Sacrum anatomy quiz

1. How many vertebrae form the sacrum in an adult?

• 3 vertebrae

  The sacrum (os sacrum) is formed by the fusion of 5 sacral vertebrae (S1–S5).

• 4 vertebrae

  The sacrum (os sacrum) is formed by the fusion of 5 sacral vertebrae (S1–S5).

• 5 vertebrae

  The sacrum (os sacrum) is formed by the fusion of 5 sacral vertebrae (S1–S5).

• 6 vertebrae

  The sacrum (os sacrum) is formed by the fusion of 5 sacral vertebrae (S1–S5).

• I find it difficult to answer

  The sacrum (os sacrum) is formed by the fusion of 5 sacral vertebrae (S1–S5).

2. What is the superior border of the sacrum that projects into the lesser pelvis called?

• Median sacral crest

  Promontorium (promontory) is the anteriorly projecting superior border of the body of S1, forming a characteristic prominence at the junction of the lumbar spine and sacrum and serving as an important landmark in the topography of the lesser pelvis.

• Promontory

  Promontorium (promontory) is the anteriorly projecting superior border of the body of S1, forming a characteristic prominence at the junction of the lumbar spine and sacrum and serving as an important landmark in the topography of the lesser pelvis.

• Base of sacrum

  Promontorium (promontory) is the anteriorly projecting superior border of the body of S1, forming a characteristic prominence at the junction of the lumbar spine and sacrum and serving as an important landmark in the topography of the lesser pelvis.

• Apex of sacrum

  Promontorium (promontory) is the anteriorly projecting superior border of the body of S1, forming a characteristic prominence at the junction of the lumbar spine and sacrum and serving as an important landmark in the topography of the lesser pelvis.

• I find it difficult to answer

  Promontorium (promontory) is the anteriorly projecting superior border of the body of S1, forming a characteristic prominence at the junction of the lumbar spine and sacrum and serving as an important landmark in the topography of the lesser pelvis.

3. What is the smooth, concave surface of the sacrum that faces anteriorly into the pelvic cavity called?

• Dorsal surface

  Facies pelvica (pelvic surface) is the concave anterior surface of the sacrum facing the cavity of the lesser pelvis. The anterior sacral foramina open on this surface.

• Lateral surface

  Facies pelvica (pelvic surface) is the concave anterior surface of the sacrum facing the cavity of the lesser pelvis. The anterior sacral foramina open on this surface.

• Pelvic surface

  Facies pelvica (pelvic surface) is the concave anterior surface of the sacrum facing the cavity of the lesser pelvis. The anterior sacral foramina open on this surface.

• Auricular surface

  Facies pelvica (pelvic surface) is the concave anterior surface of the sacrum facing the cavity of the lesser pelvis. The anterior sacral foramina open on this surface.

• I find it difficult to answer

  Facies pelvica (pelvic surface) is the concave anterior surface of the sacrum facing the cavity of the lesser pelvis. The anterior sacral foramina open on this surface.

4. How many pairs of anterior sacral foramina (foramina sacralia anteriora) are present on the pelvic surface of the sacrum?

• 3 pairs

  On the pelvic surface of the sacrum, there are 4 pairs of anterior sacral foramina (foramina sacralia anteriora), through which the anterior rami of the sacral spinal nerves and vessels exit.

• 4 pairs

  On the pelvic surface of the sacrum, there are 4 pairs of anterior sacral foramina (foramina sacralia anteriora), through which the anterior rami of the sacral spinal nerves and vessels exit.

• 5 pairs

  On the pelvic surface of the sacrum, there are 4 pairs of anterior sacral foramina (foramina sacralia anteriora), through which the anterior rami of the sacral spinal nerves and vessels exit.

• 2 pairs

  On the pelvic surface of the sacrum, there are 4 pairs of anterior sacral foramina (foramina sacralia anteriora), through which the anterior rami of the sacral spinal nerves and vessels exit.

• I find it difficult to answer

  On the pelvic surface of the sacrum, there are 4 pairs of anterior sacral foramina (foramina sacralia anteriora), through which the anterior rami of the sacral spinal nerves and vessels exit.

5. The following pass through the posterior sacral foramina (foramina sacralia posteriora):

• Anterior rami of the sacral nerves

  The posterior rami of the sacral spinal nerves (rami dorsales nn. sacrales), as well as their accompanying vessels, pass through the foramina sacralia posteriora.

• Posterior rami of lumbar nerves

  The posterior rami of the sacral spinal nerves (rami dorsales nn. sacrales), as well as their accompanying vessels, pass through the foramina sacralia posteriora.

• Internal iliac vessels

  The posterior rami of the sacral spinal nerves (rami dorsales nn. sacrales), as well as their accompanying vessels, pass through the foramina sacralia posteriora.

• Lymphatic trunks

  The posterior rami of the sacral spinal nerves (rami dorsales nn. sacrales), as well as their accompanying vessels, pass through the foramina sacralia posteriora.

• I find it difficult to answer

  The posterior rami of the sacral spinal nerves (rami dorsales nn. sacrales), as well as their accompanying vessels, pass through the foramina sacralia posteriora.

6. What is the canal that passes within the sacrum and is a continuation of the vertebral canal called?

• Canalis obturatorius

  Canalis sacralis (sacral canal) is a continuation of the canalis vertebralis and contains the cauda equina, filum terminale, and spinal cord meninges with their contents.

• Pudendal canal

  Canalis sacralis (sacral canal) is a continuation of the canalis vertebralis and contains the cauda equina, filum terminale, and spinal cord meninges with their contents.

• Sacral canal

  Canalis sacralis (sacral canal) is a continuation of the canalis vertebralis and contains the cauda equina, filum terminale, and spinal cord meninges with their contents.

• Lumbar vertebral canal

  Canalis sacralis (sacral canal) is a continuation of the canalis vertebralis and contains the cauda equina, filum terminale, and spinal cord meninges with their contents.

• I find it difficult to answer

  Canalis sacralis (sacral canal) is a continuation of the canalis vertebralis and contains the cauda equina, filum terminale, and spinal cord meninges with their contents.

7. What terminates the sacral canal inferiorly?

• Intervertebral foramen

  The sacral canal terminates inferiorly at the hiatus sacralis—the sacral hiatus.

• Sacrococcygeal symphysis

  The sacral canal terminates inferiorly at the hiatus sacralis—the sacral hiatus.

• Sacral hiatus

  The sacral canal terminates inferiorly at the hiatus sacralis—the sacral hiatus.

• Fourth anterior sacral foramen

  The sacral canal terminates inferiorly at the hiatus sacralis—the sacral hiatus.

• I find it difficult to answer

  The sacral canal terminates inferiorly at the hiatus sacralis—the sacral hiatus.

8. What are the lateral parts of the sacrum called?

• Transverse processes

  Partes laterales—the lateral parts of the sacrum.

• Lateral parts

  Partes laterales—the lateral parts of the sacrum.

• Laminae of the vertebral arches

  Partes laterales—the lateral parts of the sacrum.

• Lateral sacral crests

  Partes laterales—the lateral parts of the sacrum.

• I find it difficult to answer

  Partes laterales—the lateral parts of the sacrum.

9. What is the articular surface of the sacrum that articulates with the ilium called?

• Pelvic surface

  Facies auricularis (auricular surface) is the cartilage-covered articular surface of the lateral part of the sacrum that forms the sacroiliac joint (articulatio sacroiliaca) with the corresponding surface of the ilium.

• Dorsal surface

  Facies auricularis (auricular surface) is the cartilage-covered articular surface of the lateral part of the sacrum that forms the sacroiliac joint (articulatio sacroiliaca) with the corresponding surface of the ilium.

• Auricular surface

  Facies auricularis (auricular surface) is the cartilage-covered articular surface of the lateral part of the sacrum that forms the sacroiliac joint (articulatio sacroiliaca) with the corresponding surface of the ilium.

• Symphyseal surface

  Facies auricularis (auricular surface) is the cartilage-covered articular surface of the lateral part of the sacrum that forms the sacroiliac joint (articulatio sacroiliaca) with the corresponding surface of the ilium.

• I find it difficult to answer

  Facies auricularis (auricular surface) is the cartilage-covered articular surface of the lateral part of the sacrum that forms the sacroiliac joint (articulatio sacroiliaca) with the corresponding surface of the ilium.

10. What is the tuberositas sacralis?

• Apex of the sacrum

  Tuberositas sacralis—the sacral tuberosity, a rough surface located poster to the facies auricularis on the posterior surface of the lateral part of the sacrum. It serves as the attachment site for the strong sacroiliac ligaments.

• A rough surface poster to the auricular surface for ligament attachment

  Tuberositas sacralis—the sacral tuberosity, a rough surface located poster to the facies auricularis on the posterior surface of the lateral part of the sacrum. It serves as the attachment site for the strong sacroiliac ligaments.

• A crest on the pelvic surface

  Tuberositas sacralis—the sacral tuberosity, a rough surface located poster to the facies auricularis on the posterior surface of the lateral part of the sacrum. It serves as the attachment site for the strong sacroiliac ligaments.

• Lateral border of the sacrum

  Tuberositas sacralis—the sacral tuberosity, a rough surface located poster to the facies auricularis on the posterior surface of the lateral part of the sacrum. It serves as the attachment site for the strong sacroiliac ligaments.

• I find it difficult to answer

  Tuberositas sacralis—the sacral tuberosity, a rough surface located poster to the facies auricularis on the posterior surface of the lateral part of the sacrum. It serves as the attachment site for the strong sacroiliac ligaments.

11. Which crest is located along the midline of the dorsal surface of the sacrum and is formed by the fusion of the spinous processes?

• Lateral sacral crest

  Crista sacralis mediana (median sacral crest) is located along the midline of the dorsal surface of the sacrum and is formed by the fusion of the rudimentary spinous processes of the sacral vertebrae.

• Intermediate sacral crest

  Crista sacralis mediana (median sacral crest) is located along the midline of the dorsal surface of the sacrum and is formed by the fusion of the rudimentary spinous processes of the sacral vertebrae.

• Median sacral crest

  Crista sacralis mediana (median sacral crest) is located along the midline of the dorsal surface of the sacrum and is formed by the fusion of the rudimentary spinous processes of the sacral vertebrae.

• Crista iliaca

  Crista sacralis mediana (median sacral crest) is located along the midline of the dorsal surface of the sacrum and is formed by the fusion of the rudimentary spinous processes of the sacral vertebrae.

• I find it difficult to answer

  Crista sacralis mediana (median sacral crest) is located along the midline of the dorsal surface of the sacrum and is formed by the fusion of the rudimentary spinous processes of the sacral vertebrae.

12. Crista sacralis medialis is formed by the fusion of:

• Spinous processes

  Crista sacralis medialis (intermediate sacral crest) is formed by the fusion of the articular processes (processus articulares) of the sacral vertebrae and is located between the median and lateral crests.

• Articular processes

  Crista sacralis medialis (intermediate sacral crest) is formed by the fusion of the articular processes (processus articulares) of the sacral vertebrae and is located between the median and lateral crests.

• Transverse processes

  Crista sacralis medialis (intermediate sacral crest) is formed by the fusion of the articular processes (processus articulares) of the sacral vertebrae and is located between the median and lateral crests.

• Vertebral arches

  Crista sacralis medialis (intermediate sacral crest) is formed by the fusion of the articular processes (processus articulares) of the sacral vertebrae and is located between the median and lateral crests.

• I find it difficult to answer

  Crista sacralis medialis (intermediate sacral crest) is formed by the fusion of the articular processes (processus articulares) of the sacral vertebrae and is located between the median and lateral crests.

13. What is the inferior tapered end of the sacrum that articulates with the coccyx called?

• Base of sacrum

  Apex ossis sacri (apex of the sacrum) is the inferior narrowed end of the sacrum bearing an articular surface for articulation with the first coccygeal vertebra at the sacrococcygeal joint (junctio sacrococcygea).

• Promontory

  Apex ossis sacri (apex of the sacrum) is the inferior narrowed end of the sacrum bearing an articular surface for articulation with the first coccygeal vertebra at the sacrococcygeal joint (junctio sacrococcygea).

• Apex of sacrum

  Apex ossis sacri (apex of the sacrum) is the inferior narrowed end of the sacrum bearing an articular surface for articulation with the first coccygeal vertebra at the sacrococcygeal joint (junctio sacrococcygea).

• Sacral hiatus

  Apex ossis sacri (apex of the sacrum) is the inferior narrowed end of the sacrum bearing an articular surface for articulation with the first coccygeal vertebra at the sacrococcygeal joint (junctio sacrococcygea).

• I find it difficult to answer

  Apex ossis sacri (apex of the sacrum) is the inferior narrowed end of the sacrum bearing an articular surface for articulation with the first coccygeal vertebra at the sacrococcygeal joint (junctio sacrococcygea).

14. Crista sacralis lateralis is formed by the fusion of:

• Articular processes

  Crista sacralis lateralis (lateral sacral crest) is formed by the fusion of the transverse processes (processus transversi) of the sacral vertebrae. It is located lateral to the posterior sacral foramina.

• Spinous processes

  Crista sacralis lateralis (lateral sacral crest) is formed by the fusion of the transverse processes (processus transversi) of the sacral vertebrae. It is located lateral to the posterior sacral foramina.

• Transverse processes

  Crista sacralis lateralis (lateral sacral crest) is formed by the fusion of the transverse processes (processus transversi) of the sacral vertebrae. It is located lateral to the posterior sacral foramina.

• Vertebral bodies

  Crista sacralis lateralis (lateral sacral crest) is formed by the fusion of the transverse processes (processus transversi) of the sacral vertebrae. It is located lateral to the posterior sacral foramina.

• I find it difficult to answer

  Crista sacralis lateralis (lateral sacral crest) is formed by the fusion of the transverse processes (processus transversi) of the sacral vertebrae. It is located lateral to the posterior sacral foramina.

15. The base of the sacrum (basis ossis sacri) faces:

• Downward and anteriorly

  Basis ossis sacri is the broad superior part of the sacrum, which faces upward and anteriorly. It articulates with the body of the fifth lumbar vertebra through the intervertebral disc.

• Upward and anteriorly

  Basis ossis sacri is the broad superior part of the sacrum, which faces upward and anteriorly. It articulates with the body of the fifth lumbar vertebra through the intervertebral disc.

• Posteriorly and downward

  Basis ossis sacri is the broad superior part of the sacrum, which faces upward and anteriorly. It articulates with the body of the fifth lumbar vertebra through the intervertebral disc.

• Laterally

  Basis ossis sacri is the broad superior part of the sacrum, which faces upward and anteriorly. It articulates with the body of the fifth lumbar vertebra through the intervertebral disc.

• I find it difficult to answer

  Basis ossis sacri is the broad superior part of the sacrum, which faces upward and anteriorly. It articulates with the body of the fifth lumbar vertebra through the intervertebral disc.

16. By what age do the sacral vertebrae completely fuse with one another to form a single bone—the sacrum (os sacrum)?

• By 5–7 years of age

  By 18–25 years of age, the complete replacement of cartilage by bone is completed, and the sacrum becomes a single solid bone.

• By 18–25 years of age

  By 18–25 years of age, the complete replacement of cartilage by bone is completed, and the sacrum becomes a single solid bone.

• By 12–14 years of age

  By 18–25 years of age, the complete replacement of cartilage by bone is completed, and the sacrum becomes a single solid bone.

• By 35–40 years of age

  By 18–25 years of age, the complete replacement of cartilage by bone is completed, and the sacrum becomes a single solid bone.

• I find it difficult to answer

  By 18–25 years of age, the complete replacement of cartilage by bone is completed, and the sacrum becomes a single solid bone.

17. What do the transverse lines (lineae transversae) located on the pelvic surface of the sacrum represent anatomically?

• Attachment sites for the sacrotuberous and sacrospinous ligaments

  They form at the sites of the former cartilaginous intervertebral discs as a result of the osseous fusion of the bodies of the 5 sacral vertebrae.

• Grooves through which the anterior rami of the sacral nerves pass

  They form at the sites of the former cartilaginous intervertebral discs as a result of the osseous fusion of the bodies of the 5 sacral vertebrae.

• Traces of osseous fusion of the bodies of the five sacral vertebrae

  They form at the sites of the former cartilaginous intervertebral discs as a result of the osseous fusion of the bodies of the 5 sacral vertebrae.

• Rudiments of the costal processes of the sacral region

  They form at the sites of the former cartilaginous intervertebral discs as a result of the osseous fusion of the bodies of the 5 sacral vertebrae.

• I find it difficult to answer

  They form at the sites of the former cartilaginous intervertebral discs as a result of the osseous fusion of the bodies of the 5 sacral vertebrae.

18. Does the sacrum (os sacrum) have superior articular processes, and what is their function?

• Yes, two superior articular processes are present on the base of the sacrum and articulate with the inferior articular processes of L5

  On the base of the sacrum (basis ossis sacri), on either side of the entrance to the sacral canal, there are two superior articular processes (processus articulares superiores). They are required to form paired zygapophysial joints with the inferior articular processes of the 5th lumbar vertebra.

• No, the sacrum has no articular processes; articulation occurs only through the intervertebral disc

  On the base of the sacrum (basis ossis sacri), on either side of the entrance to the sacral canal, there are two superior articular processes (processus articulares superiores). They are required to form paired zygapophysial joints with the inferior articular processes of the 5th lumbar vertebra.

• No, only inferior articular processes directed toward the coccyx are present

  On the base of the sacrum (basis ossis sacri), on either side of the entrance to the sacral canal, there are two superior articular processes (processus articulares superiores). They are required to form paired zygapophysial joints with the inferior articular processes of the 5th lumbar vertebra.

• Articular processes are present only in embryos; in adults, they regress into the lateral masses

  On the base of the sacrum (basis ossis sacri), on either side of the entrance to the sacral canal, there are two superior articular processes (processus articulares superiores). They are required to form paired zygapophysial joints with the inferior articular processes of the 5th lumbar vertebra.

• I find it difficult to answer

  On the base of the sacrum (basis ossis sacri), on either side of the entrance to the sacral canal, there are two superior articular processes (processus articulares superiores). They are required to form paired zygapophysial joints with the inferior articular processes of the 5th lumbar vertebra.

19. Cornua sacralia are:

• Rudiments of the transverse processes of S5

  Cornua sacralia (sacral horns) are the inferiorly directed rudimentary inferior articular processes of S5. They bound the hiatus sacralis laterally and serve as landmarks for determining its location.

• Rudiments of the inferior articular processes of S5 that bound the hiatus sacralis laterally

  Cornua sacralia (sacral horns) are the inferiorly directed rudimentary inferior articular processes of S5. They bound the hiatus sacralis laterally and serve as landmarks for determining its location.

• Lateral borders of the sacrum

  Cornua sacralia (sacral horns) are the inferiorly directed rudimentary inferior articular processes of S5. They bound the hiatus sacralis laterally and serve as landmarks for determining its location.

• Projections of the body of S1

  Cornua sacralia (sacral horns) are the inferiorly directed rudimentary inferior articular processes of S5. They bound the hiatus sacralis laterally and serve as landmarks for determining its location.

• I find it difficult to answer

  Cornua sacralia (sacral horns) are the inferiorly directed rudimentary inferior articular processes of S5. They bound the hiatus sacralis laterally and serve as landmarks for determining its location.

20. At which sacral vertebral levels are complete arches absent, resulting in the formation of the hiatus sacralis?

• S1–S2

  The hiatus sacralis forms due to underdevelopment (non-fusion) of the arches of S4 and S5. This non-fusion is a variant of normal sacral development and forms the inferior opening of the sacral canal.

• S2–S3

  The hiatus sacralis forms due to underdevelopment (non-fusion) of the arches of S4 and S5. This non-fusion is a variant of normal sacral development and forms the inferior opening of the sacral canal.

• S3–S4

  The hiatus sacralis forms due to underdevelopment (non-fusion) of the arches of S4 and S5. This non-fusion is a variant of normal sacral development and forms the inferior opening of the sacral canal.

• S4–S5

  The hiatus sacralis forms due to underdevelopment (non-fusion) of the arches of S4 and S5. This non-fusion is a variant of normal sacral development and forms the inferior opening of the sacral canal.

• I find it difficult to answer

  The hiatus sacralis forms due to underdevelopment (non-fusion) of the arches of S4 and S5. This non-fusion is a variant of normal sacral development and forms the inferior opening of the sacral canal.