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. We aimed to compare intramuscular injection sites in the rectus femoris and vastus lateralis with those at the deltoid and ventrogluteal sites and identify safe intramuscular injection sites in the thigh. Twenty-seven young adult volunteers were recruited, and the thicknesses of subcutaneous tissue and muscle as well as the number of blood vessels present were evaluated at two sites on the deltoid, ventrogluteal, and thigh using ultrasound equipment. The right thighs of 24 cadavers were used, and the thickness of muscle, number of blood vessels or nerves present, and the distance between each examined site and major blood vessels or nerves were evaluated in the rectus femoris and vastus lateralis. A major blood vessel was observed in the middle of the rectus femoris in young adults. In cadavers, the descending branch of the lateral circumflex femoral artery and muscle branch of the femoral nerves to the vastus lateralis were observed at the middle point, distal two-thirds point, and middle point between the middle and distal two-thirds points of the rectus femoris, but not at the middle of the vastus lateralis. The middle of the vastus lateralis is an appropriate site for intramuscular injections because of the low risk of vascular or nerve damage. The present results support good practices for site selection for intramuscular injections.

Objective: Venipuncture is an invasive procedure, and repeated puncture attempts may be uncomfortable or even traumatic for patients. Vein visibility is one of the most influential variables for the failure of venipuncture; however, the factors affecting vein visibility remain unclear. The present study was conducted to identify the factors influencing vein visibility at the upper limb in healthy young adults. Methods: Twenty-seven healthy volunteers were included. All measurements were performed at the right arm, right cubital fossa, and right forearm. The depth and cross-sectional area of superficial veins were measured by ultrasonography. Skin color was assessed by a spectrophotometer and quantified according to Commission International d’Eclairage L*a*b* values. Results: Invisible superficial veins were significantly deeper and had a larger cross-sectional area than visible superficial veins. Skin color b* of invisible superficial veins was significantly higher than that of visible superficial veins. Vein depth, skin color b*, and gender markedly affected superficial vein visibility at the upper limb. The cutoff for vein depth was 2.3 mm (area under the curve = 0.91). Conclusion: The present results confirmed that vein depth, skin color b*, and gender strongly influenced vein visibility at the upper limb. The cutoff for vein depth was 2.3 mm.

To date no age-comparative study has been reported about effect of exercise on muscle pump action change, while its effect is suggested to differ in ages. This study aims to clarify the changes in muscle pump action with aging by measuring the muscle and vein area, and blood flow in lower legs.Methods: Subjects were healthy volunteers and consisted of three groups: young age group (N = 20), middle age group (N = 20) and old age group (N = 16). The lower leg flexor muscle area and popliteal vein area were measured by using T1-weighed magnetic resonance imaging at the condition preand post-ankle exercise in three positions. Moreover, popliteal blood flow velocity was also measured using phase contrast magnetic resonance imaging. Results: The elderly had the highest number of individuals who had exercise habits (p < .001). In a multiple linear regression analysis, sitting posture, leg muscle volume, and rate of change in the soleus muscle were significantly related to blood flow velocity change.Conclusions: No difference was found in the changes in muscle pump action with age. The study results suggested that elderly people with exercise habits might be able to maintain the muscle pump action.