Skeletal system - class-V

• The kind of tissue that forms the supportive structure in our pinna (external ears) is also found in tip of the nose. 
• As External pinna is made up of elastic cartilage. 
• It is passage towards middle ear. Hence, The supportive structure of our pinna is also found in the tip of the nose.

• The lower jaw is made up of a single bone called mandible.
  
• The mandible is the longest and strongest bone in the face. It forms the lower jaw and holds the teeth in place.
  
•  Movement of the lower jaw opens and closes the mouth and also allows for the chewing of food. The lower set of teeth in the mouth is rooted in the lower jaw.
• The mandibular joint is a joint made for power. It connects the lower jaw bone to the skull.
• So, the correct answer is 'Mandibular joint'.

• Joints are points of contact between bones, or between bones and cartilages.
  
• Synovial joints are characterized by the presence of a fluid-filled synovial cavity between the articulating surfaces of the two bones. These joints help in locomotion and many other movements.
• The synovial cavity is covered by the synovial membrane which secretes a watery fluid called synovial fluid for the lubricating and cushioning joint.
• So, the correct answer is 'Synovial membrane'.

Based on the movement ability, fibrous and cartilaginous joints are functionally classified as a synarthrosis or amphiarthrosis, the synovial joints are classified on the basis of shape.

Membranes are thin pliable layers of epithelial and/or connective tissue. They line body cavities, cover surfaces, connect, or separate regions, structures and organs of the body. 

According to functional classification joints may be immovable (synarthrosis), slightly movable (amphiarthrosis) and freely movable (diarthrosis). 

The movability of the joints varies depending on different factors. Joints have been classified into three major structural forms, namely, fibrous, cartilaginous and synovial. Synovial joints are characterised by the presence of a fluid-filled synovial cavity between the articulating surfaces of the two bones. Such an arrangement allows considerable movement. These joints help in locomotion and many other movements.

Gliding joint is a type of synovial joint, which allows movement of bone about three axes. Gliding joint is essentially flat circular surface and permits movement within narrow limits. Examples of gliding joint are between articular surfaces (zygapophyses) of vertebrae, acromioclavicular joint, some carpals and tarsal bones.

According to the structure, the joints can be classified into- fibrous, cartilaginous and synovial. 

Synovial joints are characterised by the presence of a fluid filled in synovial cavity, between the articulating surfaces of the two bones. Such an arrangement allows considerable movement by reducing friction between bones. These joints help in locomotion and many other movements. Ball and socket joint (between humerus and pectoral girdle), hinge joint (knee joint), pivot joint (between atlas and axis), gliding joint (between the carpals) and saddle joint (between carpal and metacarpal of thumb) are some examples.

Sutures, meaning to stitch, are immovable joint found between skull bones. 

Fibrous cartilage is the strongest kind of cartilage, because it has alternating layers of hyaline cartilage matrix and thick layers of dense collagen fibres oriented in the direction of functional stresses. This type of cartilage does not have a perichondrium as it is usually a transitional layer between hyaline cartilage and tendon or ligament. Thus, option B is correct.

Answer is option A i.e. "Cartilage"
Cartilage is a vertebrate skeletal connective tissue. It is an amorphous matrix and contains glycoproteins, basophilic chondroitin and fine collagen fibres.
Between tibia and femur, cartilage helps as shock absorber, it works to help the knee move smoothly. Cartilage helps in bone to bone ligation. Cartilage is a flexible connective tissue found in many parts of the body.

Answer is option A i.e. "Cartilagenous joint"
The joint between the first rib and the sternum is cartilaginous. It is also called as sternocostal joint. These joints allow a very small amount of movement.
The bones of fibrous joints are joined by fibrous tissue, e.g.  sutures in the skull or the pelvis.  Fibrous joints allow no movement at all.
The bones of synovial joints meet in a joint capsule, e.g. the knee joint where the femur and tibia meet. These joints are the most common and most moveable joints in the human body.

Freely movable joints are the most complex of the joints. Freely movable joints come in different shapes and allow different movements. Six types of freely movable joints exist. The ball-and-socket joint, of which the shoulder is an example, has a ball-shaped head and allows the widest range of motion. The elbow is a hinge joint and is able to move in only one plane etc. Therefore, (a) is the correct answer. 

A synovial joint joins bones with a fibrous joint capsule that is continuous with the periosteum of the joined bones, constitutes the outer boundary of a synovial cavity, and surrounds the bones' articulating surfaces. The synovial (or joint) cavity is filled with synovial fluid. They are the most common and most movable type of joint in the body of a mammal. 

An immovable joint is a place in the body where two bones are joined together but where little or no movement is normally possible and where no joint cavity exists. e.g. skull.

Walking and playing in fresh air keeps the body fit and healthy. One must also have a balanced diet and maintain a healthy body weight.

Ulna is produced into an oleander process, to articulate into olecranon fossa and tracheal of humerus by a hinge joint. 

Synovial fluid is present in perfect movable joints. The synovial membrane secretes synovial fluid which lubricates and provides nourishment to articular
cartilage.

A synarthrosis is a fixed joint between bones connected by fibrous tissue. A suture is a type of fibrous joint that is only found in the skull. The sutures between bones of the skull is an example of synarthrosis. So, the correct answer is 'Synarthrosis'. 

• Joints are points of contact between bones, or between bones and cartilages.
  
• A suture is a type of fibrous joint that is only found in the skull. Parietals are the bones present in the skull.
• Sutural joints are present between parietals (bones of the skull)of the skull.
• So, the correct answer is 'Parietals of the skull'.

• Joints are points of contact between bones, or between bones and cartilages.
  
• A suture is a type of fibrous joint that is only found in the skull. The skull bones are joined by the sutures.
• Parietal bone and temporal bone are skull bones.
• Hence parietal bone and temporal bone of skull are joined by fibrous joint.
• So, the correct answer is 'Parietal bone and temporal bone of skull are joined by fibrous joint'.

A suture is a type of fibrous joint that is only found in the skull. The bones are bound together by Sharpey's fibers. A tiny amount of movement is permitted at sutures, which contributes to the compliance and elasticity of the skull which is immovable.

The type of joint between the human skull bones is called 'fibrous joint'. So, the correct answer is (c).

Synovial joints are characterized by a fluid-filled cavity. Pivot, hinge, and ball-and-socket joints are all specific types of synovial joints.

Fibrous joints are connected by dense connective tissue consisting mainly of collagen, also called immovable joints.

A suture is a type of fibrous joint, which only occurs in the skull (or cranium). They are bound together by Sharpey's fibres. These joints are synarthroses. A small movement is permitted at sutures, which contributes to the compliance and elasticity of the skull.

The connective tissues which are found around joints are the ligaments and this help to stabilise the joint, maximise its strength and prevent any excess movement of the joints. The ligaments are attached to both sides of the bones and any tear or injury to the ligaments tends to make the joints unstable. So, the correct answer is option D.

The synovial membrane is the membrane that lines the articular surfaces of the bones of the synovial joint. Its secretes a watery fluid that lubricates and cushions the joint. It reduces the friction during movement.

• A skeleton is the hard structure that protects the internal organs of a living thing. 
• Skeletons can be inside the body or outside the body. 
• In mammals, which include humans, the skeleton is made of bones. 
• All the bones, when they are joined together, make the "skeletal system" of a body. Hence, the major constituent of the human body is a skeleton.

The endocrine glands in the body such as a pituitary gland, thymus, thyroid gland, parathyroid and etc secrete various hormones in the body. The bones cannot secrete hormones as they lack glands to produce and secrete hormones. It helps in protection of vital organs, haemopoiesis, and muscle attachment.

The obturator foramen is a large opening in the pelvis formed by the ischium and pubis bones, which is a characteristic feature of the mammalian skeleton, such as in the rabbit.

The skeleton is the structural framework of the body. Our skeleton system contains 206 bones. Its main function is to support muscles and tissues. It also protects the vital organs, allows movement of bones and muscles and serves as the storage house for immature blood cells and minerals.

Term innominate is used both in the context of a skeletal system and circulatory system. In the circulatory system, innominate is one of the branches of the aortic arch. The arch of the aorta, located immediately beyond the ascending aorta, gives off three large branches.
1. The brachiocephalic trunk is a short artery formerly called the innominate. Its name means that is supplies the head and the arm. After extending upward somewhat less than 5 cm (2 inches), it divides into the right subclavian artery, which supplies the right side of the head and the neck. 
2. The left common carotid artery extends upward from the highest part of the aortic arch. It supplies the left side of the neck and the head.
3. The left subclavian artery extends under the left collar bone (clavicle) and supplies the left upper extremity. This is the last branch of the aortic arch.
Innominate bone in anatomy refers to either of the two bones that form the sides of the pelvis, consisting of three fused components, the ilium, ischium, and pubis. The non-technical name is hip bone.

A snail uses its single long, muscular foot to crawl on a layer of mucus-like slime that it secretes. This mucus has unusual physical properties and scientists assumed that these sticky properties were essential for snail movement. 

• The skeleton is the site of haematopoiesis, the development of blood cells that takes place in the bone marrow. 
• In children, haematopoiesis occurs primarily in the marrow of the long bones such as the femur and tibia. 
• In adults, it occurs mainly in the pelvis, cranium, vertebrae, and sternum. Hence, the Skeleton is the site of Haematopoiesis.

Sesamoid bones develop in some tendons in locations where there is considerable friction, tension and physical stress. They are typically found in palm of hands and soles of feet. Therefore, (d) is the correct answer. 

1. Innominate is used to designate many parts otherwise unnamed.
   
2. Innominate artery is a great part of the arch of the aorta.
3. The innominate bone is the hip bone which is part of the skeleton system

There are usually 12 pairs of ribs in human body, first seven pairs of ribs are known as true ribs because these are attached to sternum.

Each hind limb contains 30 bones namely femur in thigh, patella inthe knee, tibia and fibula in the lower leg, 7 tarsals in the ankle, 5 meta-tarsals in the sole and 14 phalanges in toes.

• Hindlimb is composed of  Femur (thigh bone – the longest bone), tibia and fibula, tarsals (ankle bones – 7 in number), metatarsals (5 in number) and phalanges (digits – 14 in number).
  
• When a cricket player is chasing a ball it represents he is running. during running hind limbs assist motion hence muscles off hind limbs contribute to the motion.
  
• Hence when a cricket player is chasing a ball. the group of muscles which contribute to this movement are tarsals, femur, metatarsals, tibia.
• So, the correct answer is 'Tarsals, femur, metatarsals, tibia'.

• The osteon or Haversian system is the fundamental functional unit of much compact bone. 
• Osteons are roughly cylindrical structures. 
• Presence of the Haversian system is a typical character of mammalian bone. Panther is a mammal. Hence, bones of panther shall have a Haversian system.
  

A hinge joint is a common class of synovial joint that includes the ankle, elbow and knee joints. Hinge joints are formed between two or more bones where the bones can only move along one axis to fold or extend. The elbow is a more complex hinge joint that forms between the humerus of the upper arm and the ulna and radius of the forearm. So, the correct answer is 'Hinge'.

• The bones of the arm or forelimb are humerus, radius and ulna, carpals (wrist bones – 8 in number), metacarpals (palm bones – 5 in number) and phalanges (digits – 14 in number).
  
• Hence radius is bone of arm.
• So, the correct answer is 'Arm'.

• The bones of the hand (forelimb) are humerus, radius and ulna, carpals (wrist bones – 8 in number), metacarpals (palm bones – 5 in number) and phalanges (digits – 14 in number),
  
• The ulna is a long and curved bone.
  
• Proximally, the ulna articulates with the humerus at the elbow joint. Distally, the ulna articulates with the radius, forming the distal radio-ulnar joint.
• So, the correct answer is 'Long and curved bone'.

There are three bones of the hip bone that come together to form the acetabulum. Two-fifths of the structure is the ischium, which provides lower and side boundaries to the acetabulum. The ilium forms the upper boundary, providing a little less than two-fifths of the structure of the acetabulum. The rest is formed by the pubis, near the midline.

A synovial joint is a connection between two bones consisting of a cartilage lined cavity filled with fluid. Synovial joints are capable of the greatest movement. Knees, elbows and shoulders are examples of synovial joints. Since they allow for free movement, synovial joints are classified as diarthrosis. They allow for many types of movement including gliding, angular, rotational etc. So, the correct answer is 'Synovial joints'.

There are several examples of these joints in the human body, including joints between the bones of the skull, joints in the pelvis and joints between the teeth and the mandible, or lower jaw, and the maxilla, or upper jaw. Another name for immovable joins is a synarthrosis, which simply means immovable. The two types of immovable joints are fibrous joints and cartilaginous joints.

In the joint there is a fluid which acts as a llubricant. This fluid is called the synovial fluid.

The humerus is the long bone in the upper arm. It is located between the elbow joint and the shoulder.
So, the correct option is C.( Humerus )

Ribs serve to protect the lungs, heart, and other internal organs of the thorax. In some animals, especially snakes, ribs may provide support and protection for the entire body.

The skeleton serves a number of functions in vertebrates:

• The skull is composed of two parts: the cranium and the mandible.
•  In the human, cranium has two parts the neurocranium and the viscerocranium. 
• The neurocranium forms the cranial cavity that surrounds and protects the brain and brainstem. 
• The neurocranium consists of the occipital bone, two temporal bones, two parietal bones, the sphenoid, ethmoid, and frontal bones—all are joined together with sutures. Hence, The brain is protected by the Cranium.