Musculoskeletal System Notes

Musculoskeletal System

Key Combining Forms (Table 3.2)

  • arthr/o: joint
  • auricul/o: ear
  • burs/o: sac
  • calcane/o: heel
  • carp/o: wrist
  • cervic/o: neck; cervix
  • cheil/o: lip
  • chondr/o: cartilage
  • cost/o: rib
  • crani/o: skull
  • dactyl/o: digit, finger, toe
  • dentin/o: teeth
  • duct/o: to bring; duct
  • extens/o: to stretch out
  • femor/o: femur
  • flex/o: to bend
  • gnath/o: jaw, mandible
  • kyph/o: hump
  • lord/o: curve
  • lumb/o: lower back
  • maxill/o: maxilla, upper jaw
  • metacarp/o: metacarpals, hand bones
  • muscul/o: muscle
  • my/o: muscle
  • ophthalm/o: eye
  • orth/o: straight
  • oste/o: bone
  • palat/o: palate
  • phalang/o: phalange, finger, toe
  • rhabdomy/o: skeletal muscle
  • rheumat/o: watery flow
  • roentgen/o: unit of X-ray exposure
  • rotat/o: rotation
  • sacr/o: sacrum
  • scoli/o: crooked
  • Spondyl/o: vertebra
  • tomat/o: mouth
  • tend/o: tendon
  • ten/o: tendon
  • tendin/o: tendon
  • vertebr/o: vertebra

Key Suffixes (Table 3.3)

  • -asthenia: weakness
  • -desis: surgical fusion
  • -dynia: pain
  • -kinesis: movement
  • -listhesis: slipping
  • -malacia: softening
  • -ostosis: bone development
  • -paresis: paralysis
  • -penia: decrease
  • -phyte: plant-like growth
  • -plasia: development; formation of cells
  • -porosis: porous
  • -ptosis: drooping, drooping eyelid
  • -schisis: to split
  • -tonia: tone

Skeletal System Overview

  • Adult human skeleton contains approximately 206206 bones, most of which are paired.
  • Bones are grouped into two categories:
    • Axial skeleton: 8080 bones of the head and trunk.
    • Appendicular skeleton: 126126 bones supporting the appendages.
  • Individuals may have variations in bone number due to anatomical variation (e.g., sesamoid bones).
  • Bones serve as attachment points for muscles.
  • Muscles attach to bones via tendons (fibrous connective tissue).
  • Tendons also connect muscles to each other.
  • Ligaments connect bone to bone (fibrous connective tissue).
  • Sprain: Joint is twisted forcibly enough to tear a ligament, possibly damaging surrounding blood vessels, muscles, nerves and tendons.
  • Strain: Overstretched or partially torn muscle.

Key Terms

  • Appendicular skeleton: Part of the skeleton that includes the bones of the limbs, shoulders, and hips
  • Articular cartilage: Smooth, white tissue that covers the ends of bones where they come together to form joints
  • Axial skeleton: The part of the skeleton that consists of the bones of the head and trunk of the vertebrate
  • Cardiac muscle: A type of muscle tissue that is only found in the heart
  • Compact bone: Dense and hard type of bone tissue
  • Deep fascia: Layer of dense connective tissue that surrounds individual muscles, as well as groups of muscles with similar functions
  • Epiphysis: The end part of a long bone, initially growing separately from the shaft
  • Fascia: A band or sheet of connective tissue, primarily collagen, beneath the skin that attaches, stabilizes, encloses, and separates muscles and other internal organs
  • Fascicle: A bundle of structures, such as nerve or muscle fibers
  • Flat bone: Bones whose principal function is either extensive protection or provision of broad surfaces for muscular attachment (examples: cranial bones (skull), scapula (shoulder blade), sternum (breastbone), and rib bones.
  • Hyaline cartilage: Translucent bluish-white connective tissue consisting of cells embedded in an apparently homogeneous matrix, present in joints, the respiratory tract, and the immature skeleton
  • Intercalated disc: Microscopic identifying features of cardiac muscle, not found in smooth or skeletal muscle.
  • Irregular bone: Bones with complex shapes (examples: vertebrae, hip bones)
  • Long bone: Bones that are longer than they are wide (examples: femur, tibia, fibula, humerus, radius, ulna).
  • Medullary (marrow) cavity: The central cavity of bone shafts where red bone marrow and/or yellow bone marrow (adipose tissue) is stored
  • Muscle fiber: A single muscle cell
  • Myofibril: Any of the elongated contractile threads found in striated muscle cells
  • Myosin: A fibrous protein that forms (together with actin) the contractile filaments of muscle cells and is also involved in motion in other types of cells.
  • Periosteum: A dense layer of vascular connective tissue enveloping the bones except at the surfaces of the joints
  • Red bone marrow: Found mainly in the flat bones and the ends of long bones, and produces blood cells
  • Sarcomere: The fundamental repeating unit of striated muscle, delimited by the Z lines
  • Sesamoid bone: A small nodular bone embedded in a tendon or joint capsule
  • Skeletal muscle: A form of striated muscle tissue which is under the voluntary control of the somatic nervous system
  • Smooth muscle: Muscle tissue in which the contractile fibrils are not highly ordered, occurring in the gut and other internal organs and not under voluntary control
  • Spongy bone: Also called cancellous bone, is a very porous type of bone found in animals
  • Sprain: Occurs when the ligaments that connect bones are stretched beyond their limits and tear
  • Strain: A stretching or tearing of muscle or tendon
  • Striated muscle: Muscle tissue that is marked by transverse dark and light bands
  • Superficial fascia: The outermost layer of fascia, immediately deep to the skin; also known as hypodermis
  • Tendon: A flexible but inelastic cord of strong fibrous collagen tissue attaching a muscle to a bone
  • Thick filament: Composed of myosin, is a component of the sarcomere
  • Thin filament: Composed of actin, is a component of the sarcomere
  • Yellow bone marrow: Found in the medullary cavity of long bones in adults, and consists mainly of fat

Musculoskeletal System

  • Combination of the muscular system and the skeletal system.
  • Muscular system: Primarily muscle tissue.
  • Skeletal system: Tendons, ligaments, cartilage, and bones.
  • Work together to:
    • Maintain body structure.
    • Drive body movement.
    • Provide protection for organs.

Muscle Tissue Types

  • Skeletal muscle (striated muscle):
    • Alternating light and dark bands visible microscopically.
    • Accounts for almost 50%50\% of body weight.
    • Voluntarily controlled.
    • Acts on the skeleton for body movements.
  • Connective tissue (fascia):
    • Surrounds and protects muscle tissue.
  • Superficial fascia:
    • Separates muscle from skin.
    • Contains connective tissue and fat.
    • Allows nerves, blood vessels, and lymphatic vessels to pass.
    • Provides insulation and protection.
  • Deep fascia:
    • Tough fibrous connective tissue.
    • Holds muscles with similar functions together.
    • Lines the body walls.
    • Surrounds groups of individual muscles (muscle fibers) and assembles them into units (fascicles).
    • Muscle fibers contain myofibrils.

Ligaments of the Knee (Figure 3.7)

  • Collateral Ligaments
    • Medial
    • Lateral
  • Cruciate Ligaments
    • Anterior
    • Posterior
  • Patellar Ligament