Skeleton — Movement and Locomotion - Questions & Answers

Fill in the blanks
(i) Our skeleton consists of bones, cartilages and ligaments.
(ii) Bone is the chief component of our skeleton.
(iii) Shapewise the bones can be classified as long, short, flat and irregular.
(iv) The central hollow part of the long bones is known as marrow.
(v) A bone becomes soft and flexible when placed in dilute hydrochloric acid.

Mention if the following statements are true (T) or false (F)
(i) Humerus of the upper arm is the longest bone.
Answer: False

(ii) Axial skeleton includes shoulder and hip girdles.
Answer: False

(iii) There are 10 vertebrae in the neck.
Answer: False

(iv) There are three kinds of ribs - true, false and floating.
Answer: True

(v) The shoulder girdle is large and trough-shaped.
Answer: False

1. Mention if the following statements are true (T) or false (F).
(i) The flexor and extensor muscles of the arm are antagonistic muscles.
Answer: True

(ii) Muscles can contract as well as elongate.
Answer: False

(iii) Muscles are attached to bones by ligaments.
Answer: False

(iv) Cardiac muscle is a voluntary muscle.
Answer: False

(v) Bending of arm on elbow is an example of first order of lever mechanism.
Answer: False

2. Match the bones (Column I) with the kind of joint (Column II)
(i) Humerus and shoulder girdle — (d) Ball and socket
(ii) Two adjacent vertebrae — (b) Gliding
(iii) Skull and upper end of the backbone — (e) Pivot
(iv) Bones of brain box — (c) Immovable
(v) Rib and breast bone — (a) Partially movable

1. Choose the correct answer from the options given below :
(i) Your external ear (pinna) is supported by :
(a) Bone (b) Cartilage (c) Tendon (d) Capsule
Answer: (b) Cartilage

(ii) The type of joint found at shoulder is also found at :
(a) Elbow (b) Knee (c) Ankle (d) Hip
Answer: (d) Hip

(iii) Which one of the following categories of vertebrae are correctly numbered :
(a) Cervical — 7 (b) Thoracic — 10 (c) Lumbar — 4 (d) Sacral — 4
Answer: (a) Cervical — 7

(iv) Human skeleton altogether contains 213 bones. Which of the following are exactly 6 in number?
(a) Neck vertebrae (b) Ear ossicles (c) Carpals (d) Metacarpals
Answer: (b) Ear ossicles

(v) Which of the following binds the bones together?
(a) Tendons (b) Cartilage (c) Ligaments (d) Muscles
Answer: (c) Ligaments

(vi) The inorganic constituents of bones are :
(a) Calcium and sodium (b) Calcium and phosphorus (c) Carbon and nitrogen (d) Calcium and carbon
Answer: (b) Calcium and phosphorus

(vii) Bone cells are technically termed as :
(a) Myocytes (b) Chondrocytes (c) Leucocytes (d) Osteocytes
Answer: (d) Osteocytes

(viii) The external surface of bone is covered by a membrane called :
(a) Peritonium (b) Pericardium (c) Periosteum (d) None of these
Answer: (c) Periosteum

(ix) Involuntary muscles are present in :
(a) Leg (b) Hand (c) Iris (d) Head
Answer: (c) Iris

(x) Given below are some features of cardiac muscles. Which of the following statements are incorrect?
P Cardiac muscles are voluntary.
Q They are capable of rapid movement continuously.
R These muscles are striped and branched.
S These muscles are found in heart, liver and lungs.
(a) P and Q (b) Q and R (c) R and S (d) S and P
Answer: (d) S and P

(xi) Ischium and Pubis are two specific bones of the girdles in the human body, belonging to (P) ............... and (Q) ............... girdles respectively.
(a) P — Pectoral, Q — Pelvic
(b) P — Pectoral, Q — Pectoral
(c) P — Pelvic, Q — Pelvic
(d) P — Pelvic, Q — Pectoral
Answer: (c) P — Pelvic, Q — Pelvic

(xii) Ravi's mother is suffering from osteoporosis. Her bones have become brittle and weak. The family doctor has advised her to take certain medicines and specific food items. Which of the following two options should be taken by her ?
P Food items rich in salts or sugars.
Q Food items rich in carbohydrates and fats.
R Food items rich in calcium and proteins.
S Vitamin D capsules.
(a) P and Q (b) Q and R (c) R and S (d) S and P
Answer: (c) R and S

1. Name the parts of the skeleton where the following are located :
transverse process, glenoid cavity, shoulder-blade, acetabulum.
Answer:
Transverse process: Vertebral column (Neural arches of vertebrae)
Glenoid cavity: Shoulder (Pectoral) girdle
Shoulder-blade: Shoulder (Pectoral) girdle
Acetabulum: Hip (Pelvic) girdle

2. Name any two parts of your body where the supporting skeleton is made of cartilage instead of bone.
Answer: External ears (pinna) and the tip of the nose.

3. Name :
(a) Three main constituents of the human skeleton
Answer: Bones, cartilages, and ligaments.

(b) Two main divisions of the human skeleton
Answer: Axial skeleton and Appendicular skeleton.

(c) Four parts of Axial skeleton
Answer: Skull, vertebral column, ribs, and sternum.

(d) Five regions of vertebral column
Answer: Cervical, Thoracic, Lumbar, Sacrum, and Coccyx.

(e) Four kinds of freely movable joints
Answer: Gliding joint, Pivot joint, Hinge joint, and Ball and socket joint.

4. Given below is the structure of the forelimb of humans. Read the information below the diagram and fill in the blanks :
The upper arm consists of a single long bone, called (a) humerus. Two long bones are found in the lower arm, (b) radius found on the side of the thumb and (c) ulna. Forelimbs have eight (d) carpals in the wrist and five (e) metacarpals in the palm. Remaining fourteen bones are found in the fingers as phalanges.

5. Name the following :
(a) A joint which allows movement in all directions.
Answer: Ball and socket joint.

(b) The first vertebra of the vertebral column.
Answer: Atlas.

(c) A large hole at the back of cranium through which the spinal cord emerges out.
Answer: Foramen magnum.

(d) The muscles which cause opposing movements.
Answer: Antagonistic muscles.

(e) The fluid found between the two bones of freely movable joints.
Answer: Synovial fluid.

6. The first pair indicates the kind of relationship that exists between the first two terms. Rewrite and complete the second pair on a similar basis :
(a) Humerus : Glenoid cavity :: Femur : ............
Answer: Acetabulum

(b) Thoracic vertebrae : 12 :: .................. : 7
Answer: Cervical vertebrae

(c) Wrist : Carpals :: Ankle : ............
Answer: Tarsals

(d) Biceps : Flexor :: Triceps : ............
Answer: Extensor

(e) Brain : Cranium :: Spinal cord : ............
Answer: Vertebral column

7. Write the technical terms for each of the following :
(a) Knee cap
Answer: Patella

(b) Shoulder blade
Answer: Scapula

(c) Collar bone
Answer: Clavicle

(d) Breast bone
Answer: Sternum

(e) Bones in the palm
Answer: Metacarpals

1. Define :
(a) Skeleton system
Answer: The skeleton system is the hard supporting framework of the body consisting of bones, cartilages, and ligaments that provides shape, support, protection, and enables movement.

(b) Bone marrow
Answer: The soft tissue filling the central hollow cavities of long bones. Yellow marrow stores fat, while red marrow produces red and white blood cells.

(c) Gristle
Answer: Also known as cartilage, it is a tough, flexible connective tissue forming a cushion between bones at joints and supporting structures like the external ears and tip of the nose.

(d) Pivot joint
Answer: A freely movable joint where one bone rotates over a pivot-like end of another bone, for example, the skull rotating on the upper end of the axis vertebra.

(e) Antagonistic muscles
Answer: A pair of muscles causing opposing movements at a joint, such that when one contracts, the other relaxes (e.g., biceps and triceps).

2. Do the muscles pull the structures, or push them ? Explain briefly.
Answer: Muscles only pull the structures. They are contractile tissues that can only contract (shorten) and relax; they cannot lengthen or push. Therefore, they work in antagonistic pairs to pull bones back and forth.

3. Just as the humerus corresponds to femur, what bones correspond to tarsals, metacarpals, ulna and radius respectively ?
Answer:
Tarsals correspond to Carpals.
Metacarpals correspond to Metatarsals.
Ulna corresponds to Fibula.
Radius corresponds to Tibia.

4. What are antagonistic muscles ? Give one example.
Answer: Muscles that cause opposing movements are called antagonistic muscles. For example, the biceps (flexor) muscle bends the arm, while the triceps (extensor) muscle straightens it.

5. Give reason :
(a) Decalcified bones become soft and flexible.
Answer: The inorganic mineral part (compounds of calcium and phosphorus) that gives the bone its hardness has been dissolved and removed, leaving only the soft organic framework.

(b) People in old age complain of stiff joints.
Answer: With age, the organic part of the bone is reduced, and the synovial fluid lubricating the joints may decrease, causing friction and making joints stiff.

(c) In the female skeleton, the pelvis or hip bone is wider and trough-shaped.
Answer: This adaptation is to accommodate the developing foetus in the uterus during pregnancy.

(d) Bones are considered to be a living tissue.
Answer: Because bones consist of living cells (osteocytes) embedded in a matrix, and they are richly supplied with blood vessels, allowing them to grow and repair themselves.

(e) Vertebral column is curved.
Answer: The curves help to maintain the balance of the body in an erect position and act like a spring to absorb pressure and shock while walking or running.

6. Write one specific location of the following in the human body.
(a) Femur
Answer: In the thigh (hind limb).

(b) Malleus, Incus, Stapes
Answer: In the middle ear (as ear ossicles).

(c) Coccyx
Answer: At the lowest end of the vertebral column.

(d) An immovable joint
Answer: Between the bones of the cranium (skull).

(e) Sternum
Answer: In the middle of the front part of the chest.

1. Distinguish between the following pairs :
(a) True ribs and floating ribs
Answer: True ribs (the first seven pairs) are attached directly in front to the sternum with the help of hyaline cartilage. Floating ribs (the last two pairs, 11th and 12th) are not attached to the sternum at all.

(b) Ligaments and tendons
Answer: Ligaments are fibrous connective tissues that bind bones to other bones at joints. Tendons are tough collagen structures that attach muscles to bones.

(c) Hinge joint and gliding joint
Answer: A hinge joint allows movement in only one plane like a door hinge (e.g., elbow, knee). A gliding joint allows bones to slide over one another to a limited extent (e.g., bones of the wrist and ankle).

(d) Voluntary and involuntary muscles
Answer: Voluntary muscles are under our conscious control (e.g., muscles of the limbs). Involuntary muscles work automatically and are not controlled by our will (e.g., muscles of the internal organs, iris).

(e) Bone and cartilage
Answer: Bone is a hard, rigid tissue made of both organic matter and inorganic mineral salts (calcium and phosphorus) forming the main skeleton. Cartilage is a tough but flexible connective tissue lacking heavy mineral deposits, found in joints, ears, and the nose tip.

2. What are the uses of the skeleton in our body?
Answer: The skeleton serves six main purposes:
1. Support and shape: It provides a framework to all soft parts and gives definite shape to the body.
2. Protection: It protects delicate internal organs (e.g., skull protects brain).
3. Movement: Bones function as levers pulled by muscles to aid locomotion.
4. Leverage: Bones and joints form levers that increase the speed and distance of movement.
5. Formation of blood cells: Bone marrow produces red and white blood cells.
6. Storehouse: It stores essential minerals like calcium and phosphorus.

3. Name the different types of joints ? Give one example of each type.
Answer: There are three major categories of joints:
1. Immovable joints: e.g., Joints between the bones of the cranium.
2. Partially movable joints: e.g., Joint between a rib and the breast-bone.
3. Freely movable (synovial) joints, which include four types:
   (a) Gliding joint: e.g., Bones of the wrist.
   (b) Pivot joint: e.g., Skull resting on the axis vertebra.
   (c) Hinge joint: e.g., Elbow joint.
   (d) Ball and socket joint: e.g., Shoulder joint.

4. Draw a neat diagram of the "Internal structure of a long bone" and label the following parts :
(a) Hyaline cartilage
(b) Fatty yellow bone marrow
(c) Ligament
(d) Spongy red bone marrow
(e) Compact dense bone
Answer: [Diagram Drawing Task: Not applicable for text representation, but the specified parts can be located as follows: (a) Hyaline cartilage covers the ends, (b) Fatty yellow marrow is in the central shaft cavity, (c) Ligaments attach at the outer bone ends, (d) Spongy bone with red marrow is located in the expanded knob-like ends, and (e) Compact dense bone forms the thick outer wall of the central shaft.]

1. The figure given alongside shows a kind of vertebra. Study the figure and answer the following questions :
(a) Name the vertebra.
Answer: Thoracic vertebra.

(b) Where is this vertebra located ?
Answer: In the upper back (chest / thorax) region of the vertebral column.

(c) Label the guidelines 1, 2 and 3.
Answer:
1 - Neural spine
2 - Transverse process
3 - Centrum (or body of vertebra)

2. Abhay observed the given figure of a typical 'movable joint' which allows a considerable degree of movement. This type of joint is located in some places in the human body.
(a) Write the specific name of the freely movable joint shown above.
Answer: Synovial joint.

(b) Mention two locations of this joint in the human body.
Answer: Knee joint and shoulder joint.

(c) Name the fibrous connective tissue which holds the bones in proper position and prevent their dislocation during normal movement.
Answer: Ligament.

3. Given below is a diagram of human skeleton. Name the bones numbered 1-11.
Answer:
1. Cranium (Skull)
2. Clavicle (Collar bone)
3. Scapula (Shoulder blade)
4. Humerus
5. Radius
6. Ulna
7. Femur
8. Patella (Knee-cap)
9. Tibia
10. Fibula
11. Tarsals

(Choose the answer based on the codes given below.)
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.

(i) Assertion (A) : Axial skeleton includes the limbs and girdles of the human body.
Reason (R) : Axial skeleton lies in the central axis of the human body.
Answer: (d) A is false but R is true.

(ii) Assertion (A) : Each hip bone is made up of three fused bones - ilium, ischium and pubis.
Reason (R) : Hip bone is technically termed as pelvis. It is wider and trough-shaped in females.
Answer: (b) Both A and R are true but R is not the correct explanation of A.

(iii) Assertion (A) : Synovial fluid provides lubrication to the bones and removes friction.
Reason (R) : Synovial joint is found between the bones of cranium. These joints contain synovial fluid between them.
Answer: (c) A is true but R is false.

(iv) Assertion (A) : Hinge joint occurs between the bones of the elbow. It provides movement in only one direction.
Reason (R) : Usually, hinge joints give sufficient power.
Answer: (b) Both A and R are true but R is not the correct explanation of A.

(v) Assertion (A) : Radius and ulna are the two long bones of the lower arm.
Reason (R) : Radius and ulna connect bones of the upper arm (i.e. the humerus) with the bones in the wrist.
Answer: (a) Both A and R are true and R is the correct explanation of A.

(vi) Assertion (A) : Sternum is a large bone formed by the fusion of five vertebrae. It is found between the lumbar vertebrae and coccyx.
Reason (R) : Sternum lies in the middle of the front part of the chest.
Answer: (d) A is false but R is true.

1. While helping her father bake, Neetu opened a jar by twisting its lid, noticing how her wrist allowed this circular movement. As she reached for the ingredients kept on the counter, her elbow bent only in one direction, unlike her wrist which rotated easily. Later when she sat on the floor, she crossed her legs noticing a smooth movement at her hip joint. Through these simple actions, Neetu realised she was using different kinds of joints.

(a) Name the organ system of the human body to which the different kinds of joints belong.
Answer: Skeletal system.

(b) Write two functions of the above mentioned system other than support and shape.
Answer: Protection of delicate internal organs and aiding in movement (locomotion).

(c) Name the kind of joints found at the elbow and the hip of humans.
Answer: Hinge joint at the elbow and Ball and socket joint at the hip.

(d) Mention one structure of the human body where bones are joined to each other but no movement is possible.
Answer: The Cranium (skull).

(e) What fluid is found between the two bones of freely movable joints ?
Answer: Synovial fluid.