Download The Skeleton - Mr. Haan`s Science

THE SKELETON
Chp 6-2
I’ve checked, and
the science is sound.
A. AXIAL SKELETON (80 BONES)
Skull
1.
a.
Formed by cranial and facial bones
b.
Cranium – protects brain
c.
Facial bones
1)
Form framework for face
2)
Have cavities for senses
3)
Have openings for air and food passages
4) Secure the teeth
5) Anchor facial muscles
d. Most are flat (except mandible)
e. Sutures – interlocking joints of the skull
f. Cranium
1) Self bracing – makes it strong for how light it is
2) Frontal bone – anterior cranium
3) Nasal bone
4) Parietal bones and sutures
a) Parietal bones – superior,
lateral parts of skull
b) Most of skull
C) Sutures
i. Coronal – parietal bones
meet frontal bone
ii. Sagittal – parietal bones
meet superiorly
iii. Lambdoid suture – parietal bones meet occipital
bone
iv. Squamous suture – parietal and temporal bones
meet
5) Occipital bone
a) Posterior wall and base of skull
b) Provides opening (foramen magnum) for spinal
cord
c) External occipital protuberance
d) Occipital condyles – process which articulates
with atlas
6) Temporal bone
a) Inferior to parietal bones
b) Meet at squamous sutures
c) Zygomatic process
i. Bar like part of bone
ii. Process – muscles or ligaments attach
d) Zygomatic arch
i. Cheekbone
ii. Fuses with zygomatic process
7) Sphenoid bone
a) Butterfly shaped
b) Central wedge, touches all other cranial bones
g. Facial bones
1) Mandible
a) Lower jaw
b) Largest/strongest bone of the face
c) Anchors teeth
2) Maxillary bone – upper jaw
3) Zygomatic bones (zygoma = cheek)
4) Nasal bones – forms bridge of nose
5) Lacrimal bones – medial walls eyes
a) Contains deep groove
b) Groove forms lacrimal fossa
c) Lacrimal fossa houses the lacrimal sac
d) Lacrimal sac – passageway that allows tears to
drain from the eye into nasal cavity
e) Makes nose run when crying
6) Vomer – inferior nasal cavity
2. Special characteristics
a. Orbits
1) Bony cavities for eyes
2) Cushioned by fat
b. Nasal cavity
1) Made of bone and hyaline cartilage
2) Covered with mucus
a) Moistens and warms air
b) Cleans air of dust, pollen, bacteria
3. Vertebral column
a. General
1) Made of 26 irregular bones
2) Goes skull to pelvis
3) Protects spinal cord
4) Attachment for ribs and muscles of back and
neck
5) Infants have 33 bones
6) Get larger as you move inferiorly
7) Vertebrae separated by intervertebral discs
a) Shock absorbers
b) Account for 25% of height of vertebral column
c) Flatten during the day
8) Spinous process – bumps on back
b. Divisions
1) Cervical
a) 7 vertebrae of neck
b) C1-C7
c) Atlas (C1)
i. Supports and balances head
ii. Articulate with occipital condyles of skull
d) Axis (C2) – in ring of atlas
2) Thoracic
a) Upper back (12)
b) T1-T12
c) Hunchback – exaggerated curvature
3) Lumbar
a) Support lower back
b) Largest vertebrae – Why?
c) L1 – L5
4) Sacrum – 5 fused vertebrae
5) Coccyx
a) Tailbone
b) 4 fused vertebrae
c) Sometimes unusually long
4. Thoracic cage
a. Sternum
1) Middle of the chest
2) Made of 3 bones
a) Manubrium – top gives jugular notch
b) Body – middle bone
c) Xiphoid process – inferior bone
b. Ribs
1) 12 pairs
2) 1st 7 pairs – true ribs
3) Last 5 pairs – false ribs
4) Upper 3 false ribs connect to ribs above them
w/cartilage
5) Pairs 11 and 12 “float”
B. APPENDICULAR SKELETON
Clavicle and Scapulae
1.
a.
Allows a lot of flexibility
b.
Poorly reinforced – dislocates easily
c.
Clavicles
1)
Collarbone
2)
Connects w/scapula & manubrium
3) Very fragile and fractures easily
4) Breaks outward b/c of curve
5) Secures scapula and muscles of arm, chest, and
back
d. Scapula
1) Shoulder blades
2) Triangular flat bones
3) 15 muscles attach
4) 2 processes
a) Acromion
i. Articulates with clavicle
ii. Muscles of arm and chest attach
b) Coracoid – curves below clavicle
5) Glenoid fossa
a) Depression that articulates with humerus
b) Labrum
i. Ring of cartilage
ii. Secures shoulder more
2. Arm
a. Humerus
1) Biggest bone of arm
2) Connects to scapula, radius, ulna
3) Greater and lesser tubercle
b. Ulna
1) Longer than radius
2) Forms elbow joint
3) Closer to body when in anatomical position
HUMERUS
ULNA
c. Radius
1) Controls wrist movement
2) Larger by wrist than elbow
3) Rotates around ulna
3. Hand
a. Carpus (wrist)
1) 8 bones
2) 2 rows of 4
3) Articulates with radius
b. Metacarpus
1) Palm
2) Knuckles of fist
3) Numbered 1-5 starting with thumb
4) Pollex - thumb
c. Phalanges
1) Fingers
2) Numbered 1-5 starting w/thumb
3) Distal, middle, and proximal phalanx
4. Pelvic girdle (hip)
a. Ilium
1) Sides of the hip
2) Largest and uppermost portion
3) Hands on hip
b. Ischium
1) Rounded bottom part of hip
2) What we sit on
c. Pubis
1) Anterior portion
2) Join at the symphysis pubis
d. Structure and childbearing (females)
1) Wider
2) Shallower
3) Lighter
4) Rounder
Male
Female
5. Leg
a. Femur
1) Thigh
2) Longest, largest, strongest bone
3) Neck is weakest – if broken called a broken hip
b. Patella – knee
c. Tibia
1) Shin
2) Receives weight of body
3) 2nd largest bone
4) Medial side
d. Fibula
1) Gives bulge in ankle
2) Used for muscle attachment not weight
6. Foot
a. Calcaneus
1) Heal bone
2) Largest ankle bone
b. Metatarsus – number 1-5
c. Phalanges
1) Smaller than in fingers – less nimble
2) 3 in each except big toe
3) Hallux = big toe
BONES OF THE FOOT
C. DEVELOPMENT OF SKELETON
1. Skull bones are incomplete and fibrous
a.
Gives soft spot
b.
Allows head to compress during birth
c.
Allows for brain development
d.
8-9yrs. Head is almost adult proportions
2. Cleft palate – palate fails to fuse