ATI RN
Muscular System Test Questions Questions
Question 1 of 5
The nurse is assessing the patient s crutches. The nurse recognizes that correctly sized crutches are:
Correct Answer: C
Rationale: Crutches must fit to support posture and arm movement, typically measured as 16-18 inches below the patient's height or 2-3 finger-widths below the axilla when standing. This allows a 20-30 degree elbow bend for comfort and leverage. Shoulder height would be too tall, risking nerve damage under the arms. Twelve inches below shoulders is imprecise and often too short. Fully extended arms would overstretch, reducing control. The height-based measure ensures the crutches align with the torso and arms, providing stability and preventing strain, making it the standard for correct sizing across diverse body types.
Question 2 of 5
A muscle that has an action opposite that of the prime mover (agonist) and yields to the movement of the prime mover.
Correct Answer: C
Rationale: An antagonist is a muscle that opposes the action of the prime mover (agonist) and relaxes or yields to allow the intended movement to occur. For instance, when the biceps brachii (agonist) flexes the elbow, the triceps brachii (antagonist) extends it, working in opposition. This relationship ensures smooth, controlled motion and prevents overstretching. Compartment refers to a group of muscles, not an individual muscle's action. Anal triangle is a pelvic region, unrelated to muscle function in this context. Synergists assist the prime mover, not oppose it. The antagonist's role in opposing and yielding to the prime mover is a fundamental concept in muscle dynamics, making it the correct answer here, as it directly contrasts with the agonist's action while facilitating coordinated movement.
Question 3 of 5
Most muscles cross at least one
Correct Answer: B
Rationale: Most skeletal muscles cross at least one joint to produce movement, as their primary function is to move bones around joints by contracting between their origin and insertion. For example, the biceps brachii crosses the elbow joint to flex the forearm. Tendons connect muscles to bones but aren't crossed by muscles. Bones are attachment points, not crossed entities. Ligaments connect bones to bones, not typically spanned by muscles in this context. Joints are the correct answer, as muscles' biomechanical role hinges on crossing them to facilitate motion, a fundamental principle in musculoskeletal anatomy evident in nearly every bodily action.
Question 4 of 5
If one is stabbed on the lateral side of the abdomen, what abdominal muscles, in order from superficial to deep, will the knife go through?
Correct Answer: B
Rationale: On the lateral abdomen, the muscle layers from superficial to deep are external oblique, internal oblique, and transversus abdominis. The external oblique runs diagonally downward and medially, the internal oblique courses upward and medially, and the transversus abdominis runs horizontally, deepest of the three, compressing the abdomen. Rectus abdominis is midline, not lateral, so it's excluded. Other options misorder the layers or include incorrect muscles. External oblique, internal oblique, transversus abdominis is the correct sequence, as it follows the anatomical layering of the lateral abdominal wall, critical for surgical or assessments.
Question 5 of 5
Which muscle forcefully closes the jaw and is also superficial?
Correct Answer: D
Rationale: The masseter forcefully closes the jaw during chewing and is superficial, lying over the mandible's ramus, easily palpable. Temporalis, also a jaw closer, is deeper under the scalp. Lateral pterygoid protrudes and depresses the jaw, not closing it forcefully, and is deep. Medial pterygoid closes the jaw but is deep to the masseter. Masseter's superficial position and power make it the correct answer, as it's the primary, visible jaw-closing muscle, vital for mastication.