SKELETAL SYSTEM (SIMPLIFIED) Flashcards
Functions of skeletal system
- Support
- Movement
- Protection
- Mineral storage
- Energy storage
- Hematopoiesis
Support
Bones and cartilage support rest of body
Movement
Bones facilitate movement by serving as points of attachment for muscles and act as levers
Protection
Bones protect internal organs from injury by covering them (eg. Ribs protect lungs and heart, vertebrae protect spinal cord, skull protect brain)
Mineral storage
Bone acts as a reservoir for some minerals important for body function such as calcium and phosphorus that can be released back to bloodstream to maintain level needed for physiological processes
Energy storage
Bone marrow in softer connective tissues that fills interior of bone contains yellow bone marrow which has adipose tissue and the triglycerides here serve as energy storage
Hematopoiesis
RBC, WBC, platelet production occurs in red marrow
Bone classification
- Long
- Short
- Flat
- Irregular
- Sesamoid
Long (3)
- Cylinder shape
- Functions as leverage
- Tibia, fibula, metatarsals, metacarpals, phalanges, ulna, humerus, radius)
Short (3)
- Cube like shape equal in width, length thickness
- Functions in providing stability, support and allow motion
- Carpals, tarsals
Flat (3)
- Thin and curved
- Functions as points of attachments for muscles and protects internal organs
- Sternum, rib, scapulae, cranial bone
Irregular (3)
- Complex shapes
- Functions in protecting internal organs
- Vertebrae, facial bones
Sesamoid (3)
- Small and rounded, embedded with tendons
- Functions in protecting tendons from compressive forces
- Patallae
Diaphysis
Tubular shaft running between proximal and distal end of bone containing hollow regions called medullary cavity filled with yellow marrow
Epiphysis
Wider section at each end of bone filled with spongy bone with spaces filled with red marrow
Metaphysis
Where epiphysis and diaphysis meet that contains epiphyseal plate (layer of hyaline cartilage in growing bone)
Epiphyseal line
Indicator of boundary between epiphysis and diaphysis and becomes epiphyseal plate when bone is matured, and the cartilage layer is replaced by osseous tissue
Endosteum
Delicate membranous lining in medullary cavity where bone growth, repair, and remodelling occur
Periosteum
Fibrous membrane covering the outer surface of bone (except where epiphyses meet) containing blood vessels, nerves, and lymphatic vessels that nourish compact bone
Articular cartilage
Thin layer of cartilage that covers epiphyses to reduce friction and absorb shock
4 types bone cells
- Osteocyte
- Osteoblast
- Osteogenic cell
- Osteoclast
Osteocyte
A mature and the most common bone cell that results from when a trapped osteoblast changes in structure and becomes osteocyte; MAINTAINS BONE MATRIX AND LIVES IN LACUNAE
Osteoblast
Responsible for forming new bones found in growing portions of bone, including periosteum and endosteum; Secretes organic compounds of matrix
Osteogenic cell
Undifferentiated cells that develop into osteoblasts
Osteoclast
Found on bone surface for bone resorption, multinucleated, and originate from 2 types of WBC and not osteogenic cell; SECRETE ACID AND ENZYMES TO DISSOLVE BONE MATRIX
Osteon
Structural unit of compact bone composed of concentric rings of calcified matrix called lamellae
Central canal
Center of osteon containing blood vessels, nerves, and lymphatic vessels that branch off
Canaliculi
Small lines (ducts) in osteon that connect with caniculli of other lacunae and eventually with central canal. Allows nutrients to be transported to osteocytes and wastes removed
Nutrient arteries
Pass through nutrient foramen (small opening in diaphysis) that nourish the spongy bone and medullary cavity
How are osteocytes in spongy bone nourished
Blood vessels of the periosteum that penetrate spongy bone and blood that circulate in marrow cavities
Embryonic skeleton
Consists of only fibrous membranes and hyaline cartilage. By week 6 or 7 of development, ossification (formation of bones begins)
Intramembranous ossification vs endochondral ossification
- Intramembranous: Bone develops directly from sheets of mesenchymal connective tissue; occurs in flat bones of face, cranial bones, clavicles
- Endochondral: Bone develops by replacing hyaline cartilage; occurs on base of skull long bones
- Endochondral takes longer than intramembranous
7 Steps of intramembranous ossification
- Mesenchymal cells differentiate into specialized cells (osteogenic cells and capillary forming cells)
- Osteoblasts form clusters called ossification centers
- Osteoblasts secrete osteoid which calcifies and traps osteoblasts and transforming them into osteocytes
- Surrounding osteogenic cells differentiate into new osteoblasts
- Osteoid secretion around capillaries forms trabecular matrix, and osteoblasts on surface become periosteum
- Periosteum forms protective layer of compact bone
- Trabecular bone crowds nearby blood vessels which condense into red marrow
9 steps of endochondral ossification:
- Mesenchymal cells differentiate into chondrocytes that form cartilaginous skeletal precursor
- Perichondrium appears and chondrocytes in center grow in size
- Matrix calcifies, leading to chondrocyte death and disintegration of surrounding cartilage
- Blood vessels invade spaces, enlarging them and carrying osteogenic cells
- Space combines to form medullary cavity and capillaries penetrate cartilage
- Perichondrium transforms into periosteum and periosteal collar of compact bone forms around cartilage
- Primary ossification center forms deep in periosteal collar
- Similar events occur in secondary ossification centers in epiphyseal regions
- Cartilage remains at joint surfaces as articular cartilage and between diaphysis and epiphysis as growth plate responsible for bone lengthening
Growth plate zones (4):
- Reserve zone
- Proliferative zone
- Maturation and hypertrophy zone
- Calcified zone
Reserve zone (2)
- Closest to epiphysis consisting of resting chondrocytes that anchor the growth plate to bone
- Chondrocytes dont participate in bone growth but only secure growth plate to osseous tissue
Proliferative zone
Chondrocytes undergo rapid cell division leading to formation of new chondrocytes
Zone of maturation and hypertrophy
Chondrocytes are older and larger and contribute to the lengthening of bones
Calcified zone (2)
- Serves as bridge for invasion of blood vessels and transformation of cartilage into bone
- Cartilage matrix becomes calcified and chondrocytes die
Longitudinal bone growth cause
Result of cell division in the proliferative zone and the maturation of cells in zone of maturation and hypertrophy
Appositional growth
Refers to the fact that bones continue to grow in diameter even if lengthening stops
Bone modelling
Process of shaping and forming bone during growth and development
Bone remodelling
Refers to the lifelong process of continuous renewal and maintenance of old or damaged bones
Open (compound) fracture
At least one end of the broken bone tears through the skin; carries high risk of infection
Closed (simple) fracture
Fracture where skin remains intact
Greenstick fracture
Partial fracture in which only one side of the bone is broken
Comminuted fracture
Bone broken in two or more places causing many small pieces
2 divisions of skeleton
- Axial skeleton
- Appendicular skeleton
Axial skeleton (3)
- Vertical, central axis of body
- All bones of head, neck, chest, and back
- Serves as attachment site for muscles that move head, neck and back
2 divisions of the skull
- Facial bones
- Brain case
What is the only moveable bone in the skull
The 22nd bone (lower jaw/mandible)
Fontanelle
Areas of dense connective tissue that separate the bones of the brain case as they grow; important for infants as they allow for changes in shape as they squeeze through birth canal
Ossicles
3 inner ear bones associated with the head; malleus, incus, stapes that function to transmit sound waves from eardrum to inner ear
Hyoid bone
U shaped structure that serves as base for tongue located midline of neck (independent bone)
Appendicular skeleton (4)
- Everything else that is not part of axial skeleton; bones that append to axial skeleton
- Limbs attach to skeleton at girdles
- Upper limbs attach to pectoral (shoulder) girdle
- Lower limbs attach to pelvic girdle
4 curvatures of vertebral column
Adult vertebral column has 4 curvatures for flexibility and to absorb shock; cervical, thoracic, lumbar, pelvic
Vertebral column in fetal development
One curvature in vertebral column as they are flexed anteriorly into fetal position
Body
Anterior portion of vertebra that supports body weight
Vertebral arch
Posterior portion of vertebra supporting 7 processes
Vertebral foramen
Large opening between vertebral arch and body containing spinal cord
Vertebral canal
Encloses the vertebral foramen (protection)
Intervertebral foramen
The opening between every two vertebrae where the nerve roots exit the spine
3 types of processes in vertebra
- 1 spinous
- 2 transverse
- 4 articular
Spinous process (3)
- Single structure
- Projects posteriorly midline of back
- Site of muscle attachment
Transverse process (3)
- Paired structure
- Projects laterally from vertebrae
- Site of muscle attachment
Articular process (3)
- Superior and inferior process
- Allows for controlled and coordinated movement, while maintaining the overall stability
- Superior process extends upwards, inferior process extends downward
Intervertebral disc
Made of fibrocartilage and separates the vertebrae
C1 Atlas (4)
- Supports skull
- No body/spinous process
- Ring shape
- Transverse process longer and extend more naturally
C2 Axis (3)
- Allows rotation of head left and right
- Resembles typical cervical vertebrae
- Contains dens (bony projection extending upward from body)
- Dens joined with anterior arch of atlas held in place by transverse ligament
3 parts of sternum
- Manubrium
- Body
- Xiphoid
Ribs 1-7
True ribs; coastal cartilage attaches DIRECTLY to sternum
Ribs 8-10
False ribs; coastal cartilage attach to cartilage of next rib, and not sternum
Ribs 11-12
Floating ribs; do not attach to sternum at all
Clavical
Collarbone; S shaped
Scapula
Shoulder blade; flat and triangular shaped
Humerus
Upper arm located between shoulder and elbow joints;
Ulna and radius (2)
- Forearm located between elbow and wrist
- Radius runs parallel to ulna on LATERAL side
Carpal
Base of hand and wrist
Metacarpal
Palm of hand
Phalanx
Digits
Pelvis structure
2 hip bones, sacrum, coccyx
3 components of hip bone
- Illium (largest)
- ischium
- Pubis
Female pelvis (4)
- Lighter and thinner weight
- Round/oval inlet
- Shorter and wider shape
- Greater than 80 degree subpubic angle
Male pelvis (4)
- Thicker and heavier weight
- Heart shaped inlet
- Longer and narrower shape
- Less than 70 degree subpubic angle
Male pelvis
- Thicker and heavier weight
- Heart shaped inlet
- Longer and narrower shape
- 7
Femur
Thigh bones (strongest and longest)
Patella
Kneecaps
Tibula
Bone located between knee joint to ankle joint (second longest bone)
Fibula (2)
- Bone located between knee joint to ankle joint
- Runs parallely and laterally to tibula
Tarsal
Bones of base of feet below ankle
Metatarsal
Bones of soles of feet
Phalanges
The actual toe
Calcaneus
Largest bone of foot forming heel
Talus
Ankle joint
