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