Where does the spinal cord end in an adult?
L2 (can vary between T12 or L1)
How many pairs of spinal nerves?
Cauda equina formation
Nerve roots of lumbar and sacrococcygeal spinal nerves (from lumbosacral enlargement and consus medullaris) must grow the longest in order to exit through their correct IV foramina.
Due to disproportionate growth of vertebral column and spinal cord
Where does the dural sac end?
Where is the conus medullaris?
internal filum terminale
Extends from conus medullaris to the tip of the dural sac
external filum terminale
Extends from the tip of the dural sac to the sacrum/coccyx region to help anchor spinal cord
Enlargements of spinal cord
Cervical enlargement, lumbosacral enlargement
Provides additional neurons for innervation of limbs
What innervates dura mater?
Recurrent meningeal nerves
What is contained in the subarachnoid space?
CSF, spinal cord, spinal nerves, dorsal root ganglia
How does pia mater contribute to stability of the spinal cord?
Pia mater gives off denticulate ligaments, which run laterally between dorsal and ventral roots of spinal nerves and attaches to the underlying surface of the arachnoid and dura mater.
Helps stabilize spinal cord laterally
What is contained in the epidural space?
Adipose tissue and internal (epidural) venous plexus
Arteries of spinal cord
Vertibral, ascending/descending cervicals, intercostals, lumbar, lateral sacral
Branches from arteries of the spinal cord that enter the IV foramen
Longitudinal arteries of spinal cord
Both from vertebral artery
Anterior spinal artery (anterior)
2 posterior spinal arteries (posterolateral)
Arise from spinal arteries that entered IV foramina
Aorta-->posterior intercostal arteries-->spinal arteries-->radicular arteries
Follow and perfuse dorsal and ventral roots
Segmental medullary arteries
Arise from spinal arteries that enter IV foramina
Aorta-->posterior intercostal arteries-->spinal arteries-->segmental medullary arteries
Anastomose with and support longitudinal arteries
About 8-10 segmental medullary arteries
Great anterior segmental artery
aka artery of Adamkiewicz
The largest segmental medullary artery
Usually arises from a lower left intercostal artery and reinforces circulation to inferior 2/3 of cord
Arises from subclavian artery
Vascularizes brain, branches to vascularize spinal cord (anterior and posterior spinal arteries)
Why are surgeons concerned about clamping the aorta for too long?
Aorta-->posterior intercostal arteries-->spinal arteries-->radicular and segmental medullary arteries (including great anterior segmental artery)
Don't want to deprive the spinal cord of too much blood for too long-->could cause death to cord
Where is the supraspinous ligament?
Connects spinous processes from sacrum to C7
What is ligamentum nuchae?
Expansion of supraspinous ligament at C7
What connects spinous processes from the sacrum to C7?
What is the purpose of the ligamentum flavum?
Prevent hyperflexion of vertebral column
Where is the ligamentum flavum?
Adjoining adjacent lamina of vertebrae
Where is the anterior longitudinal ligament?
Connecting the anterior aspect of vertebral bodies
What does the anterior longitudinal ligament do?
Prevents hyperextension of the vertebral column
Where is the posterior longitudinal ligament?
Connecting posterior aspect of vertebral bodies, inside the vertebral canal
Blends with fibers of annulus fibrosus
What vein drains vertebral bodies?
What drains both basivertebral vein and veins of spinal cord surface?
Internal (epidural) venous plexus
What ligament is closely associated with IV disks?
What does the PLL do?
Prevent herniation of IV disks
Ventral root of spinal nerve
Conveys motor (afferent) axons away from spinal cord
Cell bodies located in gray matter of spinal cord
Dorsal root of spinal nerve
Conveys sensory (efferent) axons to spinal cord
Cell bodies in dorsal root ganglion
Dorsal and ventral rami
Branches of spinal nerves
Carry both sensory and motor fibers
What innervates intrinsic back muscles, synovial joints of vertebral column, and overlying skin of back?
What innervates anterolateral body wall and limbs?
Surounds spinal cord. Terminates at S2 vertebral level
Vestigal remnant of spinal cord, extension of pia
Vertebral column functions
Most important: protects spinal cord and spinal nerves
Supports body weight
Provides a flexible, yet rigid axis for our bodies
What is kyphosis?
Accentuated thoracic curvature due to compression of vertebrae, often because of osteoporosis
What is lordosis?
accentuated lumbar curvature, often a result of weight gain, pregnancy, weak trunk musculature
What is scoliosis?
Abnormal lateral curvature and rotation of the vertebral column
Purpose of vertebral body?
Weight bearing surface
Purpose of vertebral arch?
Protects spinal cord and nerves, forms vertebral canal
What type of synovial joints are zygapophysial joints?
What is the main thing that limits movement of the vertebral column?
Shape and orientation of zygapophysial joints
Where does the most flexion and extension of the vertebral column occur?
Cervical and lumbar regions
Where does lateral bending mostly occur in the vertebral column?
Mostly cervical (some lumbar)
Where does most rotation or torsion occur in the vertebral column?
Mostly cervical (some thoracic)
Functions of superficial back muscles
produce and control limb movements
Rhomboids, levator scapulae, latissimus dorsi, trapezius
Function of intermediate back muscles
Aid in respiration
serratus posterior inferior
serratus posterior superior
Layers of intrinsic back muscles
Superficial: splenius capitus and cervicus
Intermediate: errector spinae complex (iliocostalis, longissimus, spinalis)
Deep: Transeversospinalis group (Semispinalis, Multifidus, Rotatores)
What innervates the intrinsic back muscles?
What fascia surrounds and supports the intrinsic back muscles?
layers of thoracolumbar fascia
Anterior, middle, posterior
Intrinsic back muscles contained between middle and posterior layers
Where does the thoracolumbar fascia attach?
Spinous and transverse processes of vertebrae