principles of human anatomy and physiology, 11e1 chapter 7 the skeletal system: the axial skeleton...

Principles of Human Anatomy and Physiology, 11e 1

Chapter 7

The Skeletal System: The Axial Skeleton

Lecture Outline

The Axial Skeleton• The bones, muscles, and joints together form

an integrated system called the musculoskeletal system.

• Orthopedics is the branch of medicine concerned with the prevention or correction of the disorders of the musculoskeletal system.


Your Bones• Your body has 206 bones.

• 80 of them are part of the axial skeleton (Ch 7), 126 are part of the apendicular (Ch 8).



Chapter 7The Skeletal System:The Axial Skeleton

• Axial Skeleton– lie along vertical axis of

the body– Includes: skull, ear

bones, hyoid, ribs, sternum, vertebrae.


INTRODUCTION• 2 Functions of the Axial Skeleton:

– 1. The bones of the axial skeleton protect the body’s organs (brain, spinal cord, heart, lungs).

– 2. They also function in calcium storage and release.

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Types of Bones• 6 basic types of bones:

– long = long and strong (legs/arms)

– short = spongy, cube shaped (wrist/ankle)

– flat = plates of compact enclosing spongy, thin (ribs)

– irregular = variable (vertebrae)– sesamoid = develop in

tendons or ligaments (kneecaps)

– Sutural bones = in joints between skull bones


BONE SURFACE MARKINGS• There are two major types of surface markings.

– Depressions and openings allow the passage of soft tissue (nerves, veins) through bones

– Processes are projections or outgrowths that either help form joints or serve as attachment points for connective tissue.

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SKULL• The skull, composed of 22 bones, consists of the

cranial bones (cranium) and the facial bones (nose, jaw, etc)

• The skull forms the large cranial cavity and smaller cavities, including the nasal cavity and orbits (eye sockets).

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The Skull

• 8 Cranial bones– protect brain & house ear bones– muscle attachment for jaw, neck & facial muscles

• 14 Facial bones– protect delicate sense organs -- smell, taste, vision– support entrances to digestive and respiratory systems

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The 8 Cranial Bones– Frontal Bone: forms the forehead and the eye sockets– Parietal Bone: form the sides and the roof of the skull– 2 Temporal Bones: On the sides of the head behind and

above the ears– Occipital Bone: bottom and back of the skull– 2 Sphenoid Bone: middle sides, between the temporal

and frontal bones– Ethmoid Bone: Between the eye sockets and the nose

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14 Facial Bones

Nasal (2) Maxillae (2) Zygomatic (2)Mandible (1) Lacrimal (2) Palatine (2)

Inferior nasal conchae (2) Vomer (1)

14 Facial Bones• Nasal (2): form the nose• Maxillae (2): form the upper jawbone• Zygomatic (2): cheek bones• Lacrimal (2): tiny bones behind the eyes that hold the

tear ducts• Palatine (2): L shaped, top of the mouth, bottom of the

eyes• Inferior nasal conchae (2): project into the nasal cavity

and funnel air• Vomer: triangular bone that forms the bottom of the nose• Mandible: lower jawbone, largest, strongest

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Let’s Draw the Skull!• On a piece of poster paper, make 2 drawings of the

skull: one anterior and one medial.

• See pages 199-202 in the red book.

• You must clearly label each of the cranial and facial bones.

• These are due on Friday Nov. 2, 2012.

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Nasal Septum

• Divides nasal cavity into left and right sides

• Deviated septum does not line in the midline

– developmental abnormality or trauma


The orbits (eye sockets)

• The orbits contain the eyeballs and associated structures and are formed by seven bones of the skull.

Foramina• Foramina are openings in the skull for blood vessels,

nerves or ligaments.


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3 Unique Features of the Skull• 1. Sutures are immovable joints found only between

skull bones and hold skull bones together.

• 2. Paranasal sinuses are cavities in bones of the skull that communicate with the nasal cavity, they control how our voice sounds.

• 3. Fontanels are membrane-filled spaces between the cranial bones of fetuses and infants. They enable the fetus to pass through the birth canal, and for an infants brain to rapidly grow.

•

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HYOID BONE• The hyoid bone is a unique component of the axial

skeleton because it does not articulate (connect) with any other bones.

• It supports the tongue

• It gets crushed during strangulation


VERTEBRAL COLUMN

• The vertebral column, along with the sternum and ribs, makes up the trunk of the skeleton.

• The vertebral column has 26 bones.


Typical Vertebrae

• An adult has 25 vertebrae.

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Intervertebral Discs

• Between adjacent vertebrae absorbs vertical shock• Permit various movements of the vertebral column

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Normal Curves of the Vertebral Column

• There are 4 curves in the adult spine


Vertebral Column

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The parts of the Vertebral Column: Cervical Region

• There are 7 cervical vertebrae.

• They are located in the neck area.

• They are the smallest vertebrae.


Part 2: Thoracic Region

• There are 12 thoracic vertebrae.

• These vertebrae connect with the ribs.

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Part 3: Lumbar Region• There are 5 lumbar vertebrae.

• They are the largest and strongest vertebrae in the column.

Part 4: Sacrum• The sacrum is a single triangular bone

• It serves as a foundation for the pelvis.

• In females, it is shorter, wider, and more curved.


Part 5: Coccyx• The coccyx is also a single,

triangular shaped bone.

• It is also called the tailbone.

• In females, it points downward and is more moveable to provide room for the birth of babies.

• In males, it points inward and doesn’t move.

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THORAX• The term thorax refers

to the entire chest.

• The thoracic cage is made of the sternum (breastbone), ribs, and the thoracic vertebrae.

• It protects the heart and lungs.


Sternum• The sternum is the breastbone.

• It is a flat, narrow bone (6 inches) located in the center of the thoracic cavity.


Ribs• The 12 pairs of ribs give structural support to the sides of

the thoracic cavity.– The first 7 pairs of ribs are called true ribs and attach

directly to the sternum– The next 5 pairs are called false ribs because they attach

indirectly to the sternum– The last 2 ribs are called floating ribs because they do

not attach to the sternum.– Rib fractures are the most common types of chest

injuries.– Men and women have EXACTLY the same number of

ribs.

Ribs


Diseases and Disorders• Herniated (Slipped) Disc: Intervertebral discs move out

of place causing pain. Treated by bed rest and medication.

• Scoliosis: the thoracic region of the spine bends to the side

• Kyphosis: the thoracic curve is more pronounced (hump back)

• Lordosis: also called hollow back, the vertebrae bend inward

• Spina bifida: a cystlike fluid filled sac forms at the bottom of the spine, pregnant mom doesn’t get enough folic acid or vitamin B

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Diseases and Disorders• Rib fracture: blows to the chest break or crack ribs

• Sinusitis: inflammation of the nasal cavity due to allergies or infection

• Deviated nasal septum: septum does not connect to the midline of the nose, corrected surgically

• Temporomandibular joint syndrome (TMJ): popping noise when the mouth opens/closes, caused by teeth grinding

• Cleft palate: incomplete fusion of the bones between the nose and the mouth, causing a split upper lip

• Black eye: a blow to the ridge below the eye resulting in bleeding

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