human anatomy exam #2

bone functions

structural support for entire body

framework for attachment of soft tissues/organs

storage of minerals and lipids (stored in the form of adipose tissue within yellow bone marrow)

blood cell production; red bone marrow (within medullary cavity of many bones) is responsible for production of RBC, WBC, and other blood elements

protection: ribs, skull, vertebral column, pelvis

leverage and movement: joints and bones function as levers; change magnitude and direction of forces generated by skeletal muscles

what type of tissue is bone

connective tissue

bone is made of…

cells + collagen & elastic fibers + calcified ground substance

ground substance of bone

mineral crystals, calcium phosphate, calcium carbonate

creates hard, calcified matrix

cells of bone

osteoblasts, osteoclasts, osteocytes

protein fibers

collagen fibers → strong & flexible

extracellular matrix

aka bone matrix aka lamellae

made of protein fibers + ground substance

hard/dense due to calcium salts deposited around collagen protein fibers

this combination gives bone its strength: very strong but still somewhat flexible, highly resistant to shattering under high pressures but still susceptible to certain forces (twisting, bending, sudden impacts)

osteogenic cells

“mesenchymal stem cells”; divide and differentiate into osteoblasts

location: inner cellular layer of periosteum; endosteum lining medullary cavities and BV passageways

osteoblast

immature bone cell

responsible for osteogenesis (process for producing new bone matrix)

osteocytes

mature bone cells; osteoblasts surrounded by bone matrix; makes up most of bone cell population

location: lacunae (pocket btw layers of matrix)

functions: maintain protein/mineral content of surrounding matrix and repair damaged bone

osteoclasts

bone-removing cells

perform osteolysis

origin: derived from same stem cells that produce monocytes/macrophages

lamellae

“bone matrix”

protein fibers + ground substance

osteogenesis

ossification— bone production

2 steps: (1) osteoid production (2) trigger Ca deposition → bone

hematopoiesis

process of producing new blood cells from stem cells

osteolysis

bone destruction/breakdown

metaphysis

region in long bone between epiphysis and diaphysis

location: of epiphyseal cartilage of developing long bone

compact bone

dense bone containing parallel osteons

forms protective outer layers of all bones

spony bone

contains open network of struts/plates resembling 3D lattice frame

does not contain large central cavity or bone marrow between lattice framework

osteon

main structural unit of compact bone

osteocytes organized within matrix around central canal

separated by concentric lamellae

central canal

“haversian canal”

longitudinal along bone

bv and nerves

volkmann’s canal

“perforating canal”

perpendicular to bone surface

bv/nerves

connections between adjacent osteons

canaliculi

narrow passageways throughout matrix

extend between lacunae and osteocytes

passageway for BV to travel throughout bone— allows diffusion of nutrients/waste to and from osteocytes

lamellae

layers of bone matrix

form lacunae (pockets within matrix in which osteocytes are located)

types: concentric, circumferential, interstitial

concentric lamellae

forms rings around individual osteons

circumferential lamellae

form larger rings around entire bone structure just deep to periosteum

interstitial lamellae

within spaces between concentric and circumferential lamellae

periosteum

outer covering of all bone surfaces (except joints)

outer fibrous region + inner cellular region

function: isolates boens from surrounding tissues; provides route for BV/nerves to enter/leave bone

collagen fibers of periosteum interwoven with fibers of tendons/ligaments attached to bone (extremely strong attachment)

endosteum

inner covering of all bone surfaces → lines medullary cavity and trabeculae

incomplete cellular layer: active during bone growth/repair and remodeling; simple flattened layer of osteoprogenitor cells; covers most of bone matrix (osteoclasts and osteoblasts work at these exposed areas)

compact bone functional characteristics

supports most of heavy weight-bearing of the body

resists twisting/bending/linear stresses on bone created from movement

protection

compact bone structural characteristics

cells and lamellae arranged in repeating cylindrical units

dense and solid

located on outer later of all bones, and the diaphysis of long bones

spony bone functional characteristics

reduces overall weight of skeleton

redistributes weight and shock-absorption

houses most of red bone marrow

spongy bone structural characteristics

lamellae form parallel sheets

osteocytes still reside in lacunae and communicate via canaliculi

no osteons or central/perforating canals

porous and light-weight

located in epiphysis of long bones and the center of flat, irregular, and spongy bones

trabeculae

meshwork of supporting bundle of fibers that form matrix of spongy bone

branch and cross-brace to create connected, open network

red marrow

children: present in all bones

adults: axial skeleton → ribs, skull, sternum, vertebrae, pelvis, and part of humerus/femur

function: RBC production

yellow marrow

adults: appendicular skeleton → replaces red bone marrow throughout skeletal maturation

function: fat (adipocyte) storage

able to convert back into red bone marrow if necessary

skeletal development

starts during gestation and continue until skeletal maturity (age 25)

ossification

formation of bone

endochondral ossification

bone tissue replaces existing hyaline cartilage

most bones of the body

intramembranous ossification

bone tissue replaces existing fibrous connective tissue

bones of skull, face, clavicle, and pelvis

interstitial growth

bone lengthening

occurs via endochondral ossification at the epiphyseal plate

occurs until skeletal maturity

appositional growth

bone widening

osteoblast activity on outside of bone

osteoclast activity on inside of bone

occurs throughout lifetime

interstitial growth PROCESS

1) chondroctyes within hyaline cartilage of growth plate multiply on epiphyseal side

2) new cartilage moves towards diaphysis

3) mineral is deposited and cartilage ossifies

4) cartilage of epiphyseal plate eventually replaced with spongy bone

appositional growth PROCESS

1) inner cellular layer of periosteum differentiates into osteoblasts → deposits superficial layers of matrix

2) eventually surrounded by matrix → differentiate to osteocytes

3) additional layers form circumferential lamellae → deeper layers of circumferential lamellae eventually recycled/replaced by compact bone

4) osteoclasts removing matrix at inner surface of bone → medullary cavity gradually enlarges

bone remodeling

dynamic process involving bone resorption (osteoclasts) and bone formation (osteoblasts) occurring at the same site

functions: maintain bone integrity, manage mineral homeostasis, adjust bone architecture to meet mechanical needs, repair micro-damage

carried out via osteocytes (continuously removing/replacing surrounding calcium matrix), osteoclasts (constantly removing old matrix), osteoblasts (always adding new matrix and developing into osteocytes)

crest

raised edge

tuberosity

rough, raised bump; usually for muscle attachment

epicondyle

bump superior to a condyle

process

projection/raised area

trochanter

large process; only found on femur

spine

sharp, pointed process

tubercle

small, rounded process

canal

tunnel through bone

fissure

long slit for blood vessels/nerves

foramen

round opening; usually passageway for nerves/blood vessels

meatus

tube-like opening

sinus

cavity within a bone

condyle

rounded knob; usually fits into fossa on another bone

facet

flat surface

head

prominent, expanded end of a bone

fossa

wide, shallow, basin-like groove

sulcus

narrow, deeper, elongated groove

fovea

small pit, indent

axial skeleton

skull, vertebral column, sacrum, ribs, sternum (80 bones)

support and protection of brain, SC, thoracic/abdominal organs

provide attachment areas for ligaments of muscles: head/neck/trunk position, breathing movement, stabilize/position limbs

joints of axial skeleton: limited movement, very strong and heavily reinforced

appendicular skeleton

limbs, pelvic bones, scapula, clavicle (126 bones)

movement and locomotion

attachment areas for ligaments of limb muscles

protection: organs of pelvic girdle

weight distribution and support

cranial bones

8

frontal, parietal (2), temporal (2), occipital, sphenoid, ethmoid

facial bones

14

nasal (2), maxillary (2), zygomatic (2), lacrimal (2), palatine (2), inferior nasal concha (2), mandible, vomer

primary vertebral curves

thoracic & sacral

develop before birth

provide space

secondary curves

cervical & lumbar

develop after birth

support weight

vertebrae parts

spinal canal: spinal cord travels in this space

vertebral arch: forms posterior margin of spinal canal; pedicles & laminae; anchor for vertebral processes

vertebral body: weight-bearing area of the vertebrae; forms anterior margin of spinal canal

transverse processes: attachment sites; articulates with ribs in thoracic region

articular processes: articulation area for adjacent vertebrae; inferior and superior on each

intervertebral discs: fibrocartilage pads separating bodies of vertebrae

intervertebral foramina: gaps between pedicles of successive vertebrae; allow passage of spinal nerves

vertebral canal: formed by continuous line of all vertebral foramina

vertebral foramen

spinal canal

vertebral artery

travels through transverse foramen

regional vertebrae characteristics

as move down vertebral column: spinal cord diameter decreases, vertebral arch diameter decreases, vertebral bodies enlarge to compensate for increasing load

cervical vertebrae

small body

large vertebral foramen

transverse foramen

notches spinous process

thoracic vertebrae

heart-shaped body

smaller vertebral foramen

transverse costal facets (transverse process)

costal facet (vertebral body)

articulates with ribs

lumbar vertebrae

large body

support weight of body

smaller vertebral foramen

atlas

C1

articulates with occipital condyles: joint allows neck flexion/extension

transverse ligament: binds dens of axis within vertebral foramen

structurally unique: no body, no spinous process, large round vertebral foramen

axis

C2

dens (ondontoid process):

• body of atlas fuses to body of axis

large spinous process = attachment point for many neck muscles

transverse ligament: binds dens within atlas to allow rotation of atlantoaxial joint (shake head no)

sacrum

consists of 5 fused sacral vertebrae

function: protects organs within abdominopelvic cavity; attaches axial and appendicular skeleton at pelvic girdle

coccyx

3-5 fused coccygeal vertebrae

fuse after age 25-26

may fuse with sacrum later in life

rib structure

head (capitulum): articulates with vertebral column; superior and inferior articular facets

tubercle: small dorsal projection next to neck; inferior portion contains facets that articulate with thoracic vertebrae

body: curves toward the sternum; costal groove is a prominent indentation on inferior internal surface that is a pathway for BV and nerves

sternum

manubrium: widest, most superior portion

jugular notch: shallow indentation on superior surface between clavicular articulations

body

xyphoid process: attachment sites for diaphragm and rectus abdominis; palpable landmark for CPR

femur

longest/heaviest bone in body

head/epiphysis: articulates with pelvic bone in acetabulum

fovea capitis: attachment area for ligament between femur and acetabulum

medial and lateral epicondyles: small raised bump just above condyles

patellar surface: smooth area on inferior/anterior surface between medial/lateral condyles; articular surface for patella

patella

large sesamoid bone

forms within tendon of quadriceps femoris

anterior surface: rough and convex; attachment area for quadriceps tendon and patellar ligament

posterior surface: smooth and concave; area of articulation with medial and lateral femoral condyles

tibia

shinbone

medial and lateral condyles: articualte with condyles of the femur; intercondylar eminence (ridge separating condyles)

body → tibial tuberosity: rough, raised bump on anterior surface of tibia just distal to condyles; attachment site of patellar ligament

medial malleolus: large process at distal, medial tibial border; forms large medial ankle bump; supports ankle joint on medial aspect

fibula

does not bear weight

more important for muscle attachment site and lateral support of ankle

lateral malleolus: widened, distal end of fibula; forms large lateral ankle bump; supports ankle joint on lateral aspect

talus

tarsal bone

transfers weight of body from tibia towards toes

trochlea of talus: spool-shaped articular process

calcaneus

largest tarsal bone

transfers weight of body from talus to ground while standing

posterior portion: rough, knob shaped projection

coracoid process

smaller, anterior process extending above anterior surface of shoulder joint

attachment site for ligaments/tendons of shoulder joint

acromion process

larger, posterior process extending superior to shoulder joint

continuous with spine of scapula

articulates with acromial end of clavicle

attachment site for ligaments/tendons of shoulder joint

glenoid cavity

cup-shaped depression at lateral angle that forms glenohumeral joint

scapula-humerus articulation

anterior (costal) surface

smooth and concave

attachment site for many tendons/ligaments

subscapular fossa: depression in anterior surface

posterior surface

spine of scapula: ridge crossing posterior surface from acromion and to medial border

clavicle

s-shaped bone originating at superior, later border of manubrium (sternum) lateral to jugular notch

sternal end: forms sternoclavicular joint

acromial end: broad distal end that articuales with acromion process of scapular

humerus

head: articular with scapula in glenoid cavity

• greater Tubercle: Rounded projection on lateral head of humerus

• lesser Tubercle: Smaller rounded projection on anterior, medial surface of head of humerus

• Both: attachment point for rotator cuff muscles

Body:

• Medial and Lateral Epicondyles

• Medial Epicondyle - Much larger

• Ulnar Nerve crosses posterior surface, this is what you hit when you bump your “Funny Bone”

Condyle:

• Articular surfaces:

• trochlea: spool shaped medial portion of condyle that articulates with ulna; coronoid Fossa to Olecranon Fossa

• capitulum: rounded surface on lateral trochlea that articulates with radius

 Coronoid Fossa:

• Shallow depression on anterior, proximal condyle

• Fits Coronoid Process of Ulna during elbow flexion

 Olecranon Fossa:

• Shallow depression on posterior, proximal condyle

• Fits Olecranon Process of Ulna during elbow extension

 Radial Fossa:

• Shallow depression on anterior condyle superior to capitulum

• Fits radial head during elbow flexion

ulna

Medial bone of forearm

Connected to Radius via Interosseous membrane (Fibrous connective tissue)

Olecranon:

• Point of the elbow

• Trochlear Notch: Groove on anterior surface that articulates with Trochlea of Humerus

Olecranon Process: Superior point of trochlear notch

• Fits into Olecranon fossa on humerus during elbow extension

Coronoid Process: Inferior point of trochlear notch

• Fits into Coronoid fossa on humerus during elbow flexion

Radial Notch

• Area of articulation with Head of Radius

• Proximal Radio-Ulnar Joint

Ulnar Head

• Ulnar Styloid Process: Articulates with distal radius at Distal Radio-Ulnar Joint

• Does not directly articulate with carpal bones

  • Separated from carpal bones by Articular disc

radius

Lateral bone of forearm

Connected to Ulna via Interosseous membrane (Fibrous connective tissue)

 Head

• Articulations:

  • Flat superior surface: articulates with capitulum of humerus

  • Medial surface: articulates with Radial Notch of Ulna

• Radial Tuberosity: Medial projection just below radial neck where biceps Brachii tendon attaches

 Radial Styloid Process:

• Ulnar Notch: Medial surface on distal radius marking articulation site with ulnar head

• Radial Styloid Process

  • Distal surface: articulates with carpal bones

  • Lateral process: stabilizes wrist joint

carpals

forms 2 rows in wrist (4 proximal, 4 distal)

metacarpals: I-V starting medially

phalanges:

• polex → proximal and distal

• all others → proximal, middle, and distal

joint

area where adjacent bones or other structures of the skeletal system interact

“articulations”

functions: allow movement, provide stability, proprioception, accommodates growth

structural classification of joints

fibrous: bound together by fibrous CT; immovable/slightly moveable

cartilaginous: joined by cartilage; immovable/slightly moveable

bony: fibrous/cartilaginous joint ossifies; immovable

synovial: joint cavity separates adjacent bones; highly movable

functional classifications of joints

synarthrosis: immovable; fibrous or cartilaginous; axial skeleton

amphiarthrosis: slightly movable; fibrous or cartilaginous; axial skeleton

diarthrosis: highly movable; appendicular skeleton; further classifications (hinge, gliding, condyloid, saddle, pivot, ball-and-socket)