Skeleton - Movement and Locomotion

Fill in the blanks

1. Our skeleton consists of bones, ............... and ...............
2. ............... is the chief component of our skeleton.
3. Shapewise the bones can be classified as ............... , ............... , ............... and ............... .
4. The central hollow part of the long bones is known as ............... .
5. A bone becomes soft and flexible when placed in dilute ............... .

Answer

1. Our skeleton consists of bones, cartilages and ligaments
2. Bone is the chief component of our skeleton.
3. Shapewise the bones can be classified as long, short, flat and irregular .
4. The central hollow part of the long bones is known as bone marrow .
5. A bone becomes soft and flexible when placed in dilute hydrochloric acid .

Mention if the following statements are true (T) or false (F)

1. Humerus of the upper arm is the longest bone.
2. Axial skeleton includes shoulder and hip girdles.
3. There are 10 vertebrae in the neck.
4. There are three kinds of ribs - true, false and floating.
5. The shoulder girdle is large and trough-shaped.

Answer

1. False
   Corrected statement — Femur in the thigh is the longest and strongest bone in the body.
2. False
   Corrected statement — Axial skeleton includes skull, vertebral column, ribs and sternum.
3. False
   Corrected statement — There are 7 vertebrae in the neck.
4. True
5. False
   Corrected statement — The shoulder girdle is flat and triangular.

Mention if the following statements are true (T) or false (F).

1. The flexor and extensor muscles of the arm are antagonistic muscles.
2. Muscles can contract as well as elongate.
3. Muscles are attached to bones by ligaments.
4. Cardiac muscle is a voluntary muscle.
5. Bending of arm on elbow is an example of first order of lever mechanism.

Answer

1. True
2. False
   Corrected statement — The muscles can contract but cannot elongate.
3. False
   Corrected statement — Muscles are attached to bones by tendons.
4. False
   Corrected statement — Cardiac muscle is an involuntary muscle.
5. True

Match the bones (Column I) with the kind of joint (Column II)

Answer

Your external ear (pinna) is supported by

1. Bone
2. Cartilage
3. Tendon
4. Capsule

Answer

Cartilage

Reason — External ear is made up of cartilage due to which it is flexible.
The pinna is not made of bone. Bone is found in the middle ear (auditory ossicles), not in the external ear. Tendons connect muscle to bone. They do not form or support the ear structure. Capsules are protective coverings of organs or joints, not structural support for the ear.

The type of joint found at shoulder is also found at

1. Elbow
2. Knee
3. Ankle
4. Hip

Answer

Hip

Reason — Shoulder has ball and socket joint,which allows movement in multiple directions and is also found in Hip.
The elbow is a hinge joint, allowing movement in one plane (like bending and straightening). The knee is also a hinge joint, mainly for bending and straightening. The ankle is a hinge joint that mainly allows up and down movement of the foot.

Which one of the following categories of vertebrae are correctly numbered

1. Cervical — 7
2. Thoracic — 10
3. Lumbar — 4
4. Sacral — 4

Answer

Cervical — 7

Reason — There are seven cervical vertebrae, twelve thoracic, five lumbar and five sacral.
Thoracic vertebrae are 12, not 10. They are attached to ribs (T1–T12). Lumbar vertebrae are 5, not 4. They form the lower back (L1–L5). The sacral vertebrae are 5 fused vertebrae, not 4, forming the sacrum.

Human skeleton altogether contains 213 bones. Which of the following are exactly 6 in number?

1. Neck vertebrae
2. Ear ossicles
3. Carpals
4. Metacarpals

Answer

Ear ossicles

Reason — Ear ossicles have 3 bones in each ear (malleus, incus and stapes); making a total of 6 bones.
The neck has 7 cervical vertebrae. Carpals are 16 in total (8 in each hand). Metacarpals are 10 in total (5 in each hand).

Which of the following binds the bones together?

1. Tendons
2. Cartilage
3. Ligaments
4. Muscles

Answer

Ligaments

Reason — Ligaments hold bones together.
Tendons connect muscles to bones, not bones to each other. Cartilage is a flexible connective tissue that cushions bones at joints but does not primarily bind bones together. Muscles help in movement by contracting and relaxing, but they do not bind bones.

The inorganic constituents of bones are :

1. Calcium and sodium
2. Calcium and phosphorus
3. Carbon and nitrogen
4. Calcium and carbon

Answer

Calcium and phosphorus

Reason — Calcium and phosphorus are major components of bone.Bones contain inorganic salts mainly as calcium phosphate, which provides hardness and strength.
Sodium is present in body fluids, but it is not a major inorganic component of bones. Carbon and nitrogen are organic elements found in proteins (like collagen), not the main inorganic bone minerals. Carbon is part of organic compounds, not the primary inorganic bone material.

Bone cells are technically termed as :

1. Myocytes
2. Chondrocytes
3. Leucocytes
4. Osteocytes

Answer

Osteocytes

Reason — Osteocytes is the technical term used for bone cells.
Myocytes are muscle cells, not bone cells. Chondrocytes are cartilage cells, found in cartilage tissue. Leucocytes are white blood cells involved in immunity.

The external surface of bone is covered by a membrane called :

1. Peritonium
2. Pericardium
3. Periosteum
4. None of these

Answer

Periosteum

Reason — Periosteum is a complex structure composed of an outer fibrous layer that lends structural integrity and an inner cambium layer that possesses osteogenic potential.
The peritoneum is a membrane lining the abdominal cavity, not related to bones. The pericardium is the membrane surrounding the heart.

Involuntary muscles are present in :

1. Leg
2. Hand
3. Iris
4. Head

Answer

Iris

Reason — Iris is made up of involuntary muscles.
Leg muscles are skeletal (voluntary) muscles, controlled consciously. Hand muscles are also skeletal (voluntary) muscles. Most muscles in the head (like facial muscles) are voluntary skeletal muscles, not involuntary.

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.

1. P and Q
2. Q and R
3. R and S
4. S and P

Answer

S and p

Reason — Cardiac muscles are involuntary and found only in the heart. They are striated and branched and contract rhythmically throughout life.

Ischium and Pubis are two specific bones of the girdles in the human body, belonging to (P) ............... and (Q) ............... girdles respectively.

1. P — Pectoral, Q — Pelvic
2. P — Pectoral, Q — Pectoral
3. P — Pelvic, Q — Pelvic
4. P — Pelvic, Q — Pectoral

Answer

P — Pelvic, Q — Pelvic

Reason — Both ischium and pubis are part of the pelvic girdle, not different girdles. The pelvic girdle is made up of three bones: Ilium, Ischium and Pubis.
Pectoral girdle is the shoulder region. Ischium and pubis are not part of pectoral girdle. Ischium and pubis are hip bones. Pubis is not part of pectoral girdle.

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.

1. P and Q
2. Q and R
3. R and S
4. S and P

Answer

R and S

Reason — R- Calcium strengthens bones. Proteins help in bone repair and maintenance.
S- Vitamin D helps the body absorb calcium efficiently, essential for bone health.
P- Excess salt can actually increase calcium loss from bones. Sugar-rich foods do not help bone health. Q- Food items rich in carbohydrates and fats.

Name the parts of the skeleton where the following are located: Transverse process, glenoid cavity, shoulder-blade, acetabulum.

Answer

Name any two parts of your body where the supporting skeleton is made of cartilage instead of bone.

Answer

Two parts of your body where the supporting skeleton is made of cartilage instead of bone are:

1. External Ear
2. Tip of the nose

Name:

(a) Three main constituents of the human skeleton.

(b) Two main divisions of the human skeleton.

(c) Four parts of Axial skeleton.

(d) Five regions of vertebral column.

(e) Four kinds of freely movable joints.

Answer

(a) Bones, Cartilages and Ligaments

(b) Axial skeleton and Appendicular skeleton

(c) Skull, Vertebral Column, Sternum, Ribs

(d) Cervical, Thoracic, Lumbar, Sacrum, Coccyx

(e) Gliding joint, Pivot joint, Hinge joint, Ball and Socket joint.

Given below is the structure of the forelimb of humans. Read the information below the diagram and fill in the blanks:

Limbs are a part of the appendicular skeleton system. Humans have one pair of forelimbs which are used for many purposes like - holding, writing, eating and grasping, etc. Each arm consists of a total of thirty bones.

The upper arm consists of a single long bone, called (a) ............... . Two long bones are found in the lower arm, (b) ............... found on the side of the thumb and (c) ............... . Forelimbs have eight (d) ............... in the wrist and five (e) ............... in the palm. Remaining fourteen bones are found in the fingers as phalanges.

Answer

The upper arm consists of a single long bone, called Humerus . Two long bones are found in the lower arm, Radius found on the side of the thumb and Ulna . Forelimbs have eight Carpals in the wrist and five Metacarpals in the palm. Remaining fourteen bones are found in the fingers as phalanges.

Name the following :

(a) A joint which allows movements in all directions.

(b) The first vertebra of the vertebral column.

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

(d) The muscles which cause opposing movements.

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

Answer

(a) Ball and socket joint

(b) Atlas

(c) Foramen Magnum

(d) Antagonistic Muscles

(e) Synovial fluid

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 : ...............

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

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

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

(e) Brain : Cranium :: Spinal cord : ...............

Answer

(a) Humerus : Glenoid cavity :: Femur : Articular Cavity

(b) Thoracic vertebrae : 12 : Cervical : 7

(c) Wrist : Carpals :: Ankle : Tarsal

(d) Biceps : Flexor :: Triceps : Extensor

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

Write the technical terms for each of the following :

(a) Knee cap

(b) Shoulder blade

(c) Collar bone

(d) Breast bone

(e) Bones in the palm

Answer

(a) Knee cap — Patella

(b) Shoulder blade — Scapula

(c) Collar bone — Clavicle

(d) Breast bone — Sternum

(e) Bones in the palm — Metacarpals

Define:

(a) Skeleton system

(b) Bone marrow

(c) Gristle

(d) Pivot joint

(e) Antagonistic muscles

Answer

(a) Skeleton System refers to the internal framework of bones and other connective tissues including cartilage, ligaments, and tendons that provide support, shape, protection, movement and leverage to the human body.

(b) Bone marrow is a soft, spongy tissue found inside the central hollow space or the marrow of some of the long bones where certain types of blood cells including red and white blood cells are formed.

(c) A pad of cartilage intervertebral disc that forms a kind of cushion between two vertebrae is called Gristle.

(d) Joint that allow rotation about an axis is called Pivot joint.

(e) The muscles that cause opposing movements are called antagonistic muscles.

Do the muscles pull the structures, or push them? Explain briefly.

Answer

The muscles in the body provide the means of all movements. Muscles pull the structures. Each muscle usually has two ends- a fixed end where the muscle originates and a movable end which pulls some other part. The movable end is shorter and thicker and hence pulls the bone at the movable end. Muscles can only contract and relax, they cannot lengthen or elongate.
The movable end is projected out to form a tough structure referred to as a tendon which is attached to the bone. When a muscle is triggered by a nerve, contraction of the muscle occurs and it becomes thicker and shorter which causes the bone to be pulled at the movable end.

Just as the humerus corresponds to femur, what bones correspond to tarsals, metacarpals, ulna and radius respectively?

Answer

What are antagonistic muscles? Give one example.

Answer

A structure that has been moved by a muscle cannot return to its original position without the action of another muscle. Such muscles causing opposing movements are called as antagonistic muscles.

Example of antagonistic muscles—
The flexor muscles or the biceps of the upper arm bends the lower arm over the upper arm (flexes). Extension of the lower arm is caused by the extensor muscles or the triceps. Hence these two muscles are antagonistic or work in the opposite direction.

Give reason:

(a) Decalcified bones become soft and flexible.

(b) People in old age complain of stiff joints.

(c) In the female skeleton, the pelvis or hip bone is wider and trough-shaped.

(d) Bones are considered to be a living tissue.

(e) Vertebral column is curved.

Answer

(a) Two-third of entire bone mass is made of calcium and phosphorous. It gives strength and hardness to bones. Therefore, when these inorganic substance are lost or the bone is decalcified, they become soft and flexible.

(b) The freely movable joints are well lubricated by synovial fluid to remove friction between the joint surfaces. With age, the production and quality of synovial fluid decreases, leading to less effective lubrication. This coupled with degeneration of cartilage and ligaments causes stiff joints in old age.

(c) In the female skeleton, the pelvis or hip bone is wider and trough-shaped to adapt for accommodating the foetus in the uterus during pregnancy.

(d) Bones are made up of living cells (osteocytes) that are responsible for their growth, maintenance, and repair. They receive blood supply through a network of blood vessels and they produce red and white blood cells within the bone marrow. Therefore, the bones are considered to be a living tissue.

(e) Vertebral column is curved in order to provide correct posture and balance to our body. It's curvature enables us to minimize all the stress on bones and muscles that arises due to activities.

Write one specific location of the following in the human body.

(a) Femur

(b) Malleus, Incus, Stapes

(c) Coccyx

(d) An immovable joint

(e) Sternum

Answer

(a) Thigh

(b) Ear

(c) lower part of back bone

(d) Brain box

(e) In the middle of the front part of the chest.

Distinguish between the following pairs :

(a) True ribs and floating ribs

(b) Ligaments and tendons

(c) Hinge joint and gliding joint

(d) Voluntary and involuntary muscles

(e) Bone and cartilage

Answer

(a) Difference between true ribs and floating ribs:

(b) Difference between ligaments and tendons:

(c) Difference between hinge joint and gliding joint:

(d) Difference between voluntary and involuntary muscles :

(e) Difference between Bone and cartilage :

What are the uses of the skeleton in our body?

Answer

Uses of skeleton:

1. Support and shape — The skeletal system provides a framework to the body. It provides support to all soft parts and gives a definite shape to the body and all body parts.
2. Protection — Several delicate and important organs are well protected by a casing of bones.
   Example — The skull provides protection to the delicate brain.
3. Movement — Some bones are movable on each other which is brought about by the action of muscles that originate on one bone and are inserted into another.
4. Leverage — Some bones and joints form levers which causes the increase in the speed and distance of the muscle movement.
5. Formation of blood cells — Certain types of blood cells including red and white blood cells are formed in the marrow of certain long bones such as the femur.
6. The bones are storehouse of calcium and phosphorus for the rest of the body.

Name the different types of joints? Give one example of each type.

Answer

Types of joints with examples are:

1. Immovable joints — Skull bones
2. Partially movable joints — Joints between the ribs and breast-bone
3. Freely movable joints — Hip joint
4. Gliding joint — Ankle bones
5. Pivot joint — Joint between axis vertebrae and atlas
6. Hinge joint — Elbow
7. Ball and socket joint — Shoulder joint

The figure given below shows a kind of vertebra. Study the figure and answer the following questions:

(a) Name the vertebra.

(b) Where is this vertebra located?

(c) Label the guideline 1, 2 and 3.

Answer

(a) Thoracic vertebra.

(b) Thoracic region of vertebral column.

(c) The labelled guidelines are:

• 1 → Neural spine
• 2 → Neural canal
• 3 → Body of centrum

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.

(b) Mention two locations of this joint in the human body.

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

Answer

(a) Synovial Joint

(b) The shoulder joint and the knee joint.

(c) Ligament

Given below is a diagram of human skeleton. Name the bones numbered 1-11.

Answer

• 1 → Skull/Cranium
• 2 → Clavicle
• 3 → Sternum
• 4 → Humerus
• 5 → Ulna
• 6 → Coccyx
• 7 → Ribs
• 8 → Radius
• 9 → Femur
• 10 → Fibula
• 11 → Tibia

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

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.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

A is False and R is True.

Reason — A is False as the axial skeleton consists of the central core of the body: Skull, vertebral column, rib cage and sternum. It does not include the limbs or girdles.
R is True as the axial skeleton forms the central supporting axis of the body.

Therefore, A is False and R is True is the correct option.

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.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

A is True and R is False.

Reason — A is True as each hip bone is formed by the fusion of three bones: Ilium, Ischium and Pubis. These fuse during development to form a single structure.
R is False as the hip bone is a part of the pelvis, not the same as the pelvis. The pelvis includes: Two hip bones, sacrum and coccyx. The female pelvis is wider, shallower, and more rounded, to facilitate childbirth.

Therefore, A is True and R is False is the correct option.

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.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

A is True and R is False.

Reason — A is True as synovial fluid is a viscous fluid present in synovial joints. It reduces friction, lubricates the joint, and nourishes the articular cartilage.
R is False as the bones of the cranium are connected by immovable joints called sutures, not synovial joints. Sutures are fibrous joints that do not contain synovial fluid.

Therefore, A is True and R is False is the correct option.

Assertion (A): Hinge joint occurs between the bones of elbow. It provides movement in only one direction.

Reason (R): Usually, hinge joints give sufficient power.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both A and R are true but R is not the correct explanation of A.

Reason — A is true as a hinge joint allows movement in one plane (like a door hinge) and is found in the elbow, knee, ankle, and fingers.
R is true as the elbow is a hinge joint, which allows movement in only one direction (flexion and extension, like a door hinge).
Their main characteristic of hinge joint is restricted one-direction movement, not power.

Therefore, Both A and R are true but R is not the correct explanation of A is the correct option.

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.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both A and R are true and R is the correct explanation of A.

Reason — A is true as the radius and ulna are the two long bones of the forearm. They extend from the elbow to the wrist.
R is true as the radius and ulna connect the upper arm bone (humerus) to the wrist bones (carpals), forming the forearm.

Therefore, Both A and R are true and R is the correct explanation of A is the correct option.

Assertion (A): Sternum is a large bone formed by the fusion of five vertebrae. It is found between the lumbar vertebrae and соссух.

Reason (R): Sternum lies in the middle of the front part of the chest.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

A is False and R is True.

Reason — A is False as the sternum is not formed by vertebrae. It is a flat bone located in the center of the chest (anterior thoracic region).
R is True as it is located in the center of the chest, and connects to the ribs via cartilages, playing a vital role in protecting the heart and lungs.

Therefore, A is False and R is True is the correct option.

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.

(b) Write two functions of the above mentioned system other than support and shape.

(c) Name the kind of joints found at the elbow and the hip of humans.

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

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

Answer

(a) The joints belong to the skeletal system.

(b) Two functions other than support and shape are :

1. Protection of internal organs.
2. Movement with the help of muscles.

(c) The kind of joints found at elbow is hinge joint and hip is ball-and-socket joint.

(d) A structure of the human body where bones are joined to each other but no movement is possible is skull (cranium).

(e) Fluid between the two bones of freely movable joints is synovial fluid.