Download The Axial Skeleton – Vertebral column

Ch 7 – The Skeleton
Part A: The Axial Skeleton
Section 1 – Axial Skeleton Overview (pp. 198-200)
The Axial Skeleton
• Consists of 80 bones
• Divided into 3 main parts:
1) Skull
2) Vertebral column
3) Bony Thorax
• Functions of Axial Skeleton:
1) Forms longitudinal axis
2) Supports head, neck, & trunk
3) Protects brain, spinal cord, heart, & lungs
Ch 7 – The Skeleton
Part A: The Axial Skeleton
Section 2 – The Skull (pp. 200-216)
The Axial Skeleton – Skull
Skull
- Two sets of bones
1) Cranial bones (Cranium)
- enclose & protect brain
- provide attachment sites for head/neck muscles
2) Facial bones
- provide framework for the face
- contain cavities for sight, taste, & smell sense organs
- provide attachments sites for facial expression muscles
The Axial Skeleton – Skull
Skull
- Most are flat bones & are joined together by sutures
- Mandible only bone attached w/ freely movable joint
- Many bones have air-filled sinuses to reduce weight
- About 85 openings providing passageways for major
blood vessels & nerves
Cranial Bones
There are 8 cranial bones:
Frontal bone
Parietal bone (left & right)
Occipital bone
Temporal bone (left & right)
Sphenoid bone
Ethmoid bone
Cranial Bones – Frontal bone
Frontal Bone
• Most anterior portion of cranium…
forehead
• Contains frontal sinus
• Forms superior wall of orbits
• Supports frontal lobes of brain
Cranial Bones – Parietal bones
Parietal Bone (x2)
• Most superior (top) & lateral
(side) parts of cranial cavity
• Bulk of cranial cavity
Cranial Bones – Occipital bone
Occipital Bone
• Forms posterior wall of cranium
• Attachment site for many neck/back
muscles
• Occipital condyles
- form joint w/ vertebral column
• Foramen magnum
- large opening for spinal cord to
attach to brain
Cranial Bones – Temporal bone
Temporal Bone (x2)
• Inferior to parietal bones
• Forms lower sides of cranium &
part of cranial floor
• External acoustic meatus
- surrounds external ear canal
• Mandibular fossa
- forms the temporomandibular joint
w/ mandible
• Zygomatic process
- part of cheek bone nearest your ear
Cranial Bones – Major Sutures
Four sutures form major joints of the cranium:
1) Coronal suture
- between parietal & frontal bones
2) Squamous suture
- between parietal & temporal bones
3) Lamboid suture
- between parietal & occipital bones
4) Sagittal suture
- between left & right parietal bones
Cranial Bones – Sphenoid bone
Sphenoid Bone
• Complex, bat-shaped bone
• “Keystone” of the cranium
- forms joints w/ all other
cranial bones
• Sella turcica
- small enclosure for pituitary
gland
Cranial Bones – Ethmoid bone
Ethmoid Bone
• Deepest skull bone
• Superior part of nasal septum
• Cribiform plates
- roof of nasal cavities
• Crista galli
- between cribiform plates attaches to
covering of brain to help secure it to
cranial cavity
Cranial Bones
Frontal Bone
Left & Right Parietal Bones
Occipital Bone
Left & Right Temporal Bones
Sphenoid Bone
Ethmoid Bone
Facial Bones
There are 14 facial bones:
Mandible
Maxillary bones (x2)
Zygomatic bones (x2)
Nasal bones (x2)
Lacrimal bones (x2)
Palatine bones (x2)
Vomer
Inferior nasal conchae (x2)
Facial Bones – Mandible
Mandible
• Lower jaw
• Largest, strongest facial bone
• Temporomandibular joint
- only freely movable joint in skull
• Alveolar margin
- contains sockets for teeth
Facial Bones – Maxillary Bones
Maxillary Bones
• Two bones fused medially
• Form upper jaw & central portion
of face
• “Keystone” of face
- form joints w/ all other facial bones
Facial Bones – Zygomatic Bones
Zygomatic Bones
• Cheekbones
• Form lateral borders of orbits
Facial Bones – Nasal Bones
Nasal Bones
• Form bridge of nose
Facial Bones – Lacrimal Bones
Lacrimal Bones
• Form medial walls of orbits
• Houses lacrimal sac
- part of passageway that allows tears
to drain into nasal cavity
Facial Bones – Palatine Bones
Palatine Bones
• Form back 1/3 of roof of mouth…
hard palate
• Form back walls of nasal cavity
Facial Bones – Vomer
Vomer
• Plow-shaped
• Lower part of nasal septum
Facial Bones – Inferior nasal conchae
Inferior nasal conchae
• Form lateral walls of nasal cavity
• Force inhaled air to swirl so that it can pick up moisture
before traveling to lungs
Hyoid Bone
• Not a bone of the skull
• Only bone that does not articulate w/
another bone
• Attachment site for muscles of swallowing
& speech
• Acts as a moveable base for tongue
Paranasal Sinuses
• Found in frontal, sphenoid,
ethmoid, & maxillary bones
• Mucosa-lined, air-filled spaces
• Enhance resonance of voice
• Lighten the skull
Ch 7 – The Skeleton
Part A: The Axial Skeleton
Section 3 – The Vertebral Column (pp. 216-223)
The Axial Skeleton – Vertebral column
Vertebral column
- Transmits weight of trunk to lower limbs
- Surrounds & protects spinal cord
- Provides attachment points for ribs &
muscles of back/neck
- Flexible due to its curved construction
The Axial Skeleton – Vertebral column
Vertebral column
- Composed of 26 irregular bones &
divided into 5 segments
1) Cervical vertebrae (7)
- vertebrae of the neck
2) Thoracic vertebrae (12)
- vertebrae of thoracic cage
3) Lumbar vertebrae (5)
- vertebrae of lower back
4) Sacrum
5) Coccyx
The Axial Skeleton – Vertebral column
Natural Curvatures
- Increase flexibility of spine
- Function like spring instead of rod
- When viewed from side, S-shaped
- Two posteriorly concave curvatures
1) Cervical curvature
2) Lumbar curvature
- Two posteriorly convex curvatures
1) Thoracic curvature
2) Pelvic curvature
The Axial Skeleton – Vertebral column
The Axial Skeleton – Vertebral column
Scoliosis (abnormal lateral curvature)
The Axial Skeleton – Vertebral column
Kyphosis (“Hunchback”)
The Axial Skeleton – Vertebral column
Lordosis (“Swayback”)
The Axial Skeleton – Vertebral column
Ligaments
- Give added strength, support to spine
1) Anterior & posterior longitudinal ligaments
- run entire length of spine
*Anterior = front side; prevents bending too far backward
*Posterior = back side; prevents bending too far forward
2) Ligamentum flavum
- Connects 2 adjacent vertebrae
3) Short ligaments
- Connects each vertebrae to the one above & below it
The Axial Skeleton – Vertebral column
Intervertebral Discs
- cushion-like pads between vertebrae
- shock absorbers during walking, jumping, & running
- thickest in lumbar/cervical regions; enhances flexibility
- flatten during course of day; always a few millimeters
shorter at night
The Axial Skeleton – Vertebral column
Herniated Disc
- “slipped disc”
- rupture of the disc caused by compression of vertebrae
- disc “squeezes” out from between vertebrae
- if pressing on spinal cord, causes numbness or pain
- usually treated w/ exercise, massage, heat, painkillers
- may have to be surgically removed; vertebrae fused
The Axial Skeleton – Vertebral column
General Structure of Vertebrae
1) Body or centrum
- anterior; weight-bearing region
2) Vertebral foramen
Animation: Rotatable Spine (horizontal)
- opening for spinal cord
3) Intervertebral foramina
- openings between vertebrae for spinal nerves to leave
spinal cord
Animation: Rotatable Spine (vertical)
4) Spinous process
- project out the posterior side; protection
The Axial Skeleton – Vertebral column
Cervical Vertebrae (C1-C7)
- smallest, lightest vertebrae
- found in the neck
C1 vertebra = Atlas
- articulates with base of the skull
- allows you to nod “yes”
C2 vertebra = Axis
- knoblike “dens” projects up
- Atlas pivots around “dens”
- allows you to shake head “no”
The Axial Skeleton – Vertebral column
Thoracic Vertebrae (T1-T12)
- All form joints with ribs
- All have long, downwardpointing spinous processes
The Axial Skeleton – Vertebral column
Lumbar Vertebrae (L1-L5)
- “small of the back”
- receives most stress
- each has large centrum to
handle extra stress
The Axial Skeleton – Vertebral column
Sacrum
- shapes posterior wall
of pelvis
- lateral borders form
joints with hips
Coccyx
- tailbone
- nearly useless
Ch 7 – The Skeleton
Part A: The Axial Skeleton
Section 4 – The Thoracic Cage (pp. 223-225)
The Axial Skeleton – Thoracic cage
Thoracic cage
- aka “Bony thorax”
- Made up of 3 parts:
1) Sternum
2) Ribs & costal cartilage
3) Thoracic vertebrae
The Axial Skeleton – Thoracic cage
Thoracic cage
- Forms cage to protect
major organs of chest
- Supports pectoral girdle
& upper limbs
- Provides multiple muscle
attachment sites
The Axial Skeleton – Sternum
Sternum
- “breastbone”
- Composed of 3 fused bones:
1) Manubrium
- articulates w/ clavicles & ribs 1-2
2) Body
- articulates w/ ribs 2-7
3) Xiphoid process
- site of muscle attachment
- cartilage until age 40
The Axial Skeleton – Ribs
Ribs
- 12 pairs
- True ribs
* Top 7 ribs
* Attach directly to sternum
via costal cartilage
- False ribs
* Ribs 8-10
* Attach indirectly to sternum
- Floating ribs
* Ribs 11-12
* No attachment to sternum
Ch 7 – The Skeleton
Part B: The Appendicular Skeleton
Section 5 – Appendicular Skeleton Overview (p. 225)
The Appendicular Skeleton
• Everything attached to the axial skeleton
- Limbs (arms/legs)
- Pectoral girdle
- Pelvic girdle
• Enables us to carry out all body movements
Ch 7 – The Skeleton
Part B: The Appendicular Skeleton
Section 6 – The Pectoral Girdle (pp. 225-228)
The Appendicular Skeleton
Pectoral (shoulder) girdle
- Composed of two bones
1) Clavicle
2) Scapula
- Attaches arms to axial skeleton
- Provides arm w/ exceptionally
free movement
A&P Flix™: Bones of the pectoral girdle
Pectoral Girdle – Clavicle
Clavicle
- known as the “collarbone”
- acts as a brace; holds scapula & arm out laterally
- transmits compression forces of upper limb to axial skeleton
- usually fracture anteriorly; posterior fractures very
dangerous b/c of major blood vessels just behind clavicle
Pectoral Girdle – Scapula
Scapula
- known as the “shoulder blade”
- attaches to spine by way of muscles; exceptional movement
Glenoid cavity
- articulates with humerus of arm, forming shoulder joint
Acromion process
- articulates with clavicle
Ch 7 – The Skeleton
Part B: The Appendicular Skeleton
Section 7 – The Upper Limb (pp. 228-233)
The Upper Limb
Upper Limb
- 30 bones in each upper limb
3 main components
1) Arm
- Humerus
2) Forearm
- Radius & ulna
3) Hand
- 8 carpal (wrist) bones
- 5 metacarpal (palm) bones
- 14 phalanges (finger bones)
The Upper Limb – Arm
Humerus
- only bone of the arm
- largest bone of upper limb
- proximal end articulates w/
glenoid cavity of scapula
Greater & lesser tubercles
- attachment sites for rotator cuff
Trochlea
- articulates w/ ulna
Capitulum
- articulates w/ radius
The Upper Limb – Forearm
Ulna
- medial bone in forearm
- main function is forming elbow
joint w/ humerus
Radius
- lateral bone in forearm
- main function is forming wrist joint
w/ carpal bones
*Interosseous membrane
- flat, flexible ligament running
entire length between both bones
The Upper Limb – Hand
Carpals
- form “wrist”
- 8 total bones laid out in 2 rows
Proximal row (from lateral to medial)
- scaphoid, lunate, triquetrum,
& pisiform
Distal row (from lateral to medial)
- trapezium, trapezoid, capitate,
& hamate
*Only the scaphoid & lunate articulate
w/ the radius to form the wrist joint
The Upper Limb – Hand
Metacarpals
- form “palm”
- 5 total bones
- #1-5 starting w/ thumb
Phalanges
- finger #1 (thumb) = 2 phalanges
(distal & proximal)
- fingers #2-5 = 3 phalanges
(distal, middle, & proximal)
Ch 7 – The Skeleton
Part B: The Appendicular Skeleton
Section 8 – The Pelvic Girdle (pp. 233-237)
The Appendicular Skeleton – Pelvis
Pelvic girdle
- Attaches lower limbs to axial skeleton using some of the
strongest ligaments in the body
- Lacks mobility of pectoral girdle but far more stable
- Supports total weight
of upper body
- Protects pelvic organs:
1) Reproductive organs
2) Urinary bladder
3) Part of large intestine
The Appendicular Skeleton – Pelvis
Pelvic girdle
- formed by a pair of hip bones
- each hip bone is made of 3 fused bones:
1) Ilium
2) Ischium
3) Pubis
“Bony pelvis”
- the 2 hip bones plus the sacrum & coccyx
Acetabulum = deep socket that receives the head of the femur
Animation: Rotatable pelvis
The Appendicular Skeleton – Pelvis
Gender differences in pelvic girdle:
The Appendicular Skeleton – Pelvis
Gender differences in pelvic girdle:
The Appendicular Skeleton – Pelvis
Gender differences in pelvic girdle:
Ch 7 – The Skeleton
Part B: The Appendicular Skeleton
Section 9 – The Lower Limb (pp. 237-241)
The Lower Limb
The Lower Limb
- bones thicker & stronger than upper limb bones
- carries weight of the body
- subjected to exceptional forces
3 main components
1) Thigh
- Femur
2) Leg
- Tibia & fibula
3) Foot
- 7 tarsal (ankle) bones
- 5 metatarsal (foot) bones
- 14 phalanges (toe bones)
The Lower Limb – Thigh
Femur
- forms the “thigh”
- largest, strongest bone in body
- “neck” is weakest part & often
fractured; “broken hip”
Patella
- “kneecap”
- purpose is to protect knee joint
The Lower Limb – Leg
Tibia
- medial leg bone
- receives weight from femur;
transmits it to foot
Fibula
- not weight-bearing
- muscle attachment site
- does not contribute to knee joint;
only stabilizes ankle
*Bound together by interosseous membrane
The Lower Limb – Foot
Tarsals
- form “ankle” & posterior ½ of foot
- 7 total bones
1) talus
2) calcaneus
3) cuboid
4) navicular
5) medial cuneiform
6) intermediate cuneiform
7) lateral cuneiform
*Talus transfers weight from tibia to calcaneus (heel)
The Lower Limb – Foot
Metatarsals
- form anterior ½ of foot
- 5 total bones
- #1-5 starting w/ big toe
Phalanges
- toe #1 (big toe) = 2 phalanges
(distal & proximal)
- toes #2-5 = 3 phalanges
(distal, middle, & proximal)
Animation: Rotatable bones of the foot
Arches of the Foot
Foot Arches
- maintained by interlocking foot bones, ligaments, & tendons
- allow foot to bear weight
- “give” or stretch when weight is applied; spring back when
weight is removed
Ch 7 – The Skeleton
Section 10 – Developmental Aspects
(pp. 242-244)
Developmental Aspects
Fetal Skull
- very large compared to infant’s total body length
- more bones than adult skull; unfused sutures
- mandible is proportionally very small
Developmental Aspects
Fontanelles
- fibrous membranes connecting cranial bones in infants
- provide brain room to grow
- convert to bone within 24 months after birth
Developmental Aspects
Developmental Aspects
Developmental Aspects
Growth Rates:
- at birth, cranium is huge relative to face
- at 9 months, cranium is ½ adult size
- mandible & maxilla lengthen w/ age
- arms & legs grow at faster rate than head & trunk
Developmental Aspects
Spinal Curvature:
- thoracic & sacral curvatures obvious at birth
- this gives the spine a C shape
Developmental Aspects
Spinal Curvature:
- cervical & lumbar curvatures appear as child develops
(lifts head, learns
to
walk,
He’s
cute!
I etc.)
think
Hey
Mike!
Come
see
Typical
guy…
I’m
in
love!!!
what
the
dog
- positions weight over centerleft!!!
of gravity
The Boy…
Men are from Mars,
Women are from Venus…
The Girl…
Developmental Aspects
As you Age…
- intervertebral discs become thin &
less elastic
- risk of disc herniation increases
- loss of height (by several cm) is
common by age 55
- costal cartilages ossify; thorax
becomes rigid (breathing
becomes more difficult)
- all bones lose mass
Ch 7 – The Skeleton
Section 11 – Homeostatic Imbalances
(pp. 244-245)
Homeostatic Imbalances
Cleft Palate:
- right & left halves of hard palate (maxilla) fail to fuse
- opening between oral & nasal cavities
- very difficult for babies to drink from bottles
- can lead to aspiration (inhalation) of food into lungs
Homeostatic Imbalances
Clubfoot:
- congenital defect where soles of feet face medially & toes
point inferiorly
- affects 1 in 700 babies
- may be genetic defect or the result of abnormal position
of the foot in the womb during development
Homeostatic Imbalances
Spina bifida:
- congenital defect of the vertebral column
- 1 or more of the vertebral arches incomplete
- ranges in severity…may not cause any problem or may
severely impair neural function depending on location
Homeostatic Imbalances
Spinal fusion:
- surgical procedure involving insertion of bone chips to
immobilize/stabilize specific region of vertebral column
- used often with fractures involving the vertebrae &
injuries involving herniated discs