Neuraxial Anatomy Flashcards
how many bones are in the vertebral column?
33 bones
extends from the base of the skull to the tip of the coccyx
how many of each type of vertebrae are there?
- 7 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1-5 coccygeal
vertebral column functions
- protects spinal cord
- allows us to stand upright
what are the four natural curves of the vertebral column?
- anterior curves - cervical and lumbar
- posterior curves - thoracic and sacral
how many spinal nerves are there?
31 spinal nerves
NOTE - 8 cervical (one extra above C1)
C7
vertebra promins
T7
inferior angle of the scapula
L4-L5
Tuffier’s line
common elements of vertebrae
- body
- pedicle
- lamina
- transverse process
- spinous process
- vertebral foramen
- intervertebral foramen
- superior articulating process
- inferior articulating process
features of cervical vertebrae
- spinous process bifid
- small body
- vertebral foramen large and triangular
- transverse foramen for vertebral artery
- facets flat, open and dorsal facing, LARGE rotation
atlas
C1; supports the head, practically fused to the base of the skull (occipital condyles) and has no body
axis
C2; the body of C1 is fused to C2 to form the dens; dens is held in place by ligaments and pivots to allow the head to turn
features of thoracic vertebrae
- long spinous processes
- heart-shaped body
- long transverse process
- rib facets; flat and upward
- vertebral foramen round
features of thoracic vertebrae
- large bodies, kidney shaped
- vertebral foramen triangular
- thick short transverse processes
- thick, short spinous processes
- facets face medially and are cupped/curved; limited rotation
sacrum
- five fused vertebrae
- posterior sacral foramina
- posterior wall of pelvic cavity
- sacral promontory aka base
- area toward coccyx is the apex
coccyx
- tiny little pebble-like bones
- tailbone made up of 3-4 fused segments
lumbarization
L5 and S1 fused
sacralization
S1 and S2 fused
what are the three posterior ligaments
- supraspinous
- interpinous
- ligamentum flavum
supraspinous
-thick major ligament in C & T area
interspinous
-3 layers, connects spinous processes, thin in lumbar region
ligamentum flavum
-strongest in thoracic, yellow/elastic tissue
Structures traversed with spinal needle
- skin
- subcutaneous tissue and fat
- supraspinous ligament
- intraspinous ligament
- ligamentum flavum
- epidural space
- dura
- subarachnoid space
Structures traversed with epidural needle
- skin
- subcutaneous tissue and fat
- supraspinous ligament
- intraspinous ligament
- ligamentum flavum
- epidural space
how long is the spinal cord?
43 cm in women, 45 cm in men
what is the diameter of the spinal cord?
- 1 cm in diameter
- wider in the cervical region, more extremities and more cell bodies
dura mater
- outermost, tough fibrous layer
- tough mother
- extends from foramen magum to S2-S3
arachnoid mater
- delicate middle layer
- looks like spider web
- non vascular
- between dura and pia
- ends at S2
pia mater
- fine and thin; tender mother
- highly vascular
- lies directly on the brain and spinal cord
how far does the spinal cord extend
- adults = L1
- children = L3
conus medularis
the cone-like end of the spinal cord
filum terminale
- a delicate strand of fibrous tissue, about 20 cm in length, proceeding downward from the apex of the conus medullaris
- inserts onto first sacral vertebral body
- extension of pia
dorsal horn
- posterior horn
- sensory information received here
ventral horn
- anterior horn
- motor information originates here
- cell bodies exist here at all levels
lateral horn
-interomediolateral column
-autonomic
-cell bodies here bot not at all levels
T1-L2, S1-S2
dorsal root
sensory only
ventral root
motor only
mixed spinal nerve
where the dorsal and ventral roots come together
dorsal ramus
sensory and motor
ventral ramus
sensory and motor
cauda equina
- horses tail
- end of spinal cord past L1
- nerve roots hang freely within thecal sac
- like noodles in chicken noodle soup
subarachnoid space
- between pia and arachnoid
- CSF found here
- site of spinal anesthesia
- smaller amount of anesthesia (subarachnoid, intrathecal)
epidural space
- potential space
- continuous space within vertebral canal
what does the epidural space contain?
- fat
- arteries
- veins
- lymphatics
- nerve roots
what is the average distance form skin to lumbar epidural space?
5cm
RANGE 2.5 - 8 cm
CSF
- clear, colorless fluid
- selective filtrate of the blood
- function - mechanical buffer to protect brain and spinal cord
Total CSF volume in adult
150 mL
-produce 21 mL/hr
how much CSF does spinal subarachnoid space hold?
20-35 mL
what is the sp gravity of CSF?
1.003-1.009
arterial blood supply to spinal cord
- segmental arteries
- longitudinal arteries (1 anterior, 2 posterior)
- radicular
artery of adamkiewicz
- supplies blood to distal 2/3 of spinal cord
- dominant thoracolumbar segmental medullary artery
venous blood to spinal cord
- epidural veins
- valveless plexus
- most prominent lateral
