skeletal system part 2 the axial skeleton honors anatomy & physiology

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SKELETAL SYSTEM PART 2 THE AXIAL SKELETON Honors Anatomy & Physiology

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SKELETAL SYSTEMPART 2THE AXIAL SKELETON

Honors Anatomy & Physiology

Essential Question

What is the main contribution the axial skeleton makes to homeostasis?

Divisions of the Skeleton

AXIAL SKELETON

Skull Cranium Face

Hyoid Auditory

Ossicles Vertebral

Column Thorax

APPENDICULAR SKELETON:

Pectoral Girdle Upper Limbs Pelvic Girdle Lower Limbs

Types of Bone

bones fall into 1 of 5 main types based on shape: Long Short Flat Irregular Sesamoid

Long Bones

longer than they are wide may be slightly curved (to absorb

stress of weight at more points along the bone i.e. straight bones would fracture more easily)

consist of: shaft & variable #s of ends compact bone in diaphysis and spongy

bone in epiphysis

Long Bones

Short Bones

somewhat cube-shaped nearly equal in length as width consist of:

spongy bone except @ surface

Short Bones

Flat Bones

Composed of: 2 nearly parallel plates of compact

bone enclosing spongy bone inside Function:

give considerable protection place for muscle attachment

Flat Bones

Irregular Bones

complex shapes (do not fit in other categories)

vary in amt spongy bone

Sesamoid Bones

develop w/in certain tendons where there is considerable friction, tension, & physical stress

function: protect tendon from excessive wear & tear

vary in # person to person but everyone has 2 patella which develop in quadriceps femoris tendon

Sesamoid Bone

Sutural Bones

classified by location (w/in a suture: a seam between 2 cranial bones)

not everyone has them

Bone Surface Markings

2 major types:1. depressions & openings

form joints or allow passage of vessels & nerves

2. processes projections or outgrowths that either

help form joints or serve as attachment points for ligaments & tendons

Bone Surface Markings

Bone Surface Markings-2

Axial skeleton

SKULL

Skull

22 bones in 2 categories:1. Cranium

8 bones that form cranial cavity

1. 1 frontal bone2. 2 parietal bones3. 2 temporal bones4. 1 occipital bone5. 1 sphenoid bone6. 1 ethmoid bone

Skull

2. Facial Bones14 bones that form the face

2 nasal bones 2 maxillae 1 mandible 2 zygomatic 2 lacrimal 2 palantine 2 inferior nasal conchae 1 vomer

Skull: Cavities

1. Cranial Cavity2. Nasal Cavity3. Orbits4. Paranasal Sinuses5. Middle & Inner Ear Cavities

Cavities of the Skull

Movable Joints of the Skull1. Mandible2. Auditory Ossicles

Functions of Cranial Bones1. protecting brain2. stabilizing position of brain,

vessels, & nerves through attachments to the meninges

3. outer surfaces provide large areas of attachment for muscles that move parts of the head & some for facial expression

Cranial Bones: Frontal Bone forms:

forehead upper part of eye socket most of anterior part of cranial floor in newborns: rt & lt which fuse

shortly after birth

Frontal Bone

Parietal Bones

form greater portion of sides & roof of cranial cavity

Temporal Bones

form inferior, lateral aspects of the cranium & part of the cranial floor

its zygomatic process forms the lateral half of the zygomatic arch

mandibular fossa: where condylar process of mandible forms TMJ (temporal mandibular joint)

Temporal Bones

Temporal Bones

external auditory meatus: ear canal mastoid: posterior & inferior to

external auditory meatus, contains “air cells” (mastoiditis: inflammation in air cells)

Temporal Bone: Internal Surface

Occipital Bone

forms back of head & most of base of skull

foramen magnum: large hole spinal cord passes thru,

occipital condyles: articulate with 1st cervical vertebra (atlas)

Ethmoid Bone

“like a sieve” midline of anterior part of cranial

floor, anterior to sphenoid, posterior to nasal bones

cribiforme plate: forms roof of nasal cavity, the holes of the sieve where olfactory nerves pass from roof of nasal cavity to brain

crista galla: triangular process which serves as pt of attachment for meninges of brain

Ethmoid Bone

perpendicular plate: forms superior portion of nasal cavity

superior & middle nasal conchae: (or turbinate) increase vascular & mucous membrane surface area in nasal cavities: aids in sense of smell, warms, filters & moistens air being inhaled. Filters because the turbinates cause air to swirl as a result inhaled particles strike & become trapped in mucus

Maxillae

= upper jaws *articulate with every bone in face

except the mandible form part of floor of orbits, parts of

nasal cavity, & most of the hard palate (bony roof of mouth)

each one has large maxillary sinus alveolar process is small arch that

contains the alveolar sockets for upper set of teeth

Cleft Palate & Cleft Lip

10-12 wks gestation the palatine processes of maxillae typically join

not doing so cleft palate +/- cleft lip speech & swallowing can be affected many ear infections reparative surgery recommended 1st

few wks of life / surgery needs to be completed by 12 – 18 mos b/4 speech: speech therapy & orthodontic care frequently necessary

Intervertebral Discs

Parts of a Vertebra

Body thicker, anterior portion, weight bearing

portion Vertebral Foramina

contains spinal cord, adipose, areolar CT, blood vessels

Spinous Process 1 of 7 processes, posterior, palpable on

back of body

Transverse Processes: on each side, extending laterally

Typical Thoracic Vertebrae T-1 to T-12 larger &

stronger than cervical v.

distinguishing feature: articulate with ribs (facets on transverse processes of T-1 to T-10

Ribs: 12 Pair

increase in length 1st thru 7th then decrease in length to 12th

1st thru 7th ribs (true ribs) have direct anterior attachment to sternum by strip of hyaline cartilage which contribute to elasticity of thoracic cage

8th thru 10th ribs attach to each other & then to cartilages of 7th rib

11th & 12th ribs: floating ribs

Kyphoscoliosis

THAT’S ALL FOLKS