Twenty-four subjects were recruited. Thirteen subjects Eleven subjects Six examined sites were evaluated. The average thickness of subcutaneous tissue in males was within 10 mm at all examined sites, but was greater than 10 mm at all examined sites, except at a , in females. The thickness of muscle was measured using ultrasound equipment. Since only the deltoid muscle was observed at the deltoid site, the deep fascia — bone margin was measured as the thickness of the deltoid muscle Figure 2 A , Table 2.
At the ventrogluteal site, the gluteus minimus was observed under the gluteus medius in some participants. The deep fascia — bone margin was measured as the total thickness of muscle, and the deep fascia — fascia between the gluteus medius and gluteus minimus was measured as the thickness of the gluteus medius Figure 2 B , C , Table S.
In the thigh, the rectus femoris and vastus intermedius were observed at e , while the vastus lateralis and vastus intermedius were noted at f. The deep fascia — bone margin was measured as the total thickness of muscle in the thigh, and the deep fascia — fascia between the rectus femoris or vastus lateralis and vastus intermedius was measured as the thickness of the rectus femoris or vastus lateralis Figure 2 D , Table 2. Major blood vessels were detected at a , c , d , and e by the Doppler mode of ultrasound equipment.
At the deltoid site, a blood vessel, which ran between the deltoid muscle and humerus, was observed in two females within a range of 1 cm at a Figure 2 A , Table 3 , while no major blood vessel was noted at b. At the ventrogluteal site, blood vessels, which ran between the gluteus medius and gluteus minimus, were observed in one male and one female at c and in one male at d Figure 2 B, C , Table 3.
In the thigh, blood vessels were observed between the rectus femoris and vastus lateralis in seven males and eleven females at e , while no major blood vessel was observed at f Figure 2 D , Table 3.
Twenty-four right thighs were dissected because blood vessels were observed at the middle of the rectus femoris in many young adults. The profundal femoris artery, which is one branch of the femoral artery, gave off the lateral and medial circumflex femoral arteries in the proximal thigh.
The lateral circumflex femoral artery LCFA passed horizontally and was divided into two branches; ascending and descending.
The descending branch of LCFA dbLCFA ran downward behind the rectus femoris or on the vastus intermedius obliquely with veins and nerves to the vastus lateralis. It then descended along the border between the vastus intermedius and vastus lateralis and supplied muscles with a long branch that traveled through the muscle downward as far as the knee Figure 3 A.
The nerves accompanying dbLCFA on the vastus intermedius originated from the femoral nerve, and it was the muscle branch of the femoral nerve to the vastus lateralis mbFN to VL. As shown in e to h in Figure 3 B , four points were examined in order to identify safe IM injection sites in the thigh in the following sections.
The total thickness of muscle at four sites was measured by the insertion of a 14G needle Table 4. No significant differences were observed between the examined sites. No blood vessel or nerve was observed within the range of 1 cm at f Figure 3 C , Table 5. They were frequently observed at e Figure 3 D , Table 5. Number of observed blood vessels or nerves within 1 cm of each injection site in the thigh of cadavers.
Distance from major blood vessels or nerves to each injection site in the thigh of cadavers. The present results revealed that dbLCFA descended the anterior border of the vastus lateralis the boundary line between the rectus femoris or vastus intermedius and vastus lateralis.
This line corresponded to the line between the anterior superior iliac spine and the lateral border of the patella Figure 3 E. In brief, the route of dbLCFA and mbFN to VL after reaching the vastus lateralis corresponded to the line between the anterior superior iliac spine and lateral patella.
Many types of vaccines, such as diphtheria and tetanus toxoids, hepatitis B, and inactivated influenza vaccines, are administered by IM injections.
These vaccines are necessary to prevent vaccine-preventable diseases that occur in infants, children, adolescents, and adults. When vaccinators inject vaccines, they need to be familiar with the anatomy of the area into which they are injecting the vaccine.
The present study compared IM injection sites in the thigh with those at the deltoid and ventrogluteal sites. In young male adults, mean subcutaneous thickness was less than 10 mm at all examined sites and its maximum value was 15 mm at d , while it was between 8 and 13 mm at all examined sites in young female adults and its maximum value was 21 mm at f Table 1.
When an IM injection is performed, a 21 to 23 gauge 14G needle is generally used. Hence, these needles completely penetrated subcutaneous tissue at all examined sites in the present study. The total thickness of muscle in males and females was greater in the thigh than at the deltoid and ventrogluteal sites. It is important to select the largest muscle for IM injections in order to avoid any disparity between muscle mass and the volume of injected fluid.
Major blood vessels were detected at a , c , d , and e by Doppler ultrasonography Figure 2. In the deltoid site, we previously reported that an IM injection at three finger breadths below the acromion approximately 5 cm below the acromion was associated with a risk of axillary nerve and PCHA damage because the axillary nerve with the accompanying PCHA is located 3. Therefore, the site of three finger breadths below the acromion needs to be avoided for use as an IM injection site.
On the other hand, there were no blood vessels at b Table 3. The point on the anteroposterior axillary line is distant to PCHA. At the ventrogluteal site, we previously attempted to identify safe sites for IM injections at c and d. Hence, we confirmed that the blood vessel observed in the present study was the superior and inferior branches of the SGB.
The numbers of blood vessels observed at c and d were 2 and 1, respectively, in the present study Table 3 , and this result is consistent with our previous findings.
In the thigh, major blood vessels were observed at e in 7 males and 11 females young adults Table 3. The number of observed blood vessels was higher at e than at the other examined sites.
In cases in which a needle does not completely penetrate the rectus femoris, dbLCFA or mbFN to VL is not damaged and IM injections may be performed at this site; however, the minimum value of the thickness of the rectus femoris was only 15 mm in young female adults and may be smaller in the elderly.
The right thighs of 24 cadavers were dissected to identify blood vessels observed at e by Doppler ultrasonography in young adults. LCFA generally arises from the profunda femoris artery, and divides into three branches: ascending, transverse, and descending branches.
Therefore, we confirmed that the observed blood vessels at the examined sites were dbLCFA. Moreover, mbFN to VL was detected at e , g , and h in the thigh. The femoral nerve classically has three main divisions: the nerve to the pectineus, anterior, and posterior divisions. A large branch to the vastus lateralis forms a neurovascular bundle with the descending branch of LCFA in its distal part.
In the present study, the observed nerves at e originated from the femoral nerves and supplied the vastus lateralis. Therefore, we confirmed that the observed nerves at the examined sites were mbFN to VL. Previous studies recommended the rectus femoris as an IM injection site when other sites are contraindicated because of discomfort, pain, and injuries to a nerve and numerous blood vessels. Moreover, we found that the route of dbLCFA and mbFN to VL after reaching the vastus lateralis was on the line between the anterior superior iliac spine and lateral border of the patella.
On the other hand, the present study showed that no major blood vessel or nerve was observed at f and this site was sufficiently far from dbLCFA and mbFN to VL Tables 5 and 6. Previous studies recommended the middle third of the vastus lateralis as an IM injection site because of its ease of access and, more importantly, the absence of major blood vessels or significant nerves. We consider the present results to be beneficial as an evidence-based approach towards site selection for successful IM injections and the avoidance of vascular or nerve damage.
In conclusion, the present results demonstrated that the rectus femoris is not appropriate as a safe IM injection site because of the risk of damage to the descending branch of the LCFA and the muscle branch of the femoral nerve to the vastus lateralis.
The middle of the vastus lateralis is an appropriate site for IM injections because it is distant from the descending branch of the LCFA and the muscle branch of the femoral nerve to the vastus lateralis. This study was limited in terms of the number of subjects, normal BMI, and age.
Regarding obese subjects, we cannot confirm whether the vastus lateralis is a safe IM injection site because we did not examine the subcutaneous thickness of obese subjects or whether needles used for IM injections penetrate their subcutaneous tissue and reach muscle. Regarding age, we did not obtain any data on the location of dbLCFA and mbFN to VL or subcutaneous thickness in infants, toddlers, children, and young adults. We also did not directly compare data between volunteers and cadavers or generalize results obtained for all ages and ethnicities.
Large-scale studies are needed to examine safe IM injection sites in obese and individuals of various ages. Further studies are needed to support the present results. National Center for Biotechnology Information , U. Journal List Hum Vaccin Immunother v.
Hum Vaccin Immunother. Published online Aug Author information Article notes Copyright and License information Disclaimer. Intramuscular IM self-injection. ABSTRACT The anatomical safety of intramuscular injections at the deltoid and ventrogluteal sites has been investigated; however, the anatomical relationship between intramuscular injection sites in the thigh and major blood vessels and nerves remains unclear.
Introduction Intramuscular IM injections are a technique used to deliver vaccines, hormonal agents, antibiotics, and high viscosity medication deep into the muscles of patients. Open in a separate window. However, if a patient is thin, a shorter needle length is used because there is less fat tissue to advance through to reach the muscle. Additionally, the muscle mass of infants and young children cannot tolerate large amounts of medication volume. Medication fluid amounts up to 0.
Intramuscular injections are administered at a degree angle. Anatomic sites must be selected carefully for intramuscular injections and include the ventrogluteal, vastus lateralis, and the deltoid. The vastus lateralis site is preferred for infants because that muscle is most developed. The ventrogluteal site is generally recommended for IM medication administration in adults, but IM vaccines may be administered in the deltoid site.
Additional information regarding injections in each of these sites is provided in the following subsections. This site involves the gluteus medius and minimus muscle and is the safest injection site for adults and children because it provides the greatest thickness of gluteal muscles, is free from penetrating nerves and blood vessels, and has a thin layer of fat.
To locate the ventrogluteal site, place the patient in a supine or lateral position. Use your right hand for the left hip or your left hand for the right hip. Place the heel or palm of your hand on the greater trochanter, with the thumb pointed toward the belly button. Extend your index finger to the anterior superior iliac spine and spread your middle finger pointing towards the iliac crest.
This is the preferred site for all oily and irritating solutions for patients of any age. The needle gauge used at the ventrogluteal site is determined by the solution of the medication ordered. An aqueous solution can be given with a to gauge needle, whereas viscous or oil-based solutions are given with to gauge needles.
The needle length is based on patient weight and body mass index. Children and infants require shorter needles. Refer to agency policies regarding needle length for infants, children, and adolescents. Up to 3 mL of medication may be administered in the ventrogluteal muscle of an average adult and up to 1 mL in children. See Figure The vastus lateralis site is commonly used for immunizations in infants and toddlers because the muscle is thick and well-developed.
The outer middle third of the muscle is used for injections. To help relax the patient, ask the patient to lie flat with knees slightly bent or have the patient in a sitting position. Refer to agency policy for pediatric needle lengths. The gauge of the needle is determined by the type of medication administered. Call your doctor or healthcare provider right away if you experience:. Read through the steps several times until you feel comfortable with the procedure, and take your time.
When a medication is injected directly into muscle, it is called an intramuscular injection IM. The Z-track method of IM is used to prevent tracking….
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Read more about these alternatives to traditional statin…. Learn the ins and outs of MRI vs. X-ray imaging tests, including the pros and cons of each test, how they compare to CT scans, how much they cost, and…. Health Conditions Discover Plan Connect. What Are Intramuscular Injections? Medically reviewed by Deborah Weatherspoon, Ph. Purpose Injection sites How-to Helpful tips Complications We include products we think are useful for our readers. Overview An intramuscular injection is a technique used to deliver a medication deep into the muscles.
What are intramuscular injections used for? Intramuscular injection sites. Share on Pinterest. How to administer an intramuscular injection. Tips for an easier injection. What are the complications of intramuscular injections?
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