SKELETON AND MOVEMENTS

SKELETON AND MOVEMENTS

Locomotion: The change in locus of whole body or movement of a living organism from      one place to another place is called locomotion.

 

Amoeboid movement: The type of locomotion  performed by pseudopodia e.g. leucocytes

 

Ciliary movement: The type of locomotion performed by cilia e.g. ciliated epithelium. In Paramecium, cilia help in the passage of food through cytopharynx.

 

Whorling movement: The type of locomotion performed by flagella e.g. Sperms.

 

Muscular movement: The type of locomotion performed by muscles, with the help of bones and joints.

 

Skeletal muscles: The muscles which are attached to the bones by tendons and help in the movement of the parts of the skeleton are called skeletal muscle.

 

Agonists muscles: the muscles which bring about the initial movement of the body part is called agonists muscle.

 

Antagonistic muscles: Muscles working in pairs and brings about opposite action are called antagonistic muscles. e.g. Biceps (flexors) bring flexion (folding) and triceps (extensors) bring an extension of the elbow joint.

 

Synergists muscle : The muscle which assists prime mover is called synergists muscle.

 

 

Flexor muscle: Flexor muscle on contraction results in bending or flexion of a joint e.g. Biceps.

 

Extensor muscle: Extensor on contraction results in straightening or extension of a joint e.g. Triceps.

Abductor muscle: Muscle moves body part away from the body axis e.g. Deltoid muscle of the shoulder moves the arm away from the body.

 

Adductor muscle: Muscle moves body part towards the body axis e.g. Latissimus dorsi of shoulder moves the arm near to the body.

 

Pronator: They turns the palm downward.

 

Supinator: They turn the palm upward.

 

Levator: They raises a body part.

 

Depressor: They  lowers the body part

 

Sphincters: They are Circular muscles present in the inner wall of anus, stomach, etc. for closure and opening.

 

Sarcomere: The contractile unit of muscles are called sarcomere which contains contractile proteins actin and myosin.

 

F-Actin: It is a double-stranded protein form the backbone of the actin filament. Each strand is composed of polymerized G    actin molecules.

 

Tropomyosin : The actin filament contains two additional protein strands that are polymers of tropomyosin molecules are called tropomyosin.

 

Troponin: It is a complex of three globular proteins, which are attached         approximately 2/3rd distance along each tropomyosin molecule. It has an affinity for actin, tropomyosin and calcium ions.

 

Oxygen debt: A temporary shortage of oxygen in the body tissue due to strenuous exercise is called oxygen debt.

 

Rigour Mortis: The stiffening of muscles after the few hours of the death of an individual is called Rigour Mortis. It helps in fixation of hours of death after the murder.

 

Lever: A simple type of machine having a load, fulcrum and effort is called a lever.

 

Class I lever:  A type of lever which has the fulcrum in between the load and the effort applied. The joint between the first vertebra and occipital condyle of the skull is an example of a first-class lever.

 

Class II lever: A type of lever which has the fulcrum at one end and effort at the other and load is present in between. Human body raised on toes is an example of a second class lever.

 

Class III lever: A type of lever which has the fulcrum at one end and load at the other and effort applied present in between. Flexion of the forearm at elbow exhibit lever of class III. Elbow joint acts as fulcrum and Radius and ulna provides resistance. Contracting biceps muscle provides a force for the movement.

 

Axial skeleton: The skeleton which is present along the central axis of the body is called axial skeleton.

 

Appendicular skeleton: The bones of the fore limb, hind limb, and girdles together form the appendicular skeleton.

 

Single muscle twitch: A muscle contraction initiated by a single brief-stimulation is called a single muscle twitch. It occurs in 3 stages :  A latent     period of no contraction, a contraction period and a relaxation period.

 

Summation / Staircase phenomenon: If the muscle is stimulated before the end of the twitch, it generates greater tension i.e., summation or addition of effect takes place. Repeated stimuli will produce increasing    strength of contraction (staircase phenomenon).

 

Tetanus: If stimulation is very rapid and frequent the muscle does not have time to relax. It remains in a state of contraction called tetanus.

 

Refractory  Period: Immediately after one stimulus, the muscle fibre cannot respond to another stimulus. This resting or refractory period is about 0.02 seconds and is called the refractory period.

 

Threshold Stimulus: A minimum strength or intensity of a stimulus is required for the contraction of muscle fibre is called threshold stimulus.

 

Gorilla‘s Rib: Approximately 8 % of humans have an extra pair of ribs attached to the lumbar vertebra. Such a rib is found in some types of gorillas. Hence 13th pair of rib in human is called gorilla rib.

 

Arthrosis : The point, where two or more bones get articulated, is called joint or articulation or arthrosis.

 

Arthrology: Study of joints are called arthrology.

 

 Suture joint : A suture is a type of fibrous joint that is only found in the skull. 

 

Coronal suture : Suture which joins frontal bone with parietal bone is called a coronal suture.

 

Sagittal suture : Suture which joins two parietal bone together is called saggial suture.

 

Lambdiodal suture : Suture which joins two parietal bone with occipital bone is called lambdiodal suture.

 

Lateral suture : Suture which joins parietal bone with temporal bone on the lateral side is called lateral suture.

 

Synarthroses : In this joint, the articulating bones are held together by means of fibrous connective tissue. These bones do not exhibit movement. Hence it is an immovable or fixed type of joint.

 

Syndesmoses: A syndesmosis is a slightly movable fibrous joint in which bones such as the tibia and fibula are joined together by connective tissue. e.g. Distal tibiofibular ligament, interosseous membrane between tibia and fibula and that between radius and ulna.

 

Amphiarthroses / Cartilagenous  / slightly movable joints: These joints are neither fixed nor freely movable. Articulating bones are held together by hyaline or fibrocartilages.

 

Synchondroses : The two bones are held together by hyaline cartilage. They are meant for growth. On completion of growth, the joint gets ossified. Example: Epiphyseal plate found between epiphysis    and diaphysis of a long bone, Rib – Sternum junction

 

Symphysis : In this type of joint, broad flat disc of fibrocartilage connects two bones.

         These occur in midline of the body. E.g. intervertebral discs.

 

Diarthroses /  Synovial joints or freely movable joints: It is characterized by the presence of a space called synovial cavity between articulating bones that brings about free movement at the joint.

 

Pivot joint: In this, the rounded or pointed surface of one bone       articulates with a ring formed partly by another bone and partly by a ligament. Rotation only around its own longitudinal axis is possible. Example : In joint between atlas         and axis vertebrae, head turns sideways to form ‘NO’ joint.

 

Ball and socket joint: Ball like the surface of one bone fits into the cup-like depression of another bone forming a freely movable joint called ball and socket joint. This type of joint allows movements along all three axes and in all directions. Example: Shoulder and hip joint.

 

Hinge joint: In a hinge joint, convex surface of one bone fits into the concave       surface of another bone. In most hinge joints one bone remains stationery and other moves. E.g. Elbow and knee joint.

 

Saddle joint: Here, the articular surface of one bone is saddle-shaped and that of other bone fits into such saddle as a sitting rider would sit.   i.e. each bone has both concave and convex areas. Eg. Carpometacarpellar joint between trapezium carpal and metacarpal of thumb.

 

Condyloid joint: It is an ellipsoid joint. The convex oval-shaped projection of one bone fits into an oval-shaped depression in another bone. It is a biaxial joint because it permits movement along two axes eg. Metacarpophalangeal joint.

 

Gliding joint: A planar joint, where articulating surfaces of bones are flat or slightly curved. These joints are non-axial because motion they allow does not occur along an axis or a plane. Example : Intercarpal and intertarsal joints.

 

Osteoarthritis : It occurs when the joint cartilage degenerates.

 

Muscular dystrophy: It is a group of diseases that cause progressive weakness and loss of muscle mass. These are genetically inherited in families.

 

Myasthenia gravis: It is caused by an abnormality at the neuromuscular junction that partially blocks contraction. It is an autoimmune disorder caused by an excess of certain antibodies in the bloodstream.

 

Rheumatoid arthritis: It is an autoimmune disorder where the body’s immune system attacks its own tissues. In rheumatoid arthritis, synovial membrane swells up and starts secreting extra synovial fluid. This fluid exerts pressure on the joint and makes it painful.