Lecture 3: Axial Skeleton Flashcards
Vertebral Column
26 bones
Bears and transfers body weight, protects spinal cord, provides passage for spinal nerves
70 cm
5 regions of vertebral column
Cervial (CI-CVII) Thoracic (TI-TXII) Lumbar (LI-LV) Sacral (SI-SV) 5 fused vertebrae Coccygeal 4-5 fused vertebrae
Primary vs Secondary curvature
Primary: curves present at birth - thoracic, sacral
Secondary: curves acquired after birth - cervical (2-3 months), lumbar (1-1.5 years old)
Dynamic vs Static curves
Dynamic: changing - cervical, thoracic, lumbar
Static: unchanging - sacral
Kyphosis
Exaggerated thoracic curvature
Lordosis
Exaggerated lumbar curvature (pregnancy)
Scoliosis
Pathological lateral curvature
Most have scoliosis of 5 degrees
Main features of typical vertebrae
Body (anteriorly)
Vertebral arch: pedicles and laminae (posteriorly)
Body and vertebral arch surround vertebral foramen which contains vertebral canal
Transverse processes
Spinous process
Articular processes
Body of vertebrae
Increases in size throughout vertebral column for increased forces
Pedicles
2 bony projects extending posterolaterally from body
Has superior and inferior vertebral notches which form intervertebral foramen for spinal nerves and associated structures
Laminae
2 bony ridges posteromedially forming the midline
Transverse process
Lateral extension from junction of pedicle and laminae
Spinous process
Posterior projection from junction of laminae
Articular process
At junction of pedicles and laminae
Superior articular processes articulate with inferior articular process above
Smooth part of the articular process = facet
Typical cervical vertebrae features
CIII-CVI
Has bifurcated spinous process and transverse foramen
Atlas
CI
Has 2 lateral masses (instead of body) connected by anterior and posterior arch (instead of vertebral arch)
Superior surface of lateral mass articulates with occipital condyle
Inferior surface articulates with CII; anterior arch articulates with odontoid process
Has transverse foramen
Axis
CII
Pivot for rational movements of head
Superior surface is odontoid process (dens axis) that articulates with anterior arch of CI
2 articular processes lateral to odontoid process to articulate with lateral mass
Bifid spinous process
transverse foramen
CVII
Largest spinous process
Not bifurcated
Known as prominent vertebra
Typical thoracic vertebrae
TII-TIX
Costal facets on side of body and transverse process
Long slender spinous process pointing inferiorly
Typical lumbar vertebrae
LI-LV
Large body and short thick spinous process
Sacrum articulation
Apex of bone points inferiorly and articulates with coccyx
Base of bone faces superiorly and articulates with 5th lumbar vertebrae
Auricular surface
L shaped surrface that articulates with hip bone
Lateral side of sacrum
Anterior surface of sacrum
Smoother and concave
4 pairs of anterior sacral foramina (anterior rami of sacral spinal nerves)
Sacral ala (triangular surface on either side of body)
Body
Sacral promontory (landmark in pregnancy)
Transverse ridges separating bodies (previously intervertebral discs)
Posterior view of sacrum
Rougher (due to sacral crests) and convex
4 pairs of posterior sacral foramina (posterior rami of sacral spinal nerves)
Median sacral crest (remnants of spinal process)
Sacral canal (continuation of vertebral column)
Sacral hiatus (opening at SV - laminae fail to fuse; used to paralyze only the lower limbs)
Lumbarization vs Sacralization
Lumbarization: 1st sacral vertebrae doesn’t fuse = 6th lumbar vertebrae
Sacralization: 5th lumbar vertebrae fuses
Both cause severe lower back pain
Coccyx
Small triangular bone by fusion of 4-5 coccygeal vertebrae
Base articulates with SV
Apex is free
Sternum
Flat bone for anterior thoracic wall
Manubrium
Body
Xiphoid process
Manubrium
Trapezoid bony plate
Superior surface = jugular notch/suprasternal notch
On either side = clavicular notch
Articular surface on lateral side for 1st costal cartilage
Body
Convex anteriorly
Articular surfaces on side for costal cartilage of ribs II-VII
Sternal angle
Level of TIV and TV vertebrae
Articulates manubrium and body
Opens posteriorly (2 inches below jugular notch) forming short horizontal bony ridge at 2nd costal cartilage
Xiphoid process
Curves posteriorly
Articulates with body via xiphisternal joint
7th costal cartilage articulates with sides of this joint
Ribs
12 pairs
Posterior end (head) articulates with thoracic vertebrae
Anterior end of 1st 7 pairs articulate with sternum
Separated by intercostal spaces (contains intercostal muscles, nerves, vessels)
True ribs
1-7
Articulates with sternum via costal cartilage
False ribs
8-12
8-10 articulates with sternum through 7th costal cartilage
11-12 do not articulate with sternum = free/floating ribs
Typical ribs
3-9
Head articulates with costal facet of thoracic vertebrae at same level and level above
Neck extends between head and costal tubercle
Tubercle: small bony elevation articulates with costal facet of transverse transverse of thoracic vertebrae at same level
Body: thin bony plate that curves anterolaterally at costal angle (most fractures happen here)
Costal groove: medial inferior border of internal surface for intercostal nerves and vessels
Cervical rib
13th pair of ribs
CVII transverse process gives rise to a rib
Thoracic cage
Protects organs (heart, lungs) Conical bony cavity of thoracic vertebrae, ribs, costal cartilage, sternum Apex: at neck; vertebrae TI, first ribs, superior surface of manubrium = superior thoracic aperture Base/interior thoracic aperture: vertebrae TXII, 11&12 ribs, costal margin (costal carnage of ribs VII-X), xiphoid proces; sealed by diagraphram
