Download the skeletal system - Dr. Brahmbhatt`s Class Handouts

THE SKELETAL SYSTEM
CH 6
PART 2 – THE AXIAL SKELETON
AXIAL SKELETON
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SKULL
HYOID BONE
VERTEBRAE
RIBS
STERNUM
SKULL
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sutures
2 major segments:
– Cranium & Facial bones
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PURPOSE: protects the brain and the
sensory organs
The ONLY mobile bone is the MANDIBLE
(lower jaw)
The location that the skull bones unite is
at the SUTURES or seams
*SINUSES are located within
the dense portion of the skull
and are air- filled cavities
* They lessen bone weight,
provide resonating
chambers for vocalization,
moisten/warm air, and are a
site of mucous secretion
* Sinuses are usually named
for the skull bone that
contains the sinus
SKULL
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The nostrils open into 2 major air passages that
end in the throat. The nasal passages are filled
with very fine scrolls of bone called
TURBINATES. The turbinates are covered in
pink tissue (mucosa) similar to the lining of
the mouth. Air is warmed, moistened, and
filtered as it passes through the turbinates
in the nose on the way to the lungs.
turbinates
SKULL
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CRANIAL BONES
– FRONTAL BONES (#6) – form the
forehead, the orbits, and the front portion
of the cranial floor.
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Horns are an extension of the frontal bone
– PARIETAL BONES (#7) – form the roof and
upper part of each side of the skull
– OCCIPITAL BONE (#8) – forms the back of
the skull
SKULL
– FORAMEN MAGNUM– opening at the base of
the occipital bone that allows the spinal
cord to pass from the skull to the spine
– TEMPORAL BONES (#9) – form part of the
cranial floor and the lower part of the
sides. Contains middle and inner ear
structures
SKULL
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FACIAL BONES
– MAXILLA (#3) – bones that form the upper
jaw, nose, orbits, and roof of the mouth
– MANDIBLE – forms the lower jaw. Only
movable bone in the skull
maxilla
mandible
SKULL
– HYOID APPARATUS – U shaped structure
made up of both bone and cartilage.
Located above the larynx, below the
mandible, and is suspended from the
temporal bones via ligaments. Suspends the
tongue, larynx, and floor of the mouth
VERTEBRAL COLUMN
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BACKBONE
PURPOSE: protects the spinal cord,
supports the skull and thorax,
stiffens the trunk, anchors the pelvis,
provides muscle attachment
There are 5 types of vertebrae: cervical
(C), thoracic (T), lumbar (L), sacral
(S), coccygeal (Cy)
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Each vertebrae has a body and
an arch.
– Body – bears the weight
– Arch – forms the canal that
houses the spinal cord
• Intervertebral discs are
between the bodies
-Made of
cartilage and
serve as
shock absorbers
• Processes extend out from
dorsal and lateral vertebral
surfaces
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FORMULAS
– DOG/CAT: C(7), T(13),
L(7), S(3), Cy(6-23)
– HORSE: C(7), T(18),
L(7), S(5), Cy(15-21)
– COW: C(7), T(13), L(6),
S(5), Cy(18-21)
– PIG: C(7), T(14-15), L(67), S(4), Cy(20-23)
– SHEEP: C(7), T(13), L(67), S(4), Cy(16-18)
CERVICAL
VERTEBRAE
– 1st vertebrae: ATLAS:
supports the skull
– 2nd vertebrae: AXIS:
what the atlas rotates on
THORACIC
VERTEBRAE
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Attach to ribs
THORACIC CAGE
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Composed of the thoracic
vertebrae, ribs, costal cartilages,
and sternum
Thoracic cage protects the vital
organs of the chest and allows the
lungs to expand and contract
during respiration
RIBS
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RIBS
– PURPOSE: form the thoracic wall and
protect the heart and lungs
– Flat, curved
– Each rib has bony and cartilagenous
components
The cartilagenous component is located
ventrally
 They unite at the costochondral junction
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RIBS
– All attach to the thoracic vertebrae
dorsally (the number of thoracic
vertebrae = the number of ribs)
– Differ in the attachment to the sternum
1st 7-9 join directly with the sternum “TRUE
RIBS”
 The caudal ribs unite with the cartilagenous
portion of the true ribs. They are called
“FALSE RIBS”
 The most caudal ribs due not unite with
anything ventrally and appear to be
“floating”, so they are called “FLOATING
RIBS”
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RIBS
STERNUM
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BREASTBONE
Located on ventral midline of chest
Flat bones called STERNEBRAE that
connect to each other via cartilage
Most cranial aspect is the
manubrium
Most caudal aspect is the xiphoid
process
LUMBAR VERTEBRAE
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Support the abdomen
SACRAL VERTEBRAE
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One bone that results from the fusion of 3-5
vertebrae
Attaches to pelvis
COCCYGEAL VERTEBRAE
– Also called caudal or tail vertebrae
– Can be docked- spinal cord ends near the
lumbosacral junction