ANAPHY Skeletal

THE SKELETAL SYSTEM

Parts of the Skeletal System

  • bones (skeleton)

  • joints

  • cartilages

  • ligaments (bone to bone ; tendon : bone to muscle)

Divisions

  • Axial Skeleton - bones of the skull, vertebral column, and rib cage

  • Appendicular Skeleton - bones of the upper and lower limbs, shoulder and hip

Functions of Bones

  • support of the body

  • protection of soft organs

  • movement due to attached skeletal muscles

  • storage of minerals and fats

  • blood cell formation

Bones of the Human Body

  • the adult skeleton has 206 bones

  • two basic types of bone tissue

    • Compact Bone - homogenous

    • Spongy Bone - small needle-like pieces of bone, many open spaces

Classification of Bones on the Basis of Shape

Long Bones

  • typically longer than wide

  • have a shaft with heads at both ends

  • contain mostly compact bone

  • femur, humerus

  • Gross Anatomy of a Long Bone

Diaphysis

  • shaft (middle)

  • 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 tissue membrane

Sharpey’s Fibers

  • secure periosteum to underlying bone

Arteries

  • supply bone cells with nutrients

Articular Cartilage

  • covers the external surface of the epiphyses

  • made of hyaline cartilage

  • decreases friction at joint surfaces

Medullary Cavity

  • cavity of the shaft

  • contains yellow marrow (mostly fat) in adults

  • contains red marrow (for blood cell formation) in infants

Short Bones

  • generally cube-shape

  • contain mostly sponge bone

  • carpals, tarsals

Flat Bones

  • thin and flattened

  • usually curved

  • thin layers of compact bone around a layer of spongy bone

  • skull, ribs, sternum

Irregular Bones

  • irregular shape

  • do not fit into other bones classification categories

  • vertebrae and hip

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 Fractures

  • a break in a bone

  • Types of Bone Fractures

Closed (Simple) Fracture

  • break that does not penetrate the skin

Open (Compound) Fracture\

  • broken bone penetrates through the skin

  • bone fractures are treated by reduction and immobilization

    • realignment of the bone

  • Common Types of Fractures

  • Repair of Bone Fractures

    • hematoma (blood-filled swelling) is formed

    • break is splinted by fibrocartilage to form a callus

    • fibrocartilage callus is replaced by a bony callus

    • bony callus is remodeled to form a permanent patch

THE AXIAL SKELETON

  • divided into three parts

    • skull

    • vertebral column

    • 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

Paranasal Sinuses

  • hollow portions of bones surrounding the nasal cavity

  • functions of paranasal sinuses

    • lighten the skull

    • give resonance and amplification to voice

The Hyoid Bone

  • the only bone that does not articulate (move) with another bone

  • serves as a moveable base for the tongue

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 months after birth

The Vertebral Column

  • vertebrae separated by intervertebral discs

  • the spine has a normal curvature

  • each vertebrae is given a name according to its location

Structure of a Typical 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 Shoulder Girdle

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 - fingers

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

The Pelvis

Bones of the Lower Limbs

  • the thigh has one bone

    • femur - thigh bone

  • the leg has two bones

    • tibia

    • fibula

  • the foot

    • talus - ankle

    • metatarsals - sole

    • phalanges - toes

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 movable joints

Structural Classification of Joints

  • Fibrous Joints

    • generally immovable

    • bones united by fibrous tissue

    • synarthrosis or largely immovable

  • Cartilaginous Joints

    • immovable or slightly movable

    • bones connected by cartilage

    • mostly amphiarthrosis

    • examples

      • pubic symphysis

      • intervertebral joints

  • Synovial Joints

    • freely moveable

    • articulating bones are separated by a joint cavity

    • synovial fluid is found in the joint cavity

    • features of synovial joints

      • diarthroses

      • 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 tendon

    • types of synovial joints based on shape

Inflammatory Conditions Associated with Joints

  • Bursitis

    • inflammation of a bursa usually caused by a blow or friction

  • Tendonitis

    • inflammation of tendon sheaths

  • Arthritis

    • inflammatory or degenerative diseases of joints

    • over 100 different types

    • the most widespread crippling disease in the United States

    • Clinical Forms of Arthritis

      • Osteoarthritis

        • most common chronic arthritis

        • probably related to normal aging processes

      • Rheumatoid Arthritis

        • an autoimmune disease - the immune system attacks the joints

        • symptoms begin with bilateral inflammation of certain joints

        • often leads to deformities