Human Skeletal and Muscular Systems

Biology, HSSC-Punjab First Year. This chapter is split into 26 topics and has 636 practice questions. The topics covered are listed below, followed by 10 free sample questions from the chapter.

Topics in this chapter

1. Skeletal injuries and first aid (dislocation and sprain) 25 questions
2. Cartilage: structure and types 25 questions
3. Skeletal muscle: fibres, myofibrils and myofilaments 25 questions
4. Skeletal disorders: vertebral problems, sciatica and osteoporosis 25 questions
5. Axial skeleton: the skull 25 questions
6. Joints: types and joint transplantation 25 questions
7. Vertebral column and appendicular skeleton 25 questions
8. Bone cells, marrow, ossification and bone growth 25 questions
9. Chapter review: skeletal and muscular systems (end-of-chapter exercise focus) 25 questions
10. Mechanism of muscle contraction and muscle disorders 25 questions
11. Muscles: types and general structure 25 questions
12. Skeletal system overview and bone tissue structure 25 questions
13. Arthritis: osteoarthritis, rheumatoid arthritis and gout (Figure 12.14) 24 questions
14. Antagonistic muscles: origin, insertion, flexors and extensors (Figures 12.24 and 12.25) 26 questions
15. Skeleton as a lever system and why muscles pull but do not push 20 questions
16. Bipedal posture and problems due to improper posture 23 questions
17. Joint transplantation: replacement, allograft and chondrocyte implantation 21 questions
18. Joint types and the synovial joint in detail (Figure 12.10) 20 questions
19. Skull, ear bones and vertebral column: counts and figures 24 questions
20. Rib cage, girdles and limb bones: counts and features 29 questions
21. Bone and cartilage figures, bone cells and ossification (Figures 12.1 to 12.4) 25 questions
22. Muscle tissues compared: Figure 12.19 and the comparison table 20 questions
23. Myofilaments, nerve impulse and cross-bridge cycle in detail (Figures 12.21 to 12.23) 24 questions
24. Muscle fatigue, cramps, tetany and tetanus in detail 25 questions
25. Disc slip, spondylosis, sciatica and joint injuries: figures and applications 28 questions
26. Chapter exercise: structured answers on the skeleton and muscles 27 questions

Sample questions: Human Skeletal and Muscular Systems

10 sample questions with the correct answer and an explanation. Try to answer each one before reading the explanation.

Q1. Which statement correctly describes an event of muscle contraction?

• A. Myosin heads bind to troponin.
• B. ATP is used to detach the myosin head from actin.(correct answer)
• C. ATP binds to the actin binding site.
• D. Troponin blocks the binding sites.

Answer: B.During the cross-bridge cycle, the binding of ATP to the myosin head is used to detach it from actin so that the cycle can repeat. Myosin heads bind to actin (not troponin), and the binding sites are exposed, not blocked, during contraction.

Q2. Which of the following statements correctly differentiates tetany from tetanus?

• A. Tetany is more serious and potentially life-threatening than tetanus.
• B. Tetany is caused by a bacterial infection, while tetanus is caused by an electrolyte imbalance.
• C. Tetany mainly affects the jaw and neck muscles, while tetanus mainly affects the hands, feet and face.
• D. Tetanus is caused by Clostridium tetani, whose toxin affects the nervous system and causes muscle stiffness and spasms.(correct answer)

Answer: D.Tetanus is a severe bacterial infection caused by Clostridium tetani whose toxin affects the nervous system, leading to muscle stiffness and spasms. Tetany is a different condition caused by issues such as electrolyte imbalances or nerve problems and is less serious than tetanus.

Q3. Which sequence correctly describes the early steps in the ossification of a long bone?

• A. Blood vessels penetrate first -> cartilage calcifies -> chondrocytes die -> bone tissue is built
• B. The cartilage centre calcifies -> chondrocytes die leaving cavities -> blood vessels penetrate and introduce osteoblasts and osteoclasts -> bone tissue is built(correct answer)
• C. Chondrocytes die first -> blood vessels penetrate -> the cartilage centre calcifies -> bone tissue is built
• D. Osteoblasts build bone -> chondrocytes die -> the cartilage centre calcifies

Answer: B.The centre of cartilage begins to harden (calcify) and the chondrocytes in this area die, leaving cavities; blood vessels then penetrate these cavities and introduce osteoblasts and osteoclasts, and the osteoblasts start building bone tissue.

Q4. Which of the following correctly pairs a type of synovial joint with the movement it allows?

• A. Hinge joint - movement in two planes but no rotation, as in the joint of the wrist with radius
• B. Ball-and-socket joint - movement in only one plane, like a door hinge
• C. Gliding joint - movement in all directions, as in the shoulder and hip joints
• D. Pivot joint - rotational movement around a single axis, as in the joint between the first and second vertebrae of the neck(correct answer)

Answer: D.Pivot joints allow rotational movement around a single axis, e.g. between the first and second vertebrae of the neck. Hinge joints move in one plane only, ball-and-socket joints allow motion in all directions, and gliding joints permit gliding movements between bones.

Q5. A physiotherapist notes that a patient can bend the wrist up and down and move it from side to side, but the wrist itself cannot rotate. Based on this range of motion, the joint of the wrist with the radius is classified as:

• A. Pivot joint
• B. Ellipsoidal joint(correct answer)
• C. Saddle joint
• D. Ball-and-socket joint

Answer: B.Ellipsoidal joints allow movement in two planes but not rotation, e.g. the joint of the wrist with radius. Saddle joints also move in two planes but involve concave and convex surfaces (thumb joint), while pivot joints allow rotation about a single axis.

Q6. Which of the following best explains how a synovial joint achieves smooth, frictionless movement?

• A. Articular cartilage covers the ends of the bones, and the synovial membrane secretes synovial fluid that lubricates the joint(correct answer)
• B. The bones are directly connected to each other by fibrous connective tissue consisting mainly of collagen
• C. A layer of cartilage connects the bones and allows only a little movement
• D. Strong bands of connective tissue called ligaments secrete fluid into the joint cavity

Answer: A.In synovial joints, smooth, tough, elastic articular cartilage covers the ends of the bones, and the synovial membrane, the inner lining of the fibrous capsule, secretes synovial fluid that lubricates the joint. Ligaments connect the bones but do not secrete fluid, and options A and B describe fibrous and cartilaginous joints.

Q7. If the ligaments that form part of the fibrous capsule of a synovial joint are badly torn, the most likely immediate consequence is that:

• A. The bones of the joint are no longer held firmly together, so the joint becomes unstable(correct answer)
• B. The articular cartilage is converted into fibrocartilage
• C. The joint becomes a permanently immovable fibrous joint
• D. The synovial membrane stops secreting synovial fluid

Answer: A.Ligaments are strong bands of connective tissue that connect the bones in a joint, and the fibrous capsule helps hold the bones together, so tearing them destabilizes the joint. Fluid secretion is a function of the synovial membrane, and a joint does not change its type after such an injury.

Q8. Which of the following correctly matches a type of joint transplantation with its description?

• A. Total joint replacement - only the damaged part of the joint is replaced with an artificial component, often used in the knee joint
• B. Partial joint replacement - the entire damaged joint is replaced with an artificial joint made of metal, plastic or ceramic
• C. Chondrocyte implantation - an artificial ceramic joint is implanted after all of the patient's chondrocytes are removed
• D. Allograft transplantation - a healthy joint from a donor is transplanted to replace the damaged joint, often used in the ankle and knee joints(correct answer)

Answer: D.In allograft transplantation a healthy joint from a donor is transplanted to replace the damaged joint and it is often used in ankle and knee joints. In total replacement the entire joint is replaced with an artificial joint, partial replacement replaces only the damaged part, and chondrocyte implantation uses chondrocytes from the patient's own joint.

Q9. Which statement best distinguishes spondylosis from a slipped (herniated) disc?

• A. Spondylosis affects only the wrist and hands, whereas a slipped disc affects only the knee
• B. Spondylosis involves degeneration with narrowing and fusion of discs and bone outgrowths, whereas a slipped disc involves rupture of the disc's outer layer with leakage of its gel-like contents(correct answer)
• C. Spondylosis is an autoimmune disorder, whereas a slipped disc is always an infection
• D. Spondylosis is caused by uric acid crystals, whereas a slipped disc is caused by calcium deficiency

Answer: B.In spondylosis, degeneration of vertebrae, discs, ligaments or cartilage leads to narrowing and fusion of the disc and bone outgrowths; in a slipped disc the outer layer of the disc tears or ruptures and its inner gel-like substance leaks out.

Q10. Which combination of measures would best reduce the risk of osteoporosis, according to the text?

• A. Long-term corticosteroid therapy with prolonged bed rest
• B. Regular smoking and alcohol consumption
• C. Adequate dietary calcium and vitamin D, weight-bearing exercise, and avoiding smoking and alcohol(correct answer)
• D. A low-calcium diet and avoidance of all exercise

Answer: C.A lack of calcium and vitamin D, lack of weight-bearing exercise, smoking and alcohol consumption all increase the risk of osteoporosis; adequate calcium, vitamin D and weight-bearing exercise while avoiding smoking and alcohol therefore help reduce the risk.