SKELETAL SYSTEM.ppt

SKELETAL SYSTEM  The Skeletal System Parts of the skeletal system Bones (skeleton) Joints Cartilages Ligaments Divided into two divisions Axial Skeleton Consists of 80 bones Includes the body framework of the head and the trunk Appendicular Sk eleton Consists of 12...

SKELETAL SYSTEM  The Skeletal System Parts of the skeletal system Bones (skeleton) Joints Cartilages Ligaments Divided into two divisions Axial Skeleton Consists of 80 bones Includes the body framework of the head and the trunk Appendicular Sk eleton Consists of 126 bones Forms the framework for the extremities and for the shoulder and hips  Functions of Bones Support of the body  As a firm framework for the entire body Protection of soft organs Movement due to attached skeletal mus cles  To serve as levers  Storage of minerals (calcium salts) and f ats Blood cell f ormation (in the red marrow)  Bones of the Human Body The adult skeleton has 206 bones Two basic types of bone tissue Compact Bone (Homogeneous) Hard and dense Makes up the main shaft of a long bone and the outer layer of other bones Spongy Bone (Cancellous) Has more spaces than compact bone Made of a meshwork of small, bony plates filled with red marrow It is found at the epiphyses (ends) of long bones and at the center of other bones  Spongy bone Compact bone © 2018 Pearson Education, Inc.  Classification of Long Bones Bones Typically longer t han wide Have a shaft with heads at both en ds Contain mostly c ompact bone Examples: Femur, humerus Short Bones Generally cub e-shape Contain mostl y spongy bon e Examples: Carpals, tarsa ls Flat Bones Thin and flatte ned Usually curve d Thin layers of compact bone around a layer of spongy bon e Examples: Skull, ribs, ste rnum Irregular Bon es Irregular sh ape Do not fit int o other bon e classificat ion categori es Example: Vertebrae a nd hip  Gross Anatomy of a Long Bone Diaphysis  Shaft  Composed of compact bone Epiphysis  Ends of the bone  Composed mostly of spongy bone Structures of a Long Bone  Periosteum  Outside covering of the diaphysis  Fibrous connective Compact bone tissue Periosteum membrane  Sharpey’s fibe rs  Secure periost eum to underl ying bone Arteries  Supply bone c ells with nutri Perforating ents (Sharpey’s) fibers Nutrient arteries  Medullary cavity  Cavity of the shaft  Contains yellow marrow (mostly fat) in adults  Contains red marrow (for blood cell formation) in infants  Articular Cartila ge  Covers the exter nal surface of th e epiphyses  Made of hyaline cartilage  Decreases frictio n at joint surface s  Bone Markings Surface (distinguishing) features of bon es Sites of attachments for muscles, tendo ns, and ligaments Passages for nerves and blood vessels Projection s: Head A rounded, knob-like end separated from the crest of the bone by slender region, the neck Process A large projection of a bone, such as the upper part of the ulna in the forearm that creates the elbow Condyle A round projection A small projection above a condyle is an epicondyle Crest A distinct border or ridge, often rough Such as over the top of the hip bone Spine A sharp projection from the surface of a bone Such as the spine of the scapula Depressions or Holes Foramen (Foramina) A hole that allows a vessels or a nerve to pass through or between bones Sinus An air space found in som skull bones Fossa (Fossae) A depression on a bone surface Meatus A short channel or passageway Such as the channel in temporal bone that leads to the inner ear  Microscopic Anatomy of Bone Osteon (Haversian System)  A unit of bone Central (Haversian) canal  Opening in the center of an osteon  Carries blood vessels and nerves  Perforating (Volkman’s) canal  Canal perpendicular to the central canal  Carries blood vessels and nerves  Lacunae  Cavities containing bone cells (osteocytes)  Arranged in concentric rings Canaliculi  Tiny canals  Radiate from the central canal to lacunae  Form a transport system  Lamellae  Rings around the central canal  Sites of lacunae  Lamella Osteocyte Canaliculus Lacuna Central Bone matrix (Haversian) canal (b) © 2018 Pearson Education, Inc.  Osteon Interstitial lamellae Lacuna Central (Haversian) canal (c) © 2018 Pearson Education, Inc.  Figure 5.4a Microscopic structure of bone. Trabeculae of spongy bone Osteon (Haversian Perforating system) (Volkmann’s ) canalcontinues Blood vessel into medullary cavity containing marrow Blood vessel Lamellae Compact bone Central (Haversian) canal Perforating (Sharpey’s) fibers Periosteum Periosteal blood vessel (a ) © 2018 Pearson Education, Inc. Changes in the Human Skeleton In embryos, the skeleton is primarily hyaline cartilage  During development, much of this cartilage is replaced by bone Cartilage remains in isolated areas  Bridge of the nose  Parts of ribs  Joints  Bone Growth Epiphyseal plates allow for growth of long bone during childhood New cartilage is continuously formed  Bone Growth Older cartilage becomes ossified  Cartilage is broken down  Bone replaces cartilage Bones are remodeled and lengthened until growth stops  Bones change shape somewhat  Bones grow in width  Types of Bone Cells Osteocytes  Mature bone cells Osteoblasts  Bone-forming cells Osteoclasts  Bone-destroying cells  Break down bone matrix for remodeling and release of calcium Bone remodeling is a process by both osteoblasts and osteoclasts  The Axial Skeleton Forms the longi tudinal part of t he body Divided into thr ee parts:  Skull  Vertebral colum n  Bony thorax The Skull Two sets of bones  Cranium  Facial bones Bones are joined by sutures Only the mandible is attached by a freely movable joint Superior View Inferior View The Fetal Skull The fetal skull is large compared to the infants total body length Fontanelles –  fibrous membranes connecting the cranial bones Allow the brain to grow Convert to bone within 24 month Paranasal Sinuses Hollow portions of bones surrounding the nasal cavity The Hyoid Bone The only bone that does not articulate with another bone Serves as a m oveable base f or the tongue (lingual bone) The Vertebral Column Vertebrae separated by intervertebral discs  The spine has a normal curvature Each vertebrae is given a name according to its location Regional Characteristics of Vertebrae The Bony Thorax Forms a cage to protect major organs  Made-up of three parts  Sternum  Ribs  Thoracic vertebrae  The Appendicular Skeleton Limbs (appendages) Pectoral girdle Pelvic girdle The Pectoral (Shoulder) Girdle Composed of two bones  Clavicle – collarbone  Scapula – shoulder blade These bones allow the upper limb to have exceptionally free movement  Bones of the Upper Limb The arm is formed by a single bone  Humerus  The forearm has two bones  Ulna  Radius  The hand  Carpals – wrist  Metacarpals – palm  Phalanges – fin gers  Bones of the Pelvic Girdle Hip bones Composed of three pair of fused bones  Ilium  Ischium  Pubic bone  The total weight of the upper body rests on the pelvis Protects several organs  Reproductive organs  Urinary bladder  Part of the large intestine  Gender Differences of the Pelvis  Bones of the Lower Limbs The thigh has one bone  Femur – thigh bone  The foot  Tarsus – ankle  Metatarsals – sole  Phalanges – toes  The leg has two bones  Tibia  Fibula  Arches of the Foot Bones of the foot are arranged to form three strong arches  Two longitudinal  One transverse  Joints Articulations of bones Functions of joints  Hold bones together  Allow for mobility Ways joints are classified  Functionally  Structurally  Functional Classification of Joints Synarthroses – immovable joints  Amphiarthroses – slightly moveable joints  Diarthroses – freely moveable joints  Structural Classification of Joints Fibrous joints  Generally immovable Cartilaginous joints  Immovable or slightly moveable Synovial joints  Freely moveable Fibrous Joints Bones united by fibrous tissue Examples  Sutures  Syndesmoses Allows more movement than sutures Example: distal end of tibia and fibula Cartilaginous Joints Bones connected by cartilage Examples  Pubic symphysis  Intervertebral joints Synovial Joints Articulating bones are separated by a joint cavity Synovial fluid is found in the joint cavity Features of Synovial Joints Articular cartilage (hyaline cartilage) covers the ends of bones Joint surfaces are enclosed by a fibrous articular capsule Have a joint cavity filled with synovial fluid Ligaments reinforce the joint  Structures Associated with the Synovial Joint Bursae Flattened fibrous sacs Lined with synovial membranes Filled with synovial fluid Not actually part of the joint Tendon sheath Elongated bursa that wraps around a te ndon  Types of synovial joints based on shape – Plane joint – Hinge joint – Pivot joint – Condylar joint – Saddle joint – Ball-and-socket joint © 2018 Pearson Education, Inc.  Nonaxial Uniaxial Biaxial Multiaxial (f) (a) Plane joint (b) (c) (a) (e) (d) © 2018 Pearson Education, Inc.  Nonaxial Uniaxial Biaxial Multiaxial (f) (b) Humerus (c) Ulna (a) (e) (b) Hinge joint (d) © 2018 Pearson Education, Inc.  Nonaxial Uniaxial Ulna Biaxial Radius Multiaxial (f) (c) Pivot joint (b) (c) (a) (e) (d) © 2018 Pearson Education, Inc.  Nonaxial Uniaxial Biaxial Multiaxial (f) Metacarpal (b) Phalanx (c) (d) Condylar joint (a) (e) (d) © 2018 Pearson Education, Inc.  Nonaxial Carpal Uniaxial Metacarpal #1 Biaxial Multiaxial (f) (e) Saddle joint (b) (c) (a) (e) (d) © 2018 Pearson Education, Inc.  Nonaxial Uniaxial Biaxial Multiaxial (f) Head of humerus (b) (c) Scapula (f) Ball-and-socket joint (a) (e) (d) © 2018 Pearson Education, Inc.