Overview and Development of Back Flashcards
Anterior horn
Lower motor neuron cell bodies
Anterior roots
Lower motor axons
Posterior horn
Sensory neuron cell bodies
Posterior roots
Sensory axons
Posterior root ganglion
Sensory neuron cell bodies
Spinal nerve
Mixed motor and sensory axons
Anterior rami
Motor and sensory axons to muscles and skin of the anterior trunk and limbs
Posterior rami
Motor and sensory axons to muscles and skin of the back
C4 dermatome
Top of shoulder
C6 dermatome
Thumb
C8 dermatome
5th digit of hand
T4 dermatome
Nipple
T10 dermatome
umbilicus
L1 dermatome
inguinal region
L4 dermatome
medial heel and ankle
L5 dermatome
antero-lateral leg and dorsum of foot
S1 dermatome
posterior lateral lower limb
S2 dermatome
Posterior medial lower limb
Denticulate ligament
Tether pia mater and spinal cord to dura mater; divide anterior and posterior roots within dural sheath
How far does the spinal cord extend in the vertebral column? What are the anterior and posterior roots called that stretch below that?
~L2; cauda equina
Tip of spinal cord
Conus medullaris
Thread of pia mater that tethers the conus medullaris to the coccyx
Filum terminale
Anesthetic injection can be where…?
Epidural space or sacral hiatus
Sample CSF from?..
subarachnoid space
Structures encountered on a midline tap
Skin»_space; subcutaneous fat»_space; thoracolumbar fascia»_space; supraspinous ligament»_space; interspinous ligament»_space; dura mater»_space; arachnoid mater»_space; subarachnoid space
Ascent of spinal cord
3 month embryo - spinal cord runs full length of vertebral canal
5 month embryo - conus medullaris at S1 level
Newborn - conus at L3 level
Nutrient arteries
Given off of large vessels to supply periosteum
Posterior branches of arterial supply
Supply transverse and spinous processes and back muscles
Spinal branches of arterial supply
Enter intervertebral foramina and split to supply bone and meninges
Posterior and anterior spinal artery
Supply spinal cord; run along length
Radicular or segmental medullary arteries
Travel along spinal nerve and roots
Venous drainage
Spinal veins and basivertebral veins» internal and external vertebral venous plexus»_space; large veins of body and heart
Somites
4 occipital, 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 2-3 coccygeal; develop on either side of the neural tube and notochord
Each somite breaks into 3 functionally different parts…
Dermatome - deep dermis of body
Myotome - muscle of body wall and limbs
Sclerotome - vertebrae and axial bones
Origin of typical spinal nerve
Anterior horn axons - myotome
Posterior root ganglion axons - dermatome and posterior horn
Sclerotomes - split in half as fissures develop so axons can pass
Vertebral development
Intervertebral discs and intervertebral foramina will remain at fissure sites
Annulus fibrosis develops from sclerotome
Nucleus pulposus - notochord
Primary ossification centers
Form in vertebral body, pedicles, and lamina
Secondary ossification centers
Transverse and spinous processes; fuse to rest of vertebra
Spina bifida occulta
Failure of neural arch (spinous process) to ossify; marked by tuft of hair
Meningocele
Meninges and CSF herniate through the hole left by the failed neural arch
Meningomyelocele
Same as meningocele with added herniation of the spinal cord and/or roots
Rachischisis
Failure of neural tube to fold properly; neural arch cannot form; typically lose motor function
Lumbarization of S1 or Sacralization of L5 vertebrae caused by…
Abnormalities in Hox gene expression
Innvervation of dura mater
Recurrent meningeal nerves