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Flashcards in The Skeleton Deck (11):
1

Skeletal Subdivisions

Axial -Postcranial -Vertebrae
-Thorax
-Cranial (Skull) - Canium
-Facial

Appendicular - Pelvic girdle
-Pelvic Limb
-Pectoral girdle
-Pectoral limb

2

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

3

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)

4

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

5

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

6

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

7

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

8

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

9

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

10

Pelvic Girdle

-Retains its 3 ancestral elements: ilium, ishium and pubis (all unite at acetabulum

11

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