5.

SKELETAL SYSTEM
SKELETAL SYSTEM: Bones and joints from the skeletal system of the body. Functions of the
skeletal system are:

1. Support and protection of soft tissues and vital organs.

2. 2. To give attachment to muscles.
3. Formations of red blood corpuscles in the bone marrow.
4. Storage of mineral salts like phosphorus and calcium.

Classification of bones: Bones of the skeleton are classified as:

1. Long bones: they are found in the limbs along bones act a levers and help in various
movements of the body.
2. Short bones: These have no shaft. But they contain a spongy substances covered by
a shell of compact bone e.g. small bones of wrist and ankle.
3. Flat bones: They contain two layers of compact bone with a spongy substances in
between e.g. pelvic bones and scapula.
4. Irregular bones: they do not fall in any category e.g. vertebrae and bones of the face.
5. Sesasmoid bones: these are small bones which develop in the tendons of muscles
e.g. patella of knee joint.

STRUCTURE OF BONE: Bone is the hardest of the connective tissues. It consists of two kinds
of connective tissues 1) Compact bone 2) Cancellous bone

Compact bone : It is hard and dense. It is found in flat bones, in the shafts of long bones
and as a thin covering of all bones.

Cancellous bone: It is spongy in appearance. It is found in the ends of long bones, in

short bones and in between two layers of compact tissue of flat bones.

Gross structure of a long bone: A long bone has two ends(epiphysis) connected by a shaft
(diaphysis). The outer membrane covering the bone is periosteum. It is followed by a thick
layer of compact bone. Inside this is a central medullary canal. Nutrient foramen is the
opening through which arteries pierce the medullary canal.

MICROSCOPIC STRUCTURE OF BONE: Cross section of a bone under the microscope shows
the following structures:

1. Haversian canal which lies at the centre. It contains blood vessels, nerves and
lymphatics.
 2. Lamellae which are plates of bone arranged concentrically around the Haversian
canal.
3. Lacunae which are spaces between the lamellae and they contain bone cells.
4. Canaliculi which are fine channels. They radiate between the lacunae and the central
Haversian canal.

All the structure together form a unit. This unit is called as the Haversian system.

DEVELOPMENT AND GROWTH OF BONES

Formation of the bone is called is ossification bones of the skeleton are developed in two
ways:

1) Some bones develop in sheets of fibrous tissue (intra-membranous ossification)

2) Other bones develop in bars of cartilage (intra-cartilaginous ossification). In both
cases, bone cells called osteoblasts invade the area of ossification. Here, calcium
salts are deposited to give the necessary hardness. This process of bone
development occurs before birth.

After birth, the bone grows from certain centres in it. The centre in the shaft is called
diaphysis. The two centers in the ends are called as epiphysis. The layer of cartilage in
between the epiphysis and diaphysis is called as epiphyseal cartilage. This is gradually
replaced by bone. This replacement occurs till the epiphysis and diaphysis unite to from a
single bony structure. After this, growth of bone stops.

BONES OF HUMAN SKELETON: A total of 206 bones from the human skeleton. These bones
can be classified as:

1. Bones of the skull : Bones of cranium, face and lower jaw

2. Bones of the trunk : Ribs , sternum, Vertebral column
3. Bones of upper limb : scapula (shoulder girdle)
Humerus (arm bone)
Radius and ulna(forearm bones)
Phalanges (finger bones)
4. Bones of Lower limb : Pelvic girdle (hip bone)
Femur( thigh bone)
Tibia and fibula (leg bones)
Meta tarsal bones( foot bones)

Bones of the skull and trunk from the axial Skelton. Bones of the upper and lower limbs
from the appendicular skeleton.
 Bones of the skull
Bones of the skull are divided into two groups:

1. Bones of cranium (or brain box)

2. Bones of face

Bones of cranium: Cranium is formed by 8 bones.

They are: 1. One frontal bone 2. Two parietal bones 3. Two temporal bones

4One occipital bones 5. One sphenoid bones 6. One ethmoid bones

Sutures of the cranium: sutures are the immovable joints which unite the bones of the skull.
The important sutures are:

1. Coronal suture: Between the frontal bone and the two parietal bones.
2. Sagittal suture: Between the two parietal bones.
3. Lambdoid suture: between the occipital bone and the two parietal bones.

Frontal Bone: if forms the forehead and the roof of the orbit. The features of frontal bone
are:

1. Supraorbital marginsa form the arches of orbit.

2. Nasal notch bone projecting between supraorbital margins. Nasal bones are fitted to
this.
3. Supercilliary arch-lies above these two structures.
4. Frontal tuberosities- the two prominences of forehead.
5. Frontal sinus- a space behind the forehead. It contains air and is lined by mucous
membrane.

Parietal bones: they are two in number. Both form the roof and sides of the skull. It has four
borders, four angels and two surfaces.

1. The articulation of this bone are:

Anteriorly with frontal bone
Posteriorly with occipital bone
Medially with the other parietal bone
Below with the temporal bone
2. It contains an eminence called parietal tuberosity.
3. Superior and inferior temporal lines are the two lines which run parallel to each
other.
4. The inner surface is concave. It has impressions for meningeal vessels.
Temporal bones: They are two in number. They form lower part of the sides of the skull.
The parts of temporal bone are:

1. Squamous part – a flat part having the zygomatic process which is connected to
zygomatic bone.
2. Petrous part- forms the bone of internal ear.
3. Mastoid part- contains mastoid process.
4. Tympanic part- contains the external auditory meatus.

OCCIPITAL BONE: It isat the back and lower part of the cranial cavity. The features of
occipital bones are:

1. A prominence above called as external occipital protruberance.

2. Condyles, two in number which articulate with atlas.
3. An opening at the base of skull called foramen magnum. The spinal cord passes
through this opening.

SPHENOID BONE: it lies at the skull. It forms a large part of middle cranial fossa. It contains:

1. Two pairs of wing-like structures called greater and lesser wings.

2. Sella turcica or hypophyseal fossa which is a fossa for the pituitary gland.

Ethmoid bone: it is cubical in shape. It is very light and thin. It is situated at the roof of nose
and in between the orbits. It contains:

1. Two labyrinths composed of ethmoidal sinuses.

2. A perpendicular plate forming the upper part of nasal septum.
3. Cribriform plate fitting into a notch of frontal bone.
Olfactory nerves pass through perforations in this plate.

Cranial fossae: the base of the skull is divided into three fossae. These are:

1. Anterior cranial fossa: it is formed by horizontal plates of frontal bone.

2. Middle cranial fossa: formed by sphenoid bone and petrous portion of temporal
bones.
3. Posterior cranial fossa: formed mainly by the occipital bone.

The fontanelles: At birth, skull bones of the child are not completed ossified. The space
between the bones are filled by membranes. These membranes at the angles of bones are
called fontanelles. These fontanelles are:

1. Anteriora fontanelle: It is the largest of the fontanelles. It is diamond shaped. It is

situated at the junction of frontal and two parietal bones. Here, the coronal and
sagittal sutures meet. This fontanelle closes at the age of 1 year and 6 months.
 2. Posterior fontanelle: it is at the back. It occurs at the junction of two parietal and
the occipital bones. It closes soon after birth.

SINUSES OF THE SKULL: These are cavities or chambers present in the bones the skull. The
important sinuses are:

1. Frontal sinus: They are two in number present in the frontal bones. They are
present in the frontal bones. They are present on each side at the root of the nose.
2. Maxillary sinuses: Two in numbers present in the maxillary bones. They lie on each
side of the nose.
3. Ethmoidal and sphenoidal sinuses: They are the other sinuses present in the skull.

all these sinuses communicate with the nose.

functions of sinuses:

1. They give resonance to the voice.

2. They lighten the bones of face and cranium.

BONES OF THE FACE

The bones which make the face are 14 in number . these bones are : 1) Two maxillae (upper
jaw) 2) One mandible (lower jaw) 3) two palate bones 4) two zygomatic bones 5) two
lacrimal bones 6) two nasal bones 7) two inferior turbinate bones 8) one vomer

Maxillae: they are two in number . these bones from the upper jaw. The essential features
of maxilla are

1. A body which is pyramidal in shape.

2. Four processes namely zygomatic process, alveolar process, frontal process and
palantine process.
3. Maxillary sinus present in the internal aspect.

Mandible : This bone forms the lower jaw and is the only movable bone of skull. It contains:

1. A body which is the horizontal pat in the centre. It contains the lower teeth and
forms the chin.
2. Two rami, one on each side.Each ramus contains the coronoid process in the front
and condyle of jaw (head) which lies behind.

Tempero-mandibular joint is formed by the articulation of condyle with the temporal bone.

PALATE BONES: They are two in number, they from the roof the mouth cavity and the hard
palate.
ZYGOMATIC BONES: two bones . they form a part of the floor of the orbit. Each of them
contains a temporal process. This process joins with zygomatic process of temporal bone
and forms the zygomatic arch.

Lacrimal bones: They are two bones found in the interior of of the orbit. It contains the
lacrimal sac which secretes the lacrimal fluid.

Nasal bones: They are two in number. They form the nasal bridge.

Inferior turbinate bones: Two in number. They are also called as nasal conchae. They are
found in the interior of the nasal cavity.

Vomer: It forms the lower part of nasal septum.

Hyoid bone: It is V shaped bone. It has:

1) A body 2) two horns called as lesser horn and greater horn. The Tounge and to
styloid process by means of ligaments.

BONES OF UPPER LIMB

SCAPULA: It lies at the back of the thorax. It forms the posterior part of the shoulder girdle.
It has two surfaces, three angles and three borders.

The surface of scapula are:

1. Anterior or costal surface: It is called as the suprascapular fossa. It lies nearest to the
ribs. Subscapularis muscle is attached to this surface.
2. Posterior or dorsal suface: it is divided into two fossae by spine of scapula which
ends with acromion process.

The fossae are:

a) Supraspinous fossa : which is the upper one. It gives attachment to supraspinatous

muscle.
b) Infraspinous fossa: which is below. It gives attachment to infraspinatous muscle.

The borders of scapula are:

1. Superior border: It lies in the upper part. It extends from the superior angle to the
base of corocoid process. Suprascapular notch is at the inner extremity of this
border. The suprascapular vessels pass through this notch.
2. Medial or vertebral border: It is nearest to vertebral column. It extends between
superior and inferior angles.
 3. Lateral or axillary border: it is nearest to axilla. It lies between inferior angles and
glenoid cavity.

The angles of scapula are:

1. Superior angle: It lies at the junction between superior and medical borders.
2. Inferiorangle: it is the junction between medial and lateral borders. It is the lowest
point of the scapula.
3. Lateral or external angle: it contains glenoid cavity which receives the head of
humerus (to form shoulder joint). Corocoid process of scapula arises internal to
glenoid cavity.

CLAVICLE: It is also called as collar bone. it is a long and curved bone. it forms the anterior
of shoulder girdle . it contains a shaft ,two ends and four borders, the ends are;
1. Medial or sternal ends. It articulates with sternum.
2.lateral or acromial end. It articulates with acromion process scapula.

The borders of clavicle are superior ,inferoior, anterior and posterior borders.
Humerus; it is the longest bone of upper limb . it contains two extremities and a shaft .
upper extremity ; it contains;
1. A hemispherical head which articulates with glenoid cavity of scapula .
2. Anatomical neck which is below the head .
3. Greater tuberosity which is below the anatomical neck . it is in the outer side upper
extremity .
4 lesser tuberosity which is below the anatomical neck , but it is at the fornt .
5. Bicipital groove or intertubercular sulcus ; it lies in between these two tuberosities.
6. Surgical neck ; it is a narrow point of the bone below the two tuberositises .

Shaft; it contains ;
1 deltoid tuberosity which is a rough tubercle on the lateral aspect of the shaft. It receives
the insertion of deltoid muscle .
2; spiral or radial groove which is a oblique groove across the back of the shaft . the radial
nerve passes through this groove .

Lower extremity ; it contains ;

1. Trochlea which is a pulley shaped surface on the innerside. It articulates with ulna.

2. Capitulum on the outer side. It articulates with radius.

3. Coronoid fossa which is depression. It lies above the articulates surface for ulna.

4. Olecranon fossa which lies at back. It receives the olecranon process of ulna.
5. Medial and lateral epicondyles which lie on each side of the articulating surface.

Ulna; it is the inner most bone of the foream. It contains two extremities and a shaft .

Upper extremity ; it contains ;

1 . coronoid process which is a projection in front . it fits into the coronoid fossa of humerus
. 2 . olecranon process which is an upward projection at the back . the fits into olecranon
process of humerus .

3 . trochlear notch which is formed by these two processes . it articulates with trochlear
surface of humerus.

4. Radial notch which is on the out er or lateral aspect. It articulate with the head of radius.

Shaft : it is tapering towards the lower end. It contains surface and borders. It gives
attachment to:

1. muscles which control movements of wrist and fingers.

2 flexor and extensor muscles of forearm .

3 muscles of pronation and supination of forearm .

Lower extremity: it contains:

1 head of ulna which is a small rounded eminence . it articulates with lower extremity of
radius .

2 styloid process which projects downwards form back of lower extremity .

Radius : it is the lateral or outer most bone of forearm. It contains two extremities and a
shaft .

Upper extremity : it contains :

1 A head which is more or less button _ shapped .

2 neck which lies below the head .

3 biceps tubercle which lies below and to the medial side of neck it gives insertion to
biceps muscle .

Shaft : it is narrower above and wider below . it contains surfaces which give attachment to
a variety of muscles

Lower extremity ; it contains styloid process which is on outer or lateral aspect .

Bone of wrist and hand

Bone of wrist; the bones of carpus or wrist are arranged in two rows .they are

1 first or proximal row made of sacphoid ,lunate , tripuetral and pisiform bone .

2 second or distal row made of trapezium , trapezoid , capitates and hamate bone .

Bones of palm ; they are made of metacarpal bones. The thumb has two phalanges. Other
fingers have three phalanges. They are proximal middle and distal phalanges.

3 metacarpo phalangial joints are the joint between metacarpal and phalangial bones.

4 interaphalangial joints are the joints between the phalangial bones themselves.

BONES OF THORAX

1. Sternum in the front.

2twelve paris of ribs at the sides

3 twelve thoracic vertebrae at the back

Sternum: it is also called as brest bone. It is a flat bone which divided into three parts
namely manubrium sterni, body of sternum and xiphoid bone.

Manubrium sterni : It is upper part which is triangular in shape. It contain:

1. Clavicular notches on both sides. These notches articulate with clavicle.

2. suprasternal notch which is present in between the two clavicular nothes.

3Articular both sides for the first rib.

BODY OF STERNUM; the second rib is attached at the junction between manubrium sterni
and body of sterni and body of sternum.this junction is called as angle of Ludwig.

XIPHOID BONE; it is the lowest part of sternum.to this are attached the diaphragm, linea
alba and rectus abdominis muscle.

RIBS ;they are arranged in 12 pairs ,on the back side all of them are attached to the thoracic
vertebrae .

1. true ribs which are the upper 7 pairs they are attached to the sternum directly .

2. false ribs which are the lower 5 pairs .they are attached to the sternum in directly.

3. floating ribs are the lowest 2 pairs . they are not attached in front.
A . ribs consist of the following parts ;

1. Anterior or sternum end ; it has depressions for attachment of costal cartilage.

2. posterior or vertebral end ; it has a head ,neck and tubercele.

Shaft ; a. which has two surface namely Inner and outer surfaces .

B .Two borders namely inner and outer border.

c. subcostal groove present in the inner surface. It contain intercostals vessels and nerves.

COSTAL CARTILAGE: these are bars of hyaline cartilage . they contact the ribs and sternum.

VERTEBRAL COLUMN : the vertebral column is made of a number of bones . these bones are
called vertebrae. In all, there are 33 vertebrae.

CLASSIFICATION OF VERTEBRAE: according to the region they occupy ,the vertebrae are
classified as:

1. cervical vertebrae : 7 in number . they form the neck region .

2. thoracic vertebrae 12 in number . they form back of thorax .

3. lumber vertebrae ;5 in number . they form lumber region .

4. Sacral vertebrae 5 in number .they form the sacrum.

5. Coccygeal vertebrae ;4 in number. They form coccyx.

STRUCTURE OF A TYPICAL VERTEBRA: a typical vertebra contains:

1. a body which in a box shaped anterior part . it is slightly concave the upper and lower
surface .

2. Neural arch which is posterior part : it contain two laminae which are directed backward
to meet behind in the mid line.

3.Two transverse process; one on each side they lie in the junction between pedicele in
lamina.

4. One spinous process which is backward projection it occurs where they to lamina unite
in the midline.

5. Two articular process in the upper and lower surface. They lie at the junction between
pedicele and laminae.
6. Neural canal which is a circular opening . The spinal cord passes through this.

CERVICAL VERTEBRAE : they are seven in number .the first cervical vertebra is called as atlas.
The second cervical vertebra is called axis. These two cervical vertebrae have different
structure when compared with others.

It is does not have a body.

It does not have a spinous.

On the upper surface, it has two facets. These facets articulate with the condyles of
occipital bones.

AXIS: it is the second cervical vertebrae . it contains;

1, Odontoid aprocess which is an upward projection from the body . it articulate with
anterior arch of atlas.

2. Two facets on the anterior surface . they articulate with atlas.

3. A spine is small and bifid.

Other cervical vertebrae: a smaller body, oblong shape, triangular neural canal, bifid
spinous process,.

THORACIC VERTEBRA : they are 12 in number. These vertebrae carry the ribs.

1. the body is heart shaped.

2. body has facets one on each side for the attachment of the head of ribs.

3. vertebral foramen is absent

4. pedicle and laminae is absent.

5. spinous process is long and projects downwards.

LUMBER VERTEBRAE : they are 5 in number. They have following the characterstics:

1. Body is big and kideney shaped .

2. no articular facets for ribs.

3. pedicles and laminae are present.

SACRAL VERTEBRA : they are 5 in number. All of the unite to form a single bone called
sacrum. The features of sacrum are:
1. Sacral foraminae which are 4 opening present in the anterior surface . nerve passes
through these opening.

2. lateral masses on either side . they are formed by the unoon of transverse processes .

3. sacral promontory which is the projection of the upper part of sacrum.

Coccygeral vertebrae: They are four in number.All of them unite to form a single bone called
Coccyx.

LIGAMENTS:The vertebrae are held together by the following ligaments.

1.Anterior and posterior ligaments:They run the whole length of spine.They connect the
anterior and posterior aspects of the bodies respectively.

2.Ligamenta flava:They connect the laminae of vertebral arches.

3.Supraspinous ligaments:They lie between the spines and connect them.

4.Intervertebral discs:They are made of fibrocartilage.

BONES OF THE PELVIC GIRDLE

The pelvic girdle is the connection between the trunk and lower extremities.It is formed by:

1.two inominate bones,one on each side.

2.the sacrum and coccyx in between.

INOMINATE BONE:It is called as pelvic bone or hip bone.It is made of three parts namely
ilium,ischiumand pubis.All these three bones unite to form a large cup shaped cavity on the
outer surface called acetabulum.The head of femur fits into acetabulum forming the hip
joint.

ILIUM:It is the upper expanded and flat part of inominate bone.It contains:

1.External or gluteal surface:This surface contains three ridges namely superior,middle and
inferior gluteal ridges.They give attachment to gluteal muscles.

2.Internal surface which is concave.It forms part of iliac fossa and gives attachment to iliac
muscles.

3.An upper margin called as crest of ilium.The crest of ilium contains four spines.They are:

a)Anterior superior iliac spine

b)Posterior superior iliac spine

c)Anterior inferior iliac spines

d)Posterior inferior iliac spines

4.Great sciatic notch which is below the articulating surface for sacrum.

Pubis:It is the front portion of inominate bone.It contains:

1.A body which is more or less square in shape.

2.Symphysis pubis which is the the union of the public bones in the front.

3.Superior ramus which is a bridge of the bone projecting from the outer part of the body
and joins it to ilium.

4.Inferior ramus which is the lower part of body and joins it to ischium.

Ischium:It is the solid,broad portion at the lower and back part of inominate bone.It
contains:

1.A body which forms acetabulum on the outer surface.

2.Tuberosity of ischium present at the lowest point.It supports the body weight while
sitting.

3.Spine of ischium which aries from the back of ischium.

Obturator foramen is a roughly triangular opening which is bounded by:

1.Public bone in front and above.

2.Ischium behind and below.

PARTS OF PELVIS:Pelvis can be divided into:

1.False pelvis which is the upper part.It is formed by the two iliac bones.

2.True pelvis which is the lowest part.It is formed by ischiumand pubis(in the front and on
each side)and by sacrum(behind)

Pelvis brim is the upper opening of true pelvis

Iliopectineal line is the present at the junction of ilium with ischium.

Differences between female and male pelvis:

The female pelvis is adapted for pregnancy and child birth.It differ from male pelvis in the
following aspects.
1.It is shallow and wider than male pelvis.

2.Inlet and outlet are longer and nearly oval in shape.

3.Bones are lighter and smoother.

4.Pubis arch is wider.

5.ischial tuberosities are further apart.

6.The coccyx is more movale.

BONES OF LOWER LIMB

FEMUR:It is also called as thigh bone.It is the longest and strongest bone of the skeleton.It
contains two extremities and a shaft.

Upper extremity:It contains:

1.A head which is spherical and covered with hyaline cartilage.

2.A neck which lies below the head.It is long and

3.Greater trochanter which is on the the outer side where the neck joins the shalft.

4.Leeser trochanter which is on the inner side where the neck joins the shalft.

5.Anterior and posterior intertrochantric lines are two lines which unite greater and leeser
trochanters.

Shalft:It is smooth,cylindrical and rounded in front and at the sides.It contains:

1.Linea aspera which is a ridge on the posterior aspects.

2.Gluteal ridge which extends from linea aspera to the back of greater trochanter.

3.Spiral line which extends at the inner aspects from linea aspera to lesser trochanter.

Lower extremity:It contains:

1.Medical and lateral condyles lying one on each side.

2.Intercondylar notch which lies behind.It separates these two condyles.

3.Adductor tubercle which is a small tubercle above the medial condyle.

4.Patellar surface which separates the two condyles in front.Patella on this surface.
5.Popliteal surface which is abovethe condyles at the back.Popliteal vessels and nerves lie
on this surface.

PATELLA:It is a sesamoid bone developed in the tendon of quadriceps femoris muscle.It

contains:

1.An apex pointing downwards.The ligamentum patellae is attached to the apex.

2.An anterior surface which is rough and covered with a bursa.

3.Posterior surface which is smooth.It articulates with patellar surface of femur(to form
knee joint).

TIBIA:It is the innermost bone of the leg.It is a long bone containing two extremities and a
shaft.

Upper extremity:It contains:

1.A head which contains two condyles namely medial condyles and lateral condyles.The
upper surface of these condyles articulate with the corresponding condyles of femur.

2.Popliteal notch which separates the two condyles at the back.

3.Tubercle of tibia which lis below the condyles in the front.

Shaft:It is triangular shape having three borders and three sufaces.The shaft contains:

1.Crest of tibia which is present in the middle third of the anterior body.

2.Soleal line which is strong ridge of bone present in the posterior surface.

Lower extremity:It is slightly expanded.It has an articular surface for talus to form the ankle
joint.Medial malleolus is a downward projection present in the medial aspect.

FIBULA:It is the lateral and outermost bone of the leg.It is a long and slender bone.It
contains two extremities and a shaft.

Upper extremity:It contains:

1.A head which is expanded.It articulates with the back of lateral condyles of tibia. It does
not take part in the formation of knee joint.

2.Styloid process present in the apex of head.One ligament of knee is attached to this.

SHAFT: it is thin and gives attachment to several muscles.

Lower extremity: it contains:

1. Lateral malleolus which is a downward prolongation of teh lower extremity.

2. Malleolar fossa which is a rough depression behind the malleolus.

BONES OF FOOT

Bones of foot can be classified as:

1. Tarsal bones(7 bones)

2. Metatarsal bones (5 bones)

3 Phalangial bines (14 bones)

TARSAL BONES: They include Calcaneum, talus, navicular, cuboid and three cuneiform
bones.

Calcaneum: It is the largest bone of the foot. It lies at the back of foot. Above, it articulates
with talus and in front with cuboid. Calcaneum gives attachment to tendo Calcaneums of
calf muscle.

TALUS: It forms the central and highest point of foot. It articulates at the sides with medial
and lateral malleoli and below with Calcaneum.

Navicular (or scaphoid): It is a disc shaped bone. It is present in the medial aspect of foot. It
lies between talus at the back and three cuneiform bones in front.

CUBOID: it is in the lateral aspect of foot. Behind, It Articulates With Calcaneum. In front, it
articulates with two lateral metatarsal bones.

Cuneiform bones: they are three in number namely medial, intermediate and lateral
bcuneiform bones. Posteriorly the articulate with navicular bone. Anteriorly they articulate
with three metatarsal bones.

Metatarsal Bones: they are five in number. They correspond with the five toes. All of them
are long bones.

They contain a head, shaft and base.

The first metatarsal is thick and stout.

The second metatarsal is longer than others.

The fifth one has a projection at the lateral side of the base.
Phalanges: they are 14 bones, two for the first toe ad three for the rest. All of them are
long bones.

Arhes of foot: in the foot, the bones are so arranged that there are four different arches.
There are two longitudinal arches and two transverse arches. These arches are

a) Medial or internal longitudinal arch: for this

1. posterior support is given by calcaneum.

2. anterior support is given by navicular, three cuneiforms and heads of three inner
metatarsal bones.

3. summit is provided by the talus.

b) lateral or outer longitudinal arch: this is formed by calcaneum, cuboid and two outer
metatarsal bones.

c) Transverse tarsal arch: it is formed by the tarsal bones.

d) Transverse metatarsal arch: it is formed by the heads of metatarsal bones.