Back and Spinal Cord – Lecture Review

Question-and-Answer flashcards covering anatomy, ligaments, joints, spinal cord, fascia, and musculature of the back and vertebral column.

List four primary functions of the vertebral column.

Protects spinal cord/nerves, supports body weight above pelvis, provides partly rigid-yet-flexible axis & head pivot, plays major role in posture and locomotion.

How many vertebrae are found in each region of the vertebral column?

7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral, 4 fused coccygeal.

What type of joint are the zygapophysial joints between C1–S1 and what do they control?

Synovial facet joints that facilitate and control vertebral column flexibility.

What proportion of total column height is formed by vertebral bodies vs. intervertebral discs?

Vertebral bodies = ¾ of height; IV discs = ¼ of height.

Define primary vertebral curvatures and give two examples.

Curvatures concave anteriorly that develop during the fetal period; thoracic and sacral kyphoses.

When do secondary curvatures become obvious and which regions present them?

Become obvious after birth; cervical (when infant holds head erect) and lumbar (when infant begins to walk).

Name and briefly describe three abnormal spinal curvatures.

Excess thoracic kyphosis (humpback, anterior vertebral erosion), excess lumbar lordosis (hollow back, pelvic anterior tilt, weak trunk muscles), scoliosis (lateral curvature with rotation; due to muscle asymmetry, hemivertebra, or limb-length discrepancy).

Which cervical vertebra lacks a body and spinous process?

C1 (Atlas).

What bony projection on C2 acts as a pivot for head rotation?

The dens (odontoid process).

Which cervical vertebra is called the ‘vertebra prominens’ and why?

C7 because of its long, prominent spinous process that is easily palpable.

Describe the shape of thoracic vertebral bodies and the unique feature on them.

Heart-shaped with one or two costal facets for rib head articulation.

What shape are lumbar vertebral bodies?

Massive and kidney-shaped.

Name the opening formed by absence of S4–S5 laminae and spinous processes.

Sacral hiatus.

What two components make up an intervertebral disc?

Anulus fibrosus (outer fibrocartilaginous lamellae) and nucleus pulposus (gelatinous central core).

Why does human height often decrease with age?

Water content of nucleus pulposus decreases, reducing disc height.

Which ligament runs from the pelvic surface of the sacrum to the anterior tubercle of the atlas and limits extension?

Anterior longitudinal ligament.

Which ligament attaches to posterior IV discs and helps prevent hyperflexion and posterior disc herniation?

Posterior longitudinal ligament.

What movements are permitted at zygapophysial (facet) joints?

Gliding movements between articular processes of adjacent vertebrae.

Which accessory ligament joins adjacent laminae and prevents abrupt flexion?

Ligamenta flavum.

Name the craniovertebral joint that produces the ‘yes’ motion.

Atlanto-occipital joint.

Which joint allows the ‘no’ head rotation and what ligament stabilizes its dens?

Median atlantoaxial joint; stabilized by the transverse (cruciate) ligament of the atlas.

What paired ligaments attach the dens to the lateral margins of the foramen magnum?

Alar ligaments.

In which two spinal regions is the range of motion greatest?

Cervical and lumbar regions.

At what vertebral level does the adult spinal cord usually end?

Between L1 and L2 (medullary cone).

Which roots of a spinal nerve carry afferent fibers and where are their cell bodies located?

Posterior (dorsal) roots; cell bodies in the spinal (dorsal root) ganglia.

Name the three meningeal layers from superficial to deep.

Dura mater, arachnoid mater, pia mater.

Where is cerebrospinal fluid (CSF) located around the spinal cord?

Subarachnoid space between arachnoid and pia mater.

Between which spinous processes is a lumbar puncture commonly performed and why?

Between L3 and L4 (midline); spinal cord has ended, minimizing injury risk.

Which artery is formed by the union of branches of the vertebral arteries and runs along the anterior median fissure of the spinal cord?

Anterior spinal artery.

Which rami supply cutaneous innervation to the lateral vs. medial back?

Lateral back: branches of ventral rami; medial back: dorsal rami.

What are the three functional parts (upper, middle, lower) of trapezius and one action of each?

Upper: elevates scapula & shoulder; Middle: adducts scapula; Lower: depresses, adducts, and upwardly rotates scapula.

Which cranial nerve innervates trapezius motor fibers?

Accessory nerve (CN XI).

Name two major actions of latissimus dorsi at the shoulder joint.

Extension and adduction (also internal rotation).

What nerve (with root levels) supplies latissimus dorsi?

Thoracodorsal nerve (C6–C8 ventral rami).

Which muscle elevates and downwardly rotates the scapula, and what nerves supply it?

Levator scapulae; supplied by C3–C4 ventral rami and dorsal scapular nerve (C5).

Give one function shared by rhomboid major and rhomboid minor.

Scapular adduction (retraction) and downward rotation.

What thin muscle elevates ribs 2–5 and what is its innervation?

Serratus posterior superior; innervated by T2–T5 ventral rami.

What are the borders of the triangle of auscultation and why is it clinically important?

Borders: trapezius, latissimus dorsi, medial border of scapula (rhomboid major). Thin musculature allows clear breath sound auscultation.

Name the thick fascial sheet covering true back muscles in lumbar region.

Thoracolumbar fascia.

What two actions are produced bilaterally by splenius capitis?

Capital (head) extension; when unilateral: rotates & laterally bends head to same side.

List the three longitudinal columns of erector spinae from lateral to medial.

Iliocostalis, longissimus, spinalis.

What common inferior origin do the erector spinae share?

A broad tendon from iliac crest, sacrum, sacral & lumbar spinous processes, and supraspinous ligament.

Which erector spinae subdivision inserts onto mastoid process and helps extend the head?

Longissimus capitis.

What is the principal unilateral action of the transversospinalis muscle group?

Rotation of the vertebral column to the opposite side.

How many vertebral levels do semispinalis muscle bundles typically span?

Four to six vertebrae.

Name the deepest muscles of the transversospinalis group and their two subdivisions.

Rotatores; subdivided into brevis (1 level) and longus (2 levels) fibers.

Which small paired muscles connect adjacent spinous processes and assist spinal extension?

Interspinales.

What nerve innervates all four suboccipital muscles?

Suboccipital nerve (dorsal ramus of C1).

Which suboccipital muscle forms the superolateral border of the suboccipital triangle?

Obliquus capitis superior.

List the contents of the suboccipital triangle.

Posterior arch of atlas, vertebral artery, and suboccipital nerve (C1 dorsal ramus).

Describe the course of the greater occipital nerve (C2 dorsal ramus).

Emerges below obliquus capitis inferior, crosses suboccipital triangle, pierces semispinalis capitis, provides sensory innervation to posterior scalp.

Which ligament forms the superior continuation of the posterior longitudinal ligament through the foramen magnum?

Tectorial membrane.

What percentage of nucleus pulposus is water at birth?

Approximately 88%.

Which intrinsic back muscles elevate ribs and aid lateral flexion?

Levatores costarum.

Which spinal ligament merges superiorly with the nuchal ligament?

Supraspinous ligament.

What motion does the anterior longitudinal ligament restrict?

Hyperextension of the vertebral column.

Name the nerves supplying cutaneous sensation to the posterior neck, noting the exception at C1.

Dorsal rami of cervical spinal nerves; C1 dorsal ramus (suboccipital) lacks cutaneous branch, C2 dorsal ramus = greater occipital nerve.

Which intrinsic back muscle group is responsible for maintaining upright posture?

Erector spinae (iliocostalis, longissimus, spinalis).

What spinal cord region enlargement supplies the brachial plexus?

Cervical enlargement (C4–T1).

Define cauda equina.

Bundle of spinal nerve roots arising from lumbosacral enlargement and medullary cone, descending within lumbar cistern.

What fascia in the cervical region is continuous with deep cervical (prevertebral) fascia surrounding intrinsic back muscles?

The deep fascia covering true back muscles (part of prevertebral fascia).

Which vertebral ligament is rich in elastic fibers, giving it a yellowish color?

Ligamentum flavum.

During unilateral action, which muscle rotates the head to the same side: rectus capitis posterior major or semispinalis capitis?

Rectus capitis posterior major rotates head to the same side; semispinalis capitis rotates to opposite side.

Where does the spinalis thoracis muscle originate and insert?

Origin: T11–L2 spinous processes; Insertion: T1–T4 spinous processes.

Which artery accompanies the accessory nerve deep to trapezius?

Superficial branch of transverse cervical artery.

What motion is primarily allowed at the atlanto-occipital joint and which membranes limit it?

Flexion/extension (‘yes’); limited by anterior and posterior atlanto-occipital membranes.

Name two clinical borders of the lumbar triangle.

Iliac crest and latissimus dorsi (third border = external oblique).

Which small muscles span from transverse processes to ribs and assist inspiration?

Levatores costarum elevate ribs.

What is the function of intertransversarii muscles?

Lateral flexion of vertebral column and stabilization of adjacent vertebrae.

Which ligament attaches the dens to the atlas and forms the horizontal part of the cruciate ligament?

Transverse ligament of the atlas.

Describe the general fiber direction of splenius muscles relative to the midline.

Run laterally and superiorly from midline (spinous processes) to insertions.