SKELETAL SYSTEMLecture #3

Skeletal organization Axial skeleton – skull, vertebral column,

ribs, sternum Appendicular skeleton – pectoral girdle,

pelvic girdle, limbs

Axial – Skull bones Cranial – flat bones enclose and protect

brain Frontal bone: forehead and upper ridges

of eye sockets Parietal bones: upper left and right sides

of skull Temporal bones: lower left and right

(ears)

Skull bones cont’d Sphenoid bone: back of the eye sockets Ethmoid bone: contributes to eye

sockets and helps to support the nose Occipital bone: curves underneath to

form the back & base of the skull Foramen magnum (L. great opening):

where vertebrae connects to skull

But wait, there’s moreSkull bones!

Facial bones - front Maxilla – forms part of eye sockets and

sockets to anchor upper row of teeth Palatine bones – hard palate (roof of

mouth) Vomer bone – behind palatine & part of

nasal septum

But wait, there’s moreSkull bones!

Zygomatic bones: cheek bones & outer portion of eye socket

Nasal bones: underlie the upper bridge of nose (space between maxilla & nasal bones is the nasal cavity)

Lacrimal bones: inner eye sockets with tear duct (drains to nasal cavity)

All skull bones joined tightly except for mandible (speak & chew)

Mandible: lower jaw w/ sockets for teeth Sinuses are air spaces which make the

skull lighter and give the human voice its tone and resonance

Each sinus is lined with tissue that secretes mucus & connects to nasal cavity by small passageways

Blocked sinuses = pain Respiratory infections cause sinus tissue

to become inflamed and block the passages to the nasal cavity

Sinusitis = sinus inflammation Fluid gets trapped causing sinus pressure

headache

Hyoid Bone – structure & function

U-shaped, superior to larynx in the neck The only bone that isn’t articulated with

another bone Suspended from styloid processes of

temporal bone Anchors the tongue & serves as

attachment for swallowing muscles

Vertebral Column Skull to pelvis - rib attachment, pelvic

girdle attachment Protects spinal cord as it passes through

vertebral canal 33 vertebrae

7 neck / cervical 12 chest / thoracic 5 lumbar / lower back 5 sacral 3-5 tailbone / coccygeal

4 curvatures Cervical & lumbar = convex Thoracic & sacral = concave

FIGURE 5.7

Thoracic (Rib) Cage 12 thoracic vertebrae = 12 ribs connect

to vertebrae posteriorly Upper 7 connect directly to sternum via

cartilage = true ribs Lower 5 = false ribs – upper 3 attach to

sternum with common cartilage & bottom 2 are not attached to sternum (floating)

FIGURE 5.9