Download Bony Thorax

The Skeletal System
I. Overview of the skeletal system
A. Regions of the skeleton
1. axial skeleton forms the central axis
a. skull, vertebral column, ribs, bony thorax
b. appendicular skeleton includes the limbs & girdles
B. Number of bones
1. 206 in typical adult skeleton, 80-axial, 126- appendicular
a. varies with development of sesamoid bones and wormian bones
2. start at 270 at birth, decreases with age as bones fuse
C. Bony Surface markings – see table
Axial & Appendicular Skeleton
• Axial skeleton in
yellow
– skull, vertebral
column, sternum,
ribs, hyoid &
auditory ossicles
• Appendicular
skeleton in blue
–
–
–
–
pectoral girdle
upper extremity
pelvic girdle
lower extremity
Structural plan- Axial Skeleton
Skull- 28
cranial bones-8
facial bones-14
auditory ossicles- 6
Hyoid bone- 1
Vertebral column- 26
cervical vertebrae- 7
thoracic vertebrae- 12
lumbar vertebrae- 5
sacrum- 1
coccyx- 1
Bony Thorax- 25
sternum- 1
ribs- 24
Structural Plan- appendicular skeleton
• Pectoral girdle- 4
Clavicle- 2
Scapula -2
• Upper extremities- 60
humerus- 2
radius- 2
ulna- 2
carpals- 16
metacarpals-10
phalanges- 28
• Pelvic girdle- 2
Os coxae- 2
• Lower extremities-60
femur- 2
tibia- 2
fibula- 2
patella- 2
tarsals- 14
metatarsals- 10
phalanges- 28
II. The Skull
A. 22 bones joined together by sutures
B. Cranial bones surround cranial cavity
1. 8 bones in contact with meninges
a. Frontal(1), parietal(2), temporal (2), occipital (1),
sphenoid(1), ethmoid(1)
C. Facial bones support teeth & form nasal cavity,
eye orbits, and facial features
1. 14 bones form attachment of facial & jaw muscles
a. Nasal(2), maxilla(2), zygomatic(2), mandible(1),
lacrimal(2), palatine(2), inferior nasal conchae(2), vomer(1)
Frontal Bone
• Forms forehead and part
of the roof of the cranium
• Forms roof of the orbit
• Contains frontal sinus
Parietal Bone
• Forms cranial roof and
part of its lateral walls
• Bordered by 4 sutures
– coronal, sagittal, lambdoid
and squamous
Temporal lines
• Marked by temporal lines
of temporalis muscle
Temporal Bone
• Form the inferolateral
aspects of the skull and
parts of the cranial floor
– Several processes: mastoid
process, styloid process,
zygomatic process,
– External auditory meatus
Occipital Bone
• Rear & much of base of skull
• Foramen magnum holds spinal
cord
• Skull rests on atlas at occipital
condyles
Sphenoid Bone
• Irregular butterfly (bat
wing) bone
• Called the keystone of the
cranium because it the
cornerstone for all cranial
bones
Sphenoid Bone
Ethmoid Bone
• Between the orbital cavities
• Forms lateral walls and roof of nasal
cavity
• Perpendicular plate forms part of
nasal septum
• Contain superior and middle conchae
on lateral wall( nasal cavity air flow)
Maxillary Bones
• Forms upper jaw
• Forms inferomedial wall of orbit
• Forms anterior 2/3’s
of hard palate
– cleft palate (disorder)
Palatine Bones
• L-shaped bone
• Posterior 1/3 of the hard
palate
• Part of lateral nasal wall
• Part of the orbital floor
Zygomatic Bones
• Forms angles of the
cheekbones and part of
lateral orbital wall
• Zygomatic arch is formed
from zygomatic bone and
zygomatic process of
temporal bone
Lacrimal Bones
• Form part of medial wall
of each orbit
• Lacrimal fossa houses
lacrimal sac in life
– tears collect in lacrimal
sac and drain into nasal
cavity
Nasal Bones
• Forms bridge of nose and
supports cartilages of
nose
• Often fractured by blow
to the nose
Inferior Nasal Conchae
• A separate bone
• Not part of ethmoid like
the superior & middle
concha
Vomer
• Inferior half of the nasal
septum
• Supports cartilage of
nasal septum
Mandible
• Only bone of the skull that can move
• Holds the lower teeth
• Attachment of muscles of mastication
– temporalis muscle masseter muscle
• Mandibular foramen
• Mental foramen
D. Bones Associated With the Skull
1. Auditory ossicles
– Malleus (hammer)
– Incus (anvil)
– Stapes (stirrups)
2. Hyoid bone
– suspended from styloid
process of skull by
stylohyoid muscle and
ligament
The Skull in Infancy & Childhood
• Spaces between unfused skull
bones called fontanels
– filled with fibrous membrane
– allow shifting of bones during
birth & growth of brain in
infancy
– fuse by 2 years of age
III. Features of the Vertebral Column
A. 26 fused or 33 vertebrae &
discs of fibrocartilage
between them
B. Five vertebral groups
–
–
–
–
–
7 cervical in the neck
12 thoracic in the chest
5 lumbar in lower back
5 sacral fused into the sacrum
3-5 coccygeal fused into
coccyx
Newborn Spinal Curvature
• Spine exhibits one
continuous C-shaped
curve
• Known as primary
curvature
C. Adult Spinal Curvatures
1. S-shaped vertebral column
with 4 curvatures
2. Secondary curvatures
develop after birth
– lifting head as it begins to
crawl develops cervical
curvature
– walking upright develops
lumbar curvature
D. Abnormal Spinal Curvatures
• Result from disease,
posture, paralysis or
congenital defect
1. Scoliosis from lack of
proper development
of one vertebrae
2. Kyphosis is from
osteoporosis
3. Lordosis is from
weak abdominal
muscles
General Structure of a Vertebra
• Body
• Series of vertebral foramen
form the vertebral canal
• Processes
– spinous
– transverse
– articular (superior & inferior)
E. Intervertebral Foramen & Discs
1. Intervertebral foramen
– formed from vertebral
notches of adjacent vertebrae
– passageway for spinal nerves
2. Intervertebral discs
– bind vertebrae together
– absorb shock
– herniated disc puts pressure
on spinal nerve or spinal cord
– Made of fibrocartilage
– Type of cartilaginous joint
Typical Cervical Vertebrae
• Smaller body and larger vertebral foramen
• Transverse process short with transverse foramen for
protection of vertebral arteries
The Unique Atlas and Axis
• Atlas (C1) supports the skull
– concave superior articular facet
• nod your head in “yes” movement
– ring surrounding large vertebral
foramen
• anterior & posterior arch
• Axis (C2)
– dens or odontoid process is held in
place inside the vertebral foramen of
the atlas by ligaments
– allows rotation of head -- “no”
Atlas & Axis Articulation
Typical Thoracic Vertebrae
• More massive body than cervical but smaller lumbar
• Spinous processes pointed and angled downward
Lumbar Vertebrae
• Thick, stout body and blunt, squarish spinous process
Sacrum (Anterior View)
• 5 separate sacral
vertebrae fuse by age 26
Coccyx
• Single, small, triangular bone
– 4 small vertebrae fused by age of 30
• Provides attachment site for
muscles of pelvic floor
IV. Bony Thorax
A. Consists of thoracic
vertebrae, sternum & ribs
B. Attachment site for
pectoral girdle and many
limb muscles
C. Protects many organs
D. Rhythmically expanded
by respiratory muscles to
draw air into the lungs
E. Rib Structure
Tubercle
Head
• Flat blade called a shaft
– inferior margin has costal groove for
nerves & vessels
• Proximal head & tubercle are
connected by neck
• Articulation
– head with body of vertebrae
– tubercle with transverse process
True and False Ribs
• True ribs (1 to 7) attach
to sternum with hyaline
cartilage
• False ribs (8-12)
– 11-12 are floating and not
attached to sternum
Sternum
Manubrium
Sternal body
Xiphoid process
Pectoral Girdle
• Attaches upper extremity to the body
• Scapula and clavicle- 4 bones total
• Clavicle attaches medially to the sternum and
laterally to the scapula
• Scapula articulates with the humerus
- forms shoulder joint
easily dislocated because of its loose attachment
Clavicle
• S-shaped bone,
• Collarbone
• Most common fracture
Scapula
•
•
•
•
Triangular plate that dorsally overlies ribs 2 to 7
Spine ends as acromion process
Coracoid process for muscle attachment
Glenoid cavity is shallow socket for head of humerus
Upper Limb
• 30 bones per limb
• Brachium or arm contains the humerus
• Antebrachium or forearm contains the radius &
ulna (radius on thumb side)
• Carpus or wrist contains 8 small bones arranged
in two rows
• Manual region or hand contains 19 bones in 2
groups
– 5 metacarpals in the palm
– 14 phalanges in the fingers
Humerus
•
•
•
•
•
•
Head forms shoulder joint above
anatomical neck
Muscles attach to greater & lesser
tubercles and deltoid tuberosity
Rounded capitulum articulates with
radius
Pulleylike trochlea articulates with
ulna
Olecranon fossa holds olecranon
process of ulna in straightened arm
Forearm muscles attach to medial &
lateral epicondyles
Ulna and Radius
• Radius
– head is disc that rotates freely
during pronation & supination
– radial tuberosity for biceps muscle
• Ulna
– olecranon and trochlear notch form
proximal end
– radial notch holds head of ulna
• Interosseous membrane
– ligament attaches radius to ulna
Carpal Bones
• Form the wrist
– allows flexion, extension,
abduction & adduction
• 2 rows of 4 bones each
– proximal row
– distal row
Scaphoid, lunate, triquetral, pisiform
Trapezium, trapezoid, capitate, hamate
Sally left the party to take Cathy home
So Long Top Part,
Here Comes The Thumb. (clockwise)
Metacarpals and Phalanges
• Phalanges are bones of
the fingers
– thumb or pollex has
proximal & distal phalanx
– fingers have proximal,
middle & distal phalanx
• Metacarpals are bones of
the palm
Pelvic Girdle
• Composed of 2 bones:
right & left os coxae
• Supports trunk on the legs
& protects viscera
• Each os coxae is joined to
the vertebral column at the
sacroiliac joint
• Anteriorly, pubic bones are joined by pad of fibrocartilage
to form pubic symphysis
Os Coxae (Hip Bone)
• Acetabulum is hip joint socket
• Ilium is superior portion
• Pubis is anterior portion
• Ischium is posterolateral portion
– ischial tuberosity bears body weight if
sitting “sit down bone”
Comparison of Male & Female
• Female less massive, pubic arch greater than 100
degrees, and pubic inlet round or oval
• Male heavier, upper pelvis nearly vertical, coccyx more
vertical, and pelvic inlet heart-shaped
Femur
• Nearly spherical head &
constricted neck
• Greater & lesser trochanters
for muscle attachment
• Posterior ridge called linea
aspera
• Medial & lateral condyles
and epicondyles found
distally
• Largest bone in the body
Patella and Tibia
• Patella is triangular sesamoid
bone
• Tibia is thick, strong weightbearing bone on medial side of
leg
– roughened anterior surface can be
palpated below the patella
(tibial tuberosity)
– distal expansion is medial
malleolus
Fibula
• Slender lateral stick-like
that helps stabilize the
ankle
• Does not bear any of the
body’s weight
– use as spare bone tissue to
replace bone elsewhere
• Head is proximal end
• Lateral malleolus is distal
expansion
The Ankle and Foot
• Tarsal bones are shaped & arranged
differently from carpal bones due to
load-bearing role of the ankle- 7 in
each foot
• Talus is most superior tarsal bone
– forms ankle joint with tibia & fibula
• Calcaneus forms heel (Achilles tendon)
Cuboid, navicular, 3 cuneiform bones
The Foot
• Remaining bones of foot are similar
in name & arrangement to the hand
• Metatarsals- 5 in each foot
• Phalanges
– 2 in great toe
• proximal and distal
– 3 in all other toes
• proximal, middle & distal