Skeletal System

Fun Facts• 270 bones in an infant but several fuse

together • 206 bones in human body• largest is femur, smallest ossicles

http://www.youtube.com/watch?v=flIAxGsV1q0

2 Divisions1. axial – makes

longitudinal axis of body skull, spine, rib cage, sternum

2. appendicular-bones of limbs and girdles

• also includes joints, ligaments (bone-bone connectors), cartilages

Function1. Support

- maintains structure of body- helps hold some organs in place

2. Protection- protects soft body organs (brain, heart, etc.)

3. Movement- tendons attach muscles to bones

4. Storage- fat stored in cavities of bones- bones store minerals (Calcium & Phosphorus)

5. Formation of Blood Cells AKA hematopoiesis

Types of Bone• Compact Bone- dense, looks smooth• Spongy Bone- has small needle-like pieces of

bone and lots of open space

Spinal Column• spinal cord passes through center of vertebrae

– Via vertebral foramen• made of 26 irregular bones connected by

ligaments to allow flexibility of spine– When born there are 33

*think meal times to remember #’s 7am, 12 pm, 5 pm… we’ll get back to this

http://www.youtube.com/watch?v=QWCKiyKuL8c start @ 46 sec

Spinal Column

• Are pads between vertebrae intervertebral discs

• As you age discs harden – drying of discs and weakening

of the ligaments predisposes people to herniated discs

Spinal Column• Curvature in thoracic and

sacral regions are present at birth (primary curvatures)

• Curvature in cervical & lumbar regions develop after birth (secondary curvatures)– cervical curvature allows

baby to raise its head– lumbar curvature allows

walking

Abnormal Curvatures: Kyphosis

Abnormal Curvatures: Scoliosis

Abnormal Curvatures: Lordosis

Cervical Vertebrae• 7 cervical vertebrae

– 1st called Atlas• No body, superior surface has

depressions for the occipital condyles (bumps on the base of the skull) can shake head yes

– 2nd called Axis• Has a large process called

(dens) on the superior surface can shake head no

How to Know a Cervical Vertebrae When You See One…

• C3-C7– smallest, lightest vertebrae– short spinous process– foramina (holes) in transverse processes (through

which arteries flow)

How to Know a Thoracic Vertebrae When You See One…

• T1-T12– larger than cervical– only vertebrae that articulate (fit) with ribs– heart-shaped body– 2 facets- 1 set for ribs and 2 set for neighboring

vertebrae– long spinous process that hooks down

How to Know a Lumbar Vertebrae When You See One…

• L1-L5– large, block-shaped bodies– spinous process like a hatchet– sturdiest vertebrae

Remember these…

They’re back!

Skull Bones

Rib Cage• Sternum

– flat bone– formed by the fusion of 3

bones• manubrium (superior)• body (middle)• xiphoid process (inferior)

– attached to first 7 ribs– bone marrow can be take

from here since it’s superficial

Rib Cage• Ribs

– 12 pairs, make walls of chest cavity– articulate w/ vertebrae and curve downward and

toward the anterior body– 1st 7 pairs TRUE ribs - attach to sternum by

cartilage– pairs 8-12 FALSE ribs – attach to sternum

indirectly ( 3 pairs fuse with cartilage of other pair) OR lack sternal attachments

• if no attachment to sternum FLOATING rib

Clavicle

Hand and Wrist Bones

Some Ladies Try Positions That They Can't Handle

To remember the carpal bones :Scaphoid, Lunate, Triquetral, Pisiform, Trapezium, Trapezoid, Capitate, Hamate

Bone Shapes• Long bones- longer than they are wide, have a long

shaft and heads at both ends– all limb bones are long bones EXCEPT the patella, wrist

bones, & ankle bones• Short bones- cube-shaped

– patella, wrist bones, & ankle bones• Flat bones- thin, flattened usually curved; 2 thin layers

of compact bone & spongy bone between– most bones of skull, ribs, sternum

• Irregular bones- bones that don’t fit into the other 3 categories– hip bones, vertebrae

Pelvis• Purposes:– bearing weight – protects bladder, reproductive

organs, & some of the large intestines

• Hip bone made of – ilium- forms most of hips, has wings

that flare out, connects w/ the sacrum,

• iliac crest where you put hands on hips

– ischium- “sit down bone” takes weight when you sit

– pubis- most anterior part of pelvis -> forward buldge

• meets w/ ischium to make obturator foramen for muscles, nerves, and bl vessels to go to the anterior part of thigh

• all meet at the acetabulum where femur inserts

Which is which?

Males vs. Female Differences

• female pelvis is shallower & bones are lighter• iliac crest of a female flare more laterally

making opening larger and more circular• in females the pubic arch at bottom of pelvis is

more rounded and larger than 90o

• female acetabulum is more shallow more flexible

Foot and Ankle Bones

New Tricks…• Clavicle- put rounded side towards palm, large curve out from body & flat end in

opposite hand, using opposite hand feel for the bump facing towards you, if not there other side

• Tibia- Tough guy… big guy, larger side facing up, large bump to the front, longest process towards the inside/medial side of the ankle makes medial malleolus (can follow curve on shin)

• Fibula- PUNY, feel the 2 necks, skinny neck on top, larger/flatter neck on bottom, largest inferior process must be POSTERIOR and on the lateral side of the ankle makes lateral malleolus

• Femur- ball and neck medially, large fossa to the back/towards your body, the direction the ball faces is the side

• Patella- point down, hold like a controller with thumbs on smooth facets,

broader side is the side that the patella is on

• Pelvis- put knuckle of index finger in the sciatic notch, if you can wrap four fingers around and into the hip bone fossa ACETABULUM that’s the side