| Structure/Space | Description/Boundaries | Significance |
|---|---|---|
| external occipital protuberance | a bump located in the midline on the posterior surface of the occipital bone | the medial ends of the superior nuchal lines meet at the external occipital protuberance; the ligamentum nuchae attaches here |
| lumbar triangle | a triangle defined by the border of the latissimus dorsi m. medially, the external abdominal oblique m. laterally and the iliac crest inferiorly; its floor is the internal abdominal oblique m. | lumbar triangle may be the site of an abdominal hernia; also known as: triangle of Petit |
| natal cleft | midline cleft between the buttocks | natal cleft lies between the gluteus maximus muscles |
| paravertebral line | an imaginary line located lateral to the midline on the posterior surface of the body, parallel to the vertebral column | paravertebral line is used as a descriptive landmark |
| quadrangular space | an area on the posterior surface of the back bounded by the teres minor m. superiorly, the teres major m. inferiorly, the long head of the triceps brachii m. medially and the humerus laterally | the axillary n. and the posterior circumflex humeral a. pass through this space |
| triangle of auscultation | a triangle located below the inferior angle of the scapula bounded by the trapezius m. medially, rhomboideus major m. superiorly and the latissimus dorsi m. inferiorly; its floor is the posterior thoracic wall | triangle of auscultation is used to listen to (auscultate) the lungs because the stethoscope can be placed close to the thoracic wall at this location |
| triangular interval | the interval between the teres major m. superiorly, long head of the triceps brachii m. medially and humerus laterally | the radial n. passes through this interval to get from the axilla to the posterior surface of the humerus |
| triangular space | the space bounded by the teres minor m. superiorly, the teres major m. inferiorly and the long head of the triceps brachii m. laterally | the circumflex scapular vessels are located in this space as they pass from the axilla to the dorsum of the scapula |
| vertebra prominens | the C7 vertebra, so named because its spine is easily seen and palpated | vertebra prominens is an easily palpable landmark which indicates the level of transition from cervical to thoracic vertebra |
| vertebral furrow | midline furrow down the back | surface landmark that indicates the location of the vertebral spines; the erector spinae muscle masses lie on either side of it |