Human Skeleton

Role of the osseous system

It is used as frame for the organization and protects the Viscère S by the large cavities which it forms (cranium, thorax, basin).
It is at the base of the mobility of the body thanks to the articulation S which make it possible the muscles to actuate the various segments of the skeleton.
It represents an important reserve of mineral, in particular of Calcium and Phosphore.
It allows the manufacture of the blood cells, on the level of the osseous Moelle.

List bones of the skeleton

Axial skeleton (80 bones)

Head

Os of the cranium

Parietal (two. Top of the skull and side parts the top of cranium)
Temporal (two. Located under parietal) the
Ossicles of hearing

Malléus (in the past hammer) (two. In the average Ear)
Incus (in the past anvil) (two. In the middle ear)
Pillars (in the past clamp) (two. In the middle ear)

Frontal (Face and orbital vault)
Occipital or occiput (Back and cranium bases)
Sphénoïde (Base of cranium)
Ethmoïde (Between the orbits)

Os of the Face

Vomer (In the nasal cavity)
Maxillaire S (two. Under the frontal. Form the upper jaw)
Lacrymaux (two. Inside the orbits)
palatine Os S (two. Osseous palate)
nasal Horns lower (two)
Os nasal (two, in front of the rising branch of the jawbone)
zygomatic Os S (two. Under the orbits)

Mandible (two. Welded. Jaw lower, mobile)
Os hyoïde (In front of the trachea)

Total : 30 bones.

Neck and trunk

Spinal column or rachis, made up of 34 Vertèbre S. One counts 7 cervical vertebrae forming the cervical column, 12 thoracic vertebrae forming the thoracic rachis, 5 lumbar vertebrae forming the lumbar rachis, 5 amalgamated vertebrae forming the Sacrum and 4 to 5 vertebrae, also amalgamated, to form the Coccyx.
Sternum
12 pairs of coasts: 7 pairs of true ribs, 3 pairs of false ribs and 2 pairs of floating ribs

Total : 47 bones (variable).

Para-axial skeleton (126 bones)

Upper limb

Shoulder

Scapula (in the past scapula)
Clavicle

Humérus

Front armlever

Radius
Ulna (in the past ulna)

Hand

Carp (8)
Metacarpus (5)
Phalange S (14)

Total : 32 bones. (x2)

Lower extremity

Basin

Os coxal (or iliaque Os) (3 pars)

Thigh

Femur
Patella (in the past Kneecap)

Tibia
Fibula (in the past fibula)

Foot

Tarsus (7)
Métatarse (5)
Phalange S (14)

Total : 33 bones. (x2)

Variation in the composition of the skeleton

It can exist in the adult human skeleton of the bones supernumerary, inconstant, and whose presence is in general not pathological.

the Os sésamoïde S (located in the tendons, they have as a role to increase the arm of lever). The patella (kneecap) is a constant bone sésamoïde.
the Os wormien S (or suturaux bone): small additional bone of cranium which derives from a supernumerary core of ossification. (located in the joinings between the bones of cranium).
the supernumerary pairs of coasts rare, and are generally suspended with the cervical vertebrae.
Certain malformations like the Polydactyly (six fingers instead of five).
the vertebrae crowned, normally welded to form the sacrum, can not the being or the being incompletely. One speaks then about transitional anomaly.
the trigonal Os, with the posterior face of the astragale (or slope).

Description of the skeleton

The skeleton is organized around in vertical osseous axis (spinal column), this axis connecting three volumes (head, rib cage, basin), two belts (pelvic, scapular) bind the four members (lower and higher) to the trunk.

The osseous head

Located above the Spinal column, it includes/understands two parts:

the cranium, in the shape of box, which contains the Encéphale;
the Face which places the bodies of the direction and supports the muscles and bodies of the Mastication, as well as the muscles of mimicry.

Cranium

The cranium is an ovoid cavity of form at large posterior end. It includes/understands eight flat bones. The frontal presents a vertical portion and horizontal. It is dug of two sine. The éthmoïde is located at the base of cranium, between the frontal and the sphénoïde. It takes share with the constitution of the Nasal fossae. The sphénoïde is located at the average part at the base of cranium, between the éthmoïde and the frontal ahead, the occipital and the temporal behind. The occipital one forms the major part of the posterior pole of cranium. It is bored occipital foramen. The parietal are located on each side above the scale of temporal, behind the frontal, in front of the occipital one. The temporal ones are located on each side under the parietal one, in front of the occipital one, behind of the large wing of the sphénoïde. They present three parts: the scale, upper part who enters the constitution of the side wall of cranium, the Mastoïde, postéro-lower and the rock, internal. Close to the union between the scale and the mastoïde, the apophysis zygomatic is detached, directed initially outwards and ahead, then ahead.

Face

The skeleton of the face includes/understands many bones. We will be satisfied to describe the upper maxilla and the mandible .

The upper maxilla is located above the oral Cavité, apart from the nasal fossae, below the Orbite. It takes part in the constitution of these three cavities and form with that on the opposite side most of the upper jaw. It is dug of a sine which communicates with the nasal fossae. It carries the higher dental arch.

The mandible, in the shape of arcade with former convexity, is made of two ahead welded halves, on the level of the symphyse mentonnière. Each hémi-mandible presents a horizontal branch and a vertically drawn up quadrilateral blade, the rising branch. On its higher edge, the latter presents ahead the apophysis coronoïde and behind the condyle, which is articulated with the temporal bone. These two reliefs are separated by the notch coronoïdienne. The horizontal branch supports the lower dental arch and is bored dental channel, occupied by a nerve. On its inner face is a very marked peak, directed in bottom and ahead, the peak mylo-hyoïdienne.

Appendix: the Os hyoïde is a bone sésamoïde in the horseshoe shape with former convexity. It is located in lower part and behind mandible.

The neck and the trunk

Spinal column

General information

It is a long ostéo-fibrous stem, full ahead, dug with a channel behind, located on the line of centers at the posterior part of the trunk. It is made up of the Vertèbre S, separated by fibrocartilagineux discs. One distinguishes:

7 cervical vertebrae which form a convex curve ahead (lordosis);
12 dorsal vertebrae which form a concave curve ahead (kyphosis);
5 lumbar vertebrae which form a convex curve ahead (lordosis);
5 crowned vertebrae welded in a part, the Sacrum, ahead concave (kyphosis);
4 or 5 vertebrae coccygiennes welded to form the Coccyx.

General characters of the vertebrae

Each vertebra present:

a former cylindroid body;
a vertebral hole enters the body ahead and the thorny apophysis behind. The whole of the holes forms the rachidian channel, which places the Spinal-cord;
two outwards directed transverse apophyses. They are located one on each side, with the union of the blade and the pedicle;
a thorny apophysis, directed behind, which is born from fusion, on the line of centers, of the vertebral blades;
four articular apophyses: higher and the lower, on each side of the vertebral hole; They allow the articulation of the vertebrae between them;
two blades located between the transverse apophyses and the thorny apophysis;
two pedicles which link the transverse and articular apophyses with the body. The edges superior and inferior of the pedicles are indented, so that the superposition of the pedicles of two close vertebrae forms the holes of conjugation.

Two particular vertebrae: the atlas and the axis

Atlas or first cervical

The atlas is composed of:

2 side, cylindroid masses, joined together by a former arc and a posterior arc. The side masses are articulated in top with the occipital one and bottom with the axis.
a vertebral hole including/understanding two portions:

the former, quadrangular portion which places the tooth of the axis,
the portion posterior, elliptic, with transverse main roads

Axis or second cervical

The axis presents on the higher face of the body a vertical projection, the tooth or apophysis flank profile, connected to the body by the coll. Its former face presents an articular facet which answers the former arc of the atlas.

Note:: For each area, the vertebrae show characteristics of this area. We will not expose them within the framework of this course.

Sacrum

It is located under the lumbar column, above the coccyx and between the two iliaque Os S. It with the shape of a quadrangular pyramid, whose former face is concave ahead. This face presents four transverse projections (old vertebral weldings) finished each side by the former crowned holes. The posterior face is very complex. It presents, on the line of centers, the peak crowned, irregular, finished in bottom by the lower opening of the crowned channel. On each side are posterior gutters, tubers and crowned holes which are remainders of the old structures of the crowned vertebrae. The side faces have, in top, an articular surface for the articulation with the iliaque bone. The base is directed in top and ahead and is similar to the higher face of a vertebra.

Coccyx

it results from the welding from four to six vertebrae atrophied: the vertebrae coccygiennes.

The thorax

General information

It is a large ostéo-cartilagineuse cavity sheltering the Cœur and the Poumon S. It is made up of 12 Vertèbre S dorsals, of 12 pairs of coast S, the costal cartilages and the Sternum.

Sternum

Flat Os, with the former part of the thorax, directed in bottom and ahead. It includes/understands three from top to bottom segments:

manubrium, or handle;
the body, whose edges are indented to receive the costal cartilages;
the appendix xiphoïde.

The manubrium and the body form a salient angle ahead, the angle of Louis, who locates the second sterno-costal articulation.

Costal coasts and cartilages

The coasts are divided into 12 from top to bottom numbered pairs:

7 true, articulated each one with the sternum via a different cartilage;
3 false, 8th, 9th and 10th coasts, which articulate with the sternum by a common cartilage
2 pairs of floating ribs, whose cartilage presents a free former end.

From the vertebral bodies, the coasts move in bottom and outwards. They are bent then (posterior angle) to move in bottom and ahead. Lastly, the former angle carries their direction in bottom and inside.

Each coast presents a body and two ends. The body introduces faces external and intern. He is traversed on his lower board by the costal gutter. The posterior end is articulated with the two vertebrae corresponding to the level of their intervertebral disc. The former end is continued by the costal cartilage.

First coast

Its body presents faces higher and lower. The higher face is traversed with its average part by 2 transverse gutters, separated by the tuber from Lisfranc.

Skeleton of the upper limb

The upper limb includes/understands four from top to bottom segments which are: the shoulder, the arm, the Front armlever, the Hand.

Shoulder

Still called scapular girdles. It is formed by the Clavicule ahead and the scapula behind.

Clavicle

It is a bone long, even, located between the Sternum and the scapula, directed obliquely behind and outwards. It forms an S lengthened whose internal curve is concave behind and the external curve, ahead concave. The clavicle presents a body and two ends.

Scapula

It is a flat, triangular bone, applied to the posterior face of the thorax, 2nd with 7th or 8th coast. The posterior face shows with the union of sound 1/4 superior and its 3/4 inferiors, a strong blade, the spine of the scapula. Being detached almost with right angle, the spine goes high, to be prolonged behind and outwards outwards by a strong apophysis, the acromion. The supero-external angle carries the cavity glénoîde, intended to articulate itself with the head humérale.

Arm: Humérus

Long Os located between the scapula (scapula) in top, the Radius and the ulna in bottom, it presents a body and two ends.

The higher end is made of three projections:

the head humérale, which with the form of a third of sphere and articulates with the cavity glénoïde scapula. It is directed in top, inside and is supported behind by a more or less narrowed portion, the anatomical collar;
apart from the anatomical collar is two projections. One, small and former, is the trochin; the other, larger and external, is the trochiter.
between the trochiter and the trochin is the slide bicipitale.

The lower end is broad transversely. It has an articular surface and two side masses. Articular surface is divided into two portions. External the, hemispherical one, is the condyle, which is articulated with the radius. The intern, trochlée, is in the shape of pulley: it presents an external, separate slope slope interns deeper, by a throat. Trochlée articulates itself with the ulna. Above and apart from the condyle the épicondyle is. Above and in inside of trochlée, is épitrochlée. With the former face, above articular surface, the small cavity coronoïdienne is. With the posterior face, above trochlée, the deep small cavity olécrânienne is.

Front armlever

The skeleton of before arm is consisted of the Radius outwards and the Ulna in insides, articulated at their ends and separated with the average part by space inter osseous.

Ulna ( ulna )

The ulna (or ulna ) is a long bone, located between the humérus and the carpus, in inside of the radius. It presents a body and two ends. The body is thinned downwards. The higher end, in side sight, watch a broad notch opened ahead, the large sigmoid cavity. This one is articulated with trochlée the humérale. It is delimited by two apophyses: one vertical, the olécrâne and the other horizontal one, the apophysis coronoïde. The lower end shows in bottom in-inside a vertical prolongation, the apophysis styloïde.

Radius

The radius is a long bone located between the humérus and the carpus, apart from the ulna. It presents a body and two ends. The body is bulkier in bottom than in top. The higher end includes/understands the head, the collar and the tuberosity bicipitale. The head, coarsely cylindrical, form in top a cup, which is articulated with the condyle huméral. The collar forms with the body a outwards open obtuse angle. The tuberosity bicipitale is at the top of the angle. The lower end is a quadrangular pyramid, showing a prolongation, the apophysis styloïde radius.

Hand

The hand consists of 27 parts divided into three groups: the carpus, the Metacarpus, the phalanges.

Carp

The carpus is composed of 8 irregularly cubic ossicles, laid out in two transverse lines. The higher line presents of outside in inside, the scaphoïde which has with its former face a tuber, the semilunar , the pyramidal and the pea-shaped , laid out with the front of the pyramidal one. The lower line is composed, of outside in inside, by the trapezoid , equipped him also with a tuber to its former face, the trapezoidal , the large bone and the hooked bone , equipped with a former hook, the apophysis unciforme .

The carpus, as a whole, form a deep gutter opened ahead and limited outwards by the scaphoïde and the trapezoid, in inside by the pea-shaped one and the apophysis unciforme of the hooked bone.

Metacarpus

The metacarpus forms the skeleton of the palm of the hand. It includes/understands five small numbered long bones of outside in inside, the métacarpiens .

Phalanges

The phalanges form the skeleton of the fingers. Each finger has three phalanges, except the inch which has only two of them. It is, from top to bottom, the phalanges , phalangines , phalangettes .

Skeleton of the lower extremity

The lower extremity includes/understands four segments: Hip, Thigh, leg and foot.

Hip: Os coxal

Flat Os, ranging between the Sacrum and the Femur. One describes with the bone coxal two faces, external and an intern and four edges: a superior, an inferior, former, posterior. The external face presents from top to bottom: the external iliaque pit, the cavity cotyloïde, which receives the head of the femur and the obturating hole. This last is circumscribed by an osseous framework which presents two bulges, one former, the posterior pubis and other, bulkier, the ischion. The inner face of the bone coxal is traversed by a peak foams, oblique in bottom and ahead, the innominée line, which enters the constitution of the higher strait of the small basin. The higher edge, or iliaque peak, described an S very lengthened. The former edge and the posterior edge are very broken.

Thigh: the Femur

It is a long bone, located between the bone coxal and the tibia. It presents a body and two ends. The body is slightly arched ahead. The higher end presents the articular head, forming approximately two thirds of a sphere, directed in top, inside and a little behind. The collar links the head with the trochanters and form with the diaphyse a angle known as tilt (110 with 140°). The great trochanter is located at the posterior part of the coll. The end lower, bulky, presents two articular portions, the condyles. Those ahead plain by another articular surface, trochlée and are separated behind by a notch known as intercondylienne.

Leg

It includes/understands the tibia and the fibula (or fibula ).

Tibia

The tibia is a long bone, located in inside of the fibula, between the femur and the astragale (or slope ). Its body shows a former edge circumvented in S, which starts in top with the former tuberosity of the tibia. Its average part, very marked, is the crest of the shin. The end higher, bulky, presents the shape of a quadrangular pyramid. The base or shinbone has two articular surfaces slightly excavated, the cavities glénoïdes, separated by space interglénoïdien. Of this space, the spine of the tibia rises, forked. The lower end of the tibia is also in the quadrangular shape of pyramid whose inner face is prolonged in bottom to form the internal malleolus.

Fibula (in the past " péroné")

The fibula (in the new nomenclature) is a long bone, located behind and apart from the tibia. Less low than the tibia on the side of the knee, it overflows it in bottom.

Patella

The patella (in the past kneecap) is a Os sésamoïde located in the tendon quadriceps. It with the shape of a triangle.

Foot

It includes/understands the tarsus, the Métatarse and the phalanges of the toes. The tarsus joins together 7 short bones, laid out in two lines. The posterior line is made of two superimposed bones, the slope (astragale) and the Calcanéum (calcaneus). The former one is outwards made up by the cuboïde , in inside by the wedge-shaped Os naviculaire and the three . The astragale is irregularly cubic. It presents, with its higher face, the convex pulley astragalienne in the antéro-posterior and concave direction transversely. Broader behind than ahead, it is articulated with the lower face of the lower end of the tibia. The calcanéum is the bulkiest bone of the tarsus.

The métatarse is made of five small numbered long bones of insides outwards, similar to the métacarpiens . The toes have three phalanges each one, except the large one (also called hallux) which has only two of them.

Articulations

Articulation ellipsoidal (énarthrose): One finds them at the base of the fingers and the toes. They allow side movements of before behind.

flat Hinges (arthrodies): One finds them in the tarsus (ankle), the carpus (wrist). They allow small side movements by slip.

Articulations trochléennes : One finds them in the knee, ankle, the elbow, the fingers and the toes. They allow movement of bending and tension.

trochoidal Articulations : One finds them in the neck and the elbow. Movements of swivelling allow.

Articulations spheroids : One finds them in the hip and the shoulder. Movements in all the directions allow.

Articulations in saddle : One finds them in the inch. Rotation movements in two directions allow.

Diseases

Osteoporosis
Osteogenesis imperfecta
Osteoarthritis

Terminology

Organization of the bones between-them

Face and cranium

Orbit
nasal Cavity
ptérygo-palatine Pit
Crack ptérygo-jawbone
temporal Pit

Pathology

Solution of continuity

Knew?

With equal weight, the bone is six times more solid than steel.
Several people believe that the bones are dry and inert, however they are alive and wet.
the femur is largest of the bones.
the smallest bone is not larger than a grain of rice.
the skeleton of an adult weighs approximately 10 kg.

External bonds

See a detailed diagram human Skeleton

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