NEET Bio Unit2
LOCOMOTION AND
ITS MOVEMENT
DEFINITION AND INTRODUCTION
The hard protective or supportive part of the animal constitute skeletal system.
Study of skeleton is called Osteology or Skeletology.
Skeleton of different design are needed for the aquatic or terrestrial animals.
TYPES OF BONES (ON BASIS OF SHAPE AND SIZE)
(i) Long bones
e.g. Humerus, Radius, Ulna, Tibia fibula, Femur.
(ii) Short bones
e.g. Carpals and tarsals.
(iii) Flat bones
e.g. Skull bone, sternum and ribs.
(iv) Irregular bones
e.g. Ear ossicles and vertebrae.
(v) Sesamoid bones
e.g. Patella (knee cap)., pissiform
(i) A small sesamoid bone Fabella often develops in the tendon of lateral haed of gastromenius muscles
behind the knee joint.
(ii) In frog tibiofibula is the longest bone.
(iii) Bones formed by ossification in cartilages is called replacing bone e.g. Humerus, femur.
(cartilagenous bones)
(iv) The bones of a children have large amount of organic matter, so, their bones are very flexible and
less likely to break. (hence they may undergo green stick fracture)
(v) Bones formed by ossification in the dermis and sink to get attached over the cartilages. e.g. Frontals
and parietals is called investing bone of the skull.(Dermal bones or membranous bones)
(vi) Skull of reptiles and birds possess one occipital condyles so the skull is called monocondylic, skull
of amphibians and mammals possess two occipital condyles, so the skull is called dicondylic.
(vii) Os penis : A bone supporting the penis of bats is called os penis.
(viii)Os cordis : A bone supporting the heart of cattle is called oscordis.
(ix) The end of two bones are connected by ligaments. While a muscle atlaches with bone through
tendon.
(x) Procoelous - Centrum concave anteriorly but convex posteriorly 2nd to 7th vertebrae of frog. All
reptilian vertebrae are procoelous.
Amphicoelous - Centrum concave on both sides. 8th vertebrae of frog is amphicoelous.
Acoelous - Centrum remain flat. 9th vertebra of frog is acoelous.
Heterocoelous - Centrum partly convex and partly concave on both sides.
Vertebrae of birds are heterocoelous.
Coeloplatyn vertebrae - Centrum concave anteriorly but flat posteriorly.
Platycoelous vertebrae - Centrum flat anteriorly but concave posteriorly.
(xi) Bones formed by ossification in the tendons at the joint is called sesamoid bones e.g. Patella.
(xii)In Avian skull sutures remains absent.
(xiii)Weberian ossicles - These are modified in vertebrae in cat and fishes. These help in sound
production by connecting air bladder and internal ear.
(xiv)Like mammals amphibian skull is also dicondylic.
Skull of reptiles and aves are monocondylic.
(xv) The pelvic girdle of birds is attached to a complex structure formed by the fusion of last thoracic all lumbar and first five caudal vertebra this structure is called synsacrum.
(xvi)Talus in Rabbit is called as Astragalus.
Tips
Human endoskeleton is made up of 206 bones. It is grouped into two parts -
Appendicular skeleton - 126 bones.
Axial Skeleton - 80 bones.
Axial Skeleton
It consist skull, vertebral column, sternum and ribs.
Skull is composed of cranial and facial bones. Total - 22 bones
Cranial bones are 8 in number. Frontal(l), parietal(2), occipital(l), temporal(2), sphenoid(l), ethmoid(l).
Facial bones are 14 in number. Mandible(l), maxilla(2), palatine(2), nasal, vomer(l), inferior turbinals(2),
zygomatic(2), lacrimal bones(2).
Each middle ear contains three tiny bones malleus, incus and stapes, collectively called ear ossicles.
Hyoid bone:- A single U-shaped bone which is present at the base of the buccal cavity.
Vertebral column:- Formed by 26 serially arranged vertebrae. Cervical (7) Thoracic (12) Lumber (5) Sacral (1 fused),
coccygeal (1 fused)
The number of cervical vertebrae are seven in almost all mammals including human beings.
First vertebra is the atlas and it articulates with the occipital condyles of skull.
Sternum:- A flat bone on the midventral line of thorax.
Ribs - 12 pairs
Ist 7 pairs - True ribs (vertebra-sternal ribs)
8, 9, 10th pairs - vertebro-chondral ribs.
11, 12th pairs - vertebral ribs (floating ribs)
Each rib is a thin flat bone. It has two articulation surfaces on its dorsal end and is hence called bicephalic.
Thoracic vertebrae, ribs and sternum together form the rib cage.
Appendicular Skeleton
The bones of limbs along with their girdles.
Fore Limb - 30 bones. Humerus, radius, ulna, carpals (wrist bones-8) metacarpals (palm-5) phalanges (digits-14)
Hind Limb - 30 bones. Femur, Patella, Tibia, Fibula, Tarsals (Ankle-7), metatarsals (sole-5), Phalanges (digits-14)
Femur is the longest bone of body .
Pectoral girdle - Each half is made up of a clavicle (collar bone) and a scapula bones.
Glenoid cavity is a depression in the scapula bone in which the head of the humerus bone articulate and form the
shoulder joint.
Pelvic girdle - It consists of two coxal bones.
Each coxal bone is formed by fusion of ilium, ischium and pubis. At the point of fusion of the above bones
acetabulum cavity is present in which head of femur articulates. The two halves of the pelvic girdle meet ventrally
to form the pubic symphysis containing fibrous cartilage.
1. JOINTS
1. Fibrous joint - Do not allow any movement e.g.: Sutures (between skull bones)
2. Cartilaginous Joint - The bones involved are joined together with the help of cartilage e.g.: Intervertebral
disc, pubic symphysis.
3. Synovial joint - Characterised by the presence of a fluid filled synovial cavity between the articulating
surface of two bones. e.g.: Ball and Socket, Hinge, Pivot, Gliding, Saddle joints.
Ball and socket joint (between Humerus and Pectorial girdle)
Hinge Joint (Knee Joint, Elbow Joint)
Pivot Joint (between atlas and axis)
Gliding Joint (between the carpals, between the adjacent vertebrae)
Saddle Joint (between carpal and metacarpal of thumb)
QUICK LINKS:
http://www.textbooksonline.tn.nic.in
ammakalviyagam.in
TYPES OF BONES (ON BASIS OF SHAPE AND SIZE)
(i) Long bones
e.g. Humerus, Radius, Ulna, Tibia fibula, Femur.
(ii) Short bones
e.g. Carpals and tarsals.
(iii) Flat bones
e.g. Skull bone, sternum and ribs.
(iv) Irregular bones
e.g. Ear ossicles and vertebrae.
(v) Sesamoid bones
e.g. Patella (knee cap)., pissiform
(i) A small sesamoid bone Fabella often develops in the tendon of lateral haed of gastromenius muscles
behind the knee joint.
(ii) In frog tibiofibula is the longest bone.
(iii) Bones formed by ossification in cartilages is called replacing bone e.g. Humerus, femur.
(cartilagenous bones)
(iv) The bones of a children have large amount of organic matter, so, their bones are very flexible and
less likely to break. (hence they may undergo green stick fracture)
(v) Bones formed by ossification in the dermis and sink to get attached over the cartilages. e.g. Frontals
and parietals is called investing bone of the skull.(Dermal bones or membranous bones)
(vi) Skull of reptiles and birds possess one occipital condyles so the skull is called monocondylic, skull
of amphibians and mammals possess two occipital condyles, so the skull is called dicondylic.
(vii) Os penis : A bone supporting the penis of bats is called os penis.
(viii)Os cordis : A bone supporting the heart of cattle is called oscordis.
(ix) The end of two bones are connected by ligaments. While a muscle atlaches with bone through
tendon.
(x) Procoelous - Centrum concave anteriorly but convex posteriorly 2nd to 7th vertebrae of frog. All
reptilian vertebrae are procoelous.
Amphicoelous - Centrum concave on both sides. 8th vertebrae of frog is amphicoelous.
Acoelous - Centrum remain flat. 9th vertebra of frog is acoelous.
Heterocoelous - Centrum partly convex and partly concave on both sides.
Vertebrae of birds are heterocoelous.
Coeloplatyn vertebrae - Centrum concave anteriorly but flat posteriorly.
Platycoelous vertebrae - Centrum flat anteriorly but concave posteriorly.
(xi) Bones formed by ossification in the tendons at the joint is called sesamoid bones e.g. Patella.
(xii)In Avian skull sutures remains absent.
(xiii)Weberian ossicles - These are modified in vertebrae in cat and fishes. These help in sound
production by connecting air bladder and internal ear.
(xiv)Like mammals amphibian skull is also dicondylic.
Skull of reptiles and aves are monocondylic.
(xv) The pelvic girdle of birds is attached to a complex structure formed by the fusion of last thoracic all lumbar and first five caudal vertebra this structure is called synsacrum.
(xvi)Talus in Rabbit is called as Astragalus.
Tips
Human endoskeleton is made up of 206 bones. It is grouped into two parts -
Appendicular skeleton - 126 bones.
Axial Skeleton - 80 bones.
Axial Skeleton
It consist skull, vertebral column, sternum and ribs.
Skull is composed of cranial and facial bones. Total - 22 bones
Cranial bones are 8 in number. Frontal(l), parietal(2), occipital(l), temporal(2), sphenoid(l), ethmoid(l).
Facial bones are 14 in number. Mandible(l), maxilla(2), palatine(2), nasal, vomer(l), inferior turbinals(2),
zygomatic(2), lacrimal bones(2).
Each middle ear contains three tiny bones malleus, incus and stapes, collectively called ear ossicles.
Hyoid bone:- A single U-shaped bone which is present at the base of the buccal cavity.
Vertebral column:- Formed by 26 serially arranged vertebrae. Cervical (7) Thoracic (12) Lumber (5) Sacral (1 fused),
coccygeal (1 fused)
The number of cervical vertebrae are seven in almost all mammals including human beings.
First vertebra is the atlas and it articulates with the occipital condyles of skull.
Sternum:- A flat bone on the midventral line of thorax.
Ribs - 12 pairs
Ist 7 pairs - True ribs (vertebra-sternal ribs)
8, 9, 10th pairs - vertebro-chondral ribs.
11, 12th pairs - vertebral ribs (floating ribs)
Each rib is a thin flat bone. It has two articulation surfaces on its dorsal end and is hence called bicephalic.
Thoracic vertebrae, ribs and sternum together form the rib cage.
Appendicular Skeleton
The bones of limbs along with their girdles.
Fore Limb - 30 bones. Humerus, radius, ulna, carpals (wrist bones-8) metacarpals (palm-5) phalanges (digits-14)
Hind Limb - 30 bones. Femur, Patella, Tibia, Fibula, Tarsals (Ankle-7), metatarsals (sole-5), Phalanges (digits-14)
Femur is the longest bone of body .
Pectoral girdle - Each half is made up of a clavicle (collar bone) and a scapula bones.
Glenoid cavity is a depression in the scapula bone in which the head of the humerus bone articulate and form the
shoulder joint.
Pelvic girdle - It consists of two coxal bones.
Each coxal bone is formed by fusion of ilium, ischium and pubis. At the point of fusion of the above bones
acetabulum cavity is present in which head of femur articulates. The two halves of the pelvic girdle meet ventrally
to form the pubic symphysis containing fibrous cartilage.
1. JOINTS
1. Fibrous joint - Do not allow any movement e.g.: Sutures (between skull bones)
2. Cartilaginous Joint - The bones involved are joined together with the help of cartilage e.g.: Intervertebral
disc, pubic symphysis.
3. Synovial joint - Characterised by the presence of a fluid filled synovial cavity between the articulating
surface of two bones. e.g.: Ball and Socket, Hinge, Pivot, Gliding, Saddle joints.
Ball and socket joint (between Humerus and Pectorial girdle)
Hinge Joint (Knee Joint, Elbow Joint)
Pivot Joint (between atlas and axis)
Gliding Joint (between the carpals, between the adjacent vertebrae)
Saddle Joint (between carpal and metacarpal of thumb)
QUICK LINKS:
http://www.textbooksonline.tn.nic.in
ammakalviyagam.in
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