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