which muscle is responsible for the extension of the elbow

HESI A2

HESI A2 Anatomy and Physiology Practice Test 2023

1. Which muscle is responsible for the extension of the elbow?

A. Biceps brachii
B. Triceps brachii
C. Deltoid
D. Pectoralis major

Correct answer: B

Rationale: The correct answer is B: Triceps brachii. The triceps brachii muscle is responsible for extending the elbow joint. It is located on the back of the upper arm and acts in opposition to the biceps brachii, which is responsible for elbow flexion. The deltoid muscle is primarily responsible for shoulder abduction, not elbow extension. The pectoralis major muscle is involved in movements of the shoulder joint, not the elbow.

2. Which type of blood cell is involved in clotting?

A. Red blood cells
B. White blood cells
C. Platelets
D. Plasma

Correct answer: C

Rationale: Platelets, also known as thrombocytes, are cell fragments that play a crucial role in blood clotting and wound healing. They are responsible for forming blood clots to stop bleeding when a blood vessel is injured, making them the correct choice in this context. Red blood cells (Choice A) are primarily involved in oxygen transport, white blood cells (Choice B) are part of the immune system, and plasma (Choice D) is the liquid component of blood that carries various substances.

3. Which bones do the rotator cuff help to stabilize?

A. Radius and humerus
B. Scapula and clavicle
C. Humerus and scapula
D. Ulna and radius

Correct answer: C

Rationale: The correct answer is C: Humerus and scapula. The rotator cuff is a group of muscles and tendons that help stabilize the shoulder joint. Specifically, the rotator cuff muscles help to stabilize the head of the humerus (the upper arm bone) within the shallow socket of the scapula (shoulder blade). This stabilizing action is crucial for maintaining shoulder joint function and preventing injuries. Choices A, B, and D are incorrect because the rotator cuff primarily stabilizes the humerus and scapula, not the radius, ulna, or clavicle.

4. What is the primary role of the stomach in the digestive system?

A. To absorb nutrients
B. To break down food
C. To secrete digestive enzymes
D. To store glucose

Correct answer: B

Rationale: The primary role of the stomach in the digestive system is to break down food. It accomplishes this through the action of gastric acid and digestive enzymes, which work together to break down food into a semi-liquid mixture known as chyme. Option B, 'To break down food,' is the correct answer. Option A, 'To absorb nutrients,' is incorrect because absorption mainly occurs in the small intestine. Option C, 'To secrete digestive enzymes,' is partially correct as the stomach does secrete digestive enzymes, but its primary function is to break down food. Option D, 'To store glucose,' is incorrect as glucose storage primarily occurs in the liver and muscles, not the stomach.

5. To which system do the ovaries belong?

A. skeletal system
B. nervous system
C. lymphatic system
D. reproductive system

Correct answer: D

Rationale: The correct answer is D: reproductive system. The ovaries are essential organs of the female reproductive system. They play a vital role in producing eggs and secreting hormones like estrogen and progesterone. The skeletal system (choice A) consists of bones and tissues that support the body, the nervous system (choice B) controls body functions and responses, and the lymphatic system (choice C) helps the body fight off infections. Therefore, the ovaries belong to the reproductive system.