Anatomy of Spine and Spinal Cord Flashcards
what is the vertebral column made up of?
C1-7 T1-12 L1-5 5 sacral fused 4 coccygeal fused
shape of the vertebral column
cervical lordosis
thoracic kyphosis
lumbar lordosis
sacral kyphosis
five ligaments around the vertebral column
ligamentum flavum posterior longitudinal ligament anterior longitudinal ligament supraspinous ligament interspinous ligament
what does the ligamentum flavum connect?
connects adjacent laminae posterior to spinal cord
role of posterior longitudinal ligament
prevent over-flexion
role of anterior longitudinal ligament
prevent over-extension
what do the supraspinous ligaments connect?
spinous processes
what do the interspinous ligaments connect?
superior and inferior surfaces of adjacent spinous processes
where does the spinal cord begin?
foramen magnum continuing from the medulla
where does the spinal cord end?
L2 and becomes the cauda equina
where does the sub-arachnoid space end?
S2
what are the layers of the meninges?
dura mater
arachnoid mater
sub-arachnoid space and CSF
pia mater
which ligament suspends the spinal cord in the canal?
denticulate ligament
what is the denticulate ligament made of?
pia and arachnoid mater attaching to dura laterally
what is special about levels T1-L2 of the spinal cord?
also contain a smaller lateral horn for sympathetic outflow
two groups of intrinsic back muscles
- erector spinae (superficial)
2. transversospinalis (deep)
describe the erector spinae muscles
3 vertical muscle groups lateral to the spine attaching to sacrum/iliac crests and either a rib, transverse or spinous process
describe the transversospinalis muscles?
within grooves between tranverse and spinous processes
what supplied the intrinsic back muscles?
posterior rami
role of the intrinsic back muscles
contract for posture
how do the erector spinae extend the spine?
contract bilaterally
how do the erector spinae lateral flex the spine?
unilateral contraction
what muscles perform flexion of the spine?
rectus abdominis and psoas major
where are the atlanto-occipital joints?
between occipital condyles and superior articular facets of atlas
what movement does the atlanto-occipital joints allow?
flexion/ extension of the neck
what forms the atlanto-axial joint?
3 articulations with two between inferior and superior facets and one between posterior arch of atlas and odontoid process
what movement does the atlanto-axial joint allow?
rotation
arterial supply of the spinal cord
three major longitudinal arteries (anterior and 2 posterior)
segmental arteries
radicular arteries
what are the segmental arteries?
vertebral, intercostal and lumbar arteries
where do radicular arteries travel?
travel along dorsal and ventral roots
venous drainage of the spinal cord
plexuses e.g. anterior and posterior internal
what does the epidural space contain?
venous plexuses
adipose tissue
presentation of Horner’s syndrome
miosis ptosis anhidrosis increased warmth and redness ipsilateral
overall causative mechanism of Horner’s syndrome
impaired sympathetic innervation to the head and neck
causes of compression of the cervical sympathetic trunk
root of neck trauma carotid dissection IJV engorgement deep cervical node metastases Pancoast tumour (lung apex)
how many pairs of spinal nerves are there?
31 pairs
what are the 31 pairs of spinal nerves?
C1-8 T1-12 L1-5 S1-5 Co1
what do the spinal nerves pass through?
intervertebral foramina
what does the anterior rami connect?
structures of the anterolateral soma via root and rootlets
what does the posterior rami connect?
posterior soma to the spinal cord via root and rootlets
where do C1-7 spinal nerves emerge?
above their vertebra
where do C8 and below spinal nerves emerge?
below their vertebra
sensory axon pathway
spinal nerve > posterior root/rootlets > posterior horn of spinal cord
motor axon pathway
anterior horn of spinal cord > anterior rootlets > anterior root > spinal nerve
modality of anterior rootlets of the cauda equina
motor
modality of the posterior rootlets of the cauda equina
sensory
what does each spinal nerve pair supply?
a body segment with general sensory supply, somatic motor to skeletal muscles and sympathetic to skin and arterioles
define dermatome
skin supplied by a spinal nerve
define myotome
muscles supplied by spinal nerve
define a nerve plexus
intermingled anterior rami from a number of adjacent spinal nerves
what does the cervical plexus supply?
C1-4
posterior scalp
neck
diaphragm
what does the brachial plexus supply?
upper limb
C5-T1
what does the lumbar plexus supply?
L1-4
lower limb
what does the sacral plexus supply?
L5-S4
lower limb, gluteal region and perineum
what is laminectomy used for?
access spinal canal
relieve pressure
what does peripheral cutaneous nerve innervation often have?
more than 1 spinal nerve
what happens when a spinal nerve myotome is tested for motor function?
APs generated in primary somatomotor cortex and conducted via UMN of CST
reach anterior horn where LMNs are stimulated
conducted to spinal nerve then enter anterior rami
define a reflex
involuntary response to a stimulus where both sensory and motor axons are stimulated together
