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INI-SS practice questions

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Question 1Infection Control, Sanitation, and Safety

Under standard precautions, how should a healthcare worker treat a patient's intact skin and unsoiled linen when no infection is known?

  1. As completely safe, since standard precautions apply only to diagnosed infectious cases
  2. As requiring full airborne isolation until screening results return
  3. As safe to handle bare-handed but requiring a gown for all contact
  4. As potentially infectious, applying gloves only when contact with blood or body fluids is anticipated Correct answer.

Explanation

Standard precautions treat all blood, body fluids, secretions, excretions, non-intact skin, and mucous membranes as potentially infectious regardless of diagnosis. Gloves are indicated when contact with these materials is anticipated, not for routine touching of intact skin. This universal approach removes the need to know a patient's status before protecting oneself.

Question 2Infection Control, Sanitation, and Safety

A sterile field has been prepared for a wound dressing change. Which action maintains its sterility?

  1. Holding sterile supplies at the edge of the field during transfer
  2. Setting the field up more than an hour before the procedure
  3. Allowing the field to rest at waist level during the procedure
  4. Reaching across the field to place a swab while keeping the arm above it Correct answer.

Explanation

Reaching across a sterile field is acceptable only if the arm stays above the field and does not touch it; the field itself remains sterile. Supplies must be dropped from a safe height, the field must be created immediately before use, and it must stay above waist level. Any contact with non-sterile surfaces or prolonged exposure compromises sterility.

Question 3Infection Control, Sanitation, and Safety

Which statement correctly describes the sequence of donning personal protective equipment before a procedure requiring gown, mask, and gloves?

  1. Don mask, then gloves, then gown, then perform hand hygiene
  2. Perform hand hygiene, don gloves, don mask, then don gown
  3. Don gloves first, then gown, then mask, then perform hand hygiene
  4. Perform hand hygiene, don gown, don mask or respirator, then don gloves Correct answer.

Explanation

Hand hygiene comes first, followed by the gown, then the mask or respirator, and gloves last so they cover the gown cuffs. Gloves are removed first during doffing because they are the most contaminated item. Following this order minimizes transfer of organisms to the worker's skin and clothing.

Question 4Infection Control, Sanitation, and Safety

After removing gloves following contact with a patient's wound drainage, what is the correct immediate action?

  1. Apply fresh gloves without hand hygiene
  2. Rinse gloves and reuse them for the next patient
  3. Perform hand hygiene with soap and water or an alcohol-based rub Correct answer.
  4. Wipe hands on the gown and continue

Explanation

Hand hygiene is required immediately after glove removal because gloves may have tiny defects and hands can become contaminated during doffing. Alcohol-based rub is acceptable when hands are not visibly soiled; soap and water is used when they are. Gloves are single-use and never substitute for hand hygiene.

Question 5Infection Control, Sanitation, and Safety

A spill of blood occurs on a hard floor. Which initial step follows correct bloodborne pathogen spill management?

  1. Spray the area with air freshener and leave it to dry
  2. Blot the spill with paper towels and discard them in a regular waste bin
  3. Sweep the spill into a corner and mop it with plain water
  4. Contain and clean the spill after donning gloves, then disinfect the area with an appropriate agent Correct answer.

Explanation

Blood spills are managed by limiting access, donning gloves and other PPE as needed, removing visible material, and disinfecting with a tuberculocidal or appropriately diluted bleach solution. Absorbents and waste are placed in biohazard bags. Prompt disinfection reduces exposure risk to staff and patients.

Question 6Infection Control, Sanitation, and Safety

Which practice is required when handling used sharps in a clinical area?

  1. Place sharps immediately into a puncture-resistant container located close to the point of use Correct answer.
  2. Carry sharps in a pocket until a container is available
  3. Discard sharps into a plastic bag with other waste
  4. Recap needles using two hands before disposal

Explanation

Sharps must be disposed of immediately in a closable, puncture-resistant, leak-proof container positioned as close as possible to where they are used. Recapping by hand is a leading cause of needlestick injuries and is prohibited or restricted to a safe one-handed technique. Improper transport and bag disposal create injury and exposure risks.

Question 7Infection Control, Sanitation, and Safety

A needlestick injury occurs while drawing blood. Which action should the worker take first?

  1. Ignore the injury if the needle appeared clean
  2. Wash the wound with soap and water and report the exposure promptly for evaluation Correct answer.
  3. Apply a caustic disinfectant and delay reporting until the next shift
  4. Squeeze the site vigorously to express blood and apply a tight tourniquet

Explanation

After a needlestick, the site should be washed with soap and water, and mucous membranes flushed if exposed. The exposure must be reported promptly so post-exposure prophylaxis and source testing can be arranged. Prompt reporting is time-sensitive for HIV prophylaxis and hepatitis evaluation.

Question 8Infection Control, Sanitation, and Safety

Which transmission-based precaution is appropriate for a patient with active pulmonary tuberculosis?

  1. Airborne precautions with a fit-tested N95 respirator and a negative-pressure room Correct answer.
  2. Contact precautions with gown and gloves only
  3. Standard precautions alone with no additional measures
  4. Droplet precautions with a surgical mask and standard room

Explanation

Mycobacterium tuberculosis is transmitted by airborne droplet nuclei that remain suspended and travel on air currents. Airborne precautions require a negative-pressure room, door kept closed, and a fit-tested N95 or higher respirator for staff. Standard precautions alone do not address airborne spread.

Question 9Infection Control, Sanitation, and Safety

A patient has Clostridioides difficile infection with diarrhea. Which hand hygiene approach is preferred during care?

  1. Alcohol-based hand rub alone, because it is faster
  2. Soap and water, because alcohol rubs do not reliably kill C. difficile spores Correct answer.
  3. Antiseptic mouthwash rinses between patients
  4. No hand hygiene is needed if gloves are worn

Explanation

C. difficile forms spores that resist alcohol-based hand rubs, so soap and water with friction is preferred to physically remove spores. Gloves reduce but do not eliminate transmission, and hand hygiene is still required. Contact precautions are also used for these patients.

Question 10Infection Control, Sanitation, and Safety

Which statement best describes the purpose of surveillance in an infection prevention program?

  1. Systematically collect and analyze infection data to identify trends and target interventions Correct answer.
  2. Record only infections that result in death
  3. Report device use without linking it to infection outcomes
  4. Count the number of staff who attend training sessions

Explanation

Surveillance is the ongoing, systematic collection, analysis, and interpretation of infection data, used to detect outbreaks and evaluate interventions. It is not merely counting training attendance or deaths. Linking device use to infection rates allows targeted prevention efforts.

Question 11Infection Control, Sanitation, and Safety

A nurse is preparing a chlorine disinfectant solution for a blood spill. Which practice ensures correct concentration?

  1. Measure both disinfectant and water and prepare fresh solution according to the manufacturer's instructions Correct answer.
  2. Add extra disinfectant to guarantee effectiveness
  3. Store a premixed solution indefinitely for future spills
  4. Estimate the amount of disinfectant by eye and mix with warm water

Explanation

Disinfectants must be diluted exactly as directed; too little is ineffective and too much can be hazardous or corrosive. Chlorine solutions lose potency over time and should be prepared fresh. Measuring devices and manufacturer instructions ensure the correct concentration.

Question 12Infection Control, Sanitation, and Safety

Which item requires high-level disinfection rather than low-level disinfection?

  1. A bed rail in a patient room
  2. A waiting room chair
  3. A flexible endoscope used for gastrointestinal procedures Correct answer.
  4. A blood pressure cuff used on intact skin

Explanation

Flexible endoscopes contact mucous membranes and are classified as semicritical devices, requiring high-level disinfection. Blood pressure cuffs, bed rails, and chairs contact only intact skin and are noncritical, needing low-level disinfection or cleaning. Device classification by Spaulding categories guides the level of reprocessing.

Question 13Infection Control, Sanitation, and Safety

What is the correct way to store clean linen in a clinical unit?

  1. In a closed cabinet, separated from soiled linen and off the floor Correct answer.
  2. Stacked on the floor for quick access
  3. In an open cart next to the soiled utility room
  4. In the same bin as used linens until laundry day

Explanation

Clean linen is stored in a clean, dry, enclosed area away from soiled linen and off the floor to prevent contamination. Separating clean from soiled areas prevents cross-contamination. Linen on the floor or mixed with soiled items is considered contaminated.

Question 14Infection Control, Sanitation, and Safety

A food service worker in a hospital kitchen has vomiting and diarrhea. What is the appropriate action regarding work?

  1. Permit work only with hot foods
  2. Allow work if the worker wears gloves
  3. Exclude the worker from food handling until symptoms resolve and clearance criteria are met Correct answer.
  4. Allow work if hands are washed frequently

Explanation

Food handlers with vomiting or diarrhea may shed pathogens such as norovirus or Salmonella and must be excluded from work until symptom-free and meeting local clearance criteria. Gloves, hot food, and hand washing do not eliminate the risk of contaminating food. Exclusion protects patients, many of whom are immunocompromised.

Question 15Infection Control, Sanitation, and Safety

Which action is correct when a patient is placed in contact precautions for a multidrug-resistant organism?

  1. Discontinue precautions once antibiotics are started
  2. Share a stethoscope among patients without cleaning between uses
  3. Wear gloves only when the patient is visibly soiled
  4. Dedicate equipment where possible and perform hand hygiene before and after contact Correct answer.

Explanation

Contact precautions require gloves and gown for room entry, dedicated equipment when possible, and hand hygiene before and after contact. Shared equipment must be cleaned and disinfected between patients. Precautions continue for the duration defined by policy, not simply because antibiotics began.

Question 16Infection Control, Sanitation, and Safety

Which statement about alcohol-based hand rub is accurate?

  1. It should be applied and immediately wiped off with a towel
  2. It replaces hand washing in all situations, including after using the restroom
  3. It is effective against many organisms and is applied to dry hands with friction until dry Correct answer.
  4. It is used primarily when hands are visibly soiled with blood

Explanation

Alcohol-based hand rub is applied to the palms and rubbed over all surfaces until dry, typically 20 to 30 seconds. It is preferred for routine hand hygiene when hands are not visibly soiled. Soap and water is required when hands are visibly dirty or after restroom use.

Question 17Infection Control, Sanitation, and Safety

A patient is on droplet precautions for influenza. Which measure is required for staff entering the room?

  1. A fit-tested N95 respirator and negative-pressure room
  2. No precautions if the patient is afebrile
  3. Gown and gloves only, with no mask
  4. A surgical mask, with the door may remain open, plus standard precautions Correct answer.

Explanation

Droplet precautions require a surgical mask for staff within close range and standard precautions; a private room is preferred, and the door may remain open. N95 respirators and negative-pressure rooms are reserved for airborne precautions. Fever resolution does not immediately end droplet precautions.

Question 18Infection Control, Sanitation, and Safety

Which practice best prevents contamination when preparing and administering intravenous medication?

  1. Disinfect the access port with an antiseptic and allow it to dry before accessing Correct answer.
  2. Use the same syringe for multiple patients to save supplies
  3. Access the port immediately after wiping without allowing drying
  4. Store the prepared medication uncovered on a counter

Explanation

Scrubbing the hub with an antiseptic and allowing it to dry reduces contamination of the catheter access point. Drying time is essential for the disinfectant to work. Syringes are single-use per patient, and prepared medications should be covered and labeled.

Question 19Infection Control, Sanitation, and Safety

Which factor most increases the risk of a surgical site infection?

  1. Prolonged operative duration and poor glycemic control Correct answer.
  2. Appropriate preoperative antibiotic timing
  3. Maintaining normothermia during surgery
  4. Use of sterile drapes during surgery

Explanation

Prolonged surgery increases tissue exposure and bacterial contamination, and poor glycemic control impairs wound healing and immune function. Sterile drapes, timely prophylaxis, and normothermia are protective measures. Modifiable risk factors guide prevention efforts.

Question 20Infection Control, Sanitation, and Safety

What is the primary reason for cleaning before disinfection of a contaminated surface?

  1. Cleaning removes all microorganisms without disinfectant
  2. Cleaning makes the surface look presentable
  3. Organic material and soil reduce the effectiveness of the disinfectant Correct answer.
  4. Disinfectants work better on dirty surfaces

Explanation

Visible soil and organic matter can inactivate many disinfectants, so surfaces must be cleaned first. Cleaning removes soil and reduces bioburden, allowing the disinfectant to contact microorganisms. Disinfectants do not perform reliably on heavily soiled surfaces.

Question 21Infection Control, Sanitation, and Safety

A patient with a known norovirus infection has vomited in a shared bathroom. Which response is most appropriate?

  1. Clean and disinfect the area promptly with an appropriate product, using PPE and isolating the area during cleaning Correct answer.
  2. Spray a light air freshener and close the door
  3. Wait until the end of the shift to clean the bathroom
  4. Rinse the area with water and allow the next patient to use it immediately

Explanation

Norovirus is highly contagious and resistant to many common disinfectants; prompt cleaning with an appropriate product such as chlorine-based disinfectant is needed. The area should be closed off during cleaning and staff should wear PPE. Delaying cleaning allows contamination to spread to other patients.

Question 22Infection Control, Sanitation, and Safety

Which statement correctly distinguishes sterilization from disinfection?

  1. Sterilization applies only to environmental surfaces
  2. Disinfection destroys all spores, while sterilization only reduces bioburden
  3. Sterilization destroys all microbial life including bacterial spores, while disinfection reduces or eliminates many organisms but may not kill spores Correct answer.
  4. Sterilization and disinfection are interchangeable terms

Explanation

Sterilization is a validated process that destroys all forms of microbial life, including spores. Disinfection eliminates many or all pathogenic organisms except bacterial spores on inanimate objects. The distinction determines whether an item is processed by autoclave or chemical disinfectant.

Question 23Infection Control, Sanitation, and Safety

A healthcare worker is pregnant and assigned to care for a patient with a rubella infection. What is the most appropriate action?

  1. Refuse all patient care indefinitely
  2. Assume prior vaccination guarantees immunity without checking
  3. Continue care without any assessment because pregnancy does not affect risk
  4. Report the assignment so immune status can be verified and alternative duties arranged if non-immune Correct answer.

Explanation

Rubella can cause severe congenital infection, so a pregnant worker's immune status should be verified and duties adjusted if she is non-immune. Assuming immunity or ignoring the risk is unsafe. Occupational health assessment guides appropriate work restrictions.

Question 24Infection Control, Sanitation, and Safety

Which practice is correct for managing a patient with suspected Creutzfeldt-Jakob disease undergoing a procedure with reusable instruments?

  1. Discard the instruments in regular trash
  2. Sterilize once with standard autoclave and reuse immediately
  3. Use routine low-level disinfection because prions are easily killed
  4. Follow specific enhanced reprocessing protocols for prion contamination rather than routine disinfection Correct answer.

Explanation

Prions are extraordinarily resistant to routine disinfection and sterilization, so special protocols and dedicated or quarantined instruments are used. Routine low-level disinfection and standard autoclaving are insufficient. Discarding instruments in regular trash is unsafe and improper.

Question 25Infection Control, Sanitation, and Safety

Which action best reduces the risk of catheter-associated urinary tract infection?

  1. Change the catheter every 24 hours regardless of need
  2. Keep the drainage bag above bladder level
  3. Irrigate the catheter routinely with antiseptic
  4. Remove the catheter as soon as it is no longer indicated Correct answer.

Explanation

The most effective prevention is avoiding unnecessary catheters and removing them promptly when no longer indicated. The drainage bag should stay below bladder level to prevent backflow, and routine irrigation or scheduled changes are not recommended. Daily review of indication reduces infection risk.

Question 26Infection Control, Sanitation, and Safety

A hospital is reviewing how it will handle an outbreak of a novel respiratory virus. According to standard infection prevention principles, which element is essential for an effective airborne isolation room used for such patients?

  1. Negative pressure relative to surrounding areas with directed airflow and adequate air exchanges per hour Correct answer.
  2. Portable high-efficiency particulate air filtration placed in the corridor outside the room
  3. Standard room ventilation with the door kept open to allow staff observation
  4. Positive pressure relative to the corridor with recirculated air returned to the central system

Explanation

An airborne infection isolation room must be at negative pressure relative to adjacent spaces, with air exhausted or filtered and a defined number of air changes per hour, so that contaminated air does not escape into corridors. Positive pressure would push contaminated air outward, and recirculation without filtration spreads pathogens.

Question 27Infection Control, Sanitation, and Safety

A cleaning technician must disinfect a blood-contaminated surface in a patient room. Which practice is most consistent with safe work practice controls for this task?

  1. Wearing gloves and reusing the same pair for the next three patient rooms to save supplies
  2. Wearing gloves only, since the contamination is limited to a small area
  3. Wearing gloves and a fluid-resistant gown, then removing them before leaving the room and performing hand hygiene Correct answer.
  4. Wearing a surgical mask and shoe covers without gloves while applying the disinfectant

Explanation

Blood and body fluid spills carry exposure risk, so personal protective equipment including gloves and a fluid-resistant gown is appropriate, and removal must occur before leaving the room followed by hand hygiene to prevent contamination transfer. Reusing gloves between rooms or omitting gloves defeats the purpose of the control.

Question 28Infection Control, Sanitation, and Safety

A sterile processing department receives a flexible endoscope that was used for a procedure and will be reused. Which reprocessing sequence is correct before the scope is used again?

  1. Manual cleaning followed by storage, with disinfection performed immediately before the next procedure
  2. Rinsing with tap water, then storage in a closed cabinet until the next use
  3. Manual cleaning, high-level disinfection, then rinsing with filtered or sterile water and drying before storage Correct answer.
  4. High-level disinfection alone, since the disinfectant inactivates all organic material present

Explanation

Flexible endoscopes require meticulous manual cleaning to remove organic soil before high-level disinfection, because residual bioburden protects microorganisms. After disinfection, rinsing with filtered or sterile water and thorough drying prevents recontamination and biofilm formation during storage.

Question 29Infection Control, Sanitation, and Safety

A hospital's infection prevention team is analyzing a rise in central line-associated bloodstream infections. Which measure is most directly supported as a core element of a prevention bundle for these infections?

  1. Use of transparent dressings changed only when visibly soiled
  2. Routine replacement of central catheters every 72 hours regardless of need
  3. Daily review of line necessity with prompt removal when no longer indicated Correct answer.
  4. Scheduled antibiotic prophylaxis at the time of each dressing change

Explanation

Central line bundles emphasize insertion and maintenance practices, including daily assessment of whether the line is still needed and removal as soon as possible, since duration of catheterization is a major risk factor. Routine scheduled replacement and prophylactic antibiotics are not recommended bundle elements.

Question 30Infection Control, Sanitation, and Safety

An infection preventionist is evaluating whether a new ultraviolet-C room disinfection device should be added to terminal cleaning. Which consideration is most important when interpreting the evidence for this decision?

  1. Ultraviolet-C is an adjunct to manual cleaning and its benefit depends on thorough prior cleaning and adequate dosing and room shadowing Correct answer.
  2. Ultraviolet-C is equally effective against all pathogens regardless of whether surfaces are in direct line of sight
  3. Ultraviolet-C efficacy is independent of room layout, device placement, and exposure time
  4. Ultraviolet-C replaces the need for manual cleaning because ultraviolet light penetrates organic soil effectively

Explanation

Ultraviolet-C devices are supplemental to manual cleaning; organic material and shadowing reduce the delivered dose, so efficacy depends on prior cleaning, correct dosing, and line-of-sight exposure. Evidence must be interpreted with these operational constraints in mind rather than assuming universal pathogen kill.

Question 31Anatomy and Physiology of the Hand, Nail, and Skin

Which layer of the epidermis contains keratinocytes that are actively dividing and is responsible for continuous renewal of the epidermis?

  1. Stratum corneum
  2. Stratum granulosum
  3. Stratum lucidum
  4. Stratum basale Correct answer.

Explanation

The stratum basale is the deepest epidermal layer, sitting on the basement membrane, and holds the mitotically active stem-cell population that replenishes the epidermis. Cells migrate outward as they differentiate, so the other layers are post-mitotic or fully keratinized.

Question 32Anatomy and Physiology of the Hand, Nail, and Skin

The nail plate is produced primarily by which structure?

  1. The hyponychium
  2. The proximal nail fold
  3. The nail bed
  4. The nail matrix Correct answer.

Explanation

The nail matrix is the germinative epithelium from which the nail plate is formed; its proximal portion creates most of the visible plate. The nail bed contributes little to plate thickness, and the folds and hyponychium are supporting structures.

Question 33Anatomy and Physiology of the Hand, Nail, and Skin

Which muscle is primarily responsible for flexion of the distal interphalangeal joint of the index finger?

  1. Flexor digitorum superficialis
  2. Lumbrical
  3. Flexor pollicis longus
  4. Flexor digitorum profundus Correct answer.

Explanation

Flexor digitorum profundus tendons insert on the base of the distal phalanges, so they are the only flexors capable of flexing the distal interphalangeal joint. Superficialis inserts more proximally on the middle phalanx and cannot act at the DIP joint.

Question 34Anatomy and Physiology of the Hand, Nail, and Skin

Which nerve provides sensation to the palmar surface of the little finger?

  1. Ulnar nerve Correct answer.
  2. Anterior interosseous nerve
  3. Median nerve
  4. Radial nerve

Explanation

The ulnar nerve supplies the palmar and dorsal aspects of the little finger and the ulnar half of the ring finger through its superficial branch. The median nerve covers the radial three and a half digits, so it does not reach the little finger.

Question 35Anatomy and Physiology of the Hand, Nail, and Skin

In the nail unit, which structure acts as the waterproof seal between the distal nail plate and the fingertip skin?

  1. Nail bed
  2. Hyponychium Correct answer.
  3. Eponychium
  4. Lunula

Explanation

The hyponychium is the specialized epidermis beneath the free edge of the plate that forms a barrier against pathogens and moisture loss. Its disruption predisposes to paronychia and onycholysis.

Question 36Anatomy and Physiology of the Hand, Nail, and Skin

Which layer of the dermis contains the denser collagen bundles and provides the majority of skin tensile strength?

  1. Stratum spinosum
  2. Reticular dermis Correct answer.
  3. Papillary dermis
  4. Hypodermis

Explanation

The reticular dermis is the thicker, deeper layer composed of dense irregular collagen bundles that resist tensile forces. The papillary dermis is looser and more superficial, while the hypodermis is fatty subcutaneous tissue.

Question 37Anatomy and Physiology of the Hand, Nail, and Skin

Which arterial arch supplies the superficial palmar aspect of the fingers and is formed predominantly by the ulnar artery?

  1. Deep palmar arch
  2. Princeps pollicis artery
  3. Dorsal carpal arch
  4. Superficial palmar arch Correct answer.

Explanation

The superficial palmar arch is completed mainly by the ulnar artery and gives off the common palmar digital arteries. The deep arch is formed predominantly by the radial artery and lies deeper.

Question 38Anatomy and Physiology of the Hand, Nail, and Skin

A patient has a laceration over the volar aspect of the wrist that divides the median nerve. Which function is most likely lost?

  1. Flexion of the elbow
  2. Abduction of the little finger
  3. Extension of the wrist
  4. Opposition of the thumb Correct answer.

Explanation

Opposition of the thumb depends on the thenar muscles, chiefly opponens pollicis, which are innervated by the recurrent branch of the median nerve. Wrist extension is radial nerve, little-finger abduction is ulnar nerve, and elbow flexion is musculocutaneous.

Question 39Anatomy and Physiology of the Hand, Nail, and Skin

Which structure is the primary source of the nail plate's proximal portion and is often the target in matrixectomy for ingrown toenails?

  1. Proximal nail matrix Correct answer.
  2. Hyponychium
  3. Lateral nail fold
  4. Distal nail bed

Explanation

The proximal nail matrix generates the majority of the nail plate, including the dorsal surface, so its destruction is used to prevent regrowth in ingrown nail surgery. The lateral matrix contributes less, and the bed and hyponychium do not generate the plate.

Question 40Anatomy and Physiology of the Hand, Nail, and Skin

During a procedure, a clinician notes a pale crescent at the base of the nail. This structure represents which of the following?

  1. The visible distal portion of the nail matrix Correct answer.
  2. The nail bed's vascular plexus
  3. The hyponychium
  4. The proximal nail fold epidermis

Explanation

The lunula is the distal part of the matrix visible through the translucent plate; its paler color reflects the dense keratinization of matrix cells. It is not a vascular or fold structure.

Question 41Anatomy and Physiology of the Hand, Nail, and Skin

Which intrinsic hand muscle is the only one to insert on the extensor expansion and is innervated by the median nerve?

  1. Palmaris brevis
  2. First dorsal interosseous
  3. First lumbrical Correct answer.
  4. Abductor pollicis brevis

Explanation

The first and second lumbricals are innervated by the median nerve and insert into the extensor expansion. The dorsal interossei are ulnar-innervated, and abductor pollicis brevis and palmaris brevis do not insert on the extensor expansion.

Question 42Anatomy and Physiology of the Hand, Nail, and Skin

Which condition results from disruption of the hyponychium seal and allows separation of the nail plate from the nail bed distally?

  1. Onycholysis Correct answer.
  2. Paronychia
  3. Koilonychia
  4. Onychorrhexis

Explanation

Onycholysis is distal separation of the nail plate from the bed, often beginning when the hyponychium barrier is disrupted by trauma or moisture. Paronychia is fold inflammation, koilonychia is spooning, and onychorrhexis is longitudinal ridging.

Question 43Anatomy and Physiology of the Hand, Nail, and Skin

The blood supply to the nail matrix arises mainly from which arterial source?

  1. The radial recurrent artery
  2. The ulnar artery alone
  3. Digital arteries via dorsal branches Correct answer.
  4. The superficial palmar arch directly

Explanation

The nail unit is supplied by dorsal branches of the proper digital arteries, which form a network around the matrix. The palmar arch and named forearm arteries are too proximal to supply the matrix directly.

Question 44Anatomy and Physiology of the Hand, Nail, and Skin

A patient cannot actively abduct the index finger against resistance and shows wasting of the first dorsal web space. Which nerve is most likely injured?

  1. Ulnar nerve Correct answer.
  2. Median nerve
  3. Musculocutaneous nerve
  4. Radial nerve

Explanation

The first dorsal interosseous is innervated by the ulnar nerve and is the principal abductor of the index finger; its wasting indicates ulnar neuropathy. Median nerve injury affects thenar muscles, while radial and musculocutaneous injuries do not denervate the interossei.

Question 45Anatomy and Physiology of the Hand, Nail, and Skin

Which type of collagen predominates in the dermal extracellular matrix and provides tensile strength to skin?

  1. Type I collagen Correct answer.
  2. Type IV collagen
  3. Type III collagen
  4. Type VII collagen

Explanation

Type I collagen is the most abundant collagen in adult dermis and forms thick fibrils that resist tension. Type III is present in smaller amounts and dominates in fetal skin and early wound healing.

Question 46Anatomy and Physiology of the Hand, Nail, and Skin

Which structure forms the cuticle that seals the proximal nail unit?

  1. Lunula
  2. Eponychium Correct answer.
  3. Hyponychium
  4. Onychodermal band

Explanation

The eponychium is the epidermal layer at the proximal nail fold whose keratinized edge forms the cuticle, sealing the proximal nail unit. The hyponychium seals distally, and the lunula and onychodermal band are different structures.

Question 47Anatomy and Physiology of the Hand, Nail, and Skin

Which anatomical feature explains why the nail plate grows distally rather than outward from all sides?

  1. The matrix is anchored proximally and oriented distally along the nail bed Correct answer.
  2. The nail bed secretes the entire plate
  3. The lateral folds generate the plate
  4. The hyponychium pushes the plate forward

Explanation

Nail plate keratinocytes are generated in the matrix and migrate distally over the nail bed, guided by the anatomy of the proximal matrix and folds. The bed, hyponychium, and lateral folds do not generate the plate.

Question 48Anatomy and Physiology of the Hand, Nail, and Skin

Which muscle group, supplied by the ulnar nerve, is responsible for the power grip by flexing the metacarpophalangeal joints and extending the interphalangeal joints?

  1. Hypothenar muscles
  2. Lumbricals and interossei Correct answer.
  3. Thenar muscles
  4. Extensor digitorum

Explanation

The lumbricals and interossei are ulnar-innervated intrinsic muscles that flex the MCP joints and extend the IP joints, contributing to the power grip. Thenar and hypothenar muscles act on the thumb and little finger, and extensor digitorum is a forearm muscle.

Question 49Anatomy and Physiology of the Hand, Nail, and Skin

Which skin layer is absent on the palmar surface of the hand, making it more prone to certain infections and fluid loss?

  1. Stratum lucidum Correct answer.
  2. Stratum spinosum
  3. Stratum granulosum
  4. Stratum basale

Explanation

The stratum lucidum is present only in thick glabrous skin such as palms and soles; it is not found in thin skin. The other layers are present in both thick and thin epidermis.

Question 50Anatomy and Physiology of the Hand, Nail, and Skin

A patient sustains a deep laceration at the base of the distal phalanx of the thumb, severing the flexor pollicis longus tendon. Which function is most directly impaired?

  1. Flexion of the interphalangeal joint of the thumb Correct answer.
  2. Opposition of the thumb
  3. Abduction of the thumb
  4. Extension of the thumb

Explanation

Flexor pollicis longus inserts on the base of the distal phalanx of the thumb and is the sole flexor of its interphalangeal joint. Extension, abduction, and opposition are performed by other muscles.