Skeletal System Practice Questions
20 free Skeletal System practice questions for the General Science. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which of the following bones is part of the axial skeleton?
- A Clavicle
- B Sphenoid
- C Scapula
- D Femur
Correct answer: Sphenoid
The sphenoid bone is a complex bone of the skull, which is a central component of the axial skeleton. The clavicle, scapula, and femur are all parts of the appendicular skeleton, which includes the limbs and their girdles.
The structural unit of compact bone, consisting of concentric lamellae surrounding a central canal, is called a(n):
- A Lacuna
- B Trabecula
- C Osteon
- D Canaliculus
Correct answer: Osteon
The osteon, or Haversian system, is the fundamental functional unit of much compact bone. It consists of a central canal containing blood vessels, surrounded by concentric rings of hard bone matrix.
Which type of bone cell is responsible for the resorption and breakdown of bone matrix?
- A Osteocyte
- B Osteoblast
- C Osteoclast
- D Osteoprogenitor cell
Correct answer: Osteoclast
Osteoclasts are large, multinucleated cells that dissolve bone minerals and digest the organic matrix. This process is essential for bone remodeling, growth, and the regulation of calcium levels in the blood.
In a long bone, the shaft is anatomically known as the:
- A Epiphysis
- B Metaphysis
- C Diaphysis
- D Periosteum
Correct answer: Diaphysis
The diaphysis is the elongated, tubular shaft of a long bone, primarily composed of compact bone. The epiphyses are the expanded ends, and the metaphysis is the region where the shaft joins the ends.
Which of the following joints is classified as a 'ball-and-socket' joint?
- A Elbow joint
- B Glenohumeral joint
- C Knee joint
- D Interphalangeal joint
Correct answer: Glenohumeral joint
The glenohumeral (shoulder) joint is a multiaxial ball-and-socket joint where the rounded head of the humerus fits into the shallow glenoid cavity of the scapula. This type of joint allows for the greatest range of motion in multiple planes, making it the most mobile joint in the body.
What is the primary function of yellow bone marrow?
- A Production of red blood cells
- B Storage of triglycerides
- C Production of white blood cells
- D Immune system signaling
Correct answer: Storage of triglycerides
Yellow bone marrow consists mostly of adipose cells, which serve as a chemical energy reserve. While red marrow is responsible for hematopoiesis (blood cell production), yellow marrow can revert to red marrow in cases of severe anemia.
The first cervical vertebra (C1), which supports the skull and allows for the 'nodding' motion of the head, is the:
- A Axis
- B Atlas
- C Hyoid
- D Coccyx
Correct answer: Atlas
The atlas (C1) is the topmost vertebra and lacks a traditional vertebral body. It articulates with the occipital condyles of the skull, facilitating the up-and-down 'yes' motion.
Which hormone is released when blood calcium levels are too low, stimulating osteoclasts to break down bone?
- A Calcitonin
- B Thyroid-stimulating hormone
- C Parathyroid hormone
- D Insulin
Correct answer: Parathyroid hormone
Parathyroid hormone (PTH) is secreted by the parathyroid glands in response to hypocalcemia. It increases blood calcium levels by stimulating bone resorption and increasing calcium reabsorption in the kidneys.
Intramembranous ossification is the process primarily responsible for the formation of which bones?
- A Femur and tibia bones
- B Cranial flat bones
- C Vertebrae
- D Carpal bones
Correct answer: Cranial flat bones
Intramembranous ossification occurs when bone develops directly from mesenchymal connective tissue membranes. This process forms the flat bones of the skull, the mandible, and the clavicles.
Which of the following is the smallest bone in the human body?
- A Talus
- B Stapes
- C Lacrimal
- D Patella
Correct answer: Stapes
The stapes is one of the three auditory ossicles in the middle ear. It is approximately 3 millimeters long and is responsible for transmitting sound vibrations to the inner ear.
The 'soft spots' on an infant's skull where the bones have not yet fused are known as:
- A Bone sutures
- B Foramina
- C Fontanelles
- D Sinuses
Correct answer: Fontanelles
Fontanelles are fibrous membranes between the cranial bones of a fetus or infant. They allow the head to compress slightly during birth and accommodate the rapid growth of the brain during early childhood.
What type of tissue connects bone to bone, providing stability to joints?
- A Tendon
- B Ligament
- C Aponeurosis
- D Adipose
Correct answer: Ligament
Ligaments are tough bands of fibrous connective tissue that link bones together at a joint. Tendons, by contrast, connect muscles to bones to facilitate movement.
The epiphyseal plate is the site of:
- A Bone thickness increase (appositional growth)
- B Bone length increase (interstitial growth)
- C Red blood cell destruction
- D Articular cartilage repair
Correct answer: Bone length increase (interstitial growth)
The epiphyseal plate, or growth plate, is a layer of hyaline cartilage in the metaphysis of growing bones. New cartilage is produced on the epiphyseal side while older cartilage is ossified on the diaphyseal side, lengthening the bone.
Which of the following is considered a 'sesamoid' bone?
- A Sternum
- B Patella
- C Humerus
- D Parietal bone
Correct answer: Patella
Sesamoid bones are small, round bones that develop within tendons to protect them from excessive wear and tear. The patella (kneecap) is the largest and most well-known sesamoid bone in the body.
Which vitamin is essential for the absorption of calcium from the digestive tract into the blood?
- A Vitamin A
- B Vitamin C
- C Vitamin D
- D Vitamin K
Correct answer: Vitamin D
Vitamin D is converted into the hormone calcitriol, which stimulates the active transport of dietary calcium across the intestinal mucosa. A deficiency in Vitamin D can lead to bone softening diseases like rickets or osteomalacia.
The dense connective tissue membrane that covers the outer surface of bones, except at the joints, is the:
- A Endosteum
- B Perichondrium
- C Periosteum
- D Synovium
Correct answer: Periosteum
The periosteum consists of an outer fibrous layer and an inner osteogenic layer containing bone cells. It provides an attachment point for tendons and ligaments and contains the blood vessels that nourish the bone.
How many pairs of 'true ribs' (ribs that attach directly to the sternum) are found in the human body?
- A 5
- B 7
- C 10
- D 12
Correct answer: 7
The first 7 pairs of ribs are called true ribs (vertebrosternal ribs) because their costal cartilages attach directly to the sternum. Ribs 8-10 are 'false' ribs, and ribs 11-12 are 'floating' ribs.
Which cranial bone contains the 'foramen magnum,' the large opening through which the spinal cord connects to the brain?
- A Frontal bone
- B Parietal bone
- C Occipital bone
- D Temporal bone
Correct answer: Occipital bone
The occipital bone forms the posterior part of the skull and the base of the cranium. The foramen magnum is located at the base of this bone, serving as the passage for the medulla oblongata.
Symphyses, such as the pubic symphysis or the joints between vertebral bodies, are classified as:
- A Fibrous joints
- B Cartilaginous joints
- C Freely movable synovial joints
- D Diarthrotic joints
Correct answer: Cartilaginous joints
Symphyses are cartilaginous joints where the bones are connected by a broad, flat disc of fibrocartilage. They are amphiarthrotic, meaning they allow for slight movement and act as shock absorbers.
The microscopic canals that connect lacunae to one another, allowing osteocytes to communicate, are called:
- A Volkmann's canals
- B Canaliculi
- C Haversian canals
- D Lamellae
Correct answer: Canaliculi
Canaliculi are small channels that radiate from the lacunae, providing routes for nutrients to reach osteocytes and for waste to be removed. They also allow for gap junctions between the cytoplasmic processes of neighboring osteocytes.