Joints

BiologyLocomotion and MovementFor NEET aspirants

Joints are points of contact between bones, or between bones and cartilages, and every movement of a bony part depends on them. This page explains the three structural types of joints (fibrous, cartilaginous and synovial), the main kinds of synovial joints with their examples, and the disorders of the muscular and skeletal systems. It follows the NCERT Class 11 chapter Locomotion and Movement. NEET often asks match-the-list questions on joints and their examples, and on disorders and their causes.

On this page1Joints and movement2Fibrous joints3Cartilaginous joints4Synovial joints5Disorders6Exam essentials7Quick revision8Solved examples9Practice

Key Points at a Glance

★ Must learn Joint: a point of contact between bones, or between bones and cartilages.
Muscle force produces movement through joints; the joint acts as a fulcrum.
★ Must learn Three structural types: fibrous (no movement), cartilaginous (limited movement), synovial (considerable movement).
Fibrous: flat skull bones joined end-to-end by sutures to form the cranium.
Cartilaginous: bones joined by cartilage, as between adjacent vertebrae.
★ Must learn Synovial: a fluid-filled synovial cavity between the articulating surfaces of two bones.
★ Must learn Ball and socket: humerus and pectoral girdle. Hinge: knee. Pivot: atlas and axis. Gliding: between carpals. Saddle: carpal and metacarpal of thumb.
Myasthenia gravis: autoimmune, affects the neuromuscular junction. Muscular dystrophy: progressive degeneration, mostly genetic.
★ Must learn Tetany: rapid spasms due to low $C a^{2 +}$ . Gout: uric acid crystals in joints.
Arthritis: inflammation of joints. Osteoporosis: age-related loss of bone mass; decreased estrogen is a common cause.

1. Joints and Movement

Joints are essential for all types of movement involving the bony parts of the body. Locomotory movements are no exception.

★ Very important Joints: points of contact between bones, or between bones and cartilages.

The force generated by the muscles is used to carry out movement through joints, where the joint acts as a fulcrum.
The movability at these joints varies depending on different factors.
Joints are classified into three major structural forms: fibrous, cartilaginous and synovial.

Three structural types of joints

Type	How the bones are joined	Movement	Example
Fibrous	Dense fibrous connective tissue, in the form of sutures	None	Flat skull bones forming the cranium
Cartilaginous	Cartilage	Limited	Between adjacent vertebrae of the vertebral column
Synovial	Fluid-filled synovial cavity between the articulating surfaces	Considerable	Shoulder, knee, between the carpals and others (Section 4)

Memory Trick

Movement rises from Fixed to Few to Free: Fibrous joints are fixed (no movement), cartilaginous joints allow a few (limited) movements, and synovial joints move freely (considerable movement).

A joint works like the fulcrum of a see-saw: the muscle supplies the force, and the joint is the point about which the bone turns.

Key idea

Joints are where bones meet; the joint acts as a fulcrum, and its structure decides how much movement is possible.

2. Fibrous Joints

★ Exam imp Fibrous joints do not allow any movement.
They are shown by the flat skull bones, which fuse end-to-end with the help of dense fibrous connective tissue.
These fibrous junctions are called sutures; they join the flat bones to form the cranium.

Key idea

Fibrous joints are immovable sutures that lock the flat skull bones into the cranium.

3. Cartilaginous Joints

In cartilaginous joints, the bones involved are joined together with the help of cartilages.
The joint between adjacent vertebrae in the vertebral column is of this type.
It permits limited movements.

Memory Trick

Two C-words go together: the vertebral Column has Cartilaginous joints between its vertebrae.

Two S-words go together for the skull: Sutures are fibrous joints that Stop all movement.

Key idea

Cartilaginous joints, such as those between vertebrae, link bones through cartilage and allow only limited movement.

4. Synovial Joints

★ Very important Synovial joints have a fluid-filled synovial cavity between the articulating surfaces of the two bones. This arrangement allows considerable movement.

Synovial joints help in locomotion and many other movements.
Some examples of synovial joints:

Synovial joints and their examples

Synovial joint	Example
Ball and socket joint	Between the humerus and the pectoral girdle
Hinge joint	Knee joint
Pivot joint	Between the atlas and the axis
Gliding joint	Between the carpals
Saddle joint	Between the carpal and the metacarpal of the thumb

Memory Trick

Five synovial joints to learn: Big Hairy Pigs Go Swimming = Ball and socket, Hinge, Pivot, Gliding, Saddle.

Pair each with its place, in the same order: shoulder (humerus and pectoral girdle), knee, atlas and axis, between carpals, thumb.

Tips and Tricks

Both the gliding and the saddle joint are in the hand, so read the question closely. "Thumb" means saddle (carpal and metacarpal of the thumb); "between carpals" means gliding.

Pivot is between the atlas and the axis (first and second vertebrae), not between the skull and the atlas.

NEET Focus

Fibrous joints allow no movement, cartilaginous joints allow limited movement, and synovial joints allow considerable movement.
The knee is a hinge joint; the joint between the humerus and the pectoral girdle is a ball and socket joint.
Only synovial joints have a fluid-filled synovial cavity.

Quick Recall: tap to check

Which type of joint allows no movement?

Fibrous joint, as in the sutures of the skull.

Name the type of joint between adjacent vertebrae.

Cartilaginous joint.

What is found between the articulating surfaces of a synovial joint?

A fluid-filled synovial cavity.

Name the joint between the carpal and the metacarpal of the thumb.

Saddle joint.

Key idea

Synovial joints have a fluid-filled cavity and allow considerable movement: ball and socket, hinge, pivot, gliding and saddle.

5. Disorders of Muscular and Skeletal System

Disorders at a glance

Disorder	Part affected	Cause or feature
Myasthenia gravis	Neuromuscular junction	★ Exam imp Autoimmune disorder; leads to fatigue, weakening and paralysis of skeletal muscle
Muscular dystrophy	Skeletal muscle	Progressive degeneration of skeletal muscle, mostly due to genetic disorder
Tetany	Muscle	Rapid spasms (wild contractions) in muscle due to low $C a^{2 +}$ in body fluid
Arthritis	Joints	Inflammation of joints
Osteoporosis	Bone	★ Exam imp Age-related disorder; decreased bone mass and increased chances of fractures; decreased levels of estrogen is a common cause
Gout	Joints	Inflammation of joints due to accumulation of uric acid crystals

★ Very important Tetany is caused by low $C a^{2 +}$ in body fluid, not high. It shows as rapid spasms, or wild contractions, in muscle.

Memory Trick

Cause hooks: Myasthenia = My own immunity (autoimmune); Dystrophy = DNA (mostly genetic); Tetany = Too little calcium; Gout = Gathered uric acid; Osteoporosis = Old age, low estrogen.

Arthritis and gout both inflame joints; only gout names the cause (uric acid crystals).

Quick Recall: tap to check

Which disorder affects the neuromuscular junction?

Myasthenia gravis, an autoimmune disorder.

What causes gout?

Accumulation of uric acid crystals in the joints.

Name the disorder caused by low calcium ions in body fluid.

Tetany.

Name a common cause of osteoporosis.

Decreased levels of estrogen.

Key idea

Muscle disorders: myasthenia gravis, muscular dystrophy, tetany. Bone and joint disorders: arthritis, osteoporosis, gout.

6. Exam Essentials

Pairs to Match

Joint or disorder	Example, cause or feature
Fibrous joint	Sutures between flat skull bones
Cartilaginous joint	Between adjacent vertebrae
Ball and socket joint	Between the humerus and the pectoral girdle
Hinge joint	Knee joint
Pivot joint	Between the atlas and the axis
Gliding joint	Between the carpals
Saddle joint	Between the carpal and the metacarpal of the thumb
Myasthenia gravis	Autoimmune; neuromuscular junction
Muscular dystrophy	Progressive degeneration of skeletal muscle; mostly genetic
Tetany	Low $C a^{2 +}$ in body fluid
Arthritis	Inflammation of joints
Osteoporosis	Decreased bone mass; decreased estrogen
Gout	Uric acid crystals in joints

Exceptions

Not all joints have a synovial cavity: fibrous and cartilaginous joints lack it.
Arthritis and gout both inflame joints, but only gout is due to uric acid crystals.
Tetany is caused by low, not high, $C a^{2 +}$ in body fluid.
Myasthenia gravis is autoimmune, unlike muscular dystrophy, which is mostly genetic.
Osteoporosis decreases bone mass; it does not inflame joints.
The pubic symphysis contains fibrous cartilage, yet the bones are joined by cartilage, so it is a cartilaginous joint, not a fibrous joint.

7. Quick Revision

Joints are needed for all movements of bony parts, including locomotion.
Joint: a point of contact between bones, or between bones and cartilages; it acts as a fulcrum.
Three structural types: fibrous, cartilaginous and synovial.
Fibrous: no movement; sutures of flat skull bones forming the cranium.
Cartilaginous: bones joined by cartilage; limited movement; between adjacent vertebrae.
Synovial: fluid-filled synovial cavity; considerable movement; important in locomotion.
Ball and socket (humerus and pectoral girdle), hinge (knee), pivot (atlas and axis), gliding (carpals), saddle (thumb carpal and metacarpal).
Myasthenia gravis: autoimmune, neuromuscular junction; fatigue, weakening, paralysis.
Muscular dystrophy: progressive degeneration of skeletal muscle, mostly genetic.
Tetany: rapid spasms from low $C a^{2 +}$ . Arthritis: inflammation of joints.
Osteoporosis: age-related, decreased bone mass, more fractures; decreased estrogen.
Gout: inflammation of joints from uric acid crystals.

8. Solved Examples

Solved Example 1

Match List I with List II.
List I: A. Pivot joint, B. Saddle joint, C. Gliding joint, D. Hinge joint
List II: I. Between the carpals, II. Knee joint, III. Between the atlas and the axis, IV. Between the carpal and the metacarpal of the thumb
Choose the correct answer:
(A) A-IV, B-III, C-I, D-II
(B) A-III, B-I, C-IV, D-II
(C) A-II, B-IV, C-I, D-III
(D) A-III, B-IV, C-I, D-II

Solution:

Answer: (D). Pivot: atlas and axis (III). Saddle: thumb (IV). Gliding: between carpals (I). Hinge: knee (II).

Solved Example 2

Read the statements about disorders of the muscular and skeletal system.
A. Myasthenia gravis is an autoimmune disorder affecting the neuromuscular junction.
B. Tetany is caused by a high level of calcium ions in body fluid.
C. Gout is due to the accumulation of uric acid crystals in joints.
D. Muscular dystrophy is a progressive degeneration of skeletal muscle, mostly due to genetic disorder.
E. Osteoporosis is marked by an increased bone mass.
Choose the correct answer:
(A) A, B and C only
(B) B, C and D only
(C) A, C and D only
(D) A, C, D and E only

Solution:

Answer: (C). B is wrong: tetany is due to low calcium. E is wrong: osteoporosis decreases bone mass. A, C and D are correct.

Solved Example 3

Arrange the joints in increasing order of the movement they allow.
A. Joint between adjacent vertebrae
B. Knee joint
C. Joint between cranial bones
Choose the correct answer:
(A) C, A, B
(B) A, C, B
(C) C, B, A
(D) B, A, C

Solution:

Answer: (A). Cranial sutures are fibrous (no movement); vertebral joints are cartilaginous (limited); the knee is synovial (considerable).

Solved Example 4

Which of the following pairs is NOT correctly matched?
(A) Hinge joint: knee joint
(B) Ball and socket joint: humerus and pectoral girdle
(C) Gliding joint: atlas and axis
(D) Saddle joint: carpal and metacarpal of thumb

Solution:

Answer: (C). The joint between the atlas and the axis is a pivot joint; gliding joints lie between the carpals.

Solved Example 5

Statement I: Fibrous joints do not allow any movement.
Statement II: In the cranium, the flat skull bones fuse end-to-end with dense fibrous connective tissue in the form of sutures.
(A) Both Statement I and Statement II are correct
(B) Statement I is correct but Statement II is incorrect
(C) Statement I is incorrect but Statement II is correct
(D) Both Statement I and Statement II are incorrect

Solution:

Answer: (A). Both statements are correct; the sutures of the cranium are the example of fibrous joints.

Solved Example 6

A decreased level of which hormone is a common cause of osteoporosis?
(A) Insulin
(B) Estrogen
(C) Thyroxine
(D) Adrenaline

Solution:

Answer: (B). Osteoporosis is an age-related loss of bone mass, and decreased estrogen is a common cause.

9. Practice Questions

Practice Questions

Match List I with List II.
List I: A. Myasthenia gravis, B. Tetany, C. Gout, D. Osteoporosis
List II: I. Uric acid crystals in joints, II. Decreased bone mass, III. Autoimmune disorder of the neuromuscular junction, IV. Low $C a^{2 +}$ in body fluid
Choose the correct answer:
(A) A-III, B-IV, C-I, D-II
(B) A-IV, B-III, C-I, D-II
(C) A-III, B-I, C-IV, D-II
(D) A-II, B-IV, C-I, D-IIIAnswer: (A). Myasthenia gravis-III, tetany-IV, gout-I, osteoporosis-II.
Read the statements about joints.
A. Joints are points of contact between bones, or between bones and cartilages.
B. During movement, the joint acts as a fulcrum.
C. Cartilaginous joints allow considerable movement.
D. Synovial joints have a fluid-filled synovial cavity between the articulating surfaces.
E. The joint between adjacent vertebrae is a synovial joint.
Choose the correct answer:
(A) A, B and C only
(B) A, B and D only
(C) B, D and E only
(D) A, B, D and E onlyAnswer: (B). Cartilaginous joints allow only limited movement (C wrong); the joint between adjacent vertebrae is cartilaginous (E wrong).
Arrange the joints from the head towards the hand.
A. Joint between the carpal and metacarpal of the thumb
B. Joint between the atlas and the axis
C. Joints between the cranial bones
D. Joint between the humerus and the pectoral girdle
E. Joints between the carpals
Choose the correct answer:
(A) C, B, D, A, E
(B) B, C, D, E, A
(C) C, B, D, E, A
(D) C, D, B, E, AAnswer: (C). Cranial sutures, atlas and axis, shoulder, between the carpals, then the base of the thumb.
Which of the following is NOT a synovial joint?
(A) Knee joint
(B) Joint between the atlas and the axis
(C) Sutures between the cranial bones
(D) Joint between the carpalsAnswer: (C). Sutures are fibrous joints and allow no movement.
Statement I: Tetany shows rapid spasms, or wild contractions, in muscle.
Statement II: Tetany is caused by a high level of $C a^{2 +}$ in body fluid.
(A) Both Statement I and Statement II are correct
(B) Statement I is correct but Statement II is incorrect
(C) Statement I is incorrect but Statement II is correct
(D) Both Statement I and Statement II are incorrectAnswer: (B). Statement I is correct; tetany is due to low $C a^{2 +}$ .
Name the type of joint between: (a) atlas and axis (b) carpal and metacarpal of the thumb (c) the phalanges (d) femur and acetabulum (e) the cranial bones (f) the pubic bones in the pelvic girdle.Answer: (a) Pivot joint. (b) Saddle joint. (c) Hinge joint. (d) Ball and socket joint. (e) Fibrous joint (sutures). (f) Cartilaginous joint (pubic symphysis, with fibrous cartilage). Joints (a) to (d) are synovial.
Match Column I with Column II: (a) Smooth muscle, (b) Tropomyosin, (c) Red muscle, (d) Skull; (i) Myoglobin, (ii) Thin filament, (iii) Sutures, (iv) Involuntary.Answer: (a)-(iv), (b)-(ii), (c)-(i), (d)-(iii).

Common Mistakes to Avoid

Watch out

Calling the knee a ball and socket joint. Correct: the knee is a hinge joint.
Swapping the gliding and saddle joints. Correct: gliding is between the carpals; saddle is between the carpal and metacarpal of the thumb.
Saying cartilaginous joints allow no movement. Correct: they allow limited movement; fibrous joints allow none.
Thinking tetany is due to excess calcium. Correct: it is due to low calcium ions in body fluid.
Linking arthritis to uric acid. Correct: arthritis is inflammation of joints; gout is the one due to uric acid crystals.
Calling myasthenia gravis a genetic disorder. Correct: it is autoimmune; muscular dystrophy is mostly genetic.
Writing that osteoporosis increases bone mass. Correct: it decreases bone mass and raises the chance of fractures.
Placing the pivot joint between the skull and the atlas. Correct: it lies between the atlas and the axis.

Frequently Asked Questions

What is a joint and how does it help in movement?

A joint is a point of contact between bones, or between bones and cartilages. The force generated by muscles moves the bones through the joints, and the joint acts as a fulcrum for this movement. Joints are therefore essential for all movements of bony parts, including locomotion.

What are the three types of joints?

Structurally, joints are fibrous, cartilaginous or synovial. Fibrous joints, such as the sutures of the skull, allow no movement. Cartilaginous joints, such as those between adjacent vertebrae, allow limited movement. Synovial joints have a fluid-filled synovial cavity and allow considerable movement.

What is a synovial joint?

A synovial joint is a joint with a fluid-filled synovial cavity between the articulating surfaces of the two bones. This arrangement allows considerable movement, so synovial joints help in locomotion and many other movements. The ball and socket, hinge, pivot, gliding and saddle joints are all synovial joints.

Give five examples of synovial joints.

Ball and socket joint: between the humerus and the pectoral girdle. Hinge joint: the knee joint. Pivot joint: between the atlas and the axis. Gliding joint: between the carpals. Saddle joint: between the carpal and the metacarpal of the thumb. NEET often pairs these in match-the-list questions.

Why do fibrous joints not allow movement?

In fibrous joints, the flat skull bones fuse end-to-end with the help of dense fibrous connective tissue, forming sutures. Because the bones are firmly fused in this way, no movement is possible between them. Such sutures join the flat bones to form the cranium, which protects the brain.

What is the difference between arthritis and gout?

Arthritis is inflammation of joints in general. Gout is a particular inflammation of joints caused by the accumulation of uric acid crystals in them. So both affect joints, but only gout is defined by its cause, the deposit of uric acid crystals.

What causes tetany?

Tetany is a disorder of muscle in which rapid spasms, or wild contractions, occur. It is caused by a low level of calcium ions in body fluid. A common exam trap states that tetany is due to high calcium; that statement is false.

What is osteoporosis and what causes it?

Osteoporosis is an age-related disorder of bone in which bone mass decreases and the chances of fractures increase. A decreased level of the hormone estrogen is a common cause. It differs from arthritis and gout, which are inflammations of joints rather than a loss of bone mass.

Previous year questions on Joints

1 question from past papers, each with a step-by-step solution.

NEET 2023, Biology Q50

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