Sacrum & Coccyx Flashcards
What part of the sacral ala is derived from the costal element?
anterior 2/3
What part of the sacral ala is derived from the true transverse process?
posterior 1/3
How many fibrous (amphiarthorsis) symphysis joint surfaces are present on the S1 vertebral body?
four
How many joint surfaces are present on the vertebral body of the first sacral segment?
five
How many cartilagenous (amphiarthrosis) syndesmosis joint surfaces are present on the S1 vertebral body?
one
What muscle(s) may attach to the first sacral vertebral body?
psoas major
What is the position of the sacral zygapophysis in adults?
lies in coronal plane for L5/S1
What is the orientation of the first sacral superior articular facet?
backward, upward, medial (BUM);
typically concave
What is the name given to the projection on the first sacral superior articular facet?
mammillary process
What muscles will attach to the sacral mammillary processes?
multifidis
What is the usual condition for the first sacral spinous process?
non-bifid and short
An imaginary line drawn along the dorsal midline of the sacrum is identified as the ______
medial sacral crest
What is the name given to the congenital condition in which the fifth lumbar spinous process is elongated, the sacrum exhibits spina bifida, and dorsiflexsion produces pain?
Knife’s Clasp syndrome
An imaginary line drawn from the superior articular process of S1 to the sacral cornu will form what feature?
intermediate sacral crest
What features may be identified along the intermediate sacral crest?
mammillary process of S1 and the sacral cornu of S5
What does the sacral cornu represent?
inferior articular process and facet of S5
What is the name of the inferior opening of the sacral spinal canal?
sacral hiatus
An imaginary line is drawn from the transverse process of S1 to the inferior lateral sacral angle will form what feature?
lateral sacral crest
What is the sacral tuberositiy?
enlarged transverse tubercle of S2
What is the name of the joint formed by the sacral tuberosity?
accessory sacro-iliac joint
What feature is identified on the lateral surface of S1-S3?
auricular surface
What feature does the anterior surface of the superior epiphyseal rim of S2 form?
sacral promontory
The continuation of the posterior longitudinal ligament below S3 form what ligament?
deep posterior sacrococcygeal ligament
What forms the posterior boundary for the fifth sacral spinal nerve intervertebral foramen?
sacral cornu, coccygeal cornu, superficial posterior sacrococcygeal ligament, intercornual ligament
What forms the anterior boundary for the fifth sacral spinal nerve intervertebral foramen?
vertebral body S5, vertebral body Co1, deep posterior sacrococcygeal ligament, intervertebral disc
What forms the inferior boundary for the spinal canal?
the union of the superficial posterior and deep posterior sacrococcygeal
What ligament divides the sciatic foramen into the greater and lesser sciatic foramina?
sacrospinous ligament
Which ligament has a broad attachment along the lateral margin of the sacrum and coccyx and then attaches to the ischial tuberosity?
sacrotuberous ligament
Which ligament is the strongest of the sacro-iliac ligaments and is penetrated by dorsal rami of the sacral spinal nerves?
interosseous sacro-iliac ligament
What is the homolog for the inferior articular process and facet at S5?
sacral cornu
What is the homolog for the superior articular process and facet at Co1?
coccygeal cornu
What is the number of the coccygeal somites?
ten
What is the typical number of segments that unite to form the adult coccyx?
4 segments
When is ossification of coccyx completed?
about age 30
What is the direction of fusion of coccygeal segments?
from caudal to cranial, the last segments to fuse together are Co1 and Co2
What is the direction of the coccygeal curve?
posterior (kyphotic)
What is the major motion and range of motion for the coccyx?
flexion-extension: 5-20 degrees
How many coccygeal nerves are present in the fetus?
typically 5 pairs of coccygeal nerves are present
What forms the coccygeal nerve plexus?
S4, S5, and Co1 nerves
What is the ganglion impar?
a midline sympathetic ganglion
What is the coccygeal glomus or coccygeal body?
an enlarged encapsulated arteriovenous anastamosis location near the last segment of coccyx
