Skeletal and Muscular Systems

• The notes cover the skeletal and muscular systems.

Role of the Skeleton

• Protection of internal organs from injury.
• Provides structural support for the body.
• Attachment points for muscles.
• Storage of essential nutrients.
• Blood-cell formation.

Axial vs. Appendicular Skeleton

• Axial skeleton: 80 bones (26 vertebral, 1 hyoid, 22 skull, 6 auditory, 25 ribs).
• Appendicular skeleton: 126 bones (64 upper extremity, 62 lower).

About Bones

• Bones are 50% water and 50% organic and inorganic material.
• Contains elements: phosphorous, zinc, calcium, magnesium, fluorine, iron, chlorine.
• Resist compression and tension.
• Bound by joints using ligaments.
• Muscles attach to bones using tendons for movement.

Types of Bones

• Long bones are found in arms and legs.
• Short bones are found in wrists and ankles.
• Flat bones include skull bones, ribcage, and shoulder blade.
• Irregular bones are bones of the vertebrae.
• Sesamoid bones are wrapped within tendons, such as the patella.

Anatomy of a Long Bone

• Cancellous (spongy) bone.
• Compact bone.
• Medullary cavity.
• Periosteum.
• Cartilage.
• Epiphysis.
• Diaphysis.

Types of Joints

• Fibrous joint: Two bones united by connective tissue, virtually immobile.
• Cartilaginous joint: Bones united by cartilage, with very little movement.
• Synovial joint: The body's main functional joints are freely mobile.

Types of Synovial Joints

• Ball & Socket joint: Hip joint which allows movement in all directions.
• Hinge joint: Elbow joint which allows bending and straightening movement.
• Saddle joint: Thumb joint allows back-and-forth and side-to-side movement.
• Gliding joint: Wrist joint allows bones to slide over each other.
• Pivot joint: Neck joint allows rotational movement.

Characteristics of a Synovial Joint

• Contains a synovial cavity (joint).
• Articular cartilage and an articular capsule are present.
• Synovial membrane secretes synovial fluid, forming a thin, viscous film.

Tissue Properties

• Tendons are composed of collagen, attach muscle to bone, and are vascular
• Ligaments are tough bands of white, fibrous tissue, attach bone to bone, and are avascular

Common Injuries of the Skeletal System

• Strains, pulls, and tears are terms that describe injuries to all joint tissue types.
• Tendinitis is inflammation of a tendon.
• Dislocations occurs when bone becomes displaced from its original location.
• Separations is when fibrous ligaments that bind the bones tear and separate
• Shin splints: stress fractures in the lower leg bones

Diseases of the Skeletal System

• Osteoporosis cause a Loss of minerals and decrease in bone density due to increased osteoclast activity and can be caused by a diet low in calcium.
• Rickets and Osteomalacia: Demineralization of bone due to a deficiency in Vitamin D.
• Gout (Gouty Arthritis): Inflammation within joints causing pain/discomfort and is caused by high levels of protein in the diet which result in uric acid buildup in the blood

Fractures

• Fractures are any break in a bone, diagnosable through X-rays,

Types of Fractures

• Partial: Incomplete break across the bone (crack)
• Complete: Complete break into two or more pieces
• Closed fracture: Bone does not break through the skin.
• Open (compound) fracture: Bone protrudes through the skin.
• Repair involves hematoma, new blood vessels forming, bony callus, and a healed fracture.

Dislocation

• Dislocation is an injury where bone ends are forced from their normal positions.
• Causes temporary deformation and immobilization of the joint.
• Most common in shoulders and fingers.

Muscular System

• Major functions include movement, support, and heat production.
• The human body has over 600 muscles.

Types of Muscle Tissue

• Skeletal muscles: Voluntary, striated, attached to bones via tendons.
• Cardiac muscles: Involuntary, striated, found only in the heart.
• Smooth muscles: Involuntary, non-striated, surround internal organs.

Properties of Muscle Fiber

• Irritability: Responds to stimuli.
• Contractibility: Muscle shortens in length.
• Elasticity: Stretches and returns to normal position.
• Extensibility: Extends in length.
• Conductivity: Transmits nerve impulses.

Anatomy of Skeletal Muscle

• Perimysium: Binds muscle fibers together.
• Epimysium: Sheath enveloping entire muscle.
• Endomysium: Sheath of connective tissue surrounding muscle fiber.

How Muscles Are Named

• Action/Function: Flexion/Extension.
• Direction of Fibers: Rectus/Transversus.
• Location: Anterior/Posterior.
• Number of Divisions/Heads.
• Shape: Deltoid/Trapezius.
• Points of Attachment: Sternum/Clavicle/Mastoid process.

How Muscles Attach to Bone

• Indirect attachment: Epimysium extends as a tendon and attaches to periosteum.
• Direct attachment: Epimysium adheres to and fuses with the periosteum.

Origin, Insertion and Function of Muscles

• Origin: Proximal attachment to the least moveable area of the axial skeleton.
• Insertion: Distal attachment to the bone that is moved most.
• Function: Action/motion when activated.

Muscles to Know

• Sternocleidomastoid: Muscles of the neck.
• Erector Spinae Group: Muscles of the vertebral column.
• Rectus/External Obliques Abdominis: Muscles of the abdomen.
• Bicep/Tricep Brachii: Muscles of the elbow flexors/extensors.
• Forearm Flexors/Extensors.
• Quadricep/Hamstring Group: Muscles of the thigh (anterior/posterior).
• Tibialis Anterior/Gastrocnemius/Soleus: Muscles of the extrinsic foot (A/P).
• Trapezius: Muscles of the upper back.
• Deltoids: Muscles of the shoulders.
• Pectoralis Major: Muscles of the chest.
• Latissimus Dorsi: Muscles of the lower back.
• Adductor group: Muscles of the hip.
• Gluteus Maximus: Muscles of the glute.

Ways to Injure Muscles

• Contusion (bruise): Caused by a sudden, strong compressive direct blow to muscle tissue.
• Strain: Caused during sprinting, jumping, rapid muscular contraction, or overstretching.
• Laceration: Skin, tissue, and/or muscle is torn.

Grades of Soft Tissue Injuries

• Grade I strain: Only a few muscle fibers are stretched or torn.
• Grade II strain: Moderate strain, more injured fibers, mild swelling, noticeable loss of strength, and sometimes a bruise.
• Grade III strain: Complete loss of muscle function, full rupture, pain, swelling, tenderness, discoloration.

R.I.C.E.

• Rest: Immobilize injured site for 24-72 hours.
• Ice: Combat and reduce inflammation by causing vasoconstriction.
• Compression: Reduce blood flow and inflammation.
• Elevation: Place injured extremity above the heart to reduce hydrostatic pressure.