Spinal Exam 2: Section VI - Sacrum, Coccyx Flashcards
What is the generic shape of the first sacral vertebral body from the base view?
reniform or kidney-shaped
What muscle(s) may attach to the first sacral vertebral body?
psoas major
How many joint surfaces are present on the vertebral body of the first sacral segment?
five
What is the origin of the sacral ala?
on base view, the S1 true transverse process and costal element appear to originate from the vertebral body and possibly the pedicle to form the sacral ala
What part of the sacral ala is derived from the costal element?
the anterior two-thirds
What is the position of the sacral zygapophysis in adults?
the zygapophysis lies in the coronal plane for L5/S1
What is the orientation of the first sacral superior articular facet?
backward, upward, medial (BUM); typically concave
What muscles will attach to the sacral mammillary processes?
multifidis
Fusion of vertebral bodies of sacrum across the intervertebral disc is called______.
synostosis
From the anterior view, the intervertebral discs of sacrum will be replaced by what feature?
transverse ridges
What forms the median sacral crest?
fused spinous processes and their spinous tubercles
What muscles may attach to the median sacral crest?
latissimus dorsi, iliocostalis lumborum, longissimus thoracis
What forms the intermediate sacral crest?
fused articular processes and their facets
What features may be identified along the intermediate sacral crest?
the mammillary process of S1 and the sacral cornu of S5
What does the sacral cornu represent?
the inferior articular process and facet of S5
What is the name of the inferior opening of the sacral spinal canal?
the sacral hiatus
What forms the lateral sacral crest?
the fused transverse processes and transverse tubercles from S1 to S5
What features may be identified along the lateral sacral crest?
S1 transverse tubercle, sacral tuberosity of S2, transverse tubercles of S3-S5
What is the name of the joint formed by the sacral tuberosity?
the accessory sacro-iliac joint
What feature is associated with the transverse tubercle of S5?
the inferior and lateral (inferolateral) sacral angle
What muscles may attach to the lateral sacral crest?
multifidis, iliocostalis lumborum
What muscle is said to attach to the dorsal surface of sacrum?
iliacus
What feature is identified on the lateral surface of S1-S3?
auricular surface
What classification of joint is formed by the auricular surface of sacrum?
synovial plane (diarthrosis arthrodia)
What is the sacral promontory?
the bulging anterior surface of the superior epiphyseal rim of S1
The continuation of the anterior longitudinal ligament below S3 forms what ligament?
the anterior sacrococcygeal ligament
The continuation of the posterior longitudinal ligament below S3 forms what ligament?
the 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, and 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, and intervertebral disc
What ligament is attached to the sacral hiatus?
the superficial posterior sacrococcygeal ligament
What synovial joint surfaces are present at sacrum?
two superior articular facets, two auricular surfaces
How many synovial joints are typically present at sacrum?
four
What joint classifications are typically present at sacrum?
fibrous (amphiarthrosis) syndesmosis,
cartilaginous (amphiarthrosis) symphysis, and
synovial plane (diarthrosis arthrodia)
What is the homolog for the posterior longitudinal ligament at S5?
deep posterior sacrococcygeal ligament
What is the homolog for the anterior longitudinal ligament at S5?
anterior sacrococcygeal ligament
What is the homolog for the ligamentum flavum at S5?
superficial posterior sacrococcygeal ligament
What forms the inferior boundary for the spinal canal?
the union of the superficial posterior and deep posterior sacrococcygeal ligaments
What ligament is formed by the union of the superficial posterior sacrococcygeal and the deep posterior sacrococcygeal ligaments at Co1?
the posterior sacrococcygeal ligament
What ligament is a homolog of the intertransverse ligament at S5?
lateral sacrococcygeal ligament
What ligaments divides the sciatic foramen into the greater and lesser sciatic foramina?
sacrospinous ligament
What ligament has a broach attachment along the lateral margin of sacrum and coccyx and then attaches to the ischial tuberosity?
sacrotuberous ligament
Which ligament represents a thickening of the fibrous capsule of the sacro-iliac joint?
anterior sacro-iliac 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
Which ligament will attach the intermediate sacral crest of S1, lateral sacral crest of S2 to the posterior superior iliac spine?
short posterior sacro-iliac ligament
Which ligament attaches the lateral sacral crest of S3 and S4 to the posterior superior iliac spine?
long posterior 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 homolog for the capsular ligament at S5?
intercornual ligament
What is the number of 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 bony features are present on the coccyx?
all segments are represented by a “vertebral body”; Co1 has a coccygeal cornu and transverse process
What is the homolog of the superior articular process and facet on Co1?
coccygeal cornu
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 coccyx?
flexion - extension, 5-20 degrees
How many coccygeal nerves are present in the fetus?
typically 5 pairs of coccygeal nerves are present
How many coccygeal nerves are present in the adult?
typically only one pair of coccygeal nerves remain in the adult
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 anastomosis located near the last segment of coccyx
What innervates the coccygeal glomus or coccygeal body?
both sympathetic and parasympathetic fibers are identified
What muscles attach to the coccyx?
ischiococcygeus and levator ani
What joint classifications are present for coccyx?
cartilaginous (amphiarthrosis) symphysis and fibrous (amphiarthrosis) syndesmosis
What forms the inferior boundary for the spinal canal?
the union of the superficial posterior and deep posterior sacrococcygeal ligaments
What ligament is formed by the union of the superficial posterior sacrococcygeal and the deep posterior sacrococcygeal ligaments at Co1?
the posterior sacrococcygeal ligament
What ligaments form the posterior boundary for the Co1 spinal nerve intervertebral foramen?
superficial posterior sacrococcygeal ligament and intercornual ligament
What ligaments form the anterior boundary for the Co1 spinal nerve intervertebral foramen?
deep posterior sacrococcygeal ligament and intervertebral disc
