Which is the only bone in the human body that is not joined to any other bone?
- A.Hyoid
- B.Patella
- C.Clavicle
- D.Sternum
Correct answer
Explanation
The correct answer is A, the hyoid. The hyoid is a U-shaped or horseshoe-shaped bone lying in the front of the neck below the lower jaw; it is held in place only by muscles and ligaments and forms no joint with any other bone, which is why it supports the tongue and helps in speech and swallowing. Option B is wrong because the patella, the kneecap, is a sesamoid bone but still lies within the knee joint between the femur and the tibia. Option C is wrong because the clavicle, the collarbone, joins the sternum at one end and the shoulder blade at the other, and is the most frequently fractured bone. Option D is wrong because the sternum, the breastbone, is joined to the clavicles and to the cartilages of the ribs.
Read the full article: Human Body Important Facts for Competitive Exams
Practice Questions
View allWhich is the smallest bone in the human body?
- A.Stapes
- B.Malleus
- C.Incus
- D.Hyoid
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The stapes, shaped like a stirrup, is the innermost of the three ossicles of the middle ear and is the smallest bone in the human body, measuring only a few millimetres; the smallest muscle of the body, the stapedius, is attached to it.
Read the full explanation →How many bones are there in the body of an adult human being?
- A.186
- B.206
- C.256
- D.300
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The adult human skeleton has 206 bones, of which 80 belong to the axial skeleton, that is the skull, vertebral column and chest, and 126 to the appendicular skeleton of the limbs and girdles.
Read the full explanation →Which is the largest gland in the human body?
- A.Thyroid
- B.Pancreas
- C.Liver
- D.Pituitary
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The liver weighs about one and a half kilograms and is both the largest gland and the largest internal organ of the body; it secretes bile, stores glycogen, iron and vitamin A, converts ammonia into urea and detoxifies drugs and poisons.
Read the full explanation →Which structure is called the pacemaker of the human heart?
- A.Atrio-ventricular node
- B.Sino-atrial node
- C.Bundle of His
- D.Purkinje fibres
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The sino-atrial node is a small patch of specialised muscle tissue in the wall of the right atrium near the opening of the superior vena cava, and it generates the impulse that sets the rate of each heartbeat without any outside stimulus, which is why it is called the pacemaker.
Read the full explanation →What is the average life span of a red blood cell in the human body?
- A.About 10 days
- B.About 60 days
- C.About 120 days
- D.About 365 days
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Red blood cells are produced in the red bone marrow, lose their nucleus on maturing and survive roughly four months, after which they are broken down in the spleen, which is accordingly called the graveyard of red blood cells; the iron released from their haemoglobin is used again.
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