BiologyCBSE Class 11 · Locomotion and Movement

The Human Skeleton: Axial and Appendicular Bones, Joints and Disorders

Updated 17 October 2026 · Fact-checked

The adult human skeleton has 206 bones and some cartilages, divided into the axial skeleton of 80 bones (skull 22, hyoid 1, ear ossicles 6, vertebral column 26, sternum 1, ribs 24) and the appendicular skeleton of 126 bones (girdles and limbs). Joints are fibrous, cartilaginous or synovial, with synovial types such as ball and socket, hinge, pivot, gliding and saddle. Common disorders are arthritis, osteoporosis and gout.

Understand Human Skeleton, Joints and Disorders

Functions of the skeleton. Support, protection of soft organs, attachment for muscles, movement (as levers), blood cell formation (marrow). The adult human skeleton has 206 bones (and a few cartilages). Two divisions:

Axial skeleton (80 bones).

Skull (22 bones): cranial bones 8 (frontal 1, parietal 2, temporal 2, occipital 1, sphenoid 1, ethmoid 1) and facial bones 14 (maxilla 2, mandible 1, zygomatic 2, palatine 2, lacrimal 2, nasal 2, inferior nasal conchae 2, vomer 1). 8 + 14 = 22. The skull articulates with the vertebral column through two occipital condyles (dicondylic skull).
Hyoid (1) and ear ossicles (6): malleus, incus, stapes in each ear. These are counted separately from the 22 skull bones.
Vertebral column (26 bones): cervical 7, thoracic 12, lumbar 5, sacral 1 (fused 5), coccygeal 1 (fused 4): 7 + 12 + 5 + 1 + 1 = 26. The first cervical vertebra is the atlas, which articulates with the occipital condyles. The column protects the spinal cord, supports the head and gives attachment to ribs and back muscles.
Sternum (1): flat bone on the ventral midline of the thorax.
Ribs (12 pairs = 24): true ribs (first seven pairs; attach to sternum through hyaline cartilage), false ribs (8th to 10th pairs; attach indirectly to the 7th rib's cartilage) and floating ribs (11th and 12th pairs; not attached ventrally). Ribs, thoracic vertebrae and sternum form the rib cage.
Total: 22 + 1 + 6 + 26 + 1 + 24 = 80.

Appendicular skeleton (126 bones).

Pectoral girdle: clavicle 1 and scapula 1 on each side (4 bones in all); the glenoid cavity receives the head of the humerus.
Upper limb (each): humerus 1, radius 1, ulna 1, carpals 8, metacarpals 5, phalanges 14 = 30; both limbs = 60.
Pelvic girdle: two coxal bones, each formed by ilium, ischium and pubis fused; the acetabulum receives the head of the femur. Pelvic girdle = 2.
Lower limb (each): femur 1 (the longest bone), tibia 1, fibula 1, patella 1, tarsals 7, metatarsals 5, phalanges 14 = 30; both limbs = 60.
Total: 4 + 60 + 2 + 60 = 126. Grand total: 80 + 126 = 206.

Joints. Points of contact between bones or between bone and cartilage; force generated by muscles is used to carry out movement at joints.

Fibrous joints: no movement; dense fibrous connective tissue; sutures of the skull.
Cartilaginous joints: bones joined by cartilage; limited movement; joints between adjacent vertebrae.
Synovial joints: a fluid-filled synovial cavity allows considerable movement: ball and socket (shoulder, hip), hinge (knee, elbow), pivot (atlas and axis), gliding (between carpals), saddle (carpal and metacarpal of the thumb).

Disorders. Myasthenia gravis (autoimmune, affects neuromuscular junction, fatigue, weakness); muscular dystrophy (progressive degeneration of skeletal muscle, mostly genetic); tetany (rapid spasms due to low Ca²⁺ in body fluid); arthritis (inflammation of joints); osteoporosis (decreased bone mass, increased fracture risk; decline in oestrogen is a common cause); gout (inflammation of joints due to accumulation of uric acid crystals).

Draw and label: the human skeleton showing axial and appendicular parts, or a synovial joint.

Human Skeleton, Joints and Disorders: key facts

Total: $206 = 80 a x ia l + 126 a pp e n d i c u l a r$; Adult human
Axial: $S k u l l 22 + h y o i d 1 + e a r oss i c l es 6 + v er t e b r a l co l u mn 26 + s t er n u m 1 + r ib s 24 = 80$; Parts
Appendicular: $G i r d l es 4 + 2 + l imb s 60 + 60 = 126$; Parts
Vertebrae: $7 cer v i c a l ∣12 t h or a c i c ∣5 l u mba r ∣1 s a cr a l ∣1 coccy g e a l$; 26 in all

How to answer Human Skeleton, Joints and Disorders questions

Questions give a bone or joint and ask for its category, or ask for totals.

1Decide axial or appendicular.
2For totals, add the parts and check against 80 and 126.
3For joints, decide fibrous, cartilaginous or synovial from movement allowed.
4Name an example for each joint type.
5Link a disorder to its cause.

Human Skeleton, Joints and Disorders in real life

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

Door hinge and shoulder

Suppose a student compares an elbow, which swings in one plane like a door, with the shoulder, which rotates widely.

Name the joint types.

Try it first, then show the solutionSolution

Elbow is a hinge joint (one plane).
Shoulder is a ball and socket joint (many directions).
Both are synovial joints with synovial fluid.

Answer: Hinge (elbow); ball and socket (shoulder).

Memory hook: Door means hinge; ball swivels.

Tricks to remember Human Skeleton, Joints and Disorders

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

206 = 80 + 126
Axial 80; appendicular 126.
Use it when: Totals
Cervical 7, thoracic 12, lumbar 5
7-12-5 then fused sacrum and coccyx.
Use it when: Vertebrae
Hinge elbow, ball hip
Elbow hinge; hip ball and socket.
Use it when: Joints

Human Skeleton, Joints and Disorders: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Bone counts · 3 marks · Short answerBoard level

Calculate the number of bones in the axial skeleton, showing the skull and vertebral column.

Try it first, then show the solutionSolution

Skull: 8 + 14 = 22; hyoid 1 and ear ossicles 6 (1 mark).
Vertebral column: 7 + 12 + 5 + 1 + 1 = 26 (1 mark).
Axial = 22 + 1 + 6 + 26 + 1 + 24 = 80 (1 mark).

Answer: 80 bones.

Example 2: Joints · 2 marks · Very short answerBoard level

Classify each as fibrous, cartilaginous or synovial and name the synovial type: (a) sutures of the skull (b) knee (c) joint between two vertebrae (d) shoulder.

Try it first, then show the solutionSolution

(a) fibrous; (b) hinge (synovial) (1 mark).
(c) cartilaginous; (d) ball and socket (synovial) (1 mark).

Answer: Fibrous, hinge, cartilaginous, ball and socket.

Example 3: Appendicular count · 3 marks · Short answerHarder board level

Show that the appendicular skeleton has 126 bones.

Try it first, then show the solutionSolution

Pectoral girdle 4; pelvic girdle 2 (1 mark).
Each limb: upper 1+1+1+8+5+14 = 30; lower 1+1+1+1+7+5+14 = 30 (1 mark).
Total = 4 + 2 + 60 + 60 = 126 (1 mark).

Answer: 126 bones.

Example 4: Ribs · 3 marks · Short answerHarder board level

Classify the 12 pairs of ribs into true, false and floating, and give the number of ribs in each category.

Try it first, then show the solutionSolution

True: 7 pairs = 14 ribs (1 mark).
False: 3 pairs = 6 ribs (1 mark).
Floating: 2 pairs = 4 ribs; total 24 (1 mark).

Answer: 14, 6 and 4 ribs.

Example 5: Osteoporosis in older women · 5 marks · Long answerHOTS / competency

Suppose an older woman has a minor fall and breaks a hip. Link this to a skeletal disorder, a likely hormonal cause, and name a preventive measure and a different joint disorder with its cause.

Try it first, then show the solutionSolution

Osteoporosis: decrease in bone mass and increased risk of fractures (1 mark).
Fall in oestrogen after menopause is a common cause (1 mark).
Prevention: calcium and vitamin D rich diet and exercise (1 mark).
Gout: inflammation of joints due to uric acid crystals (1 mark).
Arthritis is general joint inflammation (1 mark).

Answer: Osteoporosis; low oestrogen; calcium intake.

Where students lose marks in Human Skeleton, Joints and Disorders

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

Mistake: Cervical vertebrae 8
Count error.
Wrong working
Neck has 8 vertebrae.
Right working
7 cervical vertebrae.
Do this: 7.
Usually costs: 1 mark.
Mistake: Sternum in appendicular
Division error.
Wrong working
Sternum is appendicular.
Right working
Sternum is axial.
Do this: Axial.
Usually costs: 1 mark.
Mistake: Hinge for hip
Joint mix.
Wrong working
Hip is a hinge joint.
Right working
Hip is ball and socket.
Do this: Ball.
Usually costs: 1 mark.

Exam tips

Show additions for bone counts.
Name examples for each joint.
Use correct terms: true, false, floating ribs.
Link disorders to causes.

Practice questions on Human Skeleton, Joints and Disorders

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 · MCQBoard level
The skull articulates with the vertebral column through
(a) one condyle (b) two occipital condyles (c) three condyles (d) none
Hint
Dicondylic.
Answer
(b).
Q2 · 1 mark · Assertion-reasonHarder board level
Assertion (A): The glenoid cavity is part of the pectoral girdle.
Reason (R): It receives the head of the humerus.
(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.
Hint
Socket.
Answer
(b).
Q3 · 2 marks · Very short answerHarder board level
How many bones are present in the human hand (carpals, metacarpals and phalanges) and in both feet in the same categories? Show working.
Hint
Per limb.
Answer
One hand: 8 + 5 + 14 = 27. One foot: 7 + 5 + 14 = 26. Both feet = 52.
Q4 · 4 marks · Case-basedHarder board level
Read and answer.
Suppose an X-ray shows a patient with fused sacral vertebrae and a joint between atlas and axis allowing head turning.
(a) How many vertebrae are fused in the sacrum (count as stated in textbooks)? (1)
(b) Name the joint type at atlas and axis. (1)
(c) Name the first cervical vertebra. (2)
Hint
Pivot.
Answer
(a) Sacrum is a single bone made of five fused vertebrae. (b) Pivot joint. (c) Atlas, which articulates with the skull.
Q5 · 3 marks · Short answerHOTS / competency
Suppose a person has low blood calcium and shows rapid muscle spasms. Name the condition, the link with muscle contraction, and a difference from myasthenia gravis.
Hint
Ca2+.
Answer
Tetany, caused by low Ca2+ in body fluids; calcium regulates excitability and contraction. Myasthenia gravis is an autoimmune disorder of the neuromuscular junction that causes weakness, not spasms.

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.Total bones?Show answer
206.
2.Longest bone?Show answer
Femur.
3.Thoracic vertebrae?Show answer
12.
4.Joint at the knee?Show answer
Hinge.
5.Cause of gout?Show answer
Uric acid crystals.
6.Cranial bones?Show answer
8.

Human Skeleton, Joints and Disorders: frequently asked questions

What is the axial skeleton?

Skull (22 bones), hyoid, ear ossicles, vertebral column, sternum and ribs: 80 bones in all.

What is a synovial joint?

A freely movable joint with fluid cavity.

What is osteoporosis?

Reduced bone mass.

What are floating ribs?

Ribs 11 and 12 with no ventral attachment.

How many ear ossicles?

Six (three in each ear).