Lower limbHigh yield
Gastrocnemius and soleus (calf)
The two-layered calf muscle that points the foot down and pumps blood back up the leg veins with every step.
Why the exam cares
The deep veins run inside this muscle, and when it stops squeezing, in bed rest, after surgery, or on a long flight, clots form here. The NCLEX tests the signs of a DVT, why the nurse no longer checks Homans sign, and calf pumps as prevention.
- The bulk of the back of the lower leg, narrowing into the Achilles tendon at the heel.
- Measure calf circumference at the same point on both legs, about 4 inches below the bump at the top of the shin, and compare.
- The posterior tibial pulse is felt behind the inner ankle bone at the muscle's lower end.
One calf that is swollen, warm, red, or tender compared with the other is a DVT until proven otherwise. The nurse measures both calves, keeps the leg elevated, does not massage it, and reports for an ultrasound, because rubbing or working the calf can push the clot toward the lung. If that patient suddenly becomes short of breath or has chest pain, the clot has moved: the nurse stays with the patient, sits them upright, starts oxygen, and calls for help immediately.
Forcing the foot up toward the shin to bring on calf pain misses most clots, is positive in many other conditions, and can break a clot loose. The nurse does not perform it; suspicion is confirmed by ultrasound, not by a bedside maneuver.
The nurse teaches the patient to point and flex the feet ten times every hour while awake, applies sequential compression devices as ordered, and gets the patient walking as early as possible. Each contraction squeezes the deep veins and keeps blood from pooling.
A calf that lies pointed for days shortens at the Achilles tendon until the foot cannot come back to neutral. The nurse keeps the ankles at 90 degrees with a footboard or padded boots and ranges the ankle each shift.
Reduction of Risk PotentialBasic Care and Comfort
Lower limbHigh yield
Gluteus maximus (dorsogluteal site)
The large muscle of the buttock, lying over the sciatic nerve, whose upper outer quadrant is the dorsogluteal injection site.
Why the exam cares
The dorsogluteal site is no longer a preferred IM site because the sciatic nerve and superior gluteal vessels run deep to it and the fat over it is often too thick for the needle. For IM medications, the nurse chooses the ventrogluteal site whenever it is an option.
- The dorsogluteal site is the upper outer quadrant of the buttock, above and lateral to a line drawn from the posterior superior iliac spine to the greater trochanter.
- The sciatic nerve runs deep to the muscle, roughly midway between the ischial tuberosity and the greater trochanter, then down the back of the thigh. That is why only the upper outer area was ever used.
- The ischial tuberosity, the sitting bone, is covered by the lower part of the muscle when standing but slides out from under it when sitting.
A needle placed too low or too far toward the midline can strike the sciatic nerve, causing shooting leg pain, numbness, and foot drop that may be permanent. The nurse cannot see or feel the nerve, so the nurse picks another site whenever one is available. If the patient reports sharp pain shooting down the leg as the needle enters, the nurse withdraws without injecting and reports it.
Fat over the buttock can be deeper than a 1.5-inch needle, so the drug may land in fat and absorb slowly and unpredictably. For IM medications, the nurse prefers the ventrogluteal site, and the vastus lateralis in infants. Vaccines do not go in the buttock: adults and children 3 years and older get them in the deltoid, infants in the vastus lateralis, and toddlers in the vastus lateralis or deltoid.
When a patient sits, the muscle moves off the sitting bones, so weight rests on bone through skin and fat alone. The nurse teaches a chair-bound patient to shift weight about every 15 minutes, repositions a patient who cannot at least every hour, uses a pressure-redistributing cushion instead of a donut ring, and inspects the skin over the sitting bones.
Pharmacological and Parenteral TherapiesReduction of Risk PotentialBasic Care and Comfort
Lower limbHigh yield
Gluteus medius (ventrogluteal site)
A thick, fan-shaped muscle on the outer hip that runs from the outer surface of the ilium, just below the iliac crest, down to the greater trochanter of the femur.
Why the exam cares
For most adult IM injections, the nurse picks the ventrogluteal site over the buttock because it sits away from the sciatic nerve and the large gluteal vessels. For infants, the vastus lateralis is the preferred IM site.
- Place the heel of the hand on the greater trochanter with the fingers pointing toward the patient's head. Use the hand opposite the hip: right hand on the left hip, left hand on the right.
- Put the index finger on the anterior superior iliac spine and spread the middle finger back along the iliac crest.
- The V between the index and middle fingers is the site. Inject in the center of the V.
- Have the patient lie on the side or on the back with the hip and knee bent. Bending them relaxes the gluteal muscles for landmarking and injection.
Inject at 90 degrees with a needle of about 1 to 1.5 inches, chosen by the patient's size. A well-muscled adult can take a volume of about 3 mL here, less in a thin or older adult; follow facility policy. Rotate sites when injections repeat.
For an irritating or staining drug such as iron dextran, pull the skin and tissue about 1 to 1.5 inches to one side, inject, wait about 10 seconds, withdraw, then let the skin go. Do not massage the site afterward. The shifted tissue seals the needle track, so the drug stays in the muscle instead of leaking into the skin.
The nurse feels for the greater trochanter, the anterior superior iliac spine and the iliac crest on bare skin. If the nurse cannot find these landmarks, choose another site, because the V is only safe when the hand is anchored to bone.
Pharmacological and Parenteral Therapies
Lower limb
Hamstrings
The three muscles along the back of the thigh (biceps femoris, semitendinosus, semimembranosus) that bend the knee and extend the hip.
Why the exam cares
When a knee stays bent for days, on a pillow, on a raised knee gatch, or under the residual limb after a below-knee amputation, the hamstrings shorten and lock the knee in flexion; in the amputee, a flexed residual limb may not fit a prosthesis. The NCLEX asks how the nurse positions the leg to keep the knee straight, and it expects the nurse to know that a pillow under the knee also presses on the vessels behind it.
- The back of the thigh, from the bony point a person sits on (the ischial tuberosity) down to just below the knee.
- When the knee bends against resistance, the tendons stand out as cords on either side of the hollow behind the knee: biceps femoris on the outer side, semitendinosus and semimembranosus on the inner side.
- The popliteal pulse lies deep in that hollow, between the tendons.
After a below-knee amputation, the nurse follows the surgeon's order on early elevation of the residual limb, then keeps the knee flat and extended. Once allowed, the nurse turns the patient prone several times a day as tolerated and does range of motion to full knee extension. A knee left bent lets the hamstrings shorten, and a contracture can delay or prevent prosthesis fitting.
For any patient in bed, the nurse keeps pillows out from under the knees and the knee gatch down. Pressure behind the knee slows blood return in the popliteal vein and raises the risk of deep vein thrombosis, and a knee held bent for days can stiffen in flexion. To support the legs, the nurse places the pillow under the whole lower leg instead of just the knee.
The nurse bends the knee slightly and presses deep into the hollow behind it. This pulse is hard to feel even in healthy people, so the nurse compares both legs and also checks the foot pulses. After a femoral-popliteal bypass, the nurse checks pulses, color, warmth, and sensation often, per protocol. A pulse that was there and is now gone, or a leg that turns cool, pale, and painful, can mean the graft has clotted, so the nurse notifies the surgeon right away.
Basic Care and ComfortReduction of Risk Potential
Lower limbHigh yield
Quadriceps femoris (vastus lateralis and patellar tendon)
The quadriceps femoris is the four-part muscle on the front of the thigh that straightens the knee; its outer part is the vastus lateralis, and its tendon runs over the kneecap to anchor on the top of the shin.
Why the exam cares
The NCLEX sends three questions to this muscle: where an infant's IM vaccine goes, where the epinephrine auto-injector goes in anaphylaxis, and what a lost knee-jerk means in a patient on magnesium sulfate. The vastus lateralis is the answer to the first two because no major nerve or blood vessel lies under it, and an absent patellar reflex means magnesium has reached a toxic level, so the nurse stops the infusion.
- Picture a line from the greater trochanter at the hip down to the lateral femoral condyle, the bony knob on the outer side of the knee; the injection site is the middle third of that line, on the outer front of the thigh.
- In an adult, place one hand just below the greater trochanter and one hand just above the knee; the site is the space between your hands, on the outer front of the thigh.
- Ask the patient to tighten the thigh with your palm on its outer front; the firm bulge that rises is the vastus lateralis.
- The patellar tendon is the firm cord just below the kneecap, easiest to tap with the knee bent and the leg hanging free; this reflex tests spinal segments L2 to L4.
The nurse gives infant and toddler IM vaccines in the vastus lateralis, middle third of the outer front of the thigh, at a 90-degree angle, keeping infant volumes small (about 0.5 mL, or per facility policy). It is chosen because the muscle is well developed even in a newborn and no major nerve or blood vessel lies beneath it. Adults who inject their own IM drugs are taught this same site because they can see it and reach it sitting down.
Before starting magnesium sulfate for preeclampsia and at regular intervals during the infusion, the nurse checks the patellar reflex (normal is 2+), along with respiratory rate and urine output. An absent reflex, a respiratory rate below about 12 per minute, or urine output below about 30 mL per hour signals toxicity or rising levels: stop the infusion and notify the provider. Keep calcium gluconate at the bedside as the antidote, because breathing and then the heart are affected next.
In anaphylaxis, epinephrine is the first drug given, before antihistamines or steroids, because it reverses airway swelling and falling blood pressure. The nurse or patient presses the auto-injector into the outer thigh, through clothing if needed, and holds it as the device directs; the usual adult pen is 0.3 mg and the usual child pen 0.15 mg. Call for emergency help right away, give a second dose in about 5 to 15 minutes if symptoms do not improve, and never inject into the buttock, a hand or foot, or a vein.
After a total knee replacement the nurse coaches quad sets, tightening the thigh and pressing the back of the knee toward the bed, and uses a continuous passive motion machine at the prescribed range if ordered. Both keep the quadriceps strong and the new joint moving so it does not stiffen. Do not place a pillow under the knee, because a knee that rests bent can develop a flexion contracture.
Pharmacological and Parenteral TherapiesReduction of Risk PotentialPhysiological Adaptation
Lower limb
Rectus femoris
The straight quadriceps muscle that runs down the middle of the front of the thigh, from the front of the pelvis to the kneecap.
Why the exam cares
The thigh IM injection goes into the vastus lateralis on the outer front of the thigh, not into the midline over this muscle, so the nurse must tell the two apart when giving or teaching the injection. The patellar reflex, tested through this muscle's tendon, is how the nurse checks for magnesium toxicity.
- The midline of the front of the thigh; have the patient lift the straightened leg and the muscle tightens down the middle.
- The patellar tendon, just below the kneecap, is the spot the nurse taps to test the knee-jerk reflex.
- The vastus lateralis site lies lateral to it, on the outer front of the thigh in the middle third: a hand's breadth below the greater trochanter to a hand's breadth above the knee.
- At the groin, just below the inguinal ligament and medial to where the muscle starts, the femoral pulse is felt.
For a thigh IM injection, the nurse finds the middle third of the thigh and moves to its outer front surface, the vastus lateralis, rather than the midline over the rectus femoris. CDC lists the deltoid and vastus lateralis as IM sites, and the ventrogluteal site is also taught. A patient learning to self-inject is shown the outer thigh and told never to use the inner thigh or groin.
The femoral nerve, artery, and vein pass under the inguinal ligament into the upper thigh, medial to this muscle's origin, and the femoral artery and vein then run down the inner thigh. The nurse keeps thigh injections out of the upper third and the inner thigh so the needle stays clear of them.
Tapping the patellar tendon stretches the quadriceps, and the femoral nerve carries the reflex through the L2 to L4 spinal segments; a normal response is graded 2+. For a patient on IV magnesium sulfate, the nurse checks this reflex on a set schedule, because loss of the reflex is an early sign of magnesium toxicity. If it is absent, the nurse stops the infusion and notifies the provider before breathing slows.
Pharmacological and Parenteral TherapiesReduction of Risk Potential
Lower limbHigh yield
Skeletal muscle as tissue
Skeletal muscle is the striped, voluntary muscle that moves the bones, and it holds most of the body's potassium inside its cells.
Why the exam cares
Muscle wastes fast when a patient stays in bed, goes weak when potassium, calcium, or magnesium drift, and spills potassium and myoglobin into the blood when it breaks down. The nurse keeps immobile patients moving, checks electrolytes when new weakness appears, and escalates dark urine after a crush injury or a long lie on the floor right away.
- Grade strength 0 to 5: grade 3 is full movement against gravity only, and grades 4 and 5 push against the nurse's resistance. Always compare both sides.
- Measure thigh, calf, or upper-arm circumference at a marked spot to track wasting over time.
- In bed rest, check the antigravity muscles first: quadriceps, gluteals, calves, and back extensors.
Muscle that is not used loses strength within days of bed rest. The nurse does active or passive range of motion as ordered, teaches exercises the patient can do in bed, gets the patient up as early as allowed, and checks protein intake, because muscle needs both load and building material to hold its mass.
Crush injury, hours on the floor after a fall, heat stroke, prolonged seizures, or a statin reaction can break muscle down. The nurse watches for muscle pain and tea-colored urine, reports a rising CK, gives the ordered IV fluids, measures urine output hourly, and checks potassium. The released myoglobin can injure the kidneys, and the released potassium can cause dangerous arrhythmias.
Low potassium causes leg cramps and weakness; high potassium causes twitching that can progress to flaccid paralysis; low calcium and low magnesium cause tingling, spasm, and overactive reflexes. New weakness gets an electrolyte panel, and a suspected potassium problem gets cardiac monitoring, because the same imbalance affects the heart muscle.
Basic Care and ComfortPhysiological AdaptationReduction of Risk Potential
Lower limbHigh yield
Tibialis anterior
The muscle down the front of the shin, just lateral to the sharp edge of the tibia, that pulls the foot up (dorsiflexion) and turns the sole inward.
Why the exam cares
After a tibial fracture, a new leg cast, or knee surgery, the nurse asks the patient to pull the foot up and checks feeling between the first two toes. A new loss means anterior compartment syndrome or a compressed peroneal nerve until proven otherwise, and the nurse reports it to the provider at once.
- Its belly lies just lateral to the front edge of the tibia; its tendon is the most medial tendon on the front of the ankle and stands out when the foot is pulled up.
- The head of the fibula is the bony knob on the outer leg just below the knee; the common peroneal nerve wraps around the bone just below it, right under the skin.
- The dorsalis pedis pulse sits on the top of the foot just lateral to the big-toe extensor tendon, which lies lateral to the tibialis anterior tendon.
This muscle and the deep peroneal nerve share a tight compartment, so swelling after a tibial fracture, a crush injury, or a tight cast can cut off their blood supply. Early signs are pain out of proportion to the injury that opioids do not relieve, pain when the nurse gently moves the foot downward, and numbness or tingling between the first two toes. Weak dorsiflexion and a lost pulse come later, so the nurse does not wait for them, and a pulse that is still present is not reassurance. The nurse notifies the provider immediately, keeps the leg at heart level rather than elevated, loosens or bivalves the cast as ordered, and prepares the patient for fasciotomy.
A cast edge, a knee-immobilizer strap, a lithotomy stirrup, or pressure on the outer knee in bed can crush this nerve against the fibula just below the knee. The patient develops foot drop, weak eversion, and numbness on the top of the foot, and the damage can be permanent. The nurse pads the outer knee, keeps the leg from rolling outward in bed, and reports new weakness right away so the pressure is removed.
At each neurovascular check the nurse has the patient pull the foot and toes up and tests light touch between the great and second toes, the skin supplied by the deep peroneal nerve. The nurse compares each result with the baseline, because a change here is an early warning from both the anterior compartment and the peroneal nerve.
Reduction of Risk PotentialPhysiological AdaptationBasic Care and Comfort
Lower limbHigh yield
Vastus lateralis
The largest of the four quadriceps muscles, running down the outer front of the thigh from the hip to the knee, where it helps straighten the leg.
Why the exam cares
It is the preferred IM site for infants under 12 months and the usual site for toddlers, and it is where the nurse gives or teaches IM epinephrine for anaphylaxis. The nurse picks this site because it is a large muscle with no major nerves or vessels in its middle third.
- Find the greater trochanter at the hip and the lateral femoral condyle at the outer knee; the site is the middle third of the thigh between them.
- Use the anterolateral (front-outer) surface of the thigh, not the inner thigh, where the femoral vessels and nerve run.
- In an adult, a quick check is one hand-breadth below the trochanter and one hand-breadth above the knee.
At the first signs of anaphylaxis, such as stridor, wheezing, throat or tongue swelling, or hives with low blood pressure, the nurse gives epinephrine IM into the anterolateral thigh per the anaphylaxis protocol, without waiting for IV access. It goes in first, before antihistamines, because only epinephrine reverses airway swelling and shock. An auto-injector can go through clothing and is held in place for the time the device says. Doses may be repeated about every 5 to 15 minutes if symptoms continue.
For an infant's vaccine, the nurse uses this site at a 90-degree angle. The CDC needle length is 5/8 inch for a newborn in the first 28 days and 1 inch for infants 1 to 12 months. A parent or helper holds the child and steadies the leg so a kick does not move the needle. The dorsogluteal site is avoided in young children because the muscle is thin and the sciatic nerve lies close by.
The thigh is easy for a seated patient to see and reach, so the nurse teaches patients and parents to use an epinephrine auto-injector here. The nurse teaches them to call 911 after using it, because symptoms can come back after the drug wears off.
Pharmacological and Parenteral TherapiesHealth Promotion and MaintenancePhysiological Adaptation
