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Axial (the center or “axis”)Appendicular (legs and arms)

Skeletal Organization

Skeleton is divided intotwo divisions!

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Axial skeleton 1. Skull (28 bones including auditory ossicles) 2. Hyoid bone (1 bone) 3. Vertebral column (26 bones) a. Cervical (7 vertebrae) b. Thoracic (12 vertebrae) c. Lumbar (5 vertebrae) d. Sacrum (1 – 5 fused vertebrae) e. Coccyx (1 -~4 fused vertebrae) 4. Thoracic Cage (25 bones)

a. Ribs (24)b. Sternum (1 – 3 parts)

80 total bones in axial skeleton

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The Skull – 28 bones• Braincase – encloses

cranial cavity– Surrounds & protects brain

• 6 bones, 8 when paired

• Facial bones – forms facial structure

• 8 bones, 14 when paired

• Auditory ossicles – form the middle ear– These bones transmit

vibration to eardrum• Malleus, incus, & stapes

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Braincase bones – 8 bones

• 2 parietals

• 2 temporals

• 1 frontal

• 1 occipital

• 1 sphenoid

• 1 ethmoid

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Braincase• Parietals (wall)

– Most of sides & roof of cranial cavity

– Joined to temporal by squamous suture (scale-like)

– Joined to frontal by coronal suture (crown)

– Joined to occipital by lambdoid suture ()

– Sagittal suture joins two parietals

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• Temporals (time)– Inferior part of cranium & part

of cranial floor– Joined to occipital and

parietal by squamous suture

– External auditory meatus – sound waves travel through to eardrum

– Mastoid process – neck muscle attachment for head rotation

– Other landmarks:• Zygomatic Process – articulates

with zygomatic• Mandibular Fossa – articulates

with mandible• Styloid Process – muscle

attachment for tongue, hyoid, & pharynx movement

Braincase

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• Occipital (back of head)– Posterior part & prominent portion

of the base of the cranium

– Joined to parietals by lambdoid suture

– Occipital bone landmarks:

• Foramen Magnum – passage of spinal cord (connects to brain)

• Occipital Condyles – articulate with vertebral column

• Sphenoid (wedge-shaped)– Connects to all other cranial bones

• Sella turcica (next slide) – contains pituitary gland

Braincase

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Braincase• Ethmoid

– Light, spongy bone that increases surface area of nasal cavity

• Moistens & warms inhaled air

– Anterior floor of the cranium between the orbits

– Composes much of nasal cavity & part of nasal septum

– Ethmoid bone landmarks:• Crista Galli• Perpendicular Plate – part of

nasal septum (with vomer)• Superior Nasal Conchae &

Middle Nasal Conchae – form lateral walls of nasal cavity

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Facial bones – 14 bones• 2 maxillae• 2 zygomatic• 2 palatine• 2 nasals

• 2 lacrimals• 2 inferior nasal conchae• 1 mandible • 1 vomer

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Facial Bones• Zygomatic bones

– cheek bones– form the floor & outer

walls of the orbits– Zygomatic bone

landmarks:• Temporal processes• Zygomatic arches

(temporal & zygomatic)– Muscle attachment for

moving the mandible

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Facial Bones• Maxillae

– paired bones forming upper jaw (holds teeth)

– articulate with every bone of the face except the mandible

– Maxillary bone landmark:

• Palatine Processes = horizontal projection forming the anterior 2/3 of the hard palate (palatines form the rest)

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• Mandible– Lower jaw (holds teeth)– Largest and strongest bone

in the face– the only moveable skull

bone– Articulates with the

temporal bone to form the Temporal Mandibular Joint (TMJ)

• Mandible landmarks:– Ramus = perpendicular

portion of bone– Angle– Mandibular condyle =

articulates with temporal– Mandibular Notch

Facial Bones

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• Nasal bones– Bridge of nose

• Lacrimals– Forms part of tear duct

• Palatines– Posterior 1/3 of hard

palate

Facial Bones

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• Inferior nasal conchae

• Vomer– Part of nasal septum

(with perpendicular plate of ethmoid)

Facial Bones

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• Orbits– Made by 7 bones!– Orbit landmarks:

• Superior orbital fissures & Inferior orbital fissures

– Blood vessels & nerves

• Optic foramen (optic nerve)• Nasolacrimal canal (tear duct)

• Nasal cavity– Nasal septum = vomer +

ethmoid (perpendicular plate)– Nasal conchae

• Inferior nasal concha – individual bone

• Superior & middle nasal conchae – ethmoid bone

• Increase surface area

Other Skull Features

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Paranasal sinuses• Open into nasal cavity• Decrease skull weight &

serve as resonating chambers during voice production

• Frontal, maxillary, ethmoidal, & sphenoidal

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Hyoid bone

• U-shaped• Not part of skull• No direct bony

attachment to skull (attached by muscles & ligaments)

• Attachment site for tongue & larynx muscles (speech & swallowing)

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Vertebral Column• “Backbone”• Central axis of skeleton• 5 regions:

– Cervical vertebrae (neck + to turn) (C1-C7)– Thoracic vertebrae (T1-T12)– Lumbar vertebrae (L1-L5)– Sacral (S)– Coccygeal bone (CO)

• 4 curves:– Cervical curves anteriorly– Thoracic curves posteriorly– Lumbar curves anteriorly– Sacral & coccygeal curve posteriorly

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Functions of Vertebral Column

• Supports weight of head & trunk

• Protects spinal cord

• Allows spinal nerves to exit spinal cord

• Site for muscle attachment

• Permits head & trunk movement

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Vertebral Column Defects• Lordosis –

abnormal anterior curvature– Lumbar– Swayback

• Kyphosis – abnormal posterior curvature– Usually upper

thoracic– Hunchback

• Scoliosis – abnormal lateral curvature

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Vertebral Column Damage

• Herniated disk– Compresses

nerves

• “Broken Tailbone”– Fractured coccyx– Can occur during

childbirth and from falls

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Vertebral Anatomy• Body – bears weight• Intervertebral disks –

separate bodies; dense fibrous connective tissue

• Vertebral arch – forms vertebral foramen

• Vertebral foramen – houses spinal cord

• Vertebral canal – formed by all vertebral foramina; spinal cord passage/protection

• Pedicle – extend from body to transverse process (feet); forms part of vertebral arch

• Lamina – extend from transverse process to spinous process; forms part of vertebral arch

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• Transverse process – extend laterally from the arch between pedicle & lamina

• Spinous process- project dorsally from laminae; can feel externally

• Intervertebral foramina- notches formed by adjacent vertebrae; spinal nerves exit here

• Articular process – area of vertebral articulation

• Articular facet – smooth surface articulates with ribs

Vertebral Anatomy

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Differences in Vertebrae• Cervical

– small bodies (except atlas)– Transverse foramen on

transverse process for vertebral arteries going to brain

– Some have split spinous processes

– Atlas – 1st vertebra holds up head

– Axis – 2nd vertebra allows rotation (dens)

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Differences in Vertebrae• Thoracic

– Long, think spinous processes directed inferiorly

– Lateral articular facets for rib articulation

• Lumbar– Large, thick bodies– Heavy, rectangular transverse

& spinous processes– Medially facing superior

articular facets (“locks” vertebrae together for stability)

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Differences in Vertebrae• Sacrum

– 5 fused vertebrae– Median sacral crest –

spinous processes on 1st 4 vertebrae

– Sacral hiatus- inferior end of sacrum without a crest

• Site of anesthetic injection prior to childbirth

– Sacral promontory- bulge in anterior edge of body of 1st vertebra in sacrum

• Palpated before childbirth to determine pelvic opening size

• Coccyx (“tailbone”)– 4 fused vertebrae– Reduced vertebral bodies– No foramina or processes

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Thoracic Cage

• “Rib cage”

• Functions:– Protects vital organs in thorax– Prevents collapse of thorax during respiration

• Consists of:– Thoracic vertebrae– Ribs + associated cartilages– Sternum

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Ribs & Costal Cartilages• 12 pairs (24 total)• Articulate with thoracic vertebrae• True ribs – (1-7) superior 7 attach to sternum via

cartilage• False ribs – (8-12) inferior 5 do not directly attach to

sternum– Floating ribs – (11-12) inferior 2 not attached to sternum at all

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Sternum• “Breastbone”• Three parts:

– Manubrium (handle)• Jugular notch – superior to

manubrium; between clavicular articulations

– Body• Sternal angle – at junction

of manubrium & body; locates 2nd rib & used to find apex of heart

– Xiphoid process (sword)• Used in CPR alignment

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Appendicular Skeleton, Joints & Movement

Ch. 6

Appendicular = “to hang something on”

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Appendicular Skeleton

1. Pectoral girdle (scapulae & clavicle)

2. Upper limbs (arm, forearm, wrist, hand)

3. Pelvic girdle (2 coxae)

4. Lower limbs (thigh, leg, ankle, foot)

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Pectoral Girdle

• 2 scapulae– Articulates with

humerus

• 2 clavicles– Articulates with

sternum & scapula

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Upper Limb

• Arm

• Forearm

• Wrist

• Hand

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Upper Limb: Arm

• Humerus – region between shoulder and elbow

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Upper Limb: Forearm

• Radius (lateral or thumb side) & Ulna (medial or little finger side)

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Upper Limb: Wrist & Hand

• Wrist – region between forearm and hand– 8 carpals

• Hand – attached to carpals– 5 metacarpals– 5 digits– 3 phalanges per finger

(2 on thumb)

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Pelvic Girdle

• 2 coxae– Coxa formed by 3 fused bones: ilium,

ischium, pubis– Sex differences: larger pelvic inlet and outlet

in females, broader pelvis in females, greater subpubic angle in females (childbirth)

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Lower Limb

• Thigh

• Leg

• Ankle

• Foot

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Lower Limb: Thigh

• Femur – region between hip and knee– Articulates with

coxa and tibia

• Patella

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Lower Limb: Leg

• Tibia (shin) and fibula

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Lower Limb: Foot & Ankle• Ankle = 7 tarsals; articulates with tibia &

fibula; calcaneus forms heel• Foot = 5 metatarsals; 3 phalanges per digit

(except great toe – has 2)

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Joints or “Articulations”• Articulation = place where two bones

come together

• Classification methods:– Function:

• Synarthrosis (non-movable)• Amphiarthrosis (slightly movable)• Diarthrosis (freely movable)

– Structure (connective tissue type):• Fibrous (fibrous tissue)• Cartilaginous (cartilage)• Synovial (synovial fluid)

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1. Fibrous joints• No movement• Sutures in fetal skull

2. Cartilaginous joints• Slight movements• Epiphyseal plates, costal cartilage

3. Synovial joints • Free movements• Most joints (wrist, knee, shoulder, hip, etc.)

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Fibrous Joints

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Synovial Joints

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Types of Joint Movements1. Flexion vs. extension2. Plantar flexion vs. dorsiflexion3. Abduction vs. adduction4. Pronation vs. supination5. Eversion vs. inversion6. Rotation7. Protraction vs. retraction8. Elevation vs. depression9. Circumduction10.Excursion (mandible moving side to side)11.Opposition vs. reposition (thumb & pinky together,

then apart)

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