A&P CH.7 PT A. The Skeleton

what is the skeleton composed of

bones, cartilage, joints, and ligaments

what do ligaments do

connect bone to bone and reinforce joints

what are the two major divisions of the skeleton

axial and appendicular skeleton

axial skeleton explained

•80 bones

• three regions- skull, vertebral column, and thoracic cage

•three functions: form longitudinal axis of body, support head neck and tunk, and protect brain spinal cord and thoracic organs

bone markings such as projections, depression, and openings form what

1. attachment sites for muscles, ligaments, and tendons

2. articular surfaces (joints)

3. channels for blood vessels and nerves

Bone markings;projections that are sites of muscle and ligament attatchment

tuberosity, crest, trochanter, line, tubercle, epicondyle, spine, and process

tuberosity

large rounded projection that may be roughened

crest

narrow ridge of bone; usually prominent

trochanter

very large irregularly shaped process

line

narrow ridge of bone, less prominent

tubercle

small rounded projection or process

epicondyle

raised area on or above a condyle

spine

sharp slended and often pointed projection

process

any bony prominence

projections that help form joints

head, facet, condyle

head

bony expansion carried on a narrow”neck”

facet

smooth and nearly flat articular (joint) surface

condyle

rounded articular projection; often articulated with corresponding fossa

projections for passage of vessels and nerves

groove, fissure, foramen, notch, meatus, sinus, fossa

groove

furrow

fissure

narrow, slit like opening

foramen

round or oval opening through a bone

notch

indentation at the edge of a structure

meatus

canal like passageway

sinus

cavity within bones filled w air and line with mucous membrane within skull

fossa

shallow, depression in bone which often serves as an articular surface

the skull is formed by two sets fo bones

8 cranial bones

name the 8 cranial bones (PEST OF 6)

parietals(2), ethmoid, sphenoid, temporal (2), occipital, and frontal

what does the temporal bone do

houses organs of hearing and equilibrium

frontal bone

parietal bone

temporal bone

sphenoid bone (butterfly bone)

what is included in the sphenoid

optical canal and various other foramina for passage of blood vessels and nerves

ethmoid bone is the

deepest skull bone

what do the cribriform plates do

form roof of nasal cavity and floor of anterior cranial fossa

crista galli is

point of attachment for brain’s dura mater covering

what are the three major regions of temporal bone

squamous, tympanic, and petrous region

squamous region for temporal bone

zygomatic processes articulate with zygomatic bone to form zygomatic arch and mandibular fossa makes up part of temporomandibular joint

tympanic region for temporal bone

surround external acoustic meatus (external ear canal)

what is the mastoid and styloid processes

areas for attachment of several neck and tongue muscles

petrous region for temporal bone

houses middle and internal ear cavities, makes up part of middle cranial fossa

what are the major sutures of the bone

coronal suture, sagittal suture, lambdoid suture, and squamous suture

coronal suture

between parietal bones and frontal bones

sagittal suture

between right and left parietal bones

lambdoid suture

between parietal and occipital sutures

squamous sutures

between parietal and temporal bone

what is a sutural bone?

tiny, irregularly shaped bones that appear within sutures (unknown of what they do)

what does the occipital bone articulate with

C1 vertebrae aka atlas at occipital condyles (looks like little nubs)

ligamentum nuchae

site of attachment for many neck and back muscles

what does foramen magnum do?

allows passage of spinal cord and vertebral artery and vein (Big Whole); spinal cord exits brain cavity in this area

vultures can Not make my Pet Zebra laugh (in caps= 2 of them)

vomer, inferior nasal conchae, nasals (2), maxillae, mandible, palatines (2), zygomatics (2), and lacrimals

maxilla

upper jaw, larger bone

lacrimal bones

think tear ducts

what is the largest, strongest bone of face

mandible

************does the mandibular articulate with the temporal bone

YES

alveolar process

sockets for teeth held into mandible

what does the mandibular notch do

separates processes

coronoid process

superior end of rami serves as insertion point for large temporalis muscle

orbits are formed by

7 BONES; frontal, sphenoid, zygomatic, maxilla, palatine, lacrimal, and ethmoid

nasal cavity

formed by several bones

how is the roof, lateral walls, and floor of nasal cavity formed

ethmoid bone, palatine bones, maxillary bones, and inferior nasal conchae

paranasal sinuses

•formed from five skull bones: frontal, sphenoid, ethmoid, and paired maxillary bones

•all contain mucosa-lined, air filled spaces

•function: warm+humidify air, help to lighten skull, enhances resonance of voice

hyoid bone

does not articulate with any other bones directly. held in place by ligaments. acts as movable base for tongue and site of attachment for muscles of swallowing and speech

vertebral column

spine or spinal column

cervical

consists of 7 vertebrae of the neck (c1-c7)

Thoracic

12 vertebrae of thoracic cage (T1-T12)

Lumbar

5 vertebrae of lower back (L1-L5)

sacrum

5 fused vertebrae of the pelvis

Coccyx

3-5 (usually 4) fused vertebrae of the tailbone

name the four main curves in the column

•Thoracic and sacral curvatures- convex posteriorly

•Cervical and Lumbar curvatures- concave posteriorly

ligaments attach

bone to bone

Anterior and posterior longitudinal ligaments

Help support to avoid hyperextension (backward) or hyper flexion (forward)

Ligamentum Flavum

connects adjacent vertebrae

short ligaments

connect each vertebra to those above and below

intervertebral discs

cushion like pad between vertebrae that act as shock absorbers

what are the two parts of the in vertebral disks

• Nucleus Pulposus- gives disc its elasticity and compressibility

• Annulus Fibrosus- outer collar composed of collagen and fibrocartilage/limits expansion of nucleus when compressed

Abnormal spinal curvatures+explain

• scoliosis:abnormal lateral rotation of spine most often in thoracic; can lead to breathing difficulties

•Kyphosis (hunchback): abnormal dorsal thoracic curvature and common in older women.

• Lordosis (swayback): accentuated lumbar curvature that can result from disease but also seen in men w pot bellies & pregnant women

body (centrum)

anterior weight-bearing) region

vertebral arch composed of

•two pedicles-short pillars form sides of arch

•two laminae-fused, flattened plates from posterior arch

vertebral foramen

enclosure formed by body and vertebral arch coming together; make up the vertebral canal

intervertebral foramina

lateral openings between vertebrae for passage of spinal nerves

how many processes does the vertebrae have

7

spinous process-project posteriorly

transverse processes (2)- project laterally

superior articular processes(2)-protrude superiorly

inferior articular processes (2)-protrude inferiorly

what is c7

vertebra prominens- large, triangular vertebral foramen

what is the transverse foramen (only in cervical vertebrae)

found in each transverse process for artery passage ways

C1 is the

Atlas

-no body or spinous process

-consists of anterior and posterior arches, and two lateral masses

-occipital condyles (slide 20) “carry” the skull

-movement for nodding head “yes”

C2 is the

Axis

-has body and processes like other vertebrae

-has a knoblike dens that projects superiorly (up) in the anterior arch of atlas

-movement allows side to side rotation for saying “no”

-pivot for rotation of atlas

T1-T12

-increase in size and articulate w ribs

-have only single facet not two

-foramen is circular

-transverse processes have transverse costal facets that articulate w the ribs (except T11 & T12)

articular facets allow what

rotation of this area of the spine (T1-T12)

L1-L5

-small of back; receives most stress so bodies are massive

-short thick pedicles and laminae

-flat, hatchet-shaped spinous processes point posteriorly

-vertebral foramen is triangular

S1-S5

-fused bones

-articulate superiorly w L5, articulates inferiorly w coccyx, and articulates laterally w hip bones

coccyx

-tailbone

-3-5 fused vertebrae

-articulates superiorly w sacrum

Thoracic cage is composed of

-thoracic vertebrae

-sternum

-ribs and costal cartilages

what are the functions of the thoracic cage

-protects vital organs of thoracic cavity

-supports shoulder (pectoral) girdles and upper limbs

-supports shoulder girdles and upper limbs

-provides attachment sites for muscle of neck, back, chest, and shoulders

bone marking in sternum to know

jugular notch

the sternum aka the breast bone consists of three fused bones that include

mandubrium-superior portion, articulates w clavicle and ribs 1+2

body-midportion that articulates w costal cartilages of ribs 2-7

Xiphoid process- inferior end that is site of muscle attachment

what are the three important landmarks of sternum

jugular notch, sternal angle, and xiphisternal joint

ribs

-12 pairs from sides of thoracic cage

-all attatch posteriorly to bodies

true ribs are

-pairs 1-7= true; attatch directly to sternum by individual costal cartilages

-false ribs 8-10; attatch indirectly to sternum by joining costal cartilage of rib above

-vertebral (floating) ribs 11-12; no attachment to sternum

name the main parts of the rib

-shaft-flat bone that makes up most of rib

-head (posterior end)-articulates w facets on two adjacent vertebrae

-neck-constricted portion beyond head

-tubercle: knoblike structure lateral to neck (articulates posteriorly w transverse costal facet fo same numbered thoracic vertebra