Which statement best represents skeletal muscle?

Correct Answer: D

Rationale: Skeletal muscle fibers are multinucleate, formed by myoblast fusion during development, hosting dozens of nuclei per cell for protein synthesis supporting contraction. Unlike cardiac muscle, which contracts rhythmically via an intrinsic pacemaker (sinoatrial node), skeletal muscle lacks automaticity, relying on somatic motor neuron signals for voluntary action. Rhythmic contractions occur in cardiac muscle, not skeletal, though skeletal can sustain rhythmic activity (e.g., shivering) if neurally driven, not self-initiated. Uninucleate cells typify smooth muscle, not skeletal. The 'or' phrasing suggests potential for rhythmicity or pacemaker presence, but skeletal muscle's defining trait is voluntary, multinucleate structure without inherent rhythmicity. Histology confirms its striated, multinucleate fibers, contrasting with cardiac's pacemaker-driven rhythm or smooth's uninucleate spontaneity. Physiology texts emphasize this dependency on external innervation, distinguishing skeletal muscle's control and structure in locomotion.

Correct Answer: A

Rationale: Flaccid paralysis causes muscle limpness, increasing the risk of joint stiffness or deformity from prolonged immobility. Changing joint position is the priority to prevent contractures and maintain alignment, using careful support to avoid strain. Not using a footboard might prevent footdrop in some cases, but it's secondary to overall joint care. Moving only side to side limits flexibility and risks pressure sores, ignoring full-body needs. Avoiding pillows dismisses a tool for support, which isn't the issue positioning is. Adjusting joints takes precedence, as it directly addresses the paralysis-related risk of fixed postures, ensuring long-term mobility and comfort.

Correct Answer: B

Rationale: Pain on shoulder abduction, localized to the point of the shoulder after intense activity like racquetball, suggests bursitis inflammation of the subacromial bursa from overuse. This bursa cushions the rotator cuff, and repetitive overhead motions can irritate it, causing sharp pain during movement. A rotator cuff tear would likely limit strength and range more severely. Dislocation involves joint displacement, with visible deformity and acute trauma, not just post-game pain. Subluxation is partial dislocation, also unlikely without instability signs. Bursitis fits the acute, activity-triggered presentation, making it the nurse's likely suspicion, treatable with rest and anti-inflammatories.

Correct Answer: C

Rationale: The pelvic floor is divided into two main regions: the anal triangle and the urogenital triangle. The description provided inferior to the pubic symphysis, bounded by the pubic symphysis and ischial tuberosities, and containing the external genitalia specifically refers to the urogenital triangle. This region is located anteriorly in the perineum and includes structures such as the urethra and external genitalia in both males and females. The term deep is a directional descriptor and does not define a specific region. Fixators refers to muscles that stabilize the origin of a prime mover, unrelated to pelvic floor anatomy. Superficial is another directional term and does not match the detailed anatomical boundaries provided. Thus, urogenital triangle is the correct answer, as it precisely corresponds to the anatomical area described in the question, distinguishing it from other regions like the anal triangle.

Correct Answer: A

Rationale: The rotator (musculotendinous) cuff is a group of four muscles subscapularis, supraspinatus, infraspinatus, and teres minor whose tendons encircle the shoulder joint, providing stability and enabling a wide range of motion. This cuff strengthens the glenohumeral joint, preventing dislocation during activities like throwing. Deep is a positional term, not a structure. Perineum is the pelvic floor region, unrelated to the shoulder. The diaphragm is the breathing muscle. The rotator cuff's specific role and composition match the question, making it the correct answer, as it's a critical anatomical feature in shoulder function and a common site of injury in sports or aging.