Advanced Medical Terminology: The Musculoskeletal System

Overview of the Musculoskeletal System

• The musculoskeletal system is composed of three interrelated components: bones, joints, and muscles.

• Ligaments: These are fibrous bands of tissue that connect bones to one another.

• Tendons: These are bands of tissue that attach muscles to the bone.

• Fascia: This is defined as the tough, fibrous covering of the muscles, as well as some nerves and blood vessels.

• Cartilage: A flexible form of connective tissue. It serves several functions:

  • Covers the ends of many bones.

  • Gives form to the external ear and the tip of the nose.

  • Provides support and protection to various other sites throughout the body.

Primary Functions of the Musculoskeletal System

• Framework: It acts as a structural framework for the body's organ systems.

• Protection: It protects many of the body's vital internal organs.

• Mobility: It provides the organism with the ability to move.

• Storage: Some bones are responsible for the storage of minerals, specifically calcium and phosphorus.

• Hematopoiesis: This is the process of the continual formation of blood, which occurs within the bone marrow.

Healthcare Specialties and Specialists

• Combining Form Warning: The combining form $ped/o$ can refer to either a "child" or a "foot."

• Orthopedics: This is the healthcare specialty dealing with the majority of musculoskeletal disorders.

  • Etymology: Derived from the Greek $ortho$ (meaning "straight") and $pedo$ (meaning "child"). Historically, corrective procedures for disorders like knock-knees and bow-legs were most successful in children due to their softer bones.

  • Specialist: An orthopedist or an "orthopod."

• Rheumatology: This specialty deals with the symptoms of connective tissue, including bone and cartilage.

  • Etymology: Derived from the Greeks, who believed joint disorders were caused by an effusion or outpouring of fluid into the joint space.

  • Specialist: A rheumatologist.

• Physiatry (Physical Medicine): This field concerns the diagnosis and treatment of disease or injury through the use of physical agents.

  • Agents used: Exercise, heat, massage, and light.

  • Specialist: A physiatrist.

  • Categorical Warning: Do not confuse a physiatrist with a physicist or a psychiatrist.

Anatomy and Physiology of Bones

• Total Count: Most adult bodies contain $206$ bones.

• Skeleton Divisions:

  • Axial Skeleton: Consists of the skull, rib cage, and spine.

  • Appendicular Skeleton: Consists of the shoulder bones, collarbones, pelvic bones, arms, and legs.

Shapes and Types of Human Bones

• Long Bones: Examples include the humerus and the femur.

• Short Bones: Examples include the carpal (wrist bone) and tarsal (ankle bone).

• Flat Bones: Examples include the sternum and the scapula.

• Irregular Bones: Examples include the vertebrae and the stapes (ear bone).

• Sesamoid Bones: An example is the patella (kneecap).

Bone Structure and Composition

• Cellular Components:

  • Osteocytes: Mature bone cells.

  • Matrix: The material between cells that stores calcium and phosphorus in the form of mineral salts.

  • Osteoblasts: Cells that build bone.

  • Osteoclasts: Cells that break down bone cells to transform them as needed.

• Tissue Layers:

  • Compact Bone: The hard outer layer of the bone composed of osteocytes and matrix.

  • Spongy (Cancellous) Bone: A second layer within the compact tissue. It is composed of the same materials but is less dense.

• Internal Cavities:

  • Medullary Cavity: Located within the spongy layer.

  • Red Bone Marrow: Located within the spongy layer; it produces all blood cells needed by the body.

Anatomy of a Long Bone

• Diaphysis: The long shaft of the bone.

• Epiphysis: Each end of the bone.

• Epiphyseal Plates: Located underneath the epiphyses, these are the areas where bone growth occurs. These plates generally close between the ages of $16$ and $25$, at which point growth stops.

• Metaphysis: The structure formed by the epiphysis and the epiphyseal plate together.

• Periosteum: The outer covering of the bone.

• Endosteum: The inner lining of the bone.

• Bone Remodeling: Both the periosteum and endosteum hold the cells (osteoblasts and osteoclasts) responsible for bone remodeling.

Bone Features: Depressions and Processes

• Depressions: Any groove, opening, or hollow space. These provide an entrance and exit for vessels and protection for the organs they hold.

• Processes: Raised or projected areas. These often serve as attachment sites for ligaments or tendons.

The Axial Skeleton

The Skull

• Divided into the Cranium (protecting the brain) and Facial Bones.

• Cranium Components:

  • Frontal Bone: Forms the anterior part of the skull and the forehead.

  • Parietal Bones: Form the sides of the cranium.

  • Occipital Bone: Forms the back of the skull. It contains the Foramen Magnum (meaning "large hole"), which allows communication between the brain and spinal cord.

  • Temporal Bones: Form the lower two sides of the cranium. Includes the Mastoid Process (posterior part behind the ear).

  • Ethmoid Bone: Forms the roof and walls of the nasal cavity.

  • Sphenoid Bone: Located anterior to the temporal bones and the basilar part of the occipital bone.

  • Ossicles: Tiny bones within the ear (to be discussed in Chapter 13).

• Paranasal Sinuses: Air-filled cavities lined with mucous membranes, named for the bones in which they are located.

Facial Bones

• Zygoma: The cheekbone; also called the zygomatic bone.

• Lacrimal Bones: Paired bones at the corner of each eye that cradle the tear ducts.

• Maxilla: The upper jawbone (maxillary bone).

• Mandible: The lower jawbone (mandibular bone).

• Vomer: Forms the posterior-inferior part of the nasal septal wall.

• Palatine Bones: Shell-shaped structures making up part of the roof of the mouth.

• Nasal Turbinates: Make up part of the interior of the nose.

• Nasal Bones: A pair of small bones making up the bridge of the nose.

The Rib Cage

• Consists of $12$ pairs of thin, flat bones.

• True Ribs: Seven pairs attached directly to the sternum (breastbone).

• False Ribs: Five pairs. Three attach to the sternum via cartilage, and two are Floating Ribs (not attached in the front at all).

• Sternum: Includes the Xiphoid Process at the most inferior aspect. The term $xiph/o$ is Greek for "sword."

The Spine

• Composed of $26$ bones called vertebrae, divided into five regions from the neck to the tailbone.

• Vertebral Structures:

  • Laminae: Thin, plate-like arches in the vertebrae.

  • Facets: Processes that articulate between vertebrae.

  • Spinous and Transverse Processes: Projections for muscle and ligament attachment.

The Appendicular Skeleton

Upper Appendicular Skeleton

• Shoulder Girdle: Composed of the scapula and clavicle.

  • Scapula: The shoulder blade; a flat bone. The Acromion Process is the lateral protrusion forming the highest point of the shoulder.

  • Clavicle: The collarbone; attaches to the upper sternum and the acromion process. (Fused clavicles in birds are called a wishbone).

• Upper Extremities:

  • Humerus: Upper arm bone. Contains Epicondyles, which are projections for tendon/ligament attachment.

  • Radius: Lower lateral arm bone (thumb side).

  • Ulna: Lower medial arm bone (little finger side). Contains the Olecranon, a proximal projection forming the "funny bone" or tip of the elbow.

  • Carpus: One of the $8$ wrist bones.

  • Metacarpus: One of the $5$ bones of the middle hand.

  • Phalanx (Phalanges): 14 bones of the fingers. The thumb has $2$; the other fingers have $3$ (proximal, medial, distal).

  • Interphalangeal Joints: Joints between phalanges (proximal and distal).

  • Digitus: The term used when referring to a whole finger or toe.

Lower Appendicular Skeleton

• Pelvis (Pelvic Girdle):

  • Ilium: The superior, widest bone of the pelvis. (Caution: Do not confuse with the "ileum" of the digestive system).

  • Ischium: The lower portion of the pelvic bone.

  • Pubis (Pubic Bone): The lower anterior part.

  • Acetabulum: The socket into which the femoral head fits.

• Lower Extremities:

  • Femur: Thigh bone; upper leg bone.

  • Patella: Kneecap.

  • Tibia: Shin bone; lower medial leg bone.

  • Fibula: Smaller lower lateral leg bone.

  • Malleolus: Process on the distal ends of the tibia and fibula.

  • Tarsus: One of the $7$ bones of the ankle/hindfoot. The Calcaneus is the heel bone.

  • Metatarsus: One of the $5$ foot bones between tarsals and phalanges.

  • Phalanx (Phalanges): 14 toe bones ($2$ in the great toe, $3$ in others).

  • Warning: Do not confuse $perion/o$ (fibula) with $periton/e$ (lining of the abdomen) or $perine/o$ (exterior genitalia).

Joints (Articulations)

• Range of Motion (ROM): Categorized by movement ability.

  • Synarthroses: Immovable joints held by fibrous tissue (e.g., suture lines of the skull).

  • Amphiarthroses: Limited ROM joints joined by cartilage (e.g., vertebrae, pubic bones).

  • Diarthroses (Synovial Joints): Full ROM, complex joints.

    • Ball and Socket: Hip.

    • Hinge: Knees, elbows, wrists, shoulders, ankles.

• Components of Synovial Joints:

  • Bursae: Fluid-filled sacs that cushion joints.

  • Joint Capsule: Encloses the bone ends.

  • Synovial Membrane: Lines the capsule and secretes lubricating fluid.

  • Articular Cartilage: Covers and protects the bone.

  • Menisci (Meniscus): Crescent-shaped cartilage in the knee for additional cushioning.

Muscles

• Types of Muscle:

  • Skeletal Muscle: Striated (striped); allows voluntary movement.

  • Smooth Muscle: Responsible for involuntary movement of organs.

  • Heart Muscle: Pumps blood through the circulatory system.

• Muscle Attachment:

  • Origin (O): The non-moving end nearest to the trunk.

  • Insertion (I): The moving end farthest from the trunk.

  • Action (A): The function of the muscle.

• Functional Pairs:

  • Antagonistic Muscles: Pairs that perform opposite actions (e.g., Flexor bends a joint; Extensor stretches it out).

  • Synergistic Muscles: Muscles that work together to refine movement.

• Naming Conventions:

  • By Location: e.g., Pectoralis ($pector/o$ = chest).

  • By Origin and Insertion: e.g., Sternocleidomastoid (attaches to sternum, clavicle, and mastoid process).

Trauma and Pathological Conditions

• Fractures: A broken bone.

  • Pathologic (Spontaneous) Fractures: Result from disease like osteoporosis or cancer rather than trauma.

  • Simple: Does not rupture the skin.

  • Compound: Splits open the skin; higher risk of infection.

• Injuries:

  • Sprain: Traumatic injury to a ligament. Grade 1 (stretching), Grade 2 (partial tear), Grade 3 (complete tear).

  • Strain: Overuse or overstretching of a muscle or tendon.

  • Dislocation: Bone completely out of place in a joint.

  • Subluxation: Bone partially out of the joint.

  • Compartment Syndrome: Swelling within the fascia causing increased pressure, limiting blood supply, and potentially damaging nerves and muscles.

Therapeutic Interventions

• Bone Mending Terms:

  • Malunion: Bone mends but is not aligned correctly.

  • Nonunion: No healing takes place.

  • Sequestrum: A piece of bone that dies due to lack of blood supply.

• Procedures:

  • Debridement: Removal of dirt, damaged tissue, or foreign objects from a wound.

  • Reduction (Manipulation): Alignment and immobilization. Open (OR) involves an incision; Closed (CR) does not.

  • Fixation: Internal (IF) uses pins, screws, or plates inside. External uses devices outside the body for traction.

  • Abbreviations: ORIF (Open Reduction Internal Fixation); CREF (Closed Reduction External Fixation).

Pharmacology

• Analgesics: Reduce pain. Examples: Hydromorphone (Dilaudid), OxyContin, Acetaminophen (Tylenol), NSAIDs (Naproxen/Anaprox).

• Anti-inflammatories: Reduce swelling and pain.

  • Steroids: Methylprednisolone (Medrol).

  • NSAIDs: Ibuprofen (Advil, Motrin), Celecoxib (Celebrex).

• Bisphosphonates: Inhibit bone loss for osteoporosis or Paget's disease. Examples: Alendronate (Fosamax), Zoledronic acid.

• DMARDs (Disease-Modifying Anti-Rheumatic Drugs): Slow progression of RA. Examples: Leflunomide, Etanercept (Enbrel), Infliximab (Remicade).

• Muscle Relaxants: Relieve pain from spasms. Examples: Cyclobenzaprine (Flexeril), Carisoprodol (Soma).