Axial skeleton Flashcards
Trabecular bone
- Found on the inside of mature bone
- Especially at the ends of long bones where compressive forces are greatest
- Moulded by mechanical forces & stresses
- Contains red and/or yellow bone marrow
Compact bone
- Found on the outside of mature bones
- Solid, hard surface layer
- Thickest around the shaft of long bones where tensile & torsional stresses are greatest
Long bones
- Length > breadth
- Tubular in shape – gives the strongest & lightest combination
- Shaft or body (diaphysis, which is usually hollow)
- Two expanded ends for articulation (epiphyses)
- Leavers
Short bones
- Cuboid in shape
- Thin layer of compact bone supported by a network of trabecular bone
- Found in the wrist & foot
- Resist compression
Irregular bones
*Usually have extensions of bone creating a variety of irregular shapes
* Examples - include facial bones & vertebrae
* Attachment - more SA for muscles
Pneumatized bones
- Bones with air-filled cavities
- Present in the skull
- Serves to lighten the skull & add resonance to the voice
- Examples – maxilla, ethmoid
- Dont have bone marrow
Flat (squamous bones)
- Two flat laminae of compact bone with spongy bone (& marrow) in between
- Usually protective or reinforcing
- Forms walls of cavities, eg skullcap (calvarial) bones, sternum, scapula
Sutural bones
- Small flat ‘biscuit’ like joining bones
- Typically fuse with the larger flat bones of the skull and disappear in adults
Sesamoid bones
- Round or oval nodules
- Resemble sesame seeds, hence the name
- Develop in certain tendons (postnatal), where the tendon is exposed to pressure
- Protect tendon from excessive wear
- Can help change the line of pull of muscles, giving them a mechanical advantage
- Example – patella (kneecap) – the largest sesamoid bone
- Looks like sesame seeds - protects tendons
Tuberosity
large round elevation (L. lump or swelling), eg deltoid tuberosity
Trochanter
large blunt elevation (G. a runner), eg greater trochanter of femur
Protuberance
swelling or knob (L. I bulge out), eg mental protuberance
Tubercle
small raised eminence (L. small lump or swelling), eg humerus
Malleolus
Malleolus = hammerhead-like elevation (L. small hammer), eg medial malleolus of tibia
Ridge or line
Ridge or line = linear elevation, eg supracondylar ridge
Crest
Prominent ridge, eg iliac crest
Spine or spinous process
sharp elevation or projecting part (L. thorn), eg SP of
vertebra
Head
rounded articular area, eg head of humerus
Condyle
rounded articular area (G. knuckle), eg femoral condyles
Epicondyle
prominent process just proximal to a condyle (G. epi=upon) eg elbow
Fossa
small hollow (L. ditch), eg radial and coronoid fossae
Articular facet
small, smooth flat area for articulation with another bone
Foramen
an opening in bone (L. hole) OR a notch that is bridged by a ligament
Sulcus
long narrow depression (L. groove), eg sulci on brain
Notch
indentation at the edge of a bone, eg trochlear notch
Meatus
Canal that enters a structure but does not pass through it (L. passage), eg
external auditory meatus
Bones in axial skeleton
80 bones
Skull - 22 ones and 7 associated with skull
Vertebral column - 24 vertebrae, 1 sacrum, 1 coccyx
Thoracic - 24 ribs and 1 sternum
Functions of axial skeleton
create a framework that supports and protects organs in the dorsal and ventral body cavities
- house special sense organs for taste, smell, hearing, balance and sight.
- provide an extensive surface area for the attachment of muscles
- permit limited movement
- contain red marrow for blood cell formation
Excessive curvature conditions
Scoliosis = lateral
Kyphosis = sagittal, primarily thoracic
Lordosis = sagittal, primarily lumbar
Part of vertebrae
Body, pedicle & lamina
Processes -transverse & spinous
Articular processes - superior & inferior
Vertebral foramen
Intervertebral notches - superior & inferior
Intervertebral disc
Holds vertebrae together, small amount of movement
Cervical
Typical Cervical (L. neck) Vertebrae = C3-6
* Small body
* Transverse processes have anterior & posterior tubercles
* Vertebrarterial foramen (transversarium) for vertebral artery & vein
* Large triangular vertebral foramen (for size of vertebral body)
* Almost horizontal articular facets
* Bifid spinous processes
Thoracic
Typical Thoracic (G. chest) Vertebrae = T2-9
* Heart shaped body
* Superior & inferior costal facets on vertebral body – for head of rib
* Round vertebral foramen (small in comparison to vertebral body)
* Articular facets are more vertical
* Costal (L. rib) facet on transverse process – for tubercle on typical rib
* Long sloping spinous process
Typical ribs
Ribs 3-9
* Head, neck & body (shaft)
* Tubercle, angle & costal groove
* Articular surfaces – head & articular part of tubercle
Lumbar
- Lumbar (L. loin) Vertebrae
- Large kidney-shaped vertebral body
- No ribs => No costal facets
- Triangular vertebral foramen
- Large superior & inferior articular processes
- Broad, quandrilateral spinous process
