The Skeleton Flashcards
Skeletal Subdivisions
Axial -Postcranial -Vertebrae
- Thorax
- Cranial (Skull) - Canium
- Facial
Appendicular - Pelvic girdle
- Pelvic Limb
- Pectoral girdle
- Pectoral limb
What is a skeleton?
-5 functions of the skeleton
-Skeleton comprises of bone that is articulated at joints and are united by ligaments. Also includes cartilage
FUNCTIONS:
- provides body form
- Forms non-collapsible cavities
- Levers for muscle action
- Houses bone marrow
- Calcium/Phosphate store
Number of bones in the different components of skull
Skull = 22 bones
- Cranial bones = 8 (direct contact w/ brain)
- Facial Bones = 13 (no brain contact)
- Mandible = 1 (lower jaw)
Sutures: what they are & 3 types
- Suture: generally convoluted thick fibrous joints between plates (in skull)
- some fuse, though some maintain through life
3 types w/in skull:
- Coronal suture: separates frontal bone from parietal bones
- Sagittal suture: between left and right parietal bones
- Lambdoid suture: between parietal bones and occipital bones
What is the:
Hyoid
Hard palate
-Hyoid chain of single bones that have fused in humans - supports and protects larynx
- Hard palate: mammalian features allowing infants to suckle
- separates nasal and oral cavities
- formed by shelf-like horizontal extensions of maxilla and palatine bones
- failure of process = cleft plate
The Human Spine
-has a triple curvature to balance body weight vertically
FORMULA: C7-T12-L5-S5-Co4
- Cervical vertebrae (7 bones)
- Thoracic vertebrae (12 bones)
- Lumbar vertebrae (5 bones)
- Sacrum (5 fused bones)
- Coccyx (4 fused bones)
Kyphosis: curves backwards (spine curves more towards posterior)
Lordosis: curves forwards (spine curves more towards anterior)
Scoliosis: curves to side
The Atlas & the Axis (C1 & C2 of cervical vertebrae)
Atlas:
- articulates w/ condyles of occipital bone (in skull)
- has deep superior artiular facets
- lacks a body
- allows us to nod our head*
Axis:
- has odonoid process or dens
- acts as axis of rotation between atlas and skull
- dens is what fits inside atlas
- atlanto-axis = no movement
X for no
Thorax
- 7 pairs of true ribs (1-7) [directly connect to sternum]
- 5 pairs of false ribs (8-12) [not directly connected to sternum]
- 2 of which are floating ribs (11-12) - not connected to sternum at all
Pectoral Girdle
- consist of 3 main elements: scapula, clavicle and coracoid (fused to scapula)
- clavicle derived from dermal bone of skull and forms by intramembranous ossification
- more highly evolved than pelvic girlde
Pelvic Girdle
-Retains its 3 ancestral elements: ilium, ishium and pubis (all unite at acetabulum
Limb Homology
- Both limbs consist of similar sequence of bones and joints
- *modern tetrapods are all ancestrally pentadactyl
- carpus and tarsus (wrist and ankle) consist of jumble of short bones
- carpals = hands
- tarsals = feet
