Chapter 5Skeletal System
Skeleton• Greek meaning
“dried up body”• Axial &
Appendicular• Functions:
o Supporto Protectiono Movemento Storageo Blood cell formation
Bones• 206 bones• Compact and spongy bone• Long bones• Short bones• Flat bones• Irregular bones
Long BonesGross Anatomy
• Diaphysis – compact bone
• Periosteum – covering diaphysis
• Epiphyses – ends• Articular cartilage –
covers epiphyses• Epiphyseal line –
remnant of plate• Yellow marrow – fat
storage• Red marrow – RBCs• Bone markings (table
5.1)
Long BonesMicroscopic Anatomy
• Osteocytes – mature bone cells
• Lacunae – cavities• Lamellae – circles of
lacunae• Haversian canals –
cavity with blood supply
• Osteon – canal and matrix rings
• Canaliculi – connect cells to haversian canals
• Perforating canals – canals at right angles
Bone Formation, Growth and Remodeling
• Ossification has two major phasesoHyaline model is covered with bone cells
(osteoblasts)oHyaline model digested away, making
medullary cavity.Hyaline stays in the articular cartilages
and epiphyseal platesBone remodeling:
Osteoclasts – activated by PTH to destroy bone and release calcium into the blood stream
Homeostatic Imbalance
• Rickets:o Childhood disease in which bones
fail to calcify. Lack of vitamin D or of calcium. Milk, bread and others are fortified with Vit D. Sun.
Bone Fractures• Simple fracture – bone breaks cleanly and does
not penetrate skin• Compound fracture – broken bone ends penetrate
skin• Fracture treated by reduction
o Closed reduction: bone ends are put back into normal position by doctor
o Open reduction: surgery is performed to secure them with pins/plates/wires
Open Reduction
Compound Fracture
Fracture Healing• Four events:
o 1. Hematoma formed by ruptured blood vesselso 2. Break splinted by fibrocartilage callus (cartilage matrix, bony matrix
and collagen fibers). “Splints” the bone, closing the gapo 3. Bony callus formed (spongy bone)o 4. Bony callus remodeled over months time
Axial Skeleton• Skull:
o Cranium and Facial Boneso Cranium bones:
• Frontal (forehead)• Parietal (superior & lateral. Paired… form sagittal suture and coronal suture)• Temporal (inferior to parietal… form squamous sutures. External auditory meatus,
styloid process, zygomatic process, mastoid process, jugular foramen)• Occipital (most posterior. Forms lambdoid suture. Opening called foramen magnum.
Occipital condyles)• Sphenoid (floor of cranial cavity. Sella turcica, foramen ovale, sphenoid sinuses)• Ethmoid (roof of nasal cavity. Crista galli, cribiform plates)
o Facial Bones: • Maxillae (paired and fuse to form upper jaw. Palantine process, paranasal sinuses)• Palantine (paired. Posterior part of hard palate. Cleft palate)• Zygomatic (paired. Cheekbones)• Lacrimal (paired. Medial walls of orbit)• Nasal (paired. Bridge of nose)• Vomer (single bone. Nasal septum) • Inferior Conchae (paired. Inside nasal cavity)• Mandible (single bone. Largest, strongest bone in face)
o Hyoid Bone• Closely related to mandible and temporal bones. Suspended midneck above larynx.
Movable base for tongue and attaches neck muscles)
Fetal Skull
Axial Skeleton
• Vertebral Column (spine)• Intervertebral discs• 24 bones
o 7 cervical (neck)• Atlas and axis
o 12 thoracico 5 lumbaro Sacrum
• 5 Fused vertebraeo Coccyx
• 3-5 fused tiny vertebrae. “tailbone”
Vertebrae• Body• Vertebral arch• Vertebral foramen• Transverse processes• Spinous process• Superior and inferior
articular processes
Axial Skeleton• Bony Thorax
o Sternum• Jugular notch,
sternal angle, xiphisternal joint
o Ribs• 12 pairs. True
ribs (1st 7), False ribs (last 5 NOT attached to sternum)
Appendicular Skeleton• Shoulder Girdle• Upper Limbs• Pelvic Girdle• Lower Limbs
Shoulder Girdle• Clavicle• Scapulae
o Acromiono Coracoid processo Glenoid cavity
Bones of the Arm• Humerus
o Greater, lesser tubercles
o Deltoid tuberosityo Radial grooveo Trochleao Capitulum
• Radius – lateralo Radioulnar jointso Interosseous
membraneo Radial tuberosity
• Ulna – medialo Coronoid processo Olecranon processo Trochlear notch
• Carpal boneso Carpals:
ScaphoidLunateTriquertrumPisiformTrapeziumTrapezoidCapitateHamate
o Metacarpalso Phalanges (distal, proximal)
Greater tubercle
Lesser tubercle
Deltoid tuberosity
Radial groove
TrochleaCapitulum
Distal radioulnar joint
Proximal radioulnar joint
Interosseous membrane
Radial tuberosity
Trochlear notch
Olecranon process
Coronoid process
Ulna
Radius
Anterior Humerus
Posterior Humerus
Pelvic Girdle• Ilium• Sacroiliac joint• Iliac crest• Ischium• Pubis• Pubic symphysis• Acetabulum
ilium
sacroiliac joint
iliac crest
ischiumacetabulum
sacrum
pubic bone
Pubic symphysis
Lower Limbs• Thigh
o Femuro Greater, lesser
trochanterso Intertrochanteric
line/cresto Gluteal tuberosityo intercondylar notch
• Lego Tibia (larger, more medial)
• Tibial tuberosity• Medial malleolus• Anterior crest
o Fibula• Lateral malleolus
• Footo Tarsus (7 tarsal bones)
• Calcaneus• Talus
o Metatarsalso 14 phalanges
Joints• Functionally
o Synarthroses (immovable)o Amphiarthroses (slightly movable)o Diarthroses (freely movable)
• Structurallyo Fibrouso Cartilaginouso Synovial
Fibrous Joints• Sutures of skull• Syndesmoses (tibia and fibula)
Cartilaginous Joints• Pubic symphysis• Intervertebral joints• Hyaline-cartilage
epiphyseal pates of growing long bones
• Cartilaginous joints between first ribs/sternum
Synovial Joints• Four characteristics
o Articular cartilageo Fibrous articular capsuleo Joint cavityo Reinforcing ligamentso ASSOCIATED…
• Bursae• Tendon sheath
Synovial Joints Based on Shape
• Plane Jointo Nonaxialo Intercarpal joints of
wrist
• Hinge Jointo Uniaxial o Elbow, ankle, joints
between phalanges
• Pivot Jointo Uniaxialo Proximal radioulnar
joint
• Condyloid jointo “knuckle-like”, biaxialo Metacarpophalangeal joints
• Saddle jointo Biaxialo Carpometacarpal joints in
thumb
• Ball-and-socket jointo Multiaxialo Shoulder, hip
Inflammatory Disease• Bursitis• Sprain• Arthritis
o Osteoarthritiso Rheumatoid arthritiso Gouty arthritis
Developmental Aspects
• Birth: UL ratio 1.7:1• 10 yo: UL ratio 1:1• Osteoporosis
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