Skeletal System: Bones Flashcards
How many bones are in the human skeleton
206
Two groups of human skeleton
Axial skeleton - long axis of the body, skull, vertebral column, rib cage
Appendicular skeleton - bones of upper and lower limbs, girdles attaching limbs to axial skeleton
The skull
Cranial bones (cranium)
- enclose the brain in the cranial cavity
- provide sites of attachment for head and neck muscles
Facial bones
- form framework of face
- contains cavities for special sense organs for sight, taste and smell
- provide openings for air and food passage
- secure teeth
The Vertebral Column
- five major regions
- cervical: Consists of 7 vertebrae
- Thoracic: 12 vertebrae
- Lumbar: 5 vertebrae
- Sacrum: one bone, formed from fusions of several bones articulates with hip
- Coccyx: also fused bones that form terminus column
General structure of vertebrae
- all have common structural pattern consisting of:
- body
- vertebral foramen
- vertebral canal
- intervertebral foramina
The vertebral column
Ligaments:
- anterior and posterior longitudinal ligaments
- ligamentum flavum
- intervertebral discs
Thoracic cage
composed of
- thoracic vertebrae posteriorly
- Sternum and costal cartilages anteriorly
- ribs laterally
Functions:
- protects vital organs of thoracic cavity
- supports shoulder girdles and upper limbs
provides attachment sites for muscles of neck, back, chest and shoulders
Ribs
main part of rib:
- shaft: flat bone that makes up most of rib
- costal groove: houses nerves and vessels
- head (posterior end)
- articulates with facets (demifacets) on bodies of two adjacent vertebrae
- neck: constricted portion beyond head
- tubercle: knoblike structure lateral to neck
- articulated posteriorly with transverse costal facet of same-numbered thoracic vertebra
Appendicular skeleton
Consists of bones of the limbs and their girdles
- pectoral girdle: attached upper limbs to body trunk
- pelvic girdle: attaches lower limbs to body trunk
Clavicles
- also called collarbones
- s-shaped sternal end articulated with sternum medially
- flattened acromial end articulates laterally with scapula
- anchor muscles and act as braces to hold the scapulae and arms out laterally
Scapulae
- triangular flat bones on dorsal surface of rib cage between ribs 2 and 7
- each scapula has three borders
- superior
- medial
- lateral
Female Pelvic structure
gen structure and functional modifications: tilted forward, adapted for childbearing; true pelvic defines the birth canal: cavity of the true pelvis is broad, shallow and has a greater capacity
Bone thickness: less, lighter, thinner and smoother
Acetabula: smaller, further apart
Pubic arch/subpubic angle: Broader (80-90 degrees,) rounded
sccrum: wider, shorter, sacral curvature is accentuated
coccyx: more moveable, projects inferiorly
Greater siatic notch: wide and shallow
pelvic inlet (brim): wider, oval from side to side
pelvic outlet: wider, ischial tuberosities, shorter, farther apart and everted
Male pelvic structure
gen structure and functional modications: tilted less forward, adapted for support of male heavier build and stronger muscles, cavity of the true pelvis is narrow and deep
Bone thickness: greater, bones heavier, thicker and markings are more prominent
Acetabula: large, closer
Pubic arch: acute (50-60)
sacrum: narrow, longer, sacral promontory more ventral
coccyx: less moveable, projects anteriorly
Greater sciatic notch: narrow and deep
pelvic inlet (brim): narrow, heart shaped
pelvic outlet: narrower, ischial tuberosities longer, sharper and point more medially
The upper limb
- 30 bones from skeletal framework of each upper limb
- arm, humerus
- forearm, radius, ulna
- hand, 8 carpal bones in the wrist, 5 metacarpal bones in the palm, 14 phalanges in the fingers
Forearm
- two parallel bones from forearm skeleton: ulna and radius
- proximal ends articulate with humerus and each other
- distally articulate with each other at the radioulnar joint
- interosseous membrane connects radius and ulna along their entire length
Hand
- Bones of the hand include carpus, metacarpus and phalanges
- carpus (wrist): eight bones in two rows
- proximal row: lateral to medial
- scaphoid, lunate, triquetrum and pisform
- distal row, lateral to medial
- trapezium, trapezoid, capitate and hamate
- only scaphoid, lunate and triquetrum form wrist joint
The lower limb
- carries entire weight of the body
- subjected to exceptional forces during jumping or running
- three segments of lower limb
- thigh
- leg
- foot
leg
- made up of two parallel bones, tibia, fibula
- connected bu interosseous membrane
- tibia
- fibula
- several muscles originate from fibula
Foot
- skeleton of foot includes bones of tarsus, metatarsus and phalanges
- tarsus: (7)
- Metatarsals (5)
- Phalanges (14)
Bone classification
Bones are organs because they contain different types of tissues
* Bone (osseous) tissue predominates, but a bone also has a nervous tissue, cartilage, fibrous connective tissue, muscle cells, and epithelial cells in its blood vessels
Three levels of structure of bone classification
Gross
Microscopic
Chemical
Gross anatomy
Compact and spongy bone
Compact bone: dense outer layer on every bone that appears smooth and solid
Spongy bone: made up of honeycomb of small, needle-like or flat pieces of bone called trabeculae
Open spaces between trabeculae are filled with red or yellow bone marrow
Osteon
single unit of compact bone
spongy bone
Appears less organised than compact bone
Align precisely along lines of stress to allow bone to resist stress
