護理師準備為嬰兒進行肌肉注射，下列何處是最適合的部位？

為嬰兒（Infant）進行肌肉注射（Intramuscular Injection, IM）時，選擇正確的注射部位至關重要，以確保藥物能被有效吸收，並避免損傷重要的神經血管結構。嬰兒的肌肉發育尚未成熟，解剖結構也與成人不同。 核心考量是肌肉的發育程度、鄰近的神經血管結構以及藥物的吸收。選項 A（外側股肌 Vastus lateralis muscle）是嬰兒和幼童肌肉注射的首選部位。該肌肉位於大腿前外側，是嬰兒時期發育較為完善的肌肉，且其上方無主要神經（如坐骨神經 Sciatic nerve）或血管經過，注射相對安全，吸收也較好。 選項 D（背臀肌 Dorsogluteal muscle）和 C（腹臀肌 Ventrogluteal muscle）不適合嬰兒。因為嬰兒臀部肌肉發育不全，且注射該部位有損傷坐骨神經或臀上神經血管束的風險。選項 B（三角肌 Deltoid muscle）位於上臂，雖然成人常用，但嬰兒的三角肌肌肉量非常少，注射後吸收不佳且易造成組織損傷，通常只用於注射小劑量疫苗，且建議在 18 個月以上幼兒使用。

When administering an intramuscular (IM) injection to an infant, choosing the correct injection site is crucial to ensure effective drug absorption and to avoid injuring important neurovascular structures. The infant's muscles are immature and the anatomy differs from that of adults. The central considerations are muscle development, adjacent neurovascular structures, and drug absorption. Option A (the vastus lateralis muscle) is the preferred IM site for infants and young children. This muscle is located on the anterolateral thigh, is relatively well developed in infancy, and has no major nerves (such as the sciatic nerve) or vessels passing over it, making injection comparatively safe with good absorption. Options A (dorsogluteal muscle) and C (ventrogluteal muscle) are not appropriate for infants, because the gluteal muscles are underdeveloped and there is a risk of injury to the sciatic nerve or the superior gluteal neurovascular bundle. Option B (deltoid muscle) is in the upper arm; although commonly used in adults, an infant's deltoid muscle mass is very small, absorption after injection is poor, and the risk of tissue injury is greater. It is generally reserved for small-volume vaccinations and is recommended only for children older than 18 months.