Chapter 13 Locomotion and Movement by TEACHING CARE online tuition and coaching classes

Chapter 13 Locomotion and Movement by TEACHING CARE online tuition and coaching classes


Introduction : That branch of science which deals with bones and cartilage is called Osteology. Bones are made up of a protein called ostein and cartilage are made of a protein called chondrin. Hence study of bones is called osteology and study of cartilage is called chondrology. Body of animals (vertebrates) is supported by skeleton.


The hardened tissues of the body together form the skeleton (sclero = hard). Organism will remain small and slow moving if there had been no skeleton for support and to serve as levers on which muscles can act. Skeleton of invertebrates is most often secreted on the surface, forming a lifeless or dead exoskeleton. Whereas skeleton of vertebrates develops most often underneath the surface forming a living or growing endoskeleton. Three types of skeletons develop in vertebrates :

  • Epidermal horny exoskeleton : These include hard and horny of keratinized derivatives of epidermal layer of skin, such as claws, reptilian scales, bird feathers and mammalian hairs, horns, nails and hoofs, etc. All living amphibians lack an
  • Dermal bony skeleton : Dermal bony skeleton is derived from the dermis of skin. It includes bony scales and plates or scutes (osteoderms), finrays and antlers of fishes, reptiles and mammals. In fishes, dermal scales become exposed due to wearing out of epidermis, and form
  • Endoskeleton : Greater part of vertebrate skeleton lies more deeply, forming the endoskeleton. It develops from Endoskeleton is formed by bones in vertebrates. Skeleton in different animals are as follows –

Invertebrate –

  • Protozoa – No
  • Porifera – Calcarius spicules + silicious spicules + spongin
  • Spicules in porifera represent
  • Coelentrata – Calcareous
  • Helminth – No skeleton, cuticle
  • Annaelida – No skeleton, cuticle

In earthworm and ascaris is hydrostatic skeleton is found that is fluid is filled in coelom and form turgid skeleton.

  • Arthropoda – Chitinus
  • Chitin is modified
  • Mollusca – Calcarius
  • Echinodermata – Calcareous plates are
  • In vertebrates exoskeleton may be epidermal or

Vertebrates : In vertebrates dermal skeleton is formed by bones. Bone is the connective tissue with

intercellular spaces filled with ossein matrix composed of calcium salts 2/3  (Ca Po4 , Ca2 (SO4 )3 ), CaF2 CaCO3   and

calcium oxalate) and organic matter 1/3. In the ossein osteocyte cells are found and outer surface of bone is covered by periosteum. The inner most region is full of bone marrow having various types of cells. In mammals the bone is full of haversian canals. The bones are of three types :





  • Cartilage bones : The bones which are formed by the ossification of preexisting cartilage are called cartilage bones or replacing
  • Membrane or dermal bones : The bones which are formed by independent ossification in connective tissue are called dermal, membrane or investing
  • Sesmoid bone : Ossification takes place on Ligament and
    • Functions of endoskeleton : Chief function of vertebrate endoskeleton can be enumerated as follows –
      • To provide physical support to body by forming a firm and rigid internal
      • To give definite body shape and
      • To protect by surrounding delicate internal organs like brain, heart, lungs
      • To permit growth of huge body size (whale, elephant, extinct dinosaurs), since it is living and
      • To provide surface for attachment of
      • To serve as levers on which muscles can
      • To manufacture blood corpuscles in bone
      • To help in breathing (tracheal rings, ribs). Endoskeleton in vertebrate made up of :
    • Axial endoskeleton : (Skull + Vertebral column + Sternum + Ribs)
    • Appendicular endoskeleton : (Girdle + Limb bones)




























(a) Axial skeleton : It occupies the body’s main longitudinal axis. It includes four structure : skull in the head, vertebral column in the neck, trunk and tail if present, sternum and ribs in the thorax. It form the upright axis of body and includes 80 (87 in children) bones are as follows in man –

Cranium – 8                                             Hyoid – 1

Face – 14             28 Skull                         Vertebrae – 26 (33 in children)

Ear ossicle – 6                                            Sternum – 1

Ribs – 24






(1) Skull (General structure) : It is anterior most axial skeleton. It is divisible into two main parts –

(i) Chondrocranium                (ii) Splanchocranium

  • Chondrocranium : Chondrocranium is formed by
  • brain box or cranium proper and (b) two sense capsules –



























Orbit or optic capsule (eye) and auditory or otic capsule (ear).

  • Cranium proper : It is a strong and firm bony box with a helmet-like covering over the brain, called vault of skull, and a relatively thicker and stronger floor of base upon which the brain rests. Its cavity is called cranial cavity. Size of cranial cavity averages 1475 cubic centimetres (cm3) in adult






















men. At about the middle of the floor of cranium, there is a




large opening of cranial cavity called foramen magnum. The brain is connected to spinal cord at this foramen. Cranium proper of mammal has four distinct zone –

Fig. – Human skull viewed from right side


  • Occipetal zone : Occipital zone has one supra-occipital bone on dorsal side, one basioccipital on ventral side and two exoccipital on both lateral side of foramen Foramen magnum is present in ventral side of skull, which fills on Ist atlas vertebra. Two occipital condyles forming dicondylic skull at the junction of supra and exo-occipital.
  • Parietal zone : In the dorsal side of cranium parietal zone has three bone, that is two parietal, one inter parietal and ventral side of cranium has 3 bone e. one basisphenoid with pituitary foramen and two alisphenoid bone.
  • Frontal : Frontal part of cranium has two frontal bone in dorsal side, each frontal bone has one process called supra orbital process of Two orbitosphenoid, one presphenoid bone in ventral side.
  • Ethmoidal : Ethmoidal part has one circular plate called cribriformplate. That plate is having two perforation for exit of I cranial





















SUPRA                              OCCIPITAL (1)















Occipital region (of cartilage bones)

Parietal region                                        Frontal region                      Ethmoidal region

Temporal region





Exoccipitals (on side)

Supra occipital (on roof)

Basioccipiatal (on floor)

Orbitosphenoids (on sides & floor) (Cartilage bone)

Frontals (on roof

membrane bone)

Presphenoid or Parasphenoid

(on floor – Median) (Cartilage bone)





Basisphenoid (On floor Median) (Cartilage bone)

Parietals (on roof)

(Membrane bone)

(Inter-parietal)                    Alisphenoids (on floor & sides) (Cartilage bone)






  • Sense capsule : Chondrocranium contains two sense
    • Optic or orbital capsule (2) Otic or auditory capsule


(on floor median)

Ectethmoids or lateral ethmoids (on sides)


  • Optic capsule : One pair of optic or orbital capsule are present in frontal zone of It is

made up of 7 pairs of bones which are –

I – Pre frontal                II – Post frontal                     III – Anterior orbital                IV – Posterior orbital V – Infra orbital                VI – Supra orbital               VII – Lacrymal

In frog optic capsules are absent but in place of optic capsule eye-orbit are present in same position. In between two eye capsule, a separating bone is present in mammals only. This separating bone is called inter-orbital septum. This septum is


absent in frog between two eye orbits.

When inter orbital septum is present in any skull then such



skull is called tropibasic skull. In tropibasic skull both eye face the front and can be directed at the same object, this type of vision is called binocular vision. When inter-orbital septum is absent in skull, then such skull is called basic platy skull with monocular vision. Inter-orbital septum is formed by 5 bones which are 2 orbitosphenoid, 2- alisphenoid and one basissphenoid.

  • Auditory or Otic capsule : Auditory capsule located between occipital and parietal zone. It has two parts – Tympanic bulla and External auditory Auditory capsule in vertebrates is formed by 5 pairs of otic bones.

(I) Preotic                              (II) Epiotic                                    (III) Opisthotic

(IV) Sphaenotic                       (V) Pterotic

Out of these 5 pairs only I pair i.e. preotic participate in formation of auditory capsule of frog i.e. amphibian. In mammals e.g. rabbit I, II & III pair fuse to form a fusion bone called periotic, which forms the auditory capsule. In reptiles and birds (aves) all 5 pairs bone combinedly constitute auditory capsule. Membranous labyrinth is enclosed in the pro-otic and tymanic bulla. Auditory capsule has two distinct part – Outer spongy part called patrus part and Inner bony part called mastoid part.








Auditory capsule                                          Orbital capsule (membrane bones)

Olfactory capsule




Epiotic (Superior) & Posterior

Opisthotic (Posterior) & inferior

Prootic (Anterior) & inferior

Sphenotic present

Pterotic present

Nasals (above)

Vomers (below)



Form periotic in birds and mammals                               Present in Teleosts fishes only

In amphibians and reptiles, however, only prootic is present.

Membrane bones




Post-orbital (Postero-dorsal side of orbit)

Pre-frontal (Infront and on

outer side of frontal)

Supra-orbital (Above the orbit)

Pre-orbital (Antero-dorsal side of orbit)

Lacrymal (In front)

Post-frontal (Behind and on

outer side of frontal)


  • Skull of man : In man however the skull remain erect at top of vertebral column because of perfectly erect posture of body it is divisible into the large and hollow cranium and the facial
    • Cranium (Brain case) : In skull of man all eight bones are articulated with each other to form the cranium as follows –


Name No. Description
Frontal 1 Forms the forehead (anterior or front part of the top of cranium) and some upper parts (roofs) of eye orbits or

sockets and nasal cavities. A newborn infant displays a faint suture in midline of frontal, indication that adult frontal is actually formed of two completely fused frontal.

Parietals 2 Articulated to and situated just behind frontal. Form the main parts of bulging top and sides of cranium.
Occipital 1 Articulated to and situated just behind parietals. Forms posterior (back) and lower (base) parts of cranium.

Foramen magnum is a large perforation in this bone. On each side of the foramen, the occipital bears a

prominent elevation called occipital condyle. The condyles articulate the skull with first vertebra (atlas). Thus, human skull is dicondylic.

Temporals 2 Form lower parts of right and left sides of cranium, as well as, the floor of cranial cavity. These house structures of

internal and middle ears and form a part of external auditory meatuses. The middle ear of each side encloses the three small ear ossicles – malleus, incus and stapes.

Sphenoid 1 A typically butterfly-shaped bone that forms the middle and anterior parts of base of cranium in front of occipital

in the middle and temporals on the sides. It articulates with all skull bones, keeping these firmly together. It also forms parts of lateral walls and floors of eye orbits.

Ethmoid 1 A small, irregular bone in front of sphenoid and behind nasal bones. It fashions the front (anterior) extremity and

closer of cranial cavity. It also contributes to the architecture of eye orbits and proximal parts of nasal chambers.

  • The facial region : This is the front or anterior part of our skull comprised of 14 bones as follows –







































NASAL SEPTUM                         TEMPORAL



OCCIPITAL                       PARIETAL




Fig. – Human skull viewed from in front

Fig. – Human skull viewed from below








Name No. Description
Nasals 2 Small, oblong bones in middle of upper part of face, forming proximal part of the bridge of our nose. The remaining, lower part of our nose is formed of cartilage.
Inferior nasal

conchae (Turbinales)

2 Two highly coiled, scroll-like processes of ethmoid bone, called conchae project into each nasal cavity from lateral wall of the proximal bony part of concerned nasal chamber. One ethmoidal concha is superior (uppermost). The other one is called middle concha, because it is followed by a thin, separate scroll-like bone which is named inferior nasal concha or turbinate.
Vomer 1 A thin, elongated, platelike bone, forming a part of the septum which separates the two nasal cavities.
Lacrimals 2 Small and thin, finger-shaped bones, each located in front part of the medial (inner) side of corresponding eye orbit. these form a part of the passages of corresponding tear ducts.
Zygomatics (Malars) 2 Cheek-bones; form the prominences of our cheeks and parts of the floor and side walls of eye orbits.
Palatines 2 L-shaped bones that form the back (posterior) part of our hard palate (roof of mouth). Also contribute to the framework of nasal cavities and floor of eye orbits.
Maxillae 2 Large, upper jaw bones that form the major part of our face and upper jaw. Comprise entire front (anterior) part of our hard palate. Also contribute to the architecture of eye orbits and nose. Bear the teeth of upper jaw.
Mandible 1 Largest bone of our face, and strongest of all bones of the body. Forms entire lower jaw and bears all lower jaw teeth. Articulated with temporal bones of skull.


  • Splanchnocranium : It is also known as facial. It includes following two parts –

(a) Visceral skeleton        (b) Olfactory or Nasal capsule

  • Visceral skeleton : Visceral skeleton is formed by pairs of visceral arches which are –
    • I pair – Mandibular arch
    • II pair – Hyoid arch
The mandibular arch
  • III to VII pair – Branchial arches (remaining 5 pairs)

Palato-pterygo-quadrate bar forming                      Meckel’s cartilage (forming lower jaw)

Suspensorium                                  Upper jaw




Quadrate (Autostylic suspensorium

in amphibia, reptiles and birds)

Squamosal (Craniostylic suspensorium in mammals)





Premaxilla            Maxilla              Palatine            Pterygoid           Jugal




Angular                     Articular                      Dentary                         Splenial                          Supra







(1) Mandibular arch (one pair) : It is made of two arches one is upper forming upper jaw and second is lower called lower jaw. In tadpole stage upper jaw i.e. upper part of mandibular arch is formed by the fusion of three cartilage called palatine, pterygoid and quadrate. These all fused to form palato-pterygoquadrate.

Lower jaw or II part of mandibular arch is cartilagenous initially and is called Meckel’s cartilage which soon changes into bony structure.

(i) Upper jaw : The upper jaw is made of 14 bones i.e. 7 pairs of bones which are –

(i) Premaxilla                        (ii) Maxilla                         (iii) Jugal                 (iv) Squamosal

  • Pterygoid (vi) Palatine                       (vii)

Out of these 7 pairs of bones only quadrate are not visible because they constitute II ear ossicle i.e. – incus. In man the nasal cavity is separated from the buccal cavity by bone called palatine complex. Palate of birds is identical in animal kingdom, which is used for birds classification.

Process of upper jaw

  • Premaxilla
  • Nasal process on dorsal side which are covered by
  • Palatine process of

(2)  Maxilla

  • Nasal process of
  • Palatine process of
  • Zygomatic process of
    • Squamosal : Only zygomatic process of

(ii) Lower jaw : It is composed of 6 pairs of bone i.e. 12 bones maximum. These are articular, angular, splenial, dentary, coronoid and supra angular.

In frog out of 6 pairs only 4 pairs of bones are present. Only 3 pairs form lower jaw and one pair forms I ear ossicle i.e. collumella aures. Remaining 3 pairs i.e. Angular, splenial and dentry combine to form lower jaw of frog. In mammals only one pairs of bones are present of which only one pair i.e. dentry from lower jaw. In the process development cartilaginous dentry become offified due to osteocytes. Articular of lower jaw forms malleus i.e. I ear ossicle. All the 6 pairs of bones are present in lower jaw of reptilies and aves.

Upper jaw in vertebrate is completely ossified with skull but lower jaw is always free from chondrocranium and hangs downwardly. A bone hangs lower jaw from upper jaw. This bone is called suspensorium. A skull in which suspensorium is formed by quadrate is called autostylic skull e.g. frog skull. A skull in which suspensorium is formed by squamosal is called craniostylic skull e.g. rabbit skull (all mammal).

  • Hyoid arch (II pair of visceral arch) : It is also one pair of

which is called Hyoid proper and Hyomandibular.


  • Hyoid proper : It is a horse-shoe shaped bone in our neck

Fig. – Human hyboid bone viewed from above


between lower jaw and sound box or larynx. It is not articulate to any bone but is simply suspended from temporal bones by means of ligament. It consists of an elliptical main part or body and two

processes on each side of body, called greater and lesser cornua. It supports our tongue and provides insertion to some tongue muscles. In colloboration with branchial arches forms hyoid apparatus in terrestrial vertebrates. It is absent in fishes because branchial arches form gill rackers which support gills.

  • Hyomandibular : It is second part of hyoid arch which constitutes ear ossicles in In frog hyomandibular forms stapidial plate which is IIear ossicle which is dot or lid like bone. In rabbit hyomandibular forms stapes which





is III ear ossicle. That is stirrup like bone.

Ear ossicles


Mallius Incus Stapes
Articular Quadrate Hyomandibular
Hammer Anvil Sterip
  • Branchial arches : These are five pairs, which constitute III to VII pair of visceral arches. These constitute gill racker in fishes but terrestrial animals then form hyoid apparatus in collaboration with hyoid Five pairs of branchial arches are as follows –
    • III pair (ii) IV pair i.e. is epihyal.                   (iii) V pair i.e. is stylohyal.

(iv) VI pair i.e. tympanohyal.                 (v) VII pair i.e. thyrohyal.














N          N




F      F



Sq                           Sq

























P        P






Fig. – Dorsal view of skull of mammal

Fig. – Ventral view of skull of mammal


Difference between skull and frog of rabbit


S.No. Frog Rabbit
1. Skull somewhat triangular and dorsoventrally flattened; broader than long; not bent in the snout. Skull longer than broad, not flattened, but bent in front in the snout.
2. Cranial skeleton not distinguished into cranial and facial regions; divisible into occipital, cranial and olfactory


Cranial skeleton distinguished into cranial and facial regions. Cranial region divisible into occipital, parietal

and frontal segments.

3. Eye orbits form as depressions of skin and not as sockets in skull; separated from each other by cranial skeleton itself (platybasic) Eye orbits form as sockets in skull; separated from each other only by a thin interorbital septum ( = tropibasic)
4. Auditory capsules not lodged in cranial segment of skull; each is formed by a pro-otic bone. Auditory capsules lodged in cranial skeleton; each is formed by a tympanic bone and reinforced by a compound periotic bone.
5. Occipital segment small; has only two cartilage bones; the exoccipitals, around foramen magnum; no paroccipital processes. Occipital segment large; has 4 cartilage bones around foramen magnum – dorsal supraoccipital, ventral basioccipital and lateral exoccipitals having paroccipital processes.
6. Brain box or cranium small due to smaller brain; mainly consists of cylindrical sphenethmoid reinforced only by three investing bones – two frontoparietals dorsally and one parashpenoid ventrally. Brain box larger and more complex due to large brain; its posterior, parietal segment has two parietals dorsally, two alisphenoids, laterally and one basisphenoid ventrally; anterior, frontal segment has two frontals dorsally, two orbitosphenoids laterally and presphenoid ventrally.





7. No prefrontal and lacrimal bones. These bones present.
8. Cranial cavity not anteriorly covered by cribriform plate. Cranial cavity anteriorly covered by a cribriform plate.
9. Vomers not fused together; bear vomerine teeth. Vomers fused medially; bear no teeth.
10. Olfactory capsules without turbinal bones. Olfactory capsules have turbinal bones.
11. Septomaxillary bones present. These bones absent.
12. Jaw wuspension autostylic. Jaw suspension craniostylic.
13. Premaxillac bear several small premaxillary teeth in two rows. Premaxillae bear only two incisor teeth.
14. Maxillae bear a row of several small maxillary teeth. Maxillae bear only a few large cheek teeth.
15. Upper jaw has quadratojugal bones, but no jugals. Upper jaw has jugal bones but no quadratojugals.
16. Bones of upper jaw do not form zygomatic arches. Zygomatic processes of maxillae and squamosals, together with jugal bones form zygomatic arches which form outer borders of respective eye orbits.
17. Each squamosal bears a cartilaginous tympanic ring. Squamosals do not bear such rings.
18. Lower jaw toothless; each ramus has an axis of persistent Meckel’s cartilage covered by two membrane bones – dentary and angulosplenial; Meckel’s cartilage anteriorly ossified into mentomeckelian. Lower jaw toothed; each ramus consists of a single large dentary bones bearing the teeth.
19. Hyoid apparatus mainly formed of cartilage; none of its cornua are jointed. Hyoid apparatus mainly formed of bone; anterior cornua are 4-jointed.
20. Skeletal elements in skull number – 46. Skeletal elements in skull number 53.
21. Quite a number of components of cartilaginous larval

skull persist in adult.

A few components of embryonic chondrocranium persist

in adult.

22. Foramina are few. Foramina more in number.

Important Tips

  • Exoccipital and sphenethmoid bones are cartilaginous, sphenethmoid is unpaired
  • Pterygoid is the Y-shaped bone.
  • Zygomatic arch is found in upper jaw and formed by maxilla, squamosal and
  • The bones common to face and cranium are
  • Turbinal bones are present in the nasal
  • Dermatocranium of skull comprises of membranous
  • Turbinals bones are present in the nasal passage and increase the sensory surface of olfactory
  • Tympanic bulla enclosing the tympanus in
  • Coronoid process is a part of lower jaw in mammalian
  • Lacrimal bone is situated infront of the eye orbit close to the frontal
  • Mastoid bone is found in auditory
  • Frontoparietal is the membranous bone in
  • Anterior cornua of the hyoid apparatus of frog articulate with auditory
  • Hyoid apparatus of frog is situated in the floor of
  • Sella turcica is found in base-sphenoid It is a depression in skull which lodges the pituitary body.
  • Amphibian & mammalia has dicondylic skull and reptiles, birds has monocondylic
  • Alar process is a part of hyoid
  • The hyoid apparatus of frog is entirely cartilaginous except posterior
  • Septum axillary in the paired bone in
  • Pterygoid and palatines are paired bones on ventral side of skull of
  • Hammer shaped bone in skull of frog is
  • Pterygoid is membranous bone in frog
  • Frog has no basisphenoid





  • Vertebral column : It is our backbone which extends in the mid axis of the back (posterior) part of our trunk from head to the lower (inferior) extremity of Together with the sternum and rib, it forms the supporting frame work of our trunk. It support and rotate the head, suspends the viscera, protect vital organs, provides attachment to limb girdles, facilitates some movement of the trunk and houses the spinal cord.

Curvatures of vertebral column : In spite of the erect posture of body, the vertebral column of man is not perfectly straight. It displays four curves to enhance balancing power and firmness for upright posture of body. The curvatures are cervical, thoracic, lumbar and pelvic (=sacral). At birth, the whole column curves with the convexity towards the back. By the time, the infant stands, this convexity persists only in thoracic and sacral regions. These are called primary curvatures. A cervical curvature results from the effort on an infant to hold erect (3 to 4 months old infant). A lumbar curvature results when the infant learns to walk during the age of about 10 to 18 months. Cervical and lumbar curvatures are concave towards the back. Certain abnormalities of curvatures are –

  • Kyphosis (Hunchback) : Exaggerated thoracic
  • Lordosis : Exaggerated lumbar curvature.
  • Scoliosis : A lateral curvature in any
  • Vertebra column is formed by
  • Notochord is characteristic of chordate and fundamental character of all chordates.
  • It is present at any stage of
  • It is a skeletal rod formed by chordal
  • In protochordate it persists throughout the
  • It is a skeletal rod formed by chordal
  • In vertebrates it is replaced by vertebral
  • The vestegeal notochord called nucleus pulposes is found in intervertebral Inter-vertebral disc is fibro cartilagenous disc present between centrum of vertebrate.

(i)  Typical structure vertebrae

  • Neural arch : It arises from the dorsal side of the centrum and encloses a neural canal for the spinal cord. The arch may be produced into a dorsal process, the neural spine, which may be elongated pointed or flattened and directed upwards or
  • Transverse processes : These are lateral extension of neural arch and centrum. There may be two types of these processes – a more dorsal diapophysis arising from the base of neural arch and a lateral parapophysis arising from the side of the
    • Diapophysis (dia– two; apo– from; physis – growth) : These paired processes are directed differently and provide attachment to the tubercular processes of ribs. They are commonly known as transverse processes and are found in amphibians and other higher





  • Parapophysis : These paired outgrowths are similar to diapophysis and are common in
  • Zygapophyses : These are paired and flat articular surfaces, which check the dislocation of the vertebrae. These are the only structures which enable to identify the anterior and posterior faces of


















































Fig. – Hypothetical typical vertebra (front view)


Fig. – Hypothetical typical vertebra

(side view)


  • Prezygapophyses (Pre-before) : These are paired processes arising from the base of the neural arch on the anterior face and are directed horizontally forward. The articular facets look upwards and inwards. These structures are found almost in all
  • Postzygapophyses : These are paired processes arising from the base of neural arch on the posterior face and are directed horizontally The articular facets look downwards and outwards. They articulate over the prezygapophyses of the following vertebra.
  • Hypapophysis : It is a mid-ventral process which arises from the centrum. It may be directed forwards or backwards as in certain reptilian, avian and mammalian
  • Metapophyses : These are paired swellings or out growths having broad base and arising from just above the They are directed forwards and upwards, but their articular facets look slightly downwards. They are found in certain mammalian vertebrae.
  • Anapophyses : These are paired, slender and short processes which arise just below the Their articular facets look-slightly upwards and receive for the matapophyses.


  • Heamal arch : It surrounds the haemal canal which allows the blood vessels of the tail region to pass. It may be produced into a haemal spine below g. in fishes. The haemal

arch of the caudal vertebrae of reptiles is called chevron bone. It is usually Y-shaped.

(c)  Centrum



The part of vertebra attached to second by centrum.

On the basis of centrum vertibrae may be of following type –


(1)  Procoelus-vertebrae

Fig. – Types of Centrum




  • Cavity is present on anterior side of
  • It is present only in amphibia and
  • In reptilia is strongly and weakly procoelus is

(2)  Ophisthocoelus vertebra

  • Cavity present on posterior side of centrum g. – Fishes, snake and crocodile only.

(3)  Heterocoelus vertebrae

  • Also known as SADDLE shaped e.g. – Birds.

(4)  Acoelus vertebrae

  • No cavity in centrum so centrum is e.g. – Mammals.
  • Also known as

(5)  Amphicoelus vertebrae

  • Cavity present on both side of centrum g. – VIIIth vertebra of frog.
  • All veretebrae of scoliodon (Dog fish)

(6)  Amphidi condylar (Biconvex)

  • Biconvex, condyle on both e.g. – IXth vertebra of frog.
  • In frog IXth vertebra is Acoelus (e. cavity absent).

(ii)  Vertebral column of man

  • Made up of pieces of bones known as
  • Vertebrae of man are acoelus e. Centrum is flat and without cavity.
  • Vertebral column also known as spinal column or
  • Number of vertebrae are thirty three (33) in vertebral
  • Cervical vertebrae are seven (7).
  • Thoracic vertebrae are twelve (12).
  • Lumbar vertebrae are five (5).
  • Sacral vertebrae are five (5) in child but fuse to form sacrum, caudal vertebrae are four (4) but form coccyx in

In the adult stage of man number of vertebrae are as follows –


Cervical (in neck) 7
Thoracic (in chest or thorax) 12
Lumbar ( in loins) 5
Sacral (in upper part of pelvis) 1 (formed of five fused vertebrae)
Coccygeal or Coccyx (in lower part of pelvis) 1 (formed of four fused vertebrae)






(a)  Atlas vertebra

  • First cervical
  • Body is formed by centrum and vertebral
  • It supports the globe of the head like the earth by the atlas (super man).
  • Centrum is
  • Neural spine
  • Transverse process are

(b)  Axis vertebra











Fig. – Atlas






















  • Second cervical
  • Centrum
  • Odontoid process
  • It is pivot for rotation of atlas and head around odontoid
  • Transverse process

Difference between Atlas and Axis vertebra









Fig. Man axis



S.No. Characters Atlas vertebra Axis vertebra
1. Position First vertebra of vertebral column. Second vertebral of vertebral column.
2. Centrum Absent Present
3. Neural spine Absent Upward and bifuracated.
4. Pre and post zygapophyses Absent Pre-absent and Post present.
5. Neural foramen Divided into upper spinal foramen and lower odontoid canal. Not divided.
6. Odontoid process Absent Present
7. Function Supports the skull and yes movement of head. Supports rotatory and sideways movement of head.


(c)  Cervical vertebra


























Fig. – Man cervical

Fig. – ManVII cervical






  • Long neural
  • Centrum
  • Transverse process are
  • Vertebrarteal canals
  • Vertebrarteal canals also known as foramina

(d)  Thoracic vertebra

  • Centrum
  • Neural canal is formed by union of two neural
  • Neural spine is a flat & long directed backward.
  • Club shaped transverse

































  • Neural arch with superior articular
  • Two demifacets for articulation of head of a rib are present.

(e)  Lumber vertebra


Fig. – Man thoracic




















Fig. – Man IV lumber

  • Centrum
  • Neural spine well developed.
  • Transverse process are thin and


PEDICLE                                         ACCESSARY




Fig. – Man Lumer


  • Small accessory process present near the root of each transverse
  • It is the largest

Difference between Thoracic and Lumbar vertebra

S.No. Characters Thoracic vertebra Lumbar vertebra
1. Neural spine Long undivided and downward directed. Short, flat and upward directed.
2. Facet for ribs Present on transverse process and centrum. Absent.
3. Transverse process Club-shaped. Thin and elongated.


(f)  Sacrum

  • It is fusion of five
  • Ventral curtualine increases pelvic capacity.
  • Transverse process is much modified into a broad sloping mass project laterally from the
  • Sacral canal is formed by sacral vertebral foramina.





  • In female sacrum is shorter and
  • In birds some of the vertebrae are fuse to form synsacrum. [Last thorasic+ Lumber+ Sacral+ One or two caudal]

(g)  Coccyx

  • It is formed by fusion of four caudal
  • It is last section of
  • It is small triangular
  • Two coccygeal cornua project up to articulate with sacral
  • Rudimentary transverse

(3)  Thoracic basket

  • Ribs
  • Structure : The ribs are curved bars, which movably articulate with the thoracic vertebrae at the back and white with the sternum in front all collectively forming a bony cage, the thoracic basket. These are 12 pairs of ribs. The upper seven pairs of ribs are attached in front directly to the sternum. These are called true rib. The next three pairs of rib are jointed to the rib above each. They are termed false ribs. The lower two pair of ribs are free in front they are known as floating Tenth rib is also usually floating in Japanese and some other people.

A rib consists of two parts – Vertebral and Sternal. The vertebral part is long and bony. It articulate with the thoracic vertebrae by 2 facets, the capitulum and tuberculum, (Ribs of mammal and birds are bicephalous) in the first nine ribs and by a single facet, the head in the remaining vertebrae. The sternal part is short and cartilaginous. It articulate with the sternum or sternal part of its upper rib.

Human thorax is wider from side to side then from front to back. This is an adaptation for the up right posture of the body. It help to maintain equilibrium. In birds a uncinate process is present in ribs for muscles attachment.

  • Function : The ribs serve three important functions –
    • They protect the heart, large blood vessels and
    • They bear respiratory muscle (external and internal intercostal muscle).


  • Lower two pair of ribs protect the







Ist RIB 2nd RIB

































12th RIB















7th RIB


8th RIB 9th RIB

10th RIB


11th RIB
























Fig. – Bones of thorax (front view)

(ii)  Sternum

  • Structure

Fig. – A typical rib of left side

A – Inferior aspect; B – Posterior aspect





  • It is bone of
  • It is absent in
  • It is associated with pectoral girdle in
  • In man it is made up of cervical manubrium (presternum), mesosternum and xiphoid process (Meta sternum).
  • In male it is nearly 17 cm
  • Manubrium is broad and
  • Mesosternum is made up fine
  • Metasternum is represent by xiphisternum which is smallest broad and In mammal a cartilagenous plate attached with xiphisternu known as xiphoid cartilage.
  • Sternum = manubrium + 5 sternabrae +
  • Function : The sternum has two function –
    • It takes part in the formation of the protective thoracic
    • It plays a role in the respiratory

(b) Appendicular skeleton : It forms the bony frameworks of limbs and their supporting girdles, and includes 126 bones as follows –

  1. Upper extremities 2. Lower extremities

Pectoral girdle               4                                     Pelvic girdle              2

Upper limbs (arms)         60                                   Lower limbs (legs)        60

  • Girdles : The girdle give articulation to the limb There are two types pectoral girdle (shoulder girdle) and pelvic girdle (Hip girdle). Each girdle is made up of similar right and left halves (os innominate).


(i)  Pectoral girdle




  • Structure : Each half (Os innominate) of the girdle mainly comprises a large, flattened and triangular cartilage bone, the scapula (shoulder blade). The broader side has a narrow strip of










cartilage called suprascapula. The dorsal surface of scapula has a median longitutinal ridge called acromian spine, which successively becomes more and more prominent towards the narrower end of scapula and then, projects beyond this end as a distinct acromian process. Another prominent metacromian process projects horizontally from the base of acromian process. At its narrow end, the scapula is itself fused with an inwardly bent, knob like coracoid process. A deep, cup like concavity the glenoid cavity is located at the end of scapula close to coracoid process. The head of humerus bone of upper arm fits in to this cavity. Another component of each



























half of pectoral girdle is a long and slender, rod-like membrane

Fig. ScapulaPectoral girdle


bone the clavicle, articulated with the acromian process. The other end of clavicle is connected with pre sternum by means of an elastic ligament.

  • Function : The pectoral girdle serves two functions –
    • It provides articulation to the arm (2) It affords attachment to certain muscles of the arm.

(ii)  Pelvic (Hip) girdle

  • Structure : It is located in the lower part of the It consists of 3 bones – upper ilium, lower ischium and inner pubis, fused to form a stout hip bone, the innominate. Ventral wall of pubis has a small bone called catyloid. Acetabelum is formed by ilium, ischium and pubis, but in mammals pubis is replaced by cotyloid bone. Pubis symphysis is present in mammals. Below the acetabulum, the innominate has a large oval gap, the obturator





foramen (ischio-pubic foramen) . The two innominate bones and sacrum together from a sort of bowel, the pelvis, that supports the lower abdominal viscera. This is also an adaptation for upright posture of the human body. The female pelvis is larger and has a broader front and larger bottom opening than the male pelvis. This is an adaptation for childbirth. In man ischiatic tuburocity or siting bone is present in ischiam.

  • Functions : The pelvic girdle serves the following functions –
    • It provides articulation to the bones of the
    • It contributes to the formation of a bowel for the support and protection of adominal
    • It transfers the weight of the body to the
    • It provides the attachment to certain leg


















Fig. – ManMale Pelvic










Fig. – ManPelvic Girdle








Difference between Male and Female pelvis


S.No. Characters Male pelvis Female pelvis
1. Nature of bones of pelvic girdles Heavier and longer Lighter and smaller
2. Sacrum Less concave More concave anteriorly
3. Pelvis Shallow, narrow and round Deep, wide and funnel-shaped


  • Limb bones : Limb are two types fore limb and hind

(i)  Bones of fore limbs

  • Structure
  • It includes Humerus + Radius & ulna + Carpals + Meta carpals +
  • Humerus is characterised by presence of deltoid ridges for the attachment of
  • Distal end of humerus at the elbow joint is like pully and called Its groove is called olecranon fossa whose basal part is marked by a supratrochlear foramen for the passage of branchial artery and nerve.
  • Humerus is characterised by arterial
  • Head of the humerus articulate with glenoid cavity of pectoral girdle.
  • Radius is smaller and ulna is
  • Styloid process is present in distal end of





  • Olecranum process is present in
  • Olecranum notch is formed by ulna which is also known as sigmoid
  • Carpals are eight in
  • Metacarpals are five in number, and phalanges are – fourteen, phalanges formula = 2, 3, 3, 3,
  • Special features : In the human arm, (1) The joints are more movable than in the forelimbs of animals
    • Metacarpals form a wide palm and (3) Thumb is The differences in structure are correlated to the differences in function. Animals use their forelimbs mainly for locomotion whereas man uses the arms for work (grasping).
  • Function : Bones of the arms provide strength to make the arms effective in working with













































(ii)  Bones of hind limbs

  • Structures
  • It includes Femur + Tibia and Fibula + Tarsals + Metatarsals + Phalanges
  • Femur is longest and strongest
  • Femur is known as bone of thigh.
  • Greater trochenter, lesser trochenter are present in Three trochenter present in femur.
  • Patellar groove in found in distal end of
  • Fibula is smaller and associated with knee
  • Tibia is
  • Tarsal bones are seven.
  • Metatarsals are
  • Phalonges are
  • Phalonges formula = 2, 3, 3, 3, 3
  • Patella form knee
  • Patella is formed by sesmoid Sesmoid bone is also known as fubellae.
  • Thumb of foot is called
  • Ankle bones have 6 tarsals and arranged in three rows then Ist row have astragalus and calcanum in These are longest bone for adaptation of locomotion.
  • Nutrient foramen present in Tibio-fibula
  • Tibio fibula is longest bone in

















































  • Special features : All the bones of the legs are more massive than the bones of the arms because the legs alone support the body on the ground and are used in locomotion. The broad feet provide an additional stable support in the upright
  • Function : The bones strengthen the legs to bear body weight, to balance the body while standing and to aid in

Difference between Humerus and Femur


S.No. Characters Humerus Femur
1. Position In upper arm of fore limb. In thing of hind limb.
2. Head Fits in glenoid cavity Fits in acetabulum.
3. Process on head Two tuberosities. Two trochanters.
4. Shaft With deltoid ridge. No ridge
5. Lower end With a pully-like trochlea having 2 epicondyles. With two condyles and an intercondylar groove.


Important points of skeleton

Total number of bones : 206 Bones


Skull : 29 Bones Cranium : 8 Bones

Occipital : 1 Bone Parietal : 2 Bones Frontal : 1 Bones Temporal : 2 Bones Sphenoid : 1 Bone Ethmoia : 1 Bone

Facial region : 14 Bones Nasals : 2 Bones Vomer : 1 Bones Terbinal : 2 Bones Lacrymal : 2 Bones Zygomatic : 2 Bones Palaline : 2 Bones Maxilla : 2 Bones

Mandible : 1 Bones

Coccyx : Fusion of 4 caudal vertebrae Vertebral formula = 33 (General) C    TH     L         S

¯           ¯          ¯         ¯

7        12       5      5







In boy : 5 sacral vertebrae
In adult : Only one sacrum
RIBS in man : 12 pairs
True ribs : 7 pairs






False ribs : 3 pairs Floatting ribs : 2 pairs In adult = 26

C       TH      L       S          C

¯           ¯         ¯         ¯             ¯

7       12      5       1          1

Sacrum coccyx

Ear ossicles

Mallus : 2 Bones Incus : 2 Bones Stapes : 2 Bones

Hyoid : 1 Bone

Vertebral column : 26 Bones Sternum : 1 Bone Ribs : 24 Bone

Pectoral girdle : 4 Bones Pelvic girdle : 2 Bones

Fore limbs : 60 Bones (30 in each) Hind limbs : 60 Bones (30 in each)

Total : 206 Bones

In child : Bones 300


There are many articulations or joints present in the skeleton.

Joints are classified based upon their structure and the kinds of movements which they permit. Three main types of joints are –

  • Immovable joints (Synarthroses)
  • Imperfect movable joints (Amphiarthroses)
  • Perfect movable joints (Diarthroses)



















Fig. – Three main types of joints









  • Immovable joints : No joint cavity, no movement These joints include –
  • Sutures : Found between skull bones, sutures are fixed or fibrous joints, articulating bones are held together by white fibrous
  • Gomphoses : Teeth in mandibles, present in premaxillary and maxillary
  • Shindylases : Ethmoid bone in vomer (one bone fits into slit in another).
  • Imperfect joints : Joints in which syanovial cavity is absent. Permit a small amount of Fibrocartilage is placed between the bones. These are cartilaginous joints e.g. Pubis symphysis, between bodies of the vertebrae, between the manubrium and the body of sternum, sacroilliac joint in frog.




  • Perfect joints : Syanovial cavity and ligaments are present. These are typical joints having articulate surface and syanovial Syanovial fluid act as a grease in the joint e.g.

Joints of elbow, ankle, wrist, hip, knee. Articular cartilage covers the surface of articular bones. Articular cartilage of synovial joint is hyaline cartilage. Synovial joints are surrounded by tubular articular capsule. The articular capsule consists of two layers, outer fibrous capsule and inner synovial membrane. The synovial membrane secretes synovial fluid which lubricates and provides nourishment to articular cartilage. In old age stiffness of joints is due to the decrease in synovial fluid.

  • Ball and socket joint : Also known as Ball of one bone

articulate in socket of another bone. e.g.– head of humerus and glenoid cavity of pectoral girdle, femur and acetabulum of pelvis girdle, joint between incus and stapes.

  • Hinge joint : Also known as Movement is possible in one direction only. e.g. – Joint of mallus and incus knee joint, albow joint, articulation joint of lower jaw, joint of phalanges of digits.
  • Pivot joint : Also known as rotatoria and helps in turning One bone is fixed and second articulate. e.g. – Atlas and axial of skull rotate with axis vertebra also known as atlanto axial joint.
  • Gliding joint : Also known as arthrodial, limited movement in all direction. g.– Tarsuls bones of ankle zygapophysis of vertebrae. Radius and Ulna.
  • Shaddle joint : It is ball and socket like joint but not developed e.g. – metacarpal of thumb, and carpals of hand.





 Characters, adaptation, types, movement and disorder of bones

(i) Characteristics of female’s skeleton : In female’s skeleton, (i) skull is lighter, (ii) shoulders are narrower

  • sacrum is shorter but wider, (iv) pelvis in wider, has a broader front and larger bottom opening to facilitate child birth, and (v) coccyx is more movable than in male’s
    • Adaptations in skeleton for upright posture : Human skeleton shows many adaptive features for upright posture –
  • Foramen magnum is directed downward so that the head may rest vertically on the vertebral column.
  • Four curves in the backbone keep the centre of gravity near the This helps to maintain balance and makes walking erect on two legs much easier.
  • Thorax is wider from side-to-side than from front-to-back. This helps to maintain
  • Bowel-like pelvis supports the lower abdominal




  • Metacarpals form a wide palm and the pollex is This make the hand a grasping organ to work with it.
  • Leg bones are stronger than the arm bones as the femur carry the entire weight of the body in
  • Broad feet provide stability in the upright posture.
  • The arches of the feet enable the body to move with a degree of
  • Increased mobility of the neck to see all
  • Increased skeletal height provides greater range of
    • Types of bones : Bones are divided into 4 categories regarding their size and shape –
  • Long bones, g., humerus of upper arm, radius and ulna of forearm, femur of thigh, and tibia and fibula of leg.
  • Short bones, g., metacarpals of palm and metatarsals of instep, phalanges of fingers and toes.
  • Flat bones, g., scapula of shoulder girdle, sternum, cranial bodies.
  • Irregular bones, g., vertebrae, carpals of wrist and tarsals of ankle.
    • Bone movement : Movements of bones occur only at the The movements are brought about by contractions of skeletal muscles inserted onto the articulating bones by firm cords of white fibrous tissue called tendons. Cords of yellow elastic tissue, termed ligaments, stabilise the joints by holding the articulating bones together.
    • Disorder of skeleton and joints : Any violent movement, such as jump, fall or knock, may cause injury to the The injury can be of 5 types : sprain, dislocation, fracture, arthritis and slipped disc.
  • Sprain : Sprain refers to injury to a joint capsule, typically involving a stretching or tearing of tendons or Unfortunately, both these structures have much poorer regenerative power than bone, and once stretched often remain weak. Sprain is often considered a minor disorder, but it may become chronic.
  • Arthritis or Aching Joints : Arthritis refers to inflammation of the joints. It is a common disease of the old age. Its common symptoms are pain and stiffness in the joints. It has many forms. Three more common forms are described here : osteoarthritis or degenerative arthritis, the rheumatoid arthritis and
    • Osteoarthritis : Secretion of the lubricating synovial fluid between the bones at the joint stops. The smooth cartilage covering the ends of the bones at the joint The smooth cartilage covering the ends of the bones at the joint wears out due to years of use and is replaced by uneven bony spurs. The joint becomes inflamed, its movement becomes painful, and its function is diminished. Such a stiffness or fixation of a joint is also called ankylosis. The condition of osteoarthritis is more or less permanent. It is common in old persons, mainly affecting weight bearing joints.
    • Rheumatoid arthritis : It is a chronic painful inflammation of the synovial membranes of many joints It usually starts in the small joints in the hand and progresses in centripetal and symmetrical manner. In severe cases, it eventually results in crippling deformities. There may be other manifestations such as fever, anaemia, loss of weight and morning stiffness. The rheumatoid arthritis involves erosion of joints. It usually starts at the age of 20 – 40 years, but may begin at any age. It affects the women more often than the men. Rest and exercise under medical advice may give relief.




Differences between Osteoarthritis and Rheumatoid Arthritis


S.No. Osteoarthritis Rheumatoid Arthritis
1. Synovial membrane stops secreting synovial fluid. Synovial membrane becomes inflamed.
2. Mainly affects weight bearing joints. Usually starts at small joints in the hand and progresses centripetaly.
3. Smooth cartilage at the joints wears off and replaced by uneven bony spurs. Joints get eroded.
4. Function of the affected joint gets diminished. There is crippling deformity of the joints in volved.
5. Occurs in old age. Usually occurs at the age of 20-40.


  • Gout : It is an inherited disorder of purine metabolism, occurring especially in Body forms excess amounts of uric acid and the crystals of sodium urate are deposited in the synovial joints, giving rise to a severe arthritis. It generally affects one or two joints only. It is very painful, particularly at night, and makes movement difficult. Redness and tenderness may be noticed in and about the affected joint. Gout generally affects the great toe. Occurrence of gout is related to diet. Persons suffering from gout should avoid meat. There is no cure for arthritis. However, pain relieving (analgesic) drugs are available to give comfort.

(c)  Osteoporosis

Meaning : Osteoporosis is reduction in bone tissue mass causing weakness of skeletal strength (G.osteon = bone, poros = pore, osis = condition). It results from excessive resorption of calcium and phosphorous from the bone. There is relatively greater loss or trabecular bone than of compact bone. There is relatively greater loss of trabecular bone than of compact bone. This leads to vertical compression, or crush fracture, of the vertebrae (which consist primarily of trabecular bone), and fracture of the neck of the femur (which has considerable trabecular bone).

Causes : Osteoporosis occurs in postmenopausal women and elderly men. It may result from defective intestinal calcium absorption and menopause. Possible environment factors include smoking, excessive drinking, and decreased exercise. Osteoporosis is more common in women than in men, and in older than in middle-aged persons.

Symptoms : Symptoms of osteoporosis are pain in the bone, particularly the back, and vertebral crush, usually in weight-bearing vertebrae (thoracic-8 and below).

Prevention : Preventive measures in high-risk patients include supplementary calcium and exercise, and, in postmenopausal women, estrogen replacement therapy. Supplementary calcium and sex hormones decrease bone resorption and may arrest or reduce disease progression.

  • Dislocation : Dislocation is displacement of bones from their normal positions at a joint, for instance, slipping out of the ball of one bone from the socket of another bone into which it is Dislocation is accompanied by pulling or even tearing of the ligaments. Dislocation also tends to become chronic.
Fig. – Types of bone fracture
  • Slipped disc : Slipped disc is a displacement of vertebrae and the intervertebral fibrocartilage disc from their normal It may




result from mechanical injury or defects of ligaments holding the vertebrae together.

  • Fracture : Fracture is a break of a Fracture occurs rarely in children. The bones of children have a large quantity of organic matter and are, therefore, very flexible and less likely to break. With advancing age, mineral matter (calcium phosphate) is deposited in the bones. This decreases the organic matter, making the bones hard and brittle. Thus, old people are more liable to fracture of bones.

Bones fractures are of many types –

  • Green-stick fracture : It is mearly a The bones remains partly intact.
  • Simple fracture : Bone breaks completely into two parts which remain close to each
  • Comminuted fracture : Bone breaks into more than two
  • Compound fracture : Bone breaks completely but a fragment pierces out through the
  • Evulsive fracture : A small piece breaks off fully from the bone but remains attached to the ligament. Fractures need surgical treatment for healing and should be promptly and properly attended
  • Bursitis : Bursitis in inflammation of the bursae present in the joints. It is caused by physical injury or constant pressure on a single joint for a long

 Body muscles                                                                                                                                                        In the body of all the multicellular animals muscles are found. The movement of the body takes place by these muscles. If the muscles become weak, the functioning of the body become difficult. The muscles are capable of

contraction and relaxation, hence these are elastic.

A muscle can pull a part of the body by its contraction (shortening). It cannot push that part by relaxation (elongation). Hence, the muscles are typically arranged in antagonistic (opposing) pairs, one muscle moves a body part in one direction by its contraction and the other muscle moves that part in the opposite direction by its contraction. Of course, when one muscle contracts, its opposing muscle relaxes. The principle of antagonistic muscles is true of both vertebrate as well as invertebrate muscles. Animal movements depend upon interaction of muscles and skeleton.

  • Action of body muscles : As mentioned above, the body muscles are arranged in antagonistic (opposing) One muscle of a pair moves a body part in one direction and the other in the opposite direction. For example, the muscle named biceps brings the forearm toward the upper arm, and the muscle called the triceps moves the forearm away from the upper arm. When biceps contracts to cause movement, the triceps relaxes to allow that movement to occur and vice versa. Similar pairs of opposing flexor and extensor muscles occur at the wrist, ankle and knee. The type of movement that

results from the contraction of a muscle depends entirely upon the way the muscle is attached to the levers of the skeleton.

  • Classification of body muscles : According to the type of motion they cause, the muscles are




divided into the following types. The muscles that act together to produce a movement are called synergists and the muscle that act in opposition to each other are antagonists. The muscles that act most powerfully during any given movements are called prime movers.

  • Flexor and Extensor : Muscles that bend one part over another joint is called Extensor muscle is antagonist of flexor muscle. The contraction of an extensor extends a joint by pulling one of the articulating bone apart from another.
  • Pronator and Supinator : The contraction of a pronator rotates the forearm to turn the palm downward or backward. Supinator is antagonist of pronator. A supinator contracts to rotate the forearm and thus to make palm face upward or
  • Abductor and Adductor : An abductor contracts to draw a bone away from the body midline. Muscle that brings the limb away from midline is called abductor. An adductor draws a bone towards the body midline. Muscles that brings the limb towards midline is called adductor. Abductor muscle is antagonist of adductor Abduction is levation and adduction is depression.
  • Protactor and Retractor : Protactor muscle pulls the lower jaw, tongue and the head Retraction is opposite to protaction. Retractor muscle draws the lower jaw, tongue and the head backward.
  • Inversion and Eversion : Turning of feet so that the soles face one another in Eversion is the opposite of inversion. In this movement, the soles of the feet face laterally.
  • Rotation : Rotation is term that indicates the partial revolving of a body part on the part’s long axis.


  • Arrector : Raises hairs of
  • Levator : Elevates a part of
  • Depressor : Lowers a part of
  • Agonistic : Opposed in action by another
  • Antagonistic : Counteracts the action of another




  • Sphineter : Closes a natural orifice or
  • Constrictor : Causes constriction or

The adductor and abductor, elevator and depressor, pronator and supinator, and sphincters and dilators are all antagonistic muscles.

(iii) Important muscles

In man total no. of muscles : 639 muscles


Biceps and Triceps Fore arm
Gastroenemius Shank of leg
Gluteimaximus Buttock muscles
Oblique Eye muscles
Rectus Eye muscles
Maxillaries Upper jaw
Pectoralis Major Chest
Pectoralis Minor Chest
Mandibularis Muscle of lower jaw
Latissisus dorsi Shoulder muscle
External oblique Lower abdomen
Internal oblique Lower abdomen
Transversus Lower abdomen
Rectus abdominus Lower abdomen
Stepedial muscle / arrector pilli Smallest muscle

 Movement and Locomotion

Movement is one of the most important characteristics of living organisms. Nonliving objects do not move. If nonliving objects show movement, that is always due to some external force. For example, the cart is moved by the horse and the fan revolves by the energy of electric current. The movement of a nonliving object is, therefore induced (due to external force) while the movement of living things are autonomic (self sustained). Study of movement is called kinesiology (G. Kinein = to move, Logos = study). The movement of living systems are thus autonomic or active, that is effected by the organisms themselves without external influences. On the other hand the movement of nonliving systems are induced or passive, i.e. – made to occur by external forces. Movement of animals are two main types muscular and non muscular.

  • Muscular movement : Muscular movement are found in the majority of animals bought about by sliding of Muscular movement are further divide into two kinds : Locomotion and movement of body parts.
  • Locomotion (locus = place + moveo = to move) : Locomotion is the movement of an animal as a whole from one place to

Types of locomotion : Locomotion takes several forms such as walking (man), creeping (earthworm, lizard), hopping (frog, rabbit), running (dog, horse), flying (insects, birds) and swimming (fish, whale). Locomotion distinguishes most animals from plants. The word ‘most’ has been used with animals because all animals do not have the power of locomotion. Sponges, many coelenterates (Obelia) and tunicates (Herdmania) are sedentary, i.e., they live fixed to the substratum throughout life. However, even they show considerable movement of their body parts, and their larvae are capable of locomotion (swimming) to bring about dispersal.




Animals have suitable adaptations for their specific mode of locomotion. Adaptations for running, hopping, swimming and flying are respectively called cursorial, saltatorials, natatorial, and volant adaptations.

Morphogenetic movement, i.e., the streaming of cells in the early embryo to form tissues or organs, may be considered a form of locomotion.

Advantage of locomotion : Locomotion is helpful for animals as escape from predators, search of shelter, food and water, shift to favourable environment, reproduction, collect materials for nest building, locate suitable area for breeding and dispersal to new location. All forms of locomotion require energy to overcome two forces that tend to keep the animals stationary. These are friction and gravity.

  • Swimming : Water is a much denser medium than air so body modified for swimming in the form of buoyancy, fusiform body Mode of swimming varies in animals. fishes swim by moving their body and tail from side to side. Whales and dolphins swim by undulating their body and tail up and down. Insects and 4-legged vertebrates use their legs as oars to push against the water. Cuttle fish and squid are jet-propelled, taking in water and squirting it out in bursts.
  • Locomotion of land : For walking, running, hopping and crawling on land, animal expends energy body to prevent falling down and move forward against Powerful muscles and strong skeletal support are more important for moving on land than a streamlined body. Creeping animals have their entire body in contact with the ground,. Therefore, they make a considerable effort to overcome friction.
  • Flying : Gravity is a major problem in flight. Wings must produce enough lift to make and keep the animal air-borne against the downward force of
  • Movements of body parts : Movement of the body parts help the animals in several
    • Movement of external parts : Appendages are vary in number and form in different

Many annelids have several pairs of flat parapodia, arthropids have 3 to many pairs of jointed legs, mollusks have an unpaired foot, enhinoderms have numerous paired tube-feet, vertebrates have fins in fishes or limbs in all others.

Movements of head, trunk and appendages, enable the animals to assume favourable posture for rest and equilibrium. Movements of appendages, snout, mouth, jaws, tongue, etc., enable the animals to capture and ingest food. Movements of sense organs, namely tentacles, antennae, eyeballs and pinnae of the ears, help the animals to gather information about their external environment. Movements of buccopharyngeal cavity bring about water breathing in fishes and air breathing in amphibians, and movements of chestwall cause ventilation of lungs in other vertebrates. Movement of body parts also assist the animals in mating and feeding the young ones. Facial expression and gestures also result from movements. Vibrations of vocal cords produce sound in vertebrates, and of special abdominal plates in cicada. Rubbing the edges of forewings produces sound in grasshoppers.

  • Movements of internal parts : Visceral movements make many vital activities possible :
  • Heart beats circulate blood in the blood
  • Peristalsis of alimentary canal propels food through Segmenting and pendular movements of gut help mix digestive juices with food.
  • Movements of diaphragm assist the chest in the flow of air through the respiratory
  • Peristalsis propels secretions and wastes through the
  • Movements of genital tract effect egg laying and delivery of the
  • Visceral movements are also responsible for sound production, defaecation and




  • Non-Muscular movement : Besides locomotion and movements of body parts, some of the cells of multicellular animals move like unicellular
  • Ciliary movement : The cilia present in the trachea, vasa efferentia and oviducts propel by their movements dust particles, sperms and eggs The cilia of flame cells of flatworms push excretory materials.
  • Flagellar movement : The flagella of choanocytes (collar cells) of the sponges maintain a regular current of water in the The flagella of certain cells of gastrodermis of hydra help in the circulation of food. Sperms move by flagellar movements.
  • Pseudopodial movement : Leucocytes and macrophages move by pseudopodial
  • Cytoplasmic streaming movement : Streaming movement of the cytoplasm is called cyclosis. It is observed in most of the

(iii) Locomotion in different animals

  • Locomotion in Protozoa : Locomotion in protozoans by the help of cilia, flagella and
  • Locomotion in Porifera : Sponges are sedentary or fixed animals which are always attached to some Hence locomotion never takes place.
  • Locomotion in Coelentrates : Locomotion in coelentrates is largely due to the contraction of the epidermal muscle fibres following type of movements take place in coelentrates –

(i) Swimming              (ii) Floating              (iii) Surfacing              (iv) Climbing            (v) Walking

(vi) Gliding                  (vii) Somersaulting     (viii) Looping          (ix) Bending swaying movement.

  • Locomotion in Helminths : In helminths (platyelminthes and aschelminthes) locomotion takes place by body muscles, setae and buccal
  • Locomotion in Annelids : Leech, Earthworm and Nereis have well developed circular and longitudinal muscles in the body wall that help these animals to move about. The leech performs looking or crawling movement on a substratum and swimming movement in Parapodia and setae helpful for locomotion in nereis.
  • Locomotion in Arthropods : In arthropods locomotion takes place with the help of jointed legs, and a pair of wings. The arthropods which cannot fly move with the help of jointed legs. Insects are capable of flying because most of them possess a pair of wings in the thorax which help in Cockroaches, housefly etc., move from one place to another by legs (walking) as by wings (flight) both.
  • Locomotion in Mollusca : In all the molluscs, the locomotory organ is a thick walled, muscular, broad or laterally compressed foot. In some molluscs, the foot is modified into eight or ten arms (g., Sepia, Loligo, Ocotopus etc).
  • Locomotion in Echinodermata : In echinoderms such as starfish, the locomotory organs are tubefeet and locomotion takes place by water vascular The tubefeet are associated with this system intimately. At the time of locomotion, one or two arms of a side work as main structures.
  • Locomotion in vertebrates : In vertebrates, locomotion takes place with the help of skeletal muscles, and The locomotory organs are a pair of legs.

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