Vertebral Column & Spinal Cord Anatomy

How many total vertebrae make up the vertebral column?

33 vertebrae

Name the two regions of the spine that exhibit a primary curvature.

Thoracic and sacral regions

Name the two regions of the spine that exhibit a secondary curvature.

Cervical and lumbar regions

What term describes the concave secondary curvatures in the cervical and lumbar regions?

Lordosis

What term describes the primary curvatures found in the thoracic and sacral regions?

Kyphosis

How many cervical, thoracic, and lumbar vertebrae are there, respectively?

7 cervical, 12 thoracic, 5 lumbar

How many vertebrae fuse to form the sacrum and coccyx, respectively?

5 fuse for sacrum; 3-4 fuse for coccyx

What are the two main components of a typical vertebra?

Body (anterior) and arch (posterior)

Name the bony process that connects the vertebral body to the transverse processes/lamina.

Pedicle

What structure connects the pedicles posteriorly and gives rise to the spinous process?

Lamina

What projection arises at the midline posteriorly from the junction of the laminae?

Spinous process

What paired projections extend laterally from the junction of pedicle and lamina?

Transverse processes

What structure is formed by adjacent superior and inferior vertebral notches?

Intervertebral foramen

What is C1 called, and what key feature does it lack?

Atlas; lacks a vertebral body

What is C2 called, and what unique bony projection does it have?

Axis; has the dens (odontoid process)

What is the projection on C2 that extends superiorly into C1?

Dens (odontoid process)

What opening is unique to transverse processes of cervical vertebrae, and what passes through?

Foramen transversum; transmits vertebral artery and vein

What feature is characteristic of spinous processes in C3-C7?

Bifid spinous process

What joint connects occipital bone to C1, and what movement does it allow?

Atlantooccipital joint; flexion/extension ("yes" movement)

What joint connects C1 to C2, and what movement does it allow?

Atlantoaxial joint; rotation ("no" movement)

Are there intervertebral discs between occiput-C1 or C1-C2?

No intervertebral discs at either location

What structural feature is unique to thoracic vertebrae?

Costal facets for articulation with ribs

How many pairs of ribs do typical thoracic vertebrae (T2-T9) articulate with?

Two pairs of ribs

Which lumbar vertebra is the largest and heaviest?

L5

At which spinal level does spondylolisthesis occur most frequently?

L5-sacrum (lumbosacral) articulation

What passes through the anterior and posterior sacral foramina?

Posterior and anterior rami of S1-S4 spinal nerves

What joints are formed between superior and inferior articular facets of adjacent vertebrae?

Zygapophysial (facet) joints

What opening allows spinal nerves and vessels to exit the vertebral canal?

Intervertebral foramen

What are the two components of an intervertebral disc?

Annulus fibrosus and nucleus pulposus

Which component of the intervertebral disc limits rotation between vertebrae?

Annulus fibrosus

Which central component of the intervertebral disc absorbs compression forces?

Nucleus pulposus

In a herniated disc, what structure protrudes and what can it compress?

Nucleus pulposus protrudes through annulus fibrosus; compresses spinal nerve

Which ligament runs along the anterior surface of the vertebral bodies?

Anterior longitudinal ligament

Which ligament runs along the posterior surface of vertebral bodies inside the canal?

Posterior longitudinal ligament

Which ligament connects adjacent laminae and resists abrupt flexion?

Ligamentum flavum

Which ligament connects tips of spinous processes from C7 to sacrum?

Supraspinous ligament

What is the supraspinous ligament called superior to C7?

Ligamentum nuchae

Which ligament connects adjacent spinous processes between their borders?

Interspinous ligament

Where does the vertebral canal begin and terminate?

Begins at foramen magnum; terminates at sacral hiatus

Why is a lumbar puncture performed with the spine flexed?

Flexion widens the gap between lumbar laminae

From which space is CSF withdrawn during a lumbar puncture?

Subarachnoid space

What surgical procedure removes part of the lamina to access the vertebral canal?

Laminectomy

How do target spaces compare between epidural and spinal injections?

Epidural enters epidural space; spinal enters subarachnoid space (CSF)

List the three meningeal layers from outermost to innermost.

Dura mater, arachnoid mater, pia mater

What space lies between the bone of the vertebra and dura mater?

Epidural space

What space lies between dura mater and arachnoid mater?

Subdural space

What space lies between arachnoid mater and pia mater, and what fills it?

Subarachnoid space; contains cerebrospinal fluid (CSF)

Which meningeal layer is thickest and tough?

Dura mater

What are denticulate ligaments and what layer forms them?

Pia mater projections anchor spinal cord to dura mater

What structure formed by pia mater anchors the conus medullaris inferiorly?

Filum terminale

At what vertebral level does the adult spinal cord terminate?

L1/L2 (conus medullaris)

What is the collection of nerve roots inferior to the conus medullaris called?

Cauda equina

What are the two regions of spinal cord enlargement?

Cervical enlargement and lumbar enlargement

What fluid fills the central canal of the spinal cord?

Cerebrospinal fluid (CSF)

Which type of matter in the spinal cord is rich in nerve cell bodies?

Gray matter

Which type of matter in the spinal cord contains nerve axons and tracts?

White matter

Name the deep groove on the anterior surface of the spinal cord.

Anterior median fissure

Name the shallow groove on the posterior surface of the spinal cord.

Posterior median sulcus

Where do dorsal rootlets enter the spinal cord?

Posterolateral sulcus

How many total pairs of spinal nerves are there by region?

31 total: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal

Why are there 8 cervical nerves but only 7 cervical vertebrae?

C1 exits above atlas; C8 exits below C7 vertebra

Are spinal nerves sensory, motor, or mixed?

Mixed (both motor and sensory fibers)

What structure contains sensory neuron cell bodies along the dorsal root?

Dorsal root ganglion

What fibers do dorsal roots carry?

Afferent (sensory) fibers

What fibers do ventral roots carry?

Efferent (motor) fibers

What forms when dorsal and ventral roots combine?

Spinal nerve

What does the dorsal (posterior) primary ramus innervate?

Intrinsic back muscles and skin of the back

What does the ventral (anterior) primary ramus innervate?

Skeletal muscles and skin of limbs and anterior trunk

What are the two primary arterial sources supplying the spinal cord?

Segmental spinal arteries and longitudinal arteries from cervical region

How many anterior and posterior spinal arteries supply the spinal cord?

1 anterior spinal artery, 2 posterior spinal arteries

What is the largest segmental artery supplying the lower spinal cord?

Artery of Adamkiewicz

What is the clinical significance of obstruction of the artery of Adamkiewicz?

Can cause infarction of the lower 2/3 of spinal cord

What four venous plexuses drain the vertebral column?

Anterior/posterior internal and anterior/posterior external venous plexuses

What are the three main types of spina bifida?

Spina bifida occulta, meningocele, myelomeningocele

Which spina bifida involves a sac containing meninges AND spinal cord tissue?

Myelomeningocele

Which spina bifida involves a meningeal sac without spinal cord herniation?

Meningocele

Which spina bifida is the mildest form with no external sac?

Spina bifida occulta