Back & Spine Definitions & Functions

vertebral column

part of the axial skeleton that extends from the cranium to the coccyx

functions of the vertebral column

• protects spinal cord & spinal nerves

• supports the weight of the body

• posture & locomotion

• acts as a pivot for the head

• flexible axis for the body

Composition of vertebral column

7 cervical, 12 thoracic, 5 lumbar, 5 sacral, 4 coccygeal
total is 33 vertebrae

S1-S5 is fused to form

the sacrum

Co1-Co4 are fused to form the

coccyx

Vertebral curvature function

provide additional flexibility + shock-absorbing resilience

Adults have

4 curvatures

Lordosis

bent backward

Kyphosis

bent forward/hunchback

Which parts of the column are bent backward/lordosis

cervical and lumbar

Which part of the column are bent forwards/kyphosis

thoracic + sacral

Which curvature is primary

lordosis

Which curvature is secondary

Kyphosis

Primary curvatures

Developed during the fetal period

Secondary curvatures

infant begins to hold their head erected (cervical) and begins to walk and assume upright posture (lumbar)

Excessive thoracic kyphosis

abnormal increase in thoracic curvature producing a hunchback deformity

Causes of excessive thoracic kyphosis

postural or congenital

Excessive lumbar lordosis

abnormal increase in lumbar curvature producing a swayback deformity

Causes of excessive lumbar lordosis

idiopathic, pregnancy

Scoliosis

abnormal lateral curvature

Causes of scoliosis

majority idiopathic, some congenital, & neuromuscular

Vertebral body function

support body weight

Vertebral arch includes

the pedicles + laminae

Spinous process function

muscle attachment

Transverse processes

muscle attachment

Articular processes function

articulation with adjacent vertebrae + restricts movement

Vertebral foramen includes

the vertebral body and arch

Function of the vertebral foramen

• houses + protects the spinal cord and spinal nerves

• contribute to the formation of the vertebral canal, which houses the spinal cord

Intervertebral (IV) foramen

the location where the spinal nerve exits the vertebral column

Vertebral notches

contribute to the formation of the intervertebral (IV) foramen

Stenosis

abnormal narrowing of a passage in the body

Lumbar spinal stenosis

• abnormal narrowing of the vertebral foramen in one or more lumbar vertebrae

• cause compression of one or more spinal nerve roots

Laminectomy

surgical procedure that involves cutting through the laminae and removing a portion of the vertebral arch

C1/Atlas regional characteristics

lacks body and spinous process

Structures of the Atlas

• lateral masses with 2 superior and 2 inferior articular processes

• anterior and posterior arches

• anterior and posterior tubercles

lateral masses function (2 superor and 2 inferior articular processes )

• articulates with the cranium and C2/axis

Where does the lateral masses of C1 articulate with the cranium

at the atlantooccipital joint

Where does the lateral masses of C1 articulate with the C2/axis

at the lateral atlantoaxial joint

Function of anterior arch

articulation with the dens of C2/axis

Where does the anterior arch of C1 articulate with the dens of C2

at the medial atlantoaxial joint

Anterior and posterior tubercles function

ligament attachment

C2/axis regional characteristics

lacks body

Structures in C2

dens/odontoid process

Function of dens in C2

articulation with C1/atlas at the medial atlantoaxial joint

C1-C7 structures

transverse foramen

Transverse foramen function

passageway for vertebral artery (C1-C6) and vein (C1-C7)

C3-C5 structures

short bifid spinous processes

Function of short bifid spinous processes

attachment of the nuchal ligament

C7 (vertebra prominence) structures

long spinous process

Function of long spinous process

attachment of nuchal ligament

T1-T12 structures

• Heart-shaped body with bilateral costal facets

• Long transverse processes with costal facets

Function of the heart-shaped body with bilateral costal facets

rib articulation at the head

Function of long transverse processes with costal facets

rib articulation at the tubercle

L1-L5 structures

large vertebral body

S1-S5 structures

fused to form sacrum

Function of sacrum

• support pelvis

• transfer weight to lower limb via pelvic girdle

Co1-Co4 structures

fused to form coccyx

Coccyx function

muscle and ligament attachment

Joint

articulation/place of union or junction between 2 or more rigid components/bones or cartilage

Classification of joints

• fibrous

• cartilaginous

• synovial

Fibrous joint

articular surfaces are joined by fibrous connective tissue

Primary cartilaginous tissue

articular surfaces lined by hyaline cartilage

Secondary cartilaginous tissue

articular surfaces lined by hyaline cartilage separated by fibrocartilaginous discs

Type of joints

• hinge

• pivot

• saddle

• condyloid/ellipsoid

• plane/gliding

• ball-and-socket

Hinge joint movement

• uniaxial

• flexion/extension

Pivot joint movement

• uniaxial

• rotation

Saddle joint type

• biaxial

• flexion/extension/abduction/adduction

• circumduction

Condyloid/ellipsoid movement

• biaxial

• flexion/extension/abduction/adduction

• circumduction

Plane/gliding joint movement

• usually uniaxial

• gliding/sliding

Ball-and-socket joint movement

• multiaxial

• flexion/extension/abduction/adduction

• mediolateral rotation

• circumduction

Craniovertebral joints

• atlantooccipital joint

• atlantoaxial joints

Atlantooccipital joint type

• synovial

• condyloid

Atlantooccipital articulation

• articulates with the super articular facet of C1/atlas

• articulates with the occipital condyle of the occipital bone

Movement of atlantooccipital joint

• biaxial

• flexion/extension

• lateral flexion (minimum)

Flexion/extension of the atlantooccipital joint

permits one head to nod head up/down in a yes movement

Atlantoaxial joints

• median atlantoaxial joint

• lateral atlantoaxial joints

Median atlanoaxial joint type

• synovial

• pivot

Median atlantoaxial joint articulation

• articulates with the dens of C2/axis

• articulates with the anterior arch and transverse ligament of the atlas

Movement of median atlantoaxial joint

uniaxial

Uniaxial movement of median atlantoaxial joint

Rotation of the head in “no” movement

Lateral atlantoaxial joint type

• synovial

• plane/gliding

Lateral atlantoaxial joint articulation

• C1/atlas: the inferior articular facets

• C2/axis: superior articular facets

Movement of the lateral atlantoaxial joints

uniaxial

Uniaxial movements of the lateral atlantoaxial joints

• flexion/extension

• lateral flexion (minimal)

Intervertebral joints

intervertebral (disc) joints

Intervertebral (disc) joint type

secondary cartilaginous

Articulation of intervertebral (disc) joints

adjacent vertebral bodies and the intervertebral (IV) disc

Movement of intervertebral disc joints

• flexion/extension

• lateral flexion

• axial rotation

Intervertebral (disc) joints

joints of the vertebral body

Intervertebral (IV) disc components

• inner: nucleus pulposus

• outer: anulus fibrosus

IV disc herniation

protrusion of the nucleus pulpous into or through the anulus fibrosis

Where is IV disc herniation common

in the lumbar region at L4/5 and L5/S1 vertebral levels

Common type of IV disc herniation

posterolateral

Why is posteriolateral IV disc herniation common

• annulus fibrosis is thin in this location and not supported by anterior or posterior longitudinal ligaments

• is symptomatic if hernia compresses a spinal nerve

Zygapophysial (facet) joints

joints of the vertebral arches

Zygapophysia joint type

• synovial

• plane/gliding

Articulation of facet joints

superior and inferior articular facets of adjacent vertebrae

Movement of facet joints

• uniaxial

Uniaxial movement of facet joints

• flexion/extension

• lateral flexion (minimal)

Ligament

maintains stability by connecting bones or organs to each other