the skeletal system (ch 5)

skeletal system

arranges our bones, joints, cartilage, and ligaments to make up our internal framework and allow for upright posture; strong and light-weight

axial and appendicular

two skeletal divisions:

axial skeleton

spine and skull form the longitudinal axis of the body

appendicular skeleton

the bones of our limbs and girdles (pelvic/shoulder); includes bones of arms, pectoral girdles, legs, pelvic girdles

functions of the skeletal system:

• • blood cell formation

  • storage

  • movement

  support

• protection

• hematopoiesis

formation of blood cells within the marrow cavities of bones

206

number of bones

compact and spongy

two types of bone tissue

spongy bone

also called cancellous bone; honeycomb appearance; trabeculae form a beam-like network; open spaces are filled with marrow

compact bone

dense and hard bone; looks smooth and even throughout

long bones

bone classification: longer in length than they are in width; long shaft; have head at both ends; compact bone on outside and lines with spongy bone on inside; found in limbs, metatarsals, and metacarpals

short bones

bone classification: cube shaped; mostly spongy; found in carpals, tarsals, and sesmoids

flat bones

bone classification: thin and flat, usually curved; two thin layers of compact bone with spongy bone on the inside; found in skull, ribs, and sternum

irregular bones

bone classification: bones that do not fit into any of the other categories; found in pelvis (hip) and vertebrae

diaphysis

shaft of a long bone

epiphysis

enlarged ends of a long bone

periosteum

fibrous connective tissue covering the shaft of long bone

sharpey's fibers

fibers of connective tissue that secure periosteum to the bone in long bone

articular cartilage

covers external surface of epiphysis; smooth, slippery joint surface

epiphyseal line

the remnant of epiphyseal growth plate; flat plate of cartilage; mature bone

epiphyseal plate

growth plate; found in young growing bones; causes lengthwise growth of bones; eventually replaced by bone when growth stops

medullary cavity

hollow inside of bone shaft in long bone; storage area for fat or yellow marrow in adults; for infants it is where blood cells are produced

osteocytes

mature bone cells

lacunae

house bone cells

lamellae

concentric rings of lacunae found around the central Haversian canal

Canaliculi

minute canals radiating in all directions from lacunae

Haversian canal

central, longitudinal canals of bone that carry blood vessels

Volkman canal

horizontal canals of bones that carry blood vessels and connect osteons to the medullary cavity

Osteon

each complex consisting of central canal and matrix rings; also known as haversian system

tuberosity

large, rounded projection; tibia, ischium, humerus, radius

tuburcle

small, rounded projection; humerus, femur

crest

prominent narrow ridge; tibia, ilium, sacrum

trochanter

large, blunt, irregularly shaped process; femer

condyle

large rounded weight bearing surface; humerus, femur, tibia

epicondyle

small rounded projection on surface of condyle; humerus

spine

sharp, slender, pointed projection; scapula, ischium ilium (4)

process

any bone prominence; vertebrae, radius, ulna, temporal bone

head

has a narrow neck; femur, humerus, radius, fibula

facet

smooth, flattened surface; ribs, vertebrae

ramus

arm-like bar; mandible, ischium, pubis

meatus

canal-like passage; ear canal

sinus

cavity filled with air within a bone; frontal, sphenoid, ethmoid sinuses

fossa

shallow depression; scapula, skull

groove

furrow; mandible

fissure

narrow, slit-like opening; eye sockets

foramen

round or oval opening through bone; skull, vertebrae, pelvis, sacrum

cranium and facial bones

skull is formed from 2 sets of bones

cranium

encloses and protects the brain; 8 large, flat bones (frontal, parietal x2, temporal x2, occipital, sphenoid, ethmoid) and sutures- joints (coronal, sagittal, squamous, lambdoid)

coronal suture

where the joints come together between the frontal and parietal bone

sagittal suture

where the joints come together between the two parietal bones

squamous suture

where the joints come together between parietal and temporal bones

lambdoid suture

where the joints come together between parietal bones and occipital bone

frontal bone

parietal bone

temporal bone

occipital bone

sphenoid bone

sella turcica; foramen ovale; optic canal; superior orbital fissure; sphenoid sinus; greater wing; lesser wing

ethmoid bone

crista galli, cribiform plate, superior and middle nasal conchae

temporal bones

external auditory meatus

styloid process

mastoid process

zygomatic process

jugular foramen

carotid canal

internal acoustic meatus

occipital bones

lambdoid suture

foramen magnum

occipital condyles

fetal skull

face is small compared to cranium; allows compression of skull during birth process; allows brain room to go

fontanels

fibrous membranes that have not yet converted to bone but connect the cranial bones

craniosynostosis

condition where one or more sutures of the skull closes too early; slows or impedes growth of the skull and brain; skull and facial structures change in appearance; increased brain pressure

facial bones

there are 14 of these: maxillae x2, palatine x2, zygomatic x2, lacrimal x2, nasal x2, vomer, inferior nasal conchae x2, mandible

maxillae

upper jaw; all bones except mandible joint maxillae; keystone of face; forms portion of hard palate; alveolar margins- rim of bone at teeth

palatine bones

facial bones that form the hard palate, roof of mouth

zygomatic bones

facial bones that form cheek bones and lateral wall of eye socket

lacrimal bones

facial bones that form the medial wall of eye socket

nasal bones

facial bone that forms bridge of nose

vomer

facial bone that forms medial bony nasal septum

inferior nasal conchae

facial bones that forms the lateral walls of nasal cavity

mandible

facial bone that makes up lower jaw; it is the largest and strongest bone of the face

temporomandibular joint (TMJ)

formed at the back of the mouth where the mandible and temporal bone

orbit

technical term for eye socket

treacher collins syndrome

rare congenital disorder from genetic mutation

craniofacial deformity

-downward slanting eyes

-smaller jaw bone

-absent cheek bones

-malformed ears

-decreased hearing

-airway problems

hyoid bone

the only bone that does not attach directly to another bone; forms a moveable base for tongue; attachment point for neck muscles involved in speech and swallowing; mid-neck region

vertebral column

also known as the spine; extends from the skull to the pelvis; made up of 26 irregularly shaped vertebrae (24 single vertebrae, sacrum, coccyx); flexible to allow movement; surrounds and protects the spinal cord

cervical (7), thoracic (12), lumbar (5), sacrum (5 fused), coccyx (4 fused, tailbone)

detail and number the bones of the vertebral column

normal spinal curvature

this absorbs shock, provides flexibility

primary curves

these are present at birth; kyphosis, thoracic, sacral

secondary curves

these are developmental; lordosis, cervical, lumbar

scoliosis

abnormal lateral curvature of the spine

lordosis

abnormal anterior curvature of the lumbar spine (sway-back condition)

kyphosis

excessive outward curvature of the spine, causing hunching of the back.

vertebral body

weight bearing disc of bone on the anterior side of vertebral bone