Download The Skeletal System

Chapter 8
The Skeletal System
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The Skeletal System
• Divided into:
– Axial
• Axis of the body
– Skull, vertebrae, sternum and rib
cage
– Appendicular
• Appendages
– Pectoral and pelvic girdles, arms
and legs
aclasta.co.nz
Articulations
• Condyle – rounded knob that articulates with
another bone
• Facet – smooth flat, slightly concave or convex
surface
• Head – prominent expanded end of the bone,
maybe rounded
Extensions and Projections
• Epicondyle – projection superior to a condyle
• Lines – slightly raised, elongated ridge
• Process – bony prominence
• Protuberance – bony outgrowth
• Spine – Sharp, slender, or narrow process
• Trochanter – two large processes associated with femur
• Tubercle – small rounded process
• Tuberosity – rough elevated surface
Depressions
• Alveolus – socket
• Fossa – shallow, broad, or elongated basin
• Fovea – small pit
• Sulcus – groove for blood vessel, nerve, or
tendon
Passages and Cavities
• Canal – tunnel in a bone
• Foramen – hole through bone
• Fissure – slit through a bone
• Meatus – opening into canal
• Sinus – air-filled space in bone
Skull
• Composed of 22 bones
– Cranial
• Direct contact with meninges and brain
– Facial
• No contact with meninges or brain
• Most articulate at sutures
– Coronal, sagittal, squamous, lambdoid
– Contains various cavities and sinuses
• Cranial, orbits, nasal, oral
• Frontal, sphenoid, ethmoid, maxillary
Cranial Bones
• Cranium composed of 8 bones
– Frontal, parietal (2), temporal (2), occipital, sphenoid, ethmoid
– Temporal bone
• Mastoid and styloid processes
• Stylomastoid and mastoid foramen
– Occipital
• Foramen magnum, occipital condyles, hypoglossal canal, external occipital protuberance
and nuchal line
– Sphenoid
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Superior orbital fissure and optic foramen
Sella turcica – hypophyseal fossa
Foramen rotundum and ovale – nerve passage
Foramen spinosum – blood vessel passage
– Ethmoid
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Contributes to medial wall of orbit, roof and walls of nasal cavity, and nasal septum
Crista galli, cribiform plate and cribiform foramen
Perpendicular plate and middle nasal conchae
Ethmoid sinus
Facial Bones
• Give shape to face and hold teeth
– Form parts of nasal and orbital cavities, provide sites for muscle
attachment
– 14 bones
• (2 each) maxillae, nasal, palatine, inf. nasal conchae, zygomatic,
lacrimal
• (1 each) vomer, mandible
– Maxillae
• Alveolar processes and alveolus
• Infraorbital foramen – blood vessel and nerve passage
– Mandible
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Strongest bone of skull, develops as two bones
Mental protuberance, body, angle, ramus
Coronoid process, mandibular notch, condylar process
Mental foramen and mandibular foramen – blood vessels and nerves
Bones Associated with Skull
• Auditory ossicles
– Malleus, incus, and stapes
• Hyoid
– U-shaped bone between chin and larynx
– Does not articulate with any other bone
– Attached to styloid process
– Body, lesser and greater horns
Skull: Infancy and Childhood
• Skull bone are not yet fused
• Fontanels – spaces between cranial bones
– Anterior, posterior, sphenoid, mastoid
• Frontal and mandible are two separate halves
at birth
• Skull grows more rapidly than rest of skeleton
Vertebral Column
• Functions
– Support, protection of spinal cord, shock absorption
• Composed of 33 vertebrae
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7 cervical
12 thoracic
5 lumbar
5 sacral
4 coccygeal
• Slight S-shape with four bends
– Cervical, thoracic, lumbar, and pelvic
• Intervertebral discs
http://en.wikipedia.org/wiki/Vertebral_column
– Core of gelatinous nucleus pulposus surrounded by a fibrocartilage
ring, anulus fibrosus
– 23 discs, start between C2 and C3, end between L5 and sacrum
Cervical Vertebrae
• Cervical
– Atlas and axis, C1 and C2
– C2 – C6 have a bifurcated
spinous process
– C7 spinous process long
• Vertebral prominens
– All cervical vertebrae have
transverse foramen
• Blood vessels
physioweb.org
Thoracic Vertebrae
• 12 thoracic vertebrae
• Spinous processes are more
pointed and angled down
• Body of all T vertebrae contain
costal facets
• Transverse process of T1 – T10
contain transverse costal facets
spineuniverse.com
Lumbar, Sacral, Coccyx
• Lumbar
– Large prominent bodies and blunt square spinous
process
• Sacral
– Bones fuse by third decade of life
– Median sacral crest and lateral sacral crest
– Sacral foramina – passage of nerves and blood vessels
• Coccyx
Thoracic cage
• Consists of the thoracic vertebrae, sternum,
and ribs
• Encloses the heart and lung and provides
attachment for the pectoral girdle
– Costal margin – downward arc of ribs
Thoracic Cage
• Sternum
– Bony plate anterior to heart
– Three regions
• Manubrium, gladiolus (body), xiphoid process
• Ribs
– Attached proximally to the vertebrae, distally to the sternum via
costal cartilage
– Head, neck , tubercle
– Shaft – where rib flattens and widens
– Angle – curve
– Costal groove – inferior margin of rib, blood vessels and nerves
– True ribs 1-7, direct connection to sternum
– False ribs 8-12, no direct connection
• 11-12 floating ribs
• Supports the arm
Pectoral Girdle
– Consists of two bones on each side of body
• Clavicle and scapula
• Clavicle
– S-shaped bone
– Sternal and acromial ends
• sternoclavicular and acromioclavicular joints
• Conoid tubercle – attachment of ligament, acromial end
• Scapula
– Flat, triangular bone that lies posterior to the ribs
– Three sides: superior, medial, and lateral borders
• Angles: superior, inferior, and lateral
– Subscapular fossa – broad anterior surface
– Spine – transverse ridge on posterior surface
• Suprasinous fossa and infraspinous fossa
– Acromion process
• Apex of shoulder, articulates with clavicle
– Coracoid process
– Glenoid cavity
abcopro.com
Upper Limb
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Divided into four regions, 30 bones per limb
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Brachium
– Shoulder to elbow, arm proper
– Humerus
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Antebrachium
– Elbow to wrist
– Radius and ulna
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Carpus
– Wrist
– Proximal row, thumb side: scaphoid, lunate, triquetrium, pisiform
– Distal row, thumb side: trapezium, trapezoid, capitate, hamate
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Manus
– Hand
– 5 metacarpals
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Proximall– base, body, head
– 14 phalanges
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2 in pollex, 3 in other digits
cliffsnotes.com
Pelvic Girdle
• Consists of three bones
– Sacrum, 2 coxal bones (hip bones)
• Three distinctive features
– Iliac crest
– Acetabulum
– Obturator foramen
• Hip bones
– Fusion of three bones
• Ilium
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Anterior and posterior superior spines
Anterior and posterior inferior spines
Greater sciatic notch
Iliac fossa
• Ischium
– Ischial tuberosity
• Pubis
– Superior and inferior ramus
– Pubic symphysis
cliffsnotes.com
Lower Limb
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Divide into 4 regions, 30 bones per limb
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Femoral region
– Thigh, extends from hip to knee
– Femur
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Crural region
– Leg proper, extend from knee to ankle
– Tibia (medial) and fibula (lateral)
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Tarsal region
– Ankle
– Union of crural region with foot
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Pedal region
– Foot
– 7 tarsal bones
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Proximal row hallux side: navicular, tallus, calcaneous
Distal row hallux side: medial, intermediate, lateral cuniform, cuboid
– 5 metatarsals
– 14 phalanges
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Hallux contains only two bones, all other toes contain three
cliffsnotes.com