarsus is the instep of the foot and consists of seven bones: talus, which articulates with the tibia and fibula, the calcaneus is the heel, the cuboid, the navicular and three cuneiform.

The metatarsal or sole consists of five metatarsal bones.

The fingers are made up of three battalions each, as in the fingers.



Accidents and diseases of the skeletal system

* Osteoporosis

Systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture, for over fifty years is considered that one of every four women and one in eight men have osteoporosis to some degree.

The most important influence of the deterioration of the bone in postmenopausal women could be related to a severe deficiency of progesterone secreted by the ovaries.

Other causes are identified: mineral and vitamin deficiencies, corticosteroid medications, poor eating habits, lack of exercise, too little cortisol and testosterone. Estrogen, on the other hand, hardly protect against osteoporosis when progesterone is absent. (Le magazine in March 1999).

* Osteoarthritis

Any joint disease that affects the body. It can be primary, ie that has no known underlying cause, or secondary, in which case you must specify its origin.

Among the many causes that can trigger osteoarthritis, are trauma, infection, or systemic rheumatic disease, etcetera.

In general, any factor that damages the joint cartilage wear and unleash their progressive destruction, which eventually will become a Osteoarthritis of the joint. Any arthritis can be treated, which depend on the degree of destruction of or joints.

In a first stage, treat their symptoms. Subsequently, and as it advances the articular destruction can, in advanced cases, the replacement of the damaged joint with a prosthesis.

* Osteoarthritis

Osteoporosis is not only a challenge for the elderly, but certainly also more frequent pain, silent and widespread is the derivative of osteoarthritis, with increased absolute and relative population of the elderly, it is estimated that 1, 5 million people over 65 years of our country, 80% have or have some kind of osteoarthritis on a permanent or sporadic and intermittent in frequency. Usually, as early as fifty years these disorders coexist with some other chronic type.

The most common pain disorders occur in the chest in the back, pelvis, hip and shoulder joints, especially knees, spasms in ligaments, tendons and muscles, ankles, wrists with pain to the hands, coexisting with other symptoms such as itching, thirst, sweating and local general weakness.

* Scoliosis

Is a lateral deviation of the spine with rotation of the vertebrae on top and bottom with no immediate identifiable cause. This curvature of the spine apparently affect structures such as the shoulders, back and pelvis.

It does not hurt either initially affects the life of the patient relationship. However, over time a “curved spine” will “wear” more and see a “painful adult scoliosis.”

If we understand that the column can be divided into cervical, thoracic (ribs) and back, there will be deviations for each segment. The thoracic curve is most common, followed by double thoracic and lumbar curve and the lumbar. By age, scoliosis may be congenital, infantile, adolescent and youth.

Scoliosis affects a small percentage of the population, approximately 2%. Often has a familial and hereditary (20%).

* Lordosis

Is the deviation of the spine so that it is a “hump” or Giba.

Accidents skeletal system

The most frequent accidents that occur in the skeletal system are:

* Split: when a total or partial rupture of a bone is manifested by intense pain, loss of movement and swelling of the affected part. Requires medical attention to prevent further complications. There are a variety of fractures, simple, compound, open, double, etc.

* Dislocation: is the dislocation of a joint, which occurs when exiting from its normal position. The dislocation is accompanied by intense pain from the injury to ligaments and tendons.

* Sprain: is an injury to the ligaments and tendons due to a sudden stop or a sharp blow.


Books consulted:

* Walter, J. K. Gran Enciclopedia Escolar. Johnson’s Editorial

* Mazparrote, S. 8th grade biology. Editorial Salesian

Web pages visited:


We conclude that the skeletal system is a really important part in the structure and constitution of the human body. Along with the muscular system allow movement. Other important functions of the skeletal system are: to support the body, protect vital organs and major red blood cell production or hematopoiesis (long bones)

The joints are also a major part in the bone marrow, they allow the union of the bone, its stability and in some cases the movement. The joints can be mobile, semi-mobile or fixed.

In the human skeleton, the bones of the skull are the main function of the brain protection. All facial bones are fused to the skull except the lower jaw is articulated to the skull mobile which allows movement, which is essential for mastication. There is a bone called the hyoid, which is the only one not articulated to any other bone and loose in the language. In the trunk are the ribs, which protect the lungs, the spine protects the spinal cord, among others.

The bones of the upper extremities are the main function allow grip objects and defense. For its part the lower extremities are the main functions of the body support and walking.

The bones are resistant structures are at risk although some changes such as fractures, dislocations or sprains. The bones also may have some diseases by the failure of production of its components, such as calcium. Among the most important diseases of the bones are: osteoporosis, osteoarthritis, bone cancer, osteoarthritis, scoliosis, lordosis, etc.


Karla Hernandez