Anatomy Block 2 Review

Vertebral column

Forms the basic structure of the trunk and consists of 33–34 vertebrae plus intervertebral discs

Number of cervical vertebrae

7 vertebrae, C1–C7

Number of thoracic vertebrae

12 vertebrae, T1–T12

Number of lumbar vertebrae

5 vertebrae, L1–L5

Number of sacral vertebrae

5 fused vertebrae

Number of coccygeal vertebrae

Usually 3–5 fused vertebrae forming the coccyx

Primary spinal curvatures

Thoracic and sacral curvatures; present at birth and convex posteriorly

Secondary spinal curvatures

Cervical and lumbar curvatures; develop after birth and are concave posteriorly

Cervical curvature

Secondary curvature involving the 7 cervical vertebrae

Thoracic curvature

Primary curvature involving the 12 thoracic vertebrae

Lumbar curvature

Secondary curvature involving the 5 lumbar vertebrae

Sacral curvature

Primary curvature involving the fused sacral vertebrae

*Cervical secondary curvature development

Develops around 3–4 months as the infant begins holding the head upright

*Lumbar secondary curvature development

Develops around 12–18 months as the child begins standing and walking

Scoliosis

Abnormal lateral S-shaped or C-shaped curvature of the vertebral column

Kyphosis

Excessive outward curvature of the thoracic spine

Lordosis

Excessive inward curvature of the lumbar spine

Typical vertebra parts

Body, vertebral arch, pedicles, laminae, spinous process, transverse processes, articular processes, and vertebral foramen

Typical cervical vertebrae

Smallest and lightest vertebrae; C3–C7 are typical

Cervical vertebral body

Wider laterally than anterior to posterior

Cervical spinous processes

Usually short and bifid

Cervical vertebral foramen

Large and triangular

Cervical transverse processes

Contain transverse foramina

Cervical transverse foramen contents

Vertebral artery passes through the transverse foramina of the upper six cervical vertebrae

Cervical superior articular facets

Face superoposteriorly

Atlas C1

First cervical vertebra; lacks a body and spinous process and supports the skull

Atlas articulation with skull

Superior articular facets receive the occipital condyles

Atlas movement

Permits flexion and extension used when nodding the head yes

Axis C2

Second cervical vertebra containing the dens or odontoid process

Dens

Superior projection of C2 that acts as a pivot for rotation of the atlas and skull

Axis movement

Allows rotation of the head from side to side

C7 vertebra prominens

Cervical vertebra with a prominent spinous process

Thoracic vertebrae

Have heart-shaped bodies and articulate with ribs

Thoracic T1–T10 bodies

Bear costal facets or demifacets for rib articulation

T1 rib facet

T1 has a full facet for the first rib

T10–T12 rib facets

Have a single facet rather than typical paired demifacets

Thoracic spinous processes

Long and point inferiorly

Thoracic vertebral foramina

Circular

Thoracic transverse processes

Articulate with the tubercles of ribs

Thoracic superior articular facets

Face posteriorly

Thoracic inferior articular facets

Face anteriorly

Thoracic vertebral movement

Allows rotation while limiting flexion and extension

Lumbar vertebral bodies

Thick and robust for weight bearing

Lumbar transverse processes

Thin and tapered

Lumbar spinous processes

Thick, blunt, and directed posteriorly

Lumbar vertebral foramina

Triangular

Lumbar vertebral movement

Allows flexion and extension while limiting rotation

Sacrum

Five fused vertebrae forming the posterior wall of the pelvis

Sacrum articulations

Articulates superiorly with L5 and inferiorly with the coccyx

Sacral promontory

Anterior projection where the first sacral vertebra bulges into the pelvic cavity

Coccyx

Tailbone formed by approximately 3–5 fused vertebrae

Coccydynia

Pain involving the coccyx

*Vertebral foramen contents

Contains the spinal cord with its meninges, vessels, and related structures within the vertebral canal

*Intervertebral foramen contents

Transmits spinal nerves and associated vessels between adjacent vertebrae

*Hangman fracture

Fracture involving C2, classically through the pars region, usually caused by severe hyperextension

*Clinical danger of a Hangman fracture

C2 displacement can threaten the upper spinal cord or brainstem

Intervertebral disc composition

Outer anulus fibrosus surrounding a soft jelly-like nucleus pulposus

Intervertebral disc function

Absorbs shock, is compressible, reduces friction, and permits slight movement between vertebrae

Anulus fibrosus

Tough outer portion of an intervertebral disc

Nucleus pulposus

Soft gel-like central portion of an intervertebral disc

Disc herniation

Nucleus pulposus protrudes through a weakened or torn portion of the anulus fibrosus

Direction of most disc herniations

Posterolaterally because the anulus fibrosus is thinner there

*Most common region of disc herniation

Lower lumbar region, especially L4–L5 and L5–S1

Anterior longitudinal ligament

Attaches to vertebral bodies and discs and prevents hyperextension

Posterior longitudinal ligament

Narrow, relatively weak ligament attached to intervertebral discs

Extrinsic superficial back muscles

Trapezius and latissimus dorsi

Extrinsic deep back muscles

Levator scapulae, rhomboid minor, and rhomboid major

Intermediate extrinsic back muscles

Serratus posterior superior and serratus posterior inferior

Trapezius location

Large superficial muscle covering the posterior neck and upper back

Trapezius parts

Descending, transverse, and ascending parts

Trapezius actions

Elevates, retracts, and rotates the scapula; assists arm adduction and slight elevation

Trapezius innervation

CN XI with C3–C4 fibers for proprioception and pain

Latissimus dorsi location

Large superficial muscle of the lower posterior trunk extending toward the humerus

Latissimus dorsi actions

Adducts, medially rotates, extends, and lowers the arm; helps raise the body during climbing

Latissimus dorsi nickname

Coughing muscle

Latissimus dorsi innervation

Thoracodorsal nerve C6–C8

Levator scapulae location

Posterolateral neck extending to the superior medial border of the scapula

Levator scapulae action

Elevates the scapula

Levator scapulae innervation

Dorsal scapular nerve C4–C5

Rhomboid minor location

Deep to trapezius between the vertebral column and medial border of the scapula, superior to rhomboid major

Rhomboid major location

Deep to trapezius between the vertebral column and medial border of the scapula, inferior to rhomboid minor

Rhomboid major and minor actions

Press the scapula against the thoracic wall and retract it medially

Rhomboid major and minor innervation

Dorsal scapular nerve C4–C5

Serratus posterior superior

Intermediate extrinsic back muscle that elevates ribs

Serratus posterior inferior

Intermediate extrinsic back muscle that depresses ribs

Serratus posterior innervation

Intercostal nerves

Erector spinae muscles

Iliocostalis, longissimus, and spinalis

Iliocostalis position

Most lateral portion of the erector spinae

Iliocostalis divisions

Lumborum, thoracis, and cervicis

Longissimus position

Intermediate portion of the erector spinae

Longissimus divisions

Thoracis, cervicis, and capitis

Spinalis position

Most medial portion of the erector spinae

Spinalis divisions

Mainly thoracis and cervicis

Superficial intrinsic back muscles

Splenius capitis and splenius cervicis

Splenius muscle action

Rotate and extend the head and neck

Deep intrinsic back muscles

Semispinalis, multifidus, rotatores, interspinales, intertransversarii, and levatores costarum

Suboccipital triangle boundaries

Rectus capitis posterior major, obliquus capitis superior, and obliquus capitis inferior

Suboccipital triangle contents

Suboccipital nerve C1, third part of vertebral artery, and suboccipital venous plexus

Suboccipital nerve

Dorsal ramus of C1

Vertebrobasilar syndrome

Temporary ischemia affecting the posterior brain