Lecture 3: Vertebral Column

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vertebral column (spine)

supports trunk, protects spinal cord, weight-bearing (shock-absorption), movement of trunk (movement = lateral flexion/extension, rotation of head, neck, and upper trunk)

components of vertebral column

vertebrae, intervertebral discs (25% of length), vertebral ligaments

cervical spine

C1-7 vertebrae

• located at neck

• smallest

• most mobile

thoracic spine

T1-12 vertebrae

• articulate with ribs

• limited mobility

lumbar spine

L1-5 vertebrae

• largest

• bears the most weight

sacrum

a large, triangular bone located at the base of the lumbar spine that connects the spinal column to the pelvis

sacral spine

S1-5 vertebrae

• fused

• transmit weight to pelvic girdle

coccyx

commonly called the tailbone

• a small, triangle-shaped bone at the very bottom of the spine formed by three to five fused or semi-fused vertebrae

coccygeal spine

Co1-4

• attachment point for pelvic muscles

• fused, vestigial (tailbone)

kyphosis

an outward curve of the spine in the upper back that helps balance the body against gravity

lordosis

the natural inward, forward-bending curve of the spine in the neck and lower back

primary spine curvature

a primary curve present from fetal development that bends outward (convex posteriorly)

secondary curvature

develop after birth due to impact of gravity during erect stance

thoracic and sacral kyphosis

convex (stick out) posteriorly

• primary spine curvatures that develop during the fetal period

cervical and lumbar lordosis

concave posteriorly

• secondary spine curvatures that develop after birth due to impact of gravity during erect stance

scoliosis

abnormal lateral curvature of spine and rotation of vertebrae

• most common vertebral abnormality

• typically observed in teenage female patients

• muscle assymetry may occur

• screening=observe for rib hump/shoulder assymetry during forward bending

bone features/landmarks

surface markings of bone that reflect functional roles

articulations

connection point between two or more bones in skeletal system

1. facet

2. head

facet

smooth or flat/nearly flat surface where bones touch (articulate)

head

rounded enlargement that articulates with another bone

foramen (foramina)

hole for passage of soft tissues

canal

tubular passage for soft tissues

process

projection or outgrowth

tubercle

small rounded projection

lamina

the back part of a vertebra (spinal bone) that forms a protective roof over the spinal canal and shields the spinal cord

pedicle

a short, thick cylinder of bone that connects the front part of a vertebra (the vertebral body) to the back part of the arch that protects the spinal cord

features of typical vertebra

• vertebral body

• vertebral foramen

• pedicle

• lamina

• vertebral arch

• superior/inferior articular process

• transverse process

• spinous process

• vertebral notch (inferior)

superior and inferior articular process and vertebral bodies

articulate to facilitate movement

vertebral foramen

houses spinal cord

intervertebral foramen

small, oval-shaped opening between two stacked vertebrae that allows spinal nerves and blood vessels to pass from the spinal canal out to the rest of the body

vertebral arch

protects spinal cord

sup/inferior vertebral notches

accommodate spinal nerves

• form intervertebral foramen

spinous and transverse processes

act as anchors for ligaments and muscles

features of typical cervical vertebra

• transverse foramen (C1-6)

• bidfid spinous process (C2-6)

• vertebra prominens (C7 spinous)

• superior articular facets + inferior articular facets

• uncinate process

• triangular vertebral foramen

transverse foramen

accommodates vertebral artery (C1-6)

bifid spinous process

found only in C2-6

• two prongs → greater surface area for ligament attachment

vertebra prominens (C7 spinous)

longest process in vertebral column

superior articular facets

face superoposterior and inferior articular facets face inferoanterior

• allows for rotation of head

uncinate process

raised lateral margin → concave vertebral body

• protects vertebral artery by limiting lateral movement

C1: Atlas

supports cranium through lateral masses (no body)

• superior articular facets articulate with occipital condyles permitting “nodding” motion

• ring-like structure with no spinous process and articulation with C2 (axis) permits head rotation

C2: Axis

superior articular facets articulate with inferior articular facets of C1

• dens

• transverse ligament

dens

odontoid process

• articulates with anterior arch of C1, permitting head rotation

transverse ligament

holds dens against anterior arch of C1

• prevents posterior displacement and spinal cord compression

costal facets

• unique to thoracic vertebrae

• articular surfaces on vertebra for articulation with ribs

thoracic vertebral body

• superior = articulation for head of rib (same level)

• inferior: articulation for head of rib (below)

transverse processes (thoracic)

articulation for tubercle of rib

• limit mobility

thoracic spinous processes

long, steep, and overlap like shingles

thoracic articular facets

• superior: face posterior

  • permits rotation and limits flexion

• inferior: face anterior

additional thoracic vertebrae features

• heart-shaped body

• circular vertebral formamen

features of typical lumbar vertebra

• large kidney-shaped body (bears the most weight)

• short hatchet-shaped spinous process

• superior articular facets (face medially) and inferior articular facets (face laterally) to facilitate flexion and extension

• mamillary processes

• accessory processes

mamillary processes

found in typical lumbar vertebra

• on root of transverse processes

• deep back muscle attachment

accessory processes

• on root of transverse processes

• deep back muscle attachment

• large triangular vertebral foramen

sacrum and coccyx

fused vertebrae

• sacrum articulates with pelvis at auricular surface

sacral canal

houses sacral spinal nerves and exits anteriorly at anterior sacral foramina and inferiorly at sacral hiatus