Thickness of the Deltoid Muscle and Location of the Anterior Branch of the Axillary Nerve and the Posterior Circumflex Humeral Artery for Deltoid Injections

Abstract

This study investigated the thickness of the deltoid muscle and the location of the anterior branch of the axillary nerve (AAN) and posterior circumflex humeral artery (PCHA), with the goal of maximizing the effectiveness of deltoid injections. Forty specimens from 22 adult Korean cadavers were used. A reference line was identified, connecting the anterior point of the deltoid muscle (AP) and the posterior point of the deltoid muscle (PP) on the surface. The midpoint between the AP and PP was used as the origin point (OP). The line connecting the OP and the lowest point of the deltoid tuberosity (DP) was used as the y -axis. The mean distance of the reference line from the AP to PP was 4.7 ± 0.7 cm . The vertical mean length of the deltoid muscle from the OP and DP was 16.1 ± 1.0 cm . At the 3, 5, and 7 cm sites, the thickness of the deltoid muscle was 0.62 ± 0.9 , 0.73 ± 0.7 , and 1.3 ± 1.1 cm , respectively. Most of the branches of the axillary nerve were concentrated in the third section (4-6 cm, 51%), while the branches of the PCHA were predominantly found in the fourth section (6-8 cm, 69%). The peripheral branches of the AAN entering the muscle were distributed between 2.2 and 9.8 cm from the acromion. The mean number of the peripheral branches of the AAN was 9.6 ± 3.4 . In the deltoid muscle, the mean number of peripheral branches of the PCHA was 8.2 ± 2.8 . Administering deltoid injections 5-6 cm below the OP is recommended to avoid axillary nerve injury.

‘The Recommended Deltoid Intramuscular Injection Sites in the Adult Population: A Cadaveric study with an Orthopedic Perspective’

“…Ye-Gyung Kim et al (Korea) and Nicholson et al (USA) reported significant difference in the length of the acromion between males and females. Our results agree with those of these two studies [8,15]. Nakatani et al (Japan) in their study observed that AXN is frequently positioned 5 cm below the mid-acromion point [16].…”

“…Two investigators conducted the measurements separately on each cadaver at different times in the day. A research study piloted by Ye-Gyung Kim et al (2022) in Korean population was referred to as reference study for the landmarks used for conducting anthropometric measurements in the present study [8]. Before taking the measurements, bony landmarks were identified and marked using specimen marking pins on the concerned region namely the anterior point of the lateral border of acromion (AP), the posterior point of the lateral border of acromion (PP), and the acromion.…”

“…More than 50 % of deltoid intramuscular injections (IM) are given indiscriminately by untrained staff in unregistered settings in clinical practice, especially in Southeast-Asian countries [3,5]. In the East-Asian and West, extensive research is done namely Cheung K et al, (2009) USA [6]; Chen YF et al, (2012) China [7]; Ye-Gyung Kim et al, (2022) Korea [8]; and Nakajima et al, (2017) Japan [9]. In India, only two research studies namely Patra A, et al, (2018) [10] and Gurushantappa PK, (2015) [11] exists on the anthropometry of axillary nerve.…”