Deltoid Muscle Insertion Location
Anatomical Location
The deltoid muscle inserts onto the lateral aspect of the proximal humerus at a site called the deltoid tuberosity, located approximately 6-7.5 cm distal to the greater tuberosity. 1
Detailed Anatomical Description
Distance Measurements
- The proximal edge of the deltoid insertion begins on average 61 mm (range 55-75 mm) distal to the greater tuberosity 1
- The distal edge of the insertion extends to approximately 158 mm (range 142-172 mm) from the greater tuberosity 1
- The total length of the deltoid insertion averages 97 mm (range 83-111 mm), making it a long and broad attachment 1
Circumferential Coverage
- At 5 mm from the proximal insertion point, the deltoid occupies approximately 8% of the humeral circumference 1
- At the midpoint of the insertion, it occupies 39% of the humeral circumference 1
- At 5 mm from the distal insertion point, it occupies 31% of the humeral circumference 1
Structural Organization
Tendinous Configuration
The deltoid insertion has a distinctive V-shaped tendinous confluence with two components 2:
- A broad posterior band that comprises the majority of the insertion 2
- A narrow separate anterior band that accounts for approximately the anterior one-fifth (0.44 cm) of the insertion 2
Relationship to Adjacent Structures
- The deltoid insertion is separated from the pectoralis major insertion by as little as 2 mm in most specimens (31 of 36 cadavers studied) 2
- The axillary nerve lies approximately 5.6 cm anterior and 4.5 cm posterior to the deltoid insertion 2
- The radial nerve averages 2.4 cm proximally and 1.6 cm distally from the posterior deltoid insertion 2
Clinical Relevance for Injections
Preferred Injection Site
For intramuscular injections in adults, the deltoid muscle is the recommended site, with the needle inserted over the muscle belly (not at the insertion site). 3, 4, 5
The injection should be administered: