Bones provide a definite shape to our body. Skeleton is the framework given to our body as a result of the fusion of bones. It is made up of bones, cartilage and joints. One way to know the shape of your bones is through X-ray images. Our hand is made up of small bones called carples.
Ribs are bent to form the chest bone. The chest bone and backbone together join to form the rib cage. The rib cage consists of 12 ribs on each side of the chest. It protects our internal organs such as the heart, lungs etc.
The rib cage is joined to the backbone.
It consists of 33 small bones called vertebrae.
Backbone helps our body stay erect andprovides posture.
Bones near the shoulder area are called shoulder bones and those present in the abdominal region are called pelvic bones, which encloses the portion of our body just below the stomach.
Skull is joined together by many bones and encloses our brain.
The additional part of the skeleton that can be bent is called the cartilage. Example: Ear lobe. They are also found in joints.
Muscles are the flesh on the bone. They bulge due to contraction and becomes shorter, thicker and stiffer. They work in pairs to move a bone. When one muscle contracts to pull a bone in a direction the other muscle relaxes. To move a bone in the opposite direction, relaxed muscle contracts to pull the bone towards the original direction while the first is in a relaxed position
The Human Skeleton
The skeleton is the framework formed by the bones of our body.
The skeleton of a normal adult human being is made up of bones.
Apart from bones, muscles, cartilage, ligaments, Tendons and joints also form a part of the Skeletal System.
Functions of the Skeleton
It forms the framework of our body, provides shape and support, and holds us upright.
It helps in the movement of various parts of our body.
It protects internal organs. The brain and heart and lungs are protected by the skull and ribs respectively.
Bones are filled with a spongy mass from inside called the bone marrow where blood cells are formed
Structure of the Skeleton
The skeleton comprises of four main parts-the skull, the backbone or spine, the rib cage and the limbs 1. SKULL
The skull is a bonystructure that forms the headin vertebrates. It supports the structures of the face and provides a protective cavity for the brain.The skull is composed of two parts: the cranium and the mandible. In humans, these two parts are theneurocraniumand the viscero cranium orfacial skeletonthat includes the mandible as its largestbone. The skull forms the anterior most portion of the skeleton and is a product of cephalisation —housing thebrain, and several sensor ystructures such as theeyes,ears,nose, andmouth. 2. RIB CAGE
The ribcage has three important functions: protection, support and respiration. It encloses and protects the heart and lungs. It provides a strong framework onto which the muscles of the shoulder girdle, chest, upper abdomen and back can attach. All ribs are attached in back to the thoracic vertebrae. 3. BACKBONE OR SPINE
The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord(a flexible rod of uniform composition) found in all chordates has been replaced by a segmented series of bone:vertebrae separated by intervertebral discs.The vertebral column houses the spinal canal, a cavity that encloses and protects thespinal cord.
4. LIMBS
a. FORELIMBS:
A limb, or extremity, is a jointed, or prehensile,appendage of the human or other animal body. In the human body, the upper and lower limbs are commonly called the arms and the legs, respectively. Arms and legs are connected totorso or trunk.
Humerus is the long bone in the upper arm.
The lower arm has two bones called radius and ulna.
The humerus is joined to the vertebral column by the collar bone and shoulder blade.
b. HINDLIMBS
The longest bone in our body is the thigh bone or the femur.
The lower leg consists of two bones- the tibia and the fibula.
The pelvis or hip bone is attached to the lower end of the backbone.
Facts on Human Skeleton
The Hyoid bone is the only bone that is not connected with any other bone
Ourteethform part of the skeletal system but are not counted in 206 bones.
There a just a few differences between human male and female skeletons. The female skeleton is generally slightly smaller and the pelvis bones differ in shape, size and angle in order to assist with child birth.
Joints
Our bodies contain six types of synovial joints. Synovial joints are the most movable type of joint found in the human body. Joints are formed wherebonescome together. The six types of synovial joints are the pivot, hinge, saddle, plane, and ball-and-socket joints
1. HINGE JOINT Hinge jointis abonejoint in which the articular surfaces are moulded to each other in such a manner as to permit motion only in one plane.
The direction which the distalbone takes in this motion is seldom in the same plane as that of the axis of the proximalbone; there is usually a certain amount of deviation from the straight-line duringflexion
2. Ball and socket joint
Ball and Socket joint is a type of Synovial joint such as the Hip and Shoulder joints. In this type of joint the bone has a smooth, ball-shaped head that fits onto a cup-like socket on the other end.
The ball and joint sockets contain a cup-like bone socket hat holds a rounded ball-shaped bone. It lubricates the ball and socket joint for easier movement. There are six types of freely moveable Dierthrosis (synovial) joint.
A natural or manufactured joint or couplent such as the hip joint, in which a partially spherical end lies in a socket, allowing multidirectional movement and direction.
3. PIVOT JOINT
Pivot joint is also known as rotary joint or trochid joint ,in vertebrae anatomy ,a freely movable joint that allows only rotary movement around the single axis .
Pivot joint also provide for the twisting movement of the bones forearm (radius and Ulna) against the upper arm, a movement used for instance in unscrewing the lid of a jar.
4. GLIDING JOINTS
These joints allow the bones to glide past one another in any direction along the plane of the joint.
A gliding joint, also known as a planar joint, is a common type of synovial joint formed between bones that meet at flat or nearly flat articuar surfaces.
5. FIXED JOINTS
Fixed joints are fibrous joints that do not move.
These joints are connected by dense connective tissue, consisting mainly of collagen.
Eg: joints of cranial bones
Muscles
Muscles move body parts by contracting and then relaxing. Muscles can pull bones, but they can’t push them back to the original position. So they work in pairs of flexors and extensors. The flexor contracts to bend a limb at a joint.when the movement is completed, the flexor relaxes and the extensor contracts to extend or straighten the limb at the same joint.
X-Rays
X-rays are a type of radiation called electromagnetic waves. X-ray imaging creates pictures of inside of our body. The images show the parts of our body in different shades of black and white. This is because different tissues absorb different amounts of radiation.
Movement
Movement is when the living organism moves a body part or parts to bring a change in the position with respect to its surroundings
The muscular system is responsible for themovementin animals. In plants the movements are shown by their parts in the form of growth.
Locomotion
Locomotion is directional movement that enables someone or something to move from one location to another include.
Locomotion is the ability of an organism to move. Walking, running, swimming, jumping are the different types oflocomotion.
Movement in Snail
The snail’s foot is highly muscular and adapted for travelling over hard surfaces.
It has a large flat foot which remains attached to the surfaces over which it is crawling .
Snails and slugs use waves of muscular contractions to move.
Land snails moveby gliding along on their muscular foot, which is lubricated with mucus and covered with epithelial cilia.
The motion of sea snails involves making ripping motion and leaving behind mucus that cover the area in which the snail is moving along.
Movement in Earthworm
The earthworm has an elongated body with no bones or limbs.
Its body has many ring-like segments that have muscles which helps it to move from one place to another. These muscles repeatedly expand and contract, providing a push that helps the body to move forward.
It also has special bristle like structures called setae on the underside of its body which is used to grip the ground. It helps anchor the portion of the earthworms body in the state of longitudinal contraction.
This helps drag the rest of the body ahead.
Movement in Cockroach
Cockroaches possess various type oflocomotion they can walk, climb, fly.
The body is divided into three parts—head, thorax, and abdomen.
3 pair of legs are present in thoracic part which moves by the muscles present near its limbs (legs).
The body is covered with the outer hard exoskeleton.
Movement in Fish
Fish locomotionis the variety of types of animal locomotion used byfish, principally by swimming.
This however is achieved in different groups of fish by a variety of mechanisms of propulsion inwater, most often by wavelike movements of the fish's body and tail, and in various specialised fish by movements of the fins.
Fish swim by flexing their bodies and tail back and forth.
Fish stretch or expand their muscles on one side of theirbody, while relaxing the muscles on the other side. This motion moves them forward through the water.
Fish use their back fin, called the caudal fin, to help push them through the water.
Movement in Birds
Birds fly in the air and walk on the ground. Some birds like ducks and swans can swim in water.
Modification for flying:
Their bones are hollow and light
The bones of the hind limbs are typical for walking and perching.
Bony parts of the forelimbs are modified as wings.
Thebirdshave a spindle-shaped body or streamlined body to offer less air resistance duringflight
The shoulder bones are strong.
The breastbones are modified to hold muscles of flight which are used to move the wings up and down
Movement in Snake
Snakes have a long backbone. They have many thin muscles. They are connected to each other even though they are far from one another. Muscles also interconnect the backbone, ribs and skin
Snakes movein S-shaped loops and in a zigzag manner. Each loop of the snake gives it a forward push by pressing against the ground. Since its long body makes many loops and each loop gives it this push, the snake moves forward very fast and not in a straight line.
Snakes do not have legs for movement but use their long backbone along with muscles for movement.
Their body curves into many loops, which gives it a forward push by pressing against the ground.
