Medical Medical TerminologyTerminology

AHS 115AHS 115

Skeletal SystemSkeletal System

Functions Functions

• Support:Support: body structure and shape body structure and shape

• ProtectionProtection for vital organs (brain, heart, etc.) for vital organs (brain, heart, etc.)

• MovementMovement for attached skeletal muscles for attached skeletal muscles – Tendons:Tendons: attach muscle to bone attach muscle to bone – Ligaments:Ligaments: attach bone to bone attach bone to bone

• Mineral storageMineral storage:: calcium and phosphorus calcium and phosphorus

• Blood cell formationBlood cell formation - hematopoiesis - hematopoiesis

Types of BoneTypes of Bone

Compact BoneCompact Bone• Very dense, stress bearing Very dense, stress bearing • Haversian systemsHaversian systems –basic unit –basic unit

of compact boneof compact bone• LamellaeLamellae: concentric cylinder : concentric cylinder

shaped calcified structure shaped calcified structure • LacunaeLacunae: small spaces containing : small spaces containing

tissue fluid tissue fluid • OsteocytesOsteocytes: facilitate exchange of : facilitate exchange of

calcium between blood and bone calcium between blood and bone • CanaliculiCanaliculi: canals connecting the lacunae together : canals connecting the lacunae together

and to the haversian canal which carries nutrients and to the haversian canal which carries nutrients and wastes to and from the osteocytes and wastes to and from the osteocytes

Cancellous Bone Cancellous Bone

• Light, spongy Light, spongy

• Found at ends of long bones, ribs, Found at ends of long bones, ribs, sternum, hips, vertebrae, cranium sternum, hips, vertebrae, cranium

• No haversian systems No haversian systems

• Web-like arrangement Web-like arrangement

• Highly vascularHighly vascular

Classification of BonesClassification of Bones

Long bones Long bones • Found in the extremitiesFound in the extremities• Act as levers Act as levers • Includes:Includes:

– EpiphysisEpiphysis• End of long bonesEnd of long bones• Covered with hyaline cartilage for articulation Covered with hyaline cartilage for articulation • Filled with cancellous bone Filled with cancellous bone

– DiaphysisDiaphysis– Shaft Shaft – Covered with periosteumCovered with periosteum– Medullary canal Medullary canal – Compact bone Compact bone

• Examples: femur, tibia, fibula, humerus, Examples: femur, tibia, fibula, humerus, radius, clavicle, metacarpals, phalanges radius, clavicle, metacarpals, phalanges

Short Bones Short Bones

• Cube shaped Cube shaped

• Allows flexible movement Allows flexible movement

• Cancellous bone covered by compact Cancellous bone covered by compact bone bone

• Examples: Examples: – Carpals Carpals – TarsalsTarsals

  

Flat Bones Flat Bones

• Protect vital organs and provide broad Protect vital organs and provide broad surface area for muscle attachment surface area for muscle attachment

• Examples: Examples: – Cranial bonesCranial bones– ScapulaScapula– Sternum Sternum – RibsRibs

Irregular Bones Irregular Bones

• Peculiarly shaped to provide support and Peculiarly shaped to provide support and protection, yet allow flexibility protection, yet allow flexibility

• Examples:Examples:– VertebraeVertebrae– Ear Ear – HyoidHyoid– Mandible Mandible

Sesamoid Bones Sesamoid Bones

• Extra bones found in certain tendons Extra bones found in certain tendons

• Example:Example:– PatellaPatella

  

Composition Composition

• Collagen: chief organic constituent (protein) Collagen: chief organic constituent (protein) • Inorganic calcium salts (Vitamin D essential for absorption Inorganic calcium salts (Vitamin D essential for absorption

of minerals i.e. calcium) of minerals i.e. calcium)

• Deposition favored by Deposition favored by – a. Estrogen, testosterone a. Estrogen, testosterone – b. Alkaline phosphatase b. Alkaline phosphatase – c. Thyrocalcitonin c. Thyrocalcitonin – d. Mechanical stress i.e. traction d. Mechanical stress i.e. traction

• Withdrawal favored by Withdrawal favored by – a. Alkaline phosphatase a. Alkaline phosphatase – b. Parathormone b. Parathormone – c. Inactivity c. Inactivity

Composition Composition

Cells Cells • Osteoblasts: bone building, bone repairing cells in the Osteoblasts: bone building, bone repairing cells in the

periosteum periosteum • Osteocytes: mature bone cells within the bone matrix Osteocytes: mature bone cells within the bone matrix • Osteoclast: causes reabsorption of bone Osteoclast: causes reabsorption of bone

Periosteum Periosteum • 1. Dense, fibrous membrane covering bone 1. Dense, fibrous membrane covering bone • 2. Contains blood vessels 2. Contains blood vessels • 3. Essential for bone cell survival and bone formation 3. Essential for bone cell survival and bone formation •   

Osteoblast

Osteocyte

OsteoclastEats bone

Builds new bone

Mature bone cell

Cells that Aid in Bone FormationCells that Aid in Bone Formation

Bone Formation Bone Formation • Initially collagen fibers secreted by fibroblasts Initially collagen fibers secreted by fibroblasts

• Cartilage deposited between fibers Cartilage deposited between fibers

• Skeleton fully formed by 2nd month of fetal development (all Skeleton fully formed by 2nd month of fetal development (all cartilage) cartilage)

• After 8th week of fetal development ossification (mineral matter After 8th week of fetal development ossification (mineral matter deposited and replaces cartilage) begins deposited and replaces cartilage) begins

• Childhood and adolescence: Childhood and adolescence:

– ossification exceeds bone lossossification exceeds bone loss

• Early adulthood thru middle age: Early adulthood thru middle age:

– ossification equals bone lossossification equals bone loss

• After age 35: After age 35: – bone loss exceed ossificationbone loss exceed ossification

275 bones275 bones12 weeks 12 weeks

(6-9 inches long)(6-9 inches long)

Fetal Skeleton Fetal Skeleton

Anatomy of Long BoneAnatomy of Long Bone• Diaphysis Diaphysis

– ShaftShaft– Composed of compact boneComposed of compact bone

• Epiphysis Epiphysis – Ends of bone composed mostly Ends of bone composed mostly

of spongy boneof spongy bone

• Periosteum Periosteum – outside covering of diaphysisoutside covering of diaphysis

• EndosteumEndosteum– Lines medullary cavityLines medullary cavity

• ArteriesArteries• Articular cartilageArticular cartilage• Medullary cavityMedullary cavity

– Cavity inside the shaft Cavity inside the shaft – Contains yellow marrow (mostly fat) in adultsContains yellow marrow (mostly fat) in adults

Bone MarrowBone Marrow

• Red bone marrowRed bone marrow– Found in vertebrae, ribs, sternum, cranium, Found in vertebrae, ribs, sternum, cranium,

ends of humerus and femurends of humerus and femur– Produces:Produces:

• ErythrocytesErythrocytes – red blood cells – red blood cells• Plateletes - thrombocytesPlateletes - thrombocytes – clotting cells – clotting cells• Some Some leukocytesleukocytes – white blood cells – white blood cells

• Yellow bone marrowYellow bone marrow– Found in medullary cavity of long bones Found in medullary cavity of long bones – Fat storage Fat storage

Bone MarrowBone Marrow

Yellow marrowYellow marrow • Medullary cavity of long bones Medullary cavity of long bones • Fat storage Fat storage

Red marrowRed marrow• Hematopoietic tissue Hematopoietic tissue • In all cancellous bone in children In all cancellous bone in children • In adults: cancellous bone of vertebrae, hips, sternum, In adults: cancellous bone of vertebrae, hips, sternum,

ribs, cranial bones, proximal ends of femur and humerus ribs, cranial bones, proximal ends of femur and humerus • Forms RBCs, platelets, some WBCs, and destroys old Forms RBCs, platelets, some WBCs, and destroys old

RBCs and some foreign materials RBCs and some foreign materials

Divisions of the Divisions of the Skeletal SystemSkeletal System

Axial SkeletonAxial Skeleton

Forms the longitudinal axis of the bodyForms the longitudinal axis of the body

Divided into three parts:Divided into three parts:• SkullSkull• Vertebral ColumnVertebral Column• ThoraxThorax

Appendicular SkeletonAppendicular Skeleton

• Composed of 126 bonesComposed of 126 bones

• Includes bones of the:Includes bones of the:– Limbs (appendages)Limbs (appendages)– Pectoral (shoulder) girdlePectoral (shoulder) girdle– Pelvic (hip) girdlePelvic (hip) girdle

JointsJoints

ClassificationClassification

• SynarthroticSynarthrotic: immovable - cranium: immovable - cranium• AmphiarthroticAmphiarthrotic: limited movement i.e. : limited movement i.e.

pubic symphysis, vertebral joints, pubic symphysis, vertebral joints, sacroiliac joint sacroiliac joint

• DiarthroticDiarthrotic: freely movable : freely movable – Gliding: bones of the wrist Gliding: bones of the wrist – Pivot: between radius and ulna Pivot: between radius and ulna – Ball and socket: hip Ball and socket: hip – Hinge: elbow Hinge: elbow

Immovable Joints Immovable Joints SynarthrosisSynarthrosis

Slightly Movable Joint Slightly Movable Joint AmpharthrosisAmpharthrosis

Freely Movable DiarthrosisFreely Movable Diarthrosis

Abduction

Extension

RotationFlexion

Adduction

Synovial Joint Movement