Podcast
Questions and Answers
What is the primary function of the pelvic (anterior) sacral foramina?
What is the primary function of the pelvic (anterior) sacral foramina?
- To allow passage of nerves and blood vessels. (correct)
- To articulate with the ilium.
- To provide structural support to the sacrum.
- To form the median sacral crest.
Which structure on the sacrum articulates with the ilium to form the sacroiliac joint?
Which structure on the sacrum articulates with the ilium to form the sacroiliac joint?
- Sacral horn (cornu)
- Sacral promontory
- Auricular surface (correct)
- Median sacral crest
What forms the median sacral crest?
What forms the median sacral crest?
- Fused superior articular processes
- Fused alae of the sacrum
- Fused spinous processes of the sacral vertebrae (correct)
- Fused sacral horns
The promontory of the sacrum is best demonstrated from which perspective?
The promontory of the sacrum is best demonstrated from which perspective?
What is the orientation of the sacroiliac joint relative to the sagittal plane?
What is the orientation of the sacroiliac joint relative to the sagittal plane?
Which of the following best describes the shape of the sacrum?
Which of the following best describes the shape of the sacrum?
Where are the sacral horns (cornua) located?
Where are the sacral horns (cornua) located?
What is the sacral canal a continuation of?
What is the sacral canal a continuation of?
What anatomical feature helps to form the posterior wall of the inlet of the true pelvis?
What anatomical feature helps to form the posterior wall of the inlet of the true pelvis?
The superior articular processes of the sacrum form joints with which structure?
The superior articular processes of the sacrum form joints with which structure?
What is the primary reason the auricular surface is named as such?
What is the primary reason the auricular surface is named as such?
How many posterior sacral foramina are typically found on each side of the sacrum?
How many posterior sacral foramina are typically found on each side of the sacrum?
With which bones do the sacral horns articulate?
With which bones do the sacral horns articulate?
What is the process by which the sacrum is formed?
What is the process by which the sacrum is formed?
If a patient has a fracture of the ala of the sacrum, what structure is most immediately lateral to the fracture site?
If a patient has a fracture of the ala of the sacrum, what structure is most immediately lateral to the fracture site?
A surgeon needs to access the sacral canal. Which of the following is the most direct route?
A surgeon needs to access the sacral canal. Which of the following is the most direct route?
In radiographic imaging, what consideration must be made due to the sacrum's curvature?
In radiographic imaging, what consideration must be made due to the sacrum's curvature?
Which of the following is a remnant of the enclosed sacral canal as seen from a posterior view?
Which of the following is a remnant of the enclosed sacral canal as seen from a posterior view?
What is one key difference between the anterior and posterior surfaces of the sacrum?
What is one key difference between the anterior and posterior surfaces of the sacrum?
What is the clinical significance of the sacral promontory in obstetrics?
What is the clinical significance of the sacral promontory in obstetrics?
Which elements of the sacrum are considered lateral masses used for articulation and muscle attachment?
Which elements of the sacrum are considered lateral masses used for articulation and muscle attachment?
What is the functional significance of the sacral canal?
What is the functional significance of the sacral canal?
If the sacrum did not fuse during development, what would be the most likely consequence?
If the sacrum did not fuse during development, what would be the most likely consequence?
In an individual with scoliosis, how might the sacrum be affected?
In an individual with scoliosis, how might the sacrum be affected?
Which of the following structures on the sacrum is the most superior?
Which of the following structures on the sacrum is the most superior?
What type of joint is the sacroiliac joint?
What type of joint is the sacroiliac joint?
Which of the following features is unique to the posterior surface of the sacrum compared to its anterior surface?
Which of the following features is unique to the posterior surface of the sacrum compared to its anterior surface?
What is the angle of the sacral curve (kyphosis) relative to the lumbar curve (lordosis) in a normal spine?
What is the angle of the sacral curve (kyphosis) relative to the lumbar curve (lordosis) in a normal spine?
The sacrum participates in the formation of which structure?
The sacrum participates in the formation of which structure?
If a patient reports pain radiating down the leg due to compression of a nerve exiting through a sacral foramen, which part of the sacrum is most likely involved?
If a patient reports pain radiating down the leg due to compression of a nerve exiting through a sacral foramen, which part of the sacrum is most likely involved?
What happens with the 5 segments of the sacrum in adults?
What happens with the 5 segments of the sacrum in adults?
Which vertebral group connects superiorly to the sacrum?
Which vertebral group connects superiorly to the sacrum?
What is another name for the sacral horns?
What is another name for the sacral horns?
What two bony landmarks are closely associated with the SI joint?
What two bony landmarks are closely associated with the SI joint?
What is the name of the ridges which indicate the fusion of the sacral vertebral bodies?
What is the name of the ridges which indicate the fusion of the sacral vertebral bodies?
Flashcards
Sacrum Location
Sacrum Location
Inferior to the lumbar vertebrae.
Anterior Sacrum Shape
Anterior Sacrum Shape
Concave anterior surface of the sacrum.
Pelvic (anterior) Sacral Foramina Function
Pelvic (anterior) Sacral Foramina Function
They transmit nerves and blood vessels.
Alae (wings) of the sacrum
Alae (wings) of the sacrum
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Superior Articular Processes Function
Superior Articular Processes Function
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Sacral canal
Sacral canal
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Median Sacral Crest
Median Sacral Crest
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Auricular Surface
Auricular Surface
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Auricular Surface Resemblance
Auricular Surface Resemblance
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Sacral Horns (Cornua)
Sacral Horns (Cornua)
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Auricular Surface Articulation
Auricular Surface Articulation
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Superior Articular Processes Facets
Superior Articular Processes Facets
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Sacral Horns (Cornua) location
Sacral Horns (Cornua) location
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Study Notes
- The sacrum is positioned inferior to the lumbar vertebrae.
Anterior Perspective
- The anterior surface of the sacrum is concave.
- The sacrum is formed by the fusion of five original segments into a single bone in adults.
- The sacrum has a shovel-like shape with an apex pointing inferiorly and anteriorly.
- There are four sets of pelvic (anterior) sacral foramina that transmit nerves and blood vessels. These are similar to the intervertebral foramina found in the superior sections of the spine.
- Alae (wings) are large masses of bone situated laterally to the first sacral segment.
- The two superior articular processes of the sacrum create zygapophyseal joints with the inferior articular processes of the fifth lumbar vertebra.
Lateral Perspective
- The dominant convex curve (posterior perspective) of the sacrum and the forward projection of the coccyx are visible.
- These curves dictate the angle needed for the central ray in AP radiographic projections of the sacrum or coccyx.
- The anterior ridge of the body of the first sacral segment contributes to the formation of the posterior wall of the inlet of the true pelvis and is called the promontory of the sacrum.
Sacral Canal
- The sacral canal carries sacral nerves and is a continuation of the vertebral canal. It is posterior to the first sacral segment.
- The median sacral crest is a result of the fused spinous processes of the sacral vertebrae.
Sacrum Surfaces
- The posterior surface has roughness and irregularity.
- The sacrum articulates with the ilium of the pelvis at the auricular surface, forming the sacroiliac joint.
Sacroiliac Joint
- The auricular surface resembles the auricle of the ear.
Sacral Horns
- The sacral horns (cornua) are small tubercles representing inferior articular processes projecting from each side of the fifth sacral segment.
- They project inferiorly and posteriorly to articulate with the corresponding horns (cornua) of the coccyx.
Posterior Sacrum
- The large, wedge-shaped auricular surface articulates with a similar surface on the ilium to create the sacroiliac joint.
- Each sacroiliac joint has an oblique angle of 30°.
- Articulating facets of the superior articular processes open to the rear.
- Eight posterior sacral foramina are present, with four on each side, mirroring the anterior sacral foramina.
- The sacral horns (cornua) are visible as small bony projections at the inferoposterior aspect of the sacrum.
- Remnants of the enclosed sacral canal can be observed.
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