coccyx Flashcards
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 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 five 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 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 posterior boundary for the first coccygeal spinal nerve intervertebral foramen?
sacral cornu, coccygeal cornu, superficial posterior sacrococcygeal ligament, intercornual ligament
What forms the anterior boundary for the first coccygeal spinal nerve intervertebral foramen?
vertebral body S5, vertebral body Co1, deep posterior sacrococcygeal ligament, intervertebral disc
