BiologyICSE Class 9 · Chapter 11

Skeleton: Movement and Locomotion ICSE Class 9: Axial and Appendicular Skeleton and Types of Joints

Updated 15 October 2026 · Fact-checked

The human skeleton of 206 bones supports and shapes the body, protects organs, makes blood cells, stores minerals and, with muscles, brings about movement. It has an axial part (skull, vertebral column, ribs, sternum) and an appendicular part (girdles and limbs). Bones meet at immovable, slightly movable and freely movable joints such as hinge and ball and socket joints.

What Skeleton: Movement and Locomotion is about

Movement is a change in the position of a body part (bending an arm); locomotion is movement of the whole body from one place to another (walking, running, swimming). Both depend on bones, joints and muscles working together, controlled by the nervous system.

The CISCE 2028 syllabus (Class IX, Human Anatomy and Physiology (ii)) covers: the functions of the human skeleton; the axial and appendicular skeleton; and the types of joints with reference to their location: immovable, slightly movable and freely movable (hinge, ball and socket, gliding and pivot joints).

Weightage: CISCE publishes no chapter weightage for ICSE Biology. Skeleton: Movement and Locomotion is topic 6, Human Anatomy and Physiology (ii), of the Class IX part of the 2028 syllabus; the Class IX paper (80 marks, 2 hours) is set and marked by the school.Source: CISCE ICSE Biology (Science Paper 3) syllabus, examination year 2028 (Class IX)

Key concepts

Functions of the skeleton

The adult human skeleton has 206 bones, along with cartilages and ligaments. Its functions:
1. Support and shape: a framework that holds the body upright and gives it shape.
2. Protection of delicate organs: skull → brain; vertebral column → spinal cord; ribs and sternum → heart and lungs; pelvis → urinary bladder and reproductive organs.
3. Movement and locomotion: bones act as levers worked by muscles attached to them by tendons.
4. Blood cell formation: red bone marrow (in flat bones and ends of long bones) makes red blood cells, white blood cells and platelets.
5. Storage of minerals: calcium and phosphorus are stored and released when needed.
6. Breathing: movement of ribs helps in breathing.
7. Hearing: the three ear ossicles pass sound vibrations to the inner ear.

Worked example

Name the bones that protect (a) the brain, (b) the heart and lungs, (c) the spinal cord.

Try it first, then show the solutionSolution

(a) Cranium of the skull.
(b) Ribs and sternum (rib cage).
(c) Vertebral column.

Answer: Cranium; rib cage; vertebral column.

Axial skeleton

The axial skeleton forms the main axis of the body: 80 bones.

Skull (22 bones, plus 6 ear ossicles and the hyoid often counted with it):

Cranium (8 bones): a box enclosing the brain; its bones are joined by immovable sutures.
Facial bones (14): including the upper jaw and the lower jaw (mandible), the only movable bone of the skull.

Vertebral column (backbone): 33 vertebrae in a child; in the adult some fuse, giving 26 bones:

Region	Vertebrae
Cervical (neck)	7
Thoracic (chest; carry ribs)	12
Lumbar (lower back; largest)	5
Sacral	5, fused into the sacrum
Coccygeal (tail)	4, fused into the coccyx

The first cervical vertebra is the atlas (supports the skull), the second the axis. Discs of cartilage between vertebrae act as shock absorbers. The column protects the spinal cord, supports the head and gives flexibility.

Ribs: 12 pairs, joined to the thoracic vertebrae at the back. True ribs (1st-7th pairs) join the sternum directly; false ribs (8th-10th) join it through the cartilage of the 7th; floating ribs (11th-12th) are free at the front.

Sternum (breastbone): a flat bone in the middle of the chest.

Worked example

Why does a child have 33 vertebrae but an adult only 26 vertebral bones?

Try it first, then show the solutionSolution

5 sacral vertebrae fuse into one sacrum (5 → 1).
4 coccygeal vertebrae fuse into one coccyx (4 → 1).
33 - 5 - 4 + 2 = 26.

Answer: Fusion of sacral and coccygeal vertebrae.

Appendicular skeleton

The appendicular skeleton consists of the girdles and limbs: 126 bones.

Pectoral (shoulder) girdle (each side): clavicle (collar bone) and scapula (shoulder blade). The scapula has a shallow cavity (glenoid cavity) for the head of the humerus.

Forelimb (arm) (each side, 30 bones):

Humerus (upper arm)
Radius and ulna (forearm)
Carpals (8, wrist), metacarpals (5, palm), phalanges (14, fingers)

Pelvic (hip) girdle: two hip bones (innominate bones), each made of three fused bones (ilium, ischium, pubis). Together with the sacrum they form the pelvis; each has a deep cup, the acetabulum, for the head of the femur.

Hindlimb (leg) (each side, 30 bones):

Femur (thigh; the longest and strongest bone)
Patella (knee cap)
Tibia (shin) and fibula
Tarsals (7, ankle), metatarsals (5, sole), phalanges (14, toes)

Count: 80 (axial) + 126 (appendicular) = 206.

Worked example

Count the bones in one forelimb (arm) and check that two forelimbs and two hindlimbs give 120 bones.

Try it first, then show the solutionSolution

Arm: humerus 1 + radius 1 + ulna 1 + carpals 8 + metacarpals 5 + phalanges 14 = 30.
Leg: femur 1 + patella 1 + tibia 1 + fibula 1 + tarsals 7 + metatarsals 5 + phalanges 14 = 30.
2 × 30 + 2 × 30 = 120 (the remaining 6 are the two clavicles, two scapulae and two hip bones: 126).

Answer: 30 per limb; 120 in four limbs.

Joints: immovable and slightly movable

A joint is a place where two or more bones meet.

Immovable (fixed, fibrous) joints: bones are held firmly by fibrous tissue and cannot move.

Location: sutures between the bones of the cranium; joints of teeth in their sockets.
Role: rigid protection (the brain box).

Slightly movable (cartilaginous) joints: bones joined by cartilage, allowing a little movement.

Location: between vertebrae (intervertebral discs); between the two pubic bones (pubic symphysis); between ribs and sternum.
Role: flexibility with stability; the discs cushion shocks.

Worked example

Why are the joints between the bones of the cranium immovable?

Try it first, then show the solutionSolution

The cranium protects the brain.
Fixed sutures make it a rigid, strong box that cannot be pushed in at the joints.

Answer: For rigid protection of the brain.

Freely movable (synovial) joints

In freely movable (synovial) joints, the ends of the bones are covered with smooth articular cartilage and enclosed in a capsule lined by the synovial membrane, which secretes synovial fluid that lubricates the joint and reduces friction. Strong ligaments hold the bones together.

Type	How it moves	Location (examples)
Hinge joint	like a door hinge, in one plane (bending and straightening)	elbow, knee, joints of fingers and toes
Ball and socket joint	ball-shaped head in a cup: movement in all directions and rotation	shoulder (humerus in glenoid cavity), hip (femur in acetabulum)
Gliding joint	flat surfaces slide over each other	between carpals (wrist), tarsals (ankle), between the processes of vertebrae
Pivot joint	one bone rotates around another	between the atlas and axis (turning the head side to side); between the upper ends of radius and ulna (turning the palm)

Worked example

Why can you swing your arm in a full circle at the shoulder but not at the elbow?

Try it first, then show the solutionSolution

The shoulder is a ball and socket joint: movement in all directions.
The elbow is a hinge joint: movement in one plane only.

Answer: Ball and socket versus hinge.

How bones and muscles bring about movement

Muscles can only pull (contract), not push. So skeletal muscles work in antagonistic pairs: when one contracts, the other relaxes.

Example at the elbow (a hinge joint):

Biceps (front of upper arm) contracts → forearm bends (flexion); triceps relaxes.
Triceps (back of upper arm) contracts → forearm straightens (extension); biceps relaxes.

Muscles are attached to bones by tendons; bones are held together at joints by ligaments. In locomotion, repeated, coordinated movements of the limbs at many joints move the whole body.

Worked example

What happens to the biceps and triceps when you lift a bag by bending your elbow?

Try it first, then show the solutionSolution

Bending the elbow is flexion.
Biceps contracts and pulls the forearm up; triceps relaxes.

Answer: Biceps contracts, triceps relaxes.

Skeleton: Movement and Locomotion in real life

Each concept, met in an everyday situation. Read the situation, answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Calcium, bones and age

Suppose an elderly woman breaks her hip after a minor fall, and her doctor says her bones have lost much of their calcium.

Link this to a function of the skeleton and suggest how young people can protect their bones.

Try it first, then show the solutionSolution

Bones store calcium and phosphorus, which give them hardness.
When calcium is lost faster than it is replaced, bones become weak and break easily.
Young people should get calcium (milk, curd, green leaves), vitamin D (sunlight) and regular exercise to build strong bones.

Answer: Mineral loss weakens bones; build them with calcium, vitamin D and exercise.

Memory hook: Bones are a calcium bank: deposit early.

Cricket injury

Suppose a fast bowler hurts his shoulder and the doctor says the head of the upper arm bone has slipped out of its socket.

Name the injury, the joint type and the bones involved, and say why this joint dislocates more easily than the hip.

Try it first, then show the solutionSolution

It is a dislocation of the shoulder: a ball and socket joint.
The head of the humerus has come out of the glenoid cavity of the scapula.
The shoulder's socket is shallow, giving great freedom but less stability; the hip's acetabulum is deep.

Answer: Shoulder dislocation; shallow socket allows more movement but less stability.

Memory hook: More freedom, less security.

Turning to look back

Suppose a cyclist turns her head to check traffic behind her without moving her shoulders.

Name the joint and bones that make this possible.

Try it first, then show the solutionSolution

The head turns from side to side at a pivot joint.
It is between the atlas (first cervical vertebra) and the axis (second), whose peg-like projection the atlas rotates around.

Answer: Pivot joint between atlas and axis.

Memory hook: The atlas turns on the axis.

Topics in this chapter

Human Skeleton, Joints and Movement

Skeleton: Movement and Locomotion: key facts

Total bones: $80 (axial) + 126 (appendicular) = 206$; Adult.
Vertebrae: $7 + 12 + 5 + 5 + 4 = 33 \to 26 bones in adult$; Sacrum and coccyx fused.
Bones in one limb: $1 + 2 + 8 + 5 + 14 = 30 (arm); 1 + 1 + 2 + 7 + 5 + 14 = 30 (leg)$; Phalanges 14 in each.
Ribs: $7 true + 3 false + 2 floating = 12 pairs$; 24 ribs.

Skeleton: Movement and Locomotion: diagrams to practise

Practise each one on paper: draw it from the checklist, then tick off every label.

Synovial joint

Draw a labelled diagram of a synovial (freely movable) joint.

Draw

Two bone ends facing each other, each capped with a layer of articular cartilage.
A capsule enclosing the joint, lined on the inside by the synovial membrane.
The space between filled with synovial fluid (dotted).
Ligaments as bands crossing from one bone to the other outside the capsule.

Label

bone
articular cartilage
synovial membrane
synovial fluid
capsule
ligament

Watch out: Keep the two bone ends separate; show the fluid between them.

Human skeleton (outline)

Draw a simple outline of the human skeleton labelling the axial and appendicular parts.

Draw

Skull at the top; vertebral column down the back; rib cage with sternum.
Clavicles and scapulae at the shoulders; arm bones; pelvis; leg bones.

Label

skull
vertebral column
ribs
sternum
clavicle
scapula
humerus
radius
ulna
pelvis
femur
patella
tibia
fibula

Watch out: Use one colour for axial and another for appendicular bones.

Biceps and triceps

Show how antagonistic muscles move the forearm.

Draw

Upper arm bone (humerus) with the forearm (radius, ulna) hinged at the elbow.
Biceps on the front joining the scapula to the radius by tendons.
Triceps on the back joining the scapula/humerus to the ulna.

Label

humerus
biceps (contracted)
triceps (relaxed)
tendon
elbow (hinge joint)
radius
ulna

Watch out: Draw the bent arm with a thick, short biceps.

How the school exam asks Skeleton: Movement and Locomotion

The question patterns to expect, and the method that works for each.

Question type	How it is asked	Method
Functions	State four functions of the skeleton; name the bone protecting an organ.	Support, protection, movement, blood cells, minerals.
Axial and appendicular	Classify bones; name the parts of the vertebral column with numbers; girdle bones.	Learn the two lists and the counts.
Joints	Name the type of joint at a location; give an example of each type; draw a synovial joint.	Location ↔ type table.
Differences	Hinge versus ball and socket; tendon versus ligament; movement versus locomotion.	Table form.
Application	Effects of a dislocation, fracture or worn cartilage; antagonistic muscles.	Link structure to the movement lost.

Tricks to remember Skeleton: Movement and Locomotion

Short memory aids. Say each one aloud once, then use it on a question the same day.

Vertebrae: 'Breakfast at 7, lunch at 12, dinner at 5'
Cervical 7, thoracic 12, lumbar 5 (then sacral 5, coccygeal 4).
Use it when: Vertebral column.
Hinge = door; ball and socket = joystick
Elbow and knee swing like doors; shoulder and hip turn like a joystick.
Use it when: Freely movable joints.
Pivot = 'No' joint
Atlas-axis pivot lets you shake your head 'no'; atlas lets you nod 'yes'.
Use it when: Pivot joint location.
Limb count 1-2-8-5-14
Arm: 1 humerus, 2 forearm bones, 8 carpals, 5 metacarpals, 14 phalanges = 30. Leg: swap 8 carpals for 7 tarsals and add the patella = 30.
Use it when: Bones in a limb.

Skeleton: Movement and Locomotion: exam-level solved questions

Ordered from exam level to HOTS. Cover the solution, write your own, then compare step by step.

Example 1: Ball and socket · 1 mark · MCQExam level

A ball and socket joint is found at the:
(a) elbow
(b) knee
(c) hip
(d) wrist

Try it first, then show the solutionSolution

The head of the femur fits in the acetabulum of the hip bone.

Answer: (c)

Example 2: Lower jaw · 1 mark · Assertion-reasonHarder exam level

Assertion (A): All the joints of the skull are immovable.
Reason (R): The bones of the cranium are joined by sutures.
(a) Both (A) and (R) are true, and (R) is the correct explanation for (A).
(b) Both (A) and (R) are true, but (R) is not the correct explanation for (A).
(c) (A) is true and (R) is false.
(d) (A) is false and (R) is true.

Try it first, then show the solutionSolution

The lower jaw (mandible) moves at its joint with the skull: A false.
Cranial bones are joined by sutures: R true.

Answer: (d)

Example 3: Functions · 2 marks · Short answerExam level

State four functions of the human skeleton.

Try it first, then show the solutionSolution

Support and shape.
Protection of internal organs.
Movement (levers for muscles).
Formation of blood cells in red marrow (also storage of minerals).

Answer: As above.

Example 4: Vertebral column · 3 marks · Short answerExam level

Name the five regions of the vertebral column with the number of vertebrae in each. Which regions show fusion in the adult?

Try it first, then show the solutionSolution

Cervical 7, thoracic 12, lumbar 5, sacral 5, coccygeal 4 (total 33).
Sacral fuse into the sacrum; coccygeal fuse into the coccyx.

Answer: As above.

Example 5: Joint locations · 3 marks · Short answerHarder exam level

Name the type of joint at (a) knee, (b) between atlas and axis, (c) between carpals, (d) between bones of the cranium, (e) between vertebral bodies.

Try it first, then show the solutionSolution

(a) Hinge.
(b) Pivot.
(c) Gliding.
(d) Immovable (sutures).
(e) Slightly movable (cartilaginous).

Answer: As above.

Example 6: Synovial joint · 4 marks · Long answerHarder exam level

Describe the structure of a synovial joint and give the function of the synovial fluid, articular cartilage and ligaments.

Try it first, then show the solutionSolution

Bone ends covered by articular cartilage, enclosed in a capsule lined by synovial membrane, filled with synovial fluid, held by ligaments.
Synovial fluid: lubricates, reduces friction.
Articular cartilage: smooth surface, absorbs shock.
Ligaments: hold bones together, prevent dislocation.

Answer: As above.

Example 7: Antagonistic muscles · 3 marks · Short answerHOTS / competency

Explain how the forearm is (a) bent and (b) straightened. Why do muscles have to work in pairs?

Try it first, then show the solutionSolution

(a) Biceps contracts, triceps relaxes: the forearm bends at the elbow.
(b) Triceps contracts, biceps relaxes: the forearm straightens.
Muscles can only pull, not push, so a second muscle is needed to move the bone back.

Answer: As above.

Example 8: Bone count · 3 marks · Short answerHOTS / competency

Show by counting that the appendicular skeleton has 126 bones.

Try it first, then show the solutionSolution

Pectoral girdles: 2 clavicles + 2 scapulae = 4.
Pelvic girdle: 2 hip bones = 2.
Limbs: 2 arms × 30 + 2 legs × 30 = 120.
Total = 4 + 2 + 120 = 126.

Answer: 126

Case-study practice (Section B style)

Read the situation, then answer every part. In a school exam set on the board pattern this is a 5-mark question split into 1 + 2 + 2 marks.

The knee

Suppose an X-ray of a footballer's knee shows the lower end of the thigh bone, the upper end of the shin bone, a small rounded bone in front, and a joint space. He complains of pain on bending because the smooth covering of the bone ends has worn thin.

(i) · 1 mark
Name the three bones seen.
Answer
Answer: Femur, tibia, patella.
(ii) · 2 marks
Name the type of joint and the movement it allows.
Answer
Answer: Hinge joint (synovial); bending and straightening in one plane.
(iii) · 2 marks
Which structure has worn thin, and why does this cause pain?
Answer
Answer: Articular cartilage; without its smooth cushioning, bone rubs on bone, causing friction and pain.

Where the marks are

How a typical answer is split into step marks. Show every step: a right final answer alone rarely earns full marks.

Distinguish between movement and locomotion with an example of each. (2 marks) (2 marks)

Step	Marks
Movement: change in position of a body part, e.g. bending the arm	1
Locomotion: whole body moves from place to place, e.g. walking	1

Give one location each of a hinge, a ball and socket and a pivot joint. (3 marks) (3 marks)

Step	Marks
Hinge: elbow / knee	1
Ball and socket: shoulder / hip	1
Pivot: atlas and axis (neck)	1

Where students lose marks in Skeleton: Movement and Locomotion

The slips examiners see most often, and what to write instead.

Mistake: Girdles placed in the axial skeleton
Girdles lie near the trunk.
Wrong working
Scapula and hip bones are part of the axial skeleton.
Right working
Girdles belong to the appendicular skeleton; axial = skull, vertebral column, ribs, sternum.
Do this: Axial = the body's central axis only.
Usually costs: 1 mark.
Mistake: Knee called a ball and socket joint
Any big joint is assumed to be ball and socket.
Wrong working
Knee: ball and socket joint.
Right working
Knee: hinge joint; hip: ball and socket.
Do this: Ask: can it move in all directions?
Usually costs: 1 mark.
Mistake: Ligament and tendon mixed
Both connect structures at joints.
Wrong working
Ligaments attach muscles to bones.
Right working
Tendons: muscle to bone; ligaments: bone to bone.
Do this: LigaMENT = bone MEETS bone.
Usually costs: 1 mark.
Mistake: Wrong vertebra numbers
Thoracic and lumbar counts are swapped.
Wrong working
Lumbar 12, thoracic 5.
Right working
Cervical 7, thoracic 12, lumbar 5, sacral 5, coccygeal 4.
Do this: Thoracic carry the 12 pairs of ribs.
Usually costs: 1 mark.

Practice questions on Skeleton: Movement and Locomotion

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQExam level
The number of cervical vertebrae in humans is:
(a) 5
(b) 7
(c) 12
(d) 4
Hint
Neck.
Answer
(b)
Q2 · 1 mark · MCQExam level
A gliding joint is found between:
(a) humerus and scapula
(b) femur and tibia
(c) carpals
(d) atlas and axis
Hint
Wrist.
Answer
(c)
Q3 · 3 marks · Very short answerExam level
Name the bone: (a) the knee cap, (b) the collar bone, (c) the breastbone.
Hint
Patella...
Answer
(a) Patella (b) Clavicle (c) Sternum
Q4 · 3 marks · Short answerExam level
What are true, false and floating ribs?
Hint
How they join the sternum.
Answer
True ribs (pairs 1-7) join the sternum directly by cartilage; false ribs (8-10) join it indirectly through the cartilage of the 7th rib; floating ribs (11-12) do not join the sternum at the front.
Q5 · 2 marks · Short answerHarder exam level
Give two differences between a hinge joint and a ball and socket joint.
Hint
Planes; shape.
Answer
Hinge: movement in one plane only; convex surface fits a concave one like a door hinge (elbow, knee). Ball and socket: movement in all directions; rounded head fits a cup-shaped socket (shoulder, hip).
Q6 · 2 marks · Short answerHarder exam level
Why are the intervertebral discs important? What could happen if one is damaged?
Hint
Shock absorbers.
Answer
They are cartilage cushions that absorb shocks and allow slight bending of the backbone. If damaged ('slipped disc'), it may press on the spinal nerves, causing back pain and numbness.
Q7 · 3 marks · Short answerHarder exam level
Explain how the skeleton helps in (a) breathing, (b) hearing, (c) making blood.
Hint
Ribs; ossicles; marrow.
Answer
(a) Ribs move up and out with muscles, enlarging the chest. (b) Ear ossicles pass sound vibrations to the inner ear. (c) Red bone marrow produces blood cells.
Q8 · 2 marks · Short answerHarder exam level
Why is the femur the longest and strongest bone?
Hint
Weight and walking.
Answer
It supports the weight of the whole upper body when standing and walking, and the large leg muscles attached to it need a long, strong lever for locomotion.
Q9 · 2 marks · Short answerHarder exam level
Classify into axial and appendicular: sternum, scapula, rib, femur, coccyx, clavicle.
Hint
Girdles are appendicular.
Answer
Axial: sternum, rib, coccyx. Appendicular: scapula, femur, clavicle.
Q10 · 3 marks · Short answerHOTS / competency
An old man's finger joints become stiff and painful; an X-ray shows the gap between bones has narrowed. Suggest the tissue that is worn and the joint type affected, and explain the stiffness.
Hint
Cartilage in a hinge joint.
Answer
The articular cartilage (and synovial lining) is worn; the finger joints are hinge (synovial) joints. Without smooth cartilage and enough synovial fluid, the bone ends rub, causing pain and stiffness.
Q11 · 3 marks · Short answerHOTS / competency
If muscles could only contract, explain how a person can both kick a ball (straighten the knee) and then bend the knee again. Name the muscle groups involved.
Hint
Front and back of thigh.
Answer
Muscles on the front of the thigh (quadriceps) contract to straighten the knee for the kick while the back-of-thigh muscles (hamstrings) relax. To bend the knee, the hamstrings contract and the quadriceps relax. They are an antagonistic pair working at a hinge joint.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.Number of bones in the adult human body?Show answer
206.
2.Longest bone?Show answer
Femur.
3.Only movable bone of the skull?Show answer
Lower jaw (mandible).
4.Number of thoracic vertebrae?Show answer
12.
5.Floating ribs are which pairs?Show answer
11th and 12th.
6.Joint between atlas and axis?Show answer
Pivot joint.
7.Fluid that lubricates freely movable joints?Show answer
Synovial fluid.
8.Bones of the pectoral girdle?Show answer
Clavicle and scapula.

Best order to study it

Learn the seven functions of the skeleton.
Learn the axial skeleton: skull, vertebral regions with numbers, ribs, sternum.
Learn the appendicular skeleton: girdles and limb bones.
Learn the three types of joints and the four freely movable types with locations.
Learn the synovial joint and antagonistic muscles; practise diagrams.

Quick revision checklist

The night before the exam: can you do each of these without looking?

Can you state five functions of the skeleton?
Can you list the vertebral regions with numbers?
Can you divide bones into axial and appendicular?
Can you name the joint type at ten locations?
Can you draw and label a synovial joint?
Can you explain biceps and triceps action?

Skeleton: Movement and Locomotion: frequently asked questions

Do I need the names of all 206 bones?

No. Learn the main bones of the axial and appendicular skeleton, the numbers in the vertebral column and limbs, and the girdle bones.

Is the joint between the radius and ulna a pivot joint?

Yes, at their upper ends: the radius rotates around the ulna when you turn your palm up and down. The atlas-axis joint is the standard example.

Why do babies have more bones than adults?

A newborn has many separate bony parts (about 270-300) which fuse during growth, for example in the skull, sacrum and coccyx, giving 206 bones in the adult.

Are cartilages part of the skeleton?

Yes. Cartilage is found at the ends of bones, between vertebrae, in the nose, ear and ribs; it is part of the skeletal system.

Based on: CISCE ICSE 2028 Science (52) Biology (Science Paper 3) syllabus, Classes IX and X