On the battlefield, traumatic injuries often make peripheral intravenous (IV) access unattainable making it difficult to provide lifesaving medical interventions to the warfighter. Given this, The Committee on Tactical Combat Casualty Care (COTCCC) recommends emergent intraosseous (IO) access in traumatic injuries when unable to start IV access or when fluids or meds are needed urgently. With this in mind, the need for further research into optimizing IO blood transfusion strategies is needed. Despite the demonstrated superiority of sternal IO access in terms of flow rates and pharmacokinetics compared to other IO routes, provider hesitancy remains due to concerns about the potential risk of penetrating the sternum’s posterior cortex that can lead to fatal mediastinal injuries. With limited research regarding sternal anatomy in active-duty males, this retrospective study aims to address crucial questions. First, it evaluates variations in sternal anatomy among activeduty military males to establish parameters for safe and effective sternal IO needle catheter placement. Second, it investigates whether the presence or absence of a sternomanubrial (SM) joint changes the target depth for safe IO infusion in the earliest phases of battlefield care. This study reviewed contrast CT images from the Naval Medical Center San Diego. The inclusion criteria consisted of military-age service members who received a head and neck CTA with arterial and venous phase contrast imaging. The sample consists of 93 active-duty male subjects aged 18-30. From these images, various manubrial measurements, differences in Hounsfield units (HU) between venous and arterial contrast phases, and the presence or absence of an SM joint were assessed. Results from this retrospective study indicate the average military-age male was 23.5 years of age. Mean soft tissue thickness overlying the manubrium was 10.2 +/- 4.2 mm, mean cortical thickness was 2.4 mm (+/- 0.5 mm), and the mean medullary thickness of the upper manubrium was 10.2 mm (+/- 1.9 mm). Approximately 15% of subjects lack a SM joint, and its absence is associated with a statistically thicker cortex (2.6 mm vs 2.4 mm, p = 0.04). Variance in cortex thickness was 4.4% with an 11% difference between groups. Hounsfield units were higher during the venous phase in 78.5% of the subjects compared to the arterial phase. Two sternal IO catheters are currently approved for medical use: the FAST1 IO infusion system and the TALON needle set. The TALON is commonly used by military personnel and limits its IO insertion to less than 14.9 mm below the skin, while the FAST1 utilizes manual pressure and a spring-loaded mechanism to limit catheter penetration to 6mm. The data obtained from this study suggests a low variability in patients, both with and without, atypical sternal anatomy. The data obtained from this study suggests a low variability in patients, both with and without, atypical sternal anatomy. The data also supports the use of manubrium as a safe and effective primary site for IO access in injured military-age males.