Free Human Skeleton MCQs with Answers

11. The only freely movable bone of the skull is the

• A. maxilla
• B. mandible
• C. nasal bone
• D. zygomatic bone

Explanation: The mandible hinges at the temporomandibular joint, allowing chewing and speech, while every other skull bone is locked to its neighbours by sutures. The maxilla is the fixed upper jaw.

12. When the arm is bent at the elbow, the biceps contracts while the triceps

• A. contracts at the same time
• B. contracts even more strongly
• C. relaxes
• D. detaches from the bone

Explanation: Muscles can only pull, so the flexor biceps and the extensor triceps work as antagonists: one contracts while the other relaxes, and they swap roles when the arm is straightened. Both contracting together would lock the joint.

13. Skeletal muscles are attached to the bones they move by

• A. ligaments
• B. cartilage
• C. synovial fluid
• D. tendons

Explanation: Tendons are cords of tough collagen that tie muscle to bone and transmit the pull of contraction. Ligaments join bone to bone across a joint, and mixing these two up is one of the commonest slips in anatomy.

14. Which type of muscle is involuntary and non striated?

• A. Smooth muscle
• B. Skeletal muscle
• C. Cardiac muscle
• D. Biceps muscle

Explanation: Smooth muscle lines the gut, blood vessels and airways, contracting slowly and without conscious control. Skeletal muscle is striated and voluntary, while cardiac muscle is striated but involuntary, covering every combination between the three types.

15. A skeletal muscle fibre differs from most body cells in being

• A. without a plasma membrane
• B. multinucleated
• C. without any cytoplasm
• D. prokaryotic

Explanation: Each fibre is a long cylinder formed by the fusion of many cells, so it carries a row of nuclei beneath its membrane. This giant structure allows thousands of myofibrils to contract as one unit.

16. The strong bands of tissue that connect bone to bone across a joint are called

• A. tendons
• B. muscle fibres
• C. ligaments
• D. cartilage discs

Explanation: Ligaments stabilise a joint by tying the bones together while still permitting movement. Tendons attach muscle to bone, so the question to ask is what the band connects: bone to bone means ligament every time.

17. Two muscles that produce opposite movements at the same joint are described as

• A. synergists
• B. flexors only
• C. rotators
• D. antagonists

Explanation: Antagonistic pairs such as biceps and triceps allow controlled movement in both directions because muscles can pull but never push. Synergists assist one another, which is the opposite relationship.

18. The thick filaments of the sarcomere are composed mainly of the protein

• A. myosin
• B. actin
• C. troponin
• D. tubulin

Explanation: Myosin molecules form the thick filament, their heads projecting to pull on actin during contraction. Actin makes the thin filament, troponin regulates it, and tubulin builds microtubules, so each protein has its own place in the sarcomere.

19. ATP is required during muscle contraction for

• A. storing glycogen in the muscle
• B. detaching myosin heads from actin and pumping calcium back after contraction
• C. synthesising haemoglobin
• D. nothing once contraction has begun

Explanation: Each myosin head needs a fresh ATP to release actin and re-cock, and the calcium pump needs ATP to restore relaxation. Without ATP the heads stay locked, which is exactly what causes rigor mortis.

20. The light band of the myofibril that contains actin but no myosin is the

• A. A band
• B. H zone
• C. I band
• D. Z line

Explanation: The I band holds only thin actin filaments and shortens during contraction, while the A band spans the whole length of the myosin. The Z line bisects each I band and marks the boundary of the sarcomere.