Spine and Pelvis
32 Sacrum and Coccyx
Anatomy
Superior articular process, sacral promontory, ala, anterior and posterior sacral foramina, apex, sacral canal, median sacral crest, sacral horn (cornu), auricular surface, horn (cornu) of coccyx, transverse process of coccyx, 4 segments, coccygeal apex, coccygeal base
Projections
[Part], PA or AP
CR Location
[Part], PA or AP –
Evaluation Criteria
AP Sacrum Image Criteria: Entire sacrum should be included and not superimposed by pelvis.
AP Coccyx Image Criteria: Coccyx should be clearly visible projected above the pubis. Coccygeal segments should be separated (if they are not fused). Coccyx should be equal distances from both sides of the lateral pelvic walls if there is not any rotation.
Lateral Image Criteria: Sacrum and coccyx should be seen in lateral profile. Only one lateral projection of both the sacrum and coccyx should be performed to reduce gonadal dose. Posterior margins of pelvis and greater sciatic notches should be aligned if the patient is not rotated.
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Hows & Whys of Sacrum & Coccyx Radiography
- The auricular surfaces of the sacrum form the medial walls of what joint?
- Sacroiliac.
- How many segments originally made up the sacrum?
- Five.
- What openings transmit nerves and blood vessels in the sacrum?
- Anterior sacral foramina.
- The sacral promontory forms the posterior wall of what opening?
- The inlet of the true pelvis.
- What forms the median sacral crest?
- The fusion of the spinous processes of the sacral vertebrae.
- What are the horns or cornu of the sacrum and coccyx?
- The cornu are small tubercles remaining from the inferior and superior articular processes.
- How many segments make up the coccyx?
- Three to five.