Musculoskeletal System: Medical Terminology and Anatomy Study Guide

Musculoskeletal System Overview

Introduction

The musculoskeletal system is a complex network of bones, joints, and muscles that provides structure, protection, movement, and support to the human body. Understanding the terminology, anatomy, and physiology of this system is essential for students in medical and allied health fields.

Skeletal System

General Structure and Function

• Bones: The adult human skeleton consists of 206 bones, forming the internal framework of the body.

• Functions: Support, protection of organs, muscle attachment, blood cell production (hematopoiesis), and mineral storage (e.g., calcium, phosphorus).

• Organs: Bones and joints are considered the organs of the skeletal system.

Bone Structure and Classification

• Osseous tissue: The specialized connective tissue that forms bones, among the hardest materials in the body.

• Ossification: The process by which cartilage is gradually replaced by bone tissue, beginning in the fetal skeleton and continuing through adolescence.

• Remodeling: Continuous process where old bone is broken down by osteoclasts and new bone is formed by osteoblasts; in adults, the skeleton is replaced approximately every 10 years.

Classification by Shape

• Long bones: e.g., femur, humerus

• Short bones: e.g., carpals, tarsals

• Flat bones: e.g., scapula, ribs

• Irregular bones: e.g., vertebrae

Long Bone Anatomy

• Diaphysis: The central shaft containing the medullary cavity (yellow marrow).

• Epiphysis: The wide ends of the bone, covered with articular cartilage for joint movement.

• Periosteum: Tough, fibrous membrane covering the bone except at joint surfaces.

• Compact (cortical) bone: Dense outer layer providing strength.

• Cancellous (spongy) bone: Porous inner bone containing red marrow for blood cell production.

Bony Projections and Depressions

• Processes: Projections or outgrowths on bones that serve as attachment points for muscles or form joints.

• Examples: Trochanter, tubercle, condyle, crest, spine (projections); fossa, foramen, sinus (depressions).

Divisions of the Skeleton

• Axial skeleton: Skull, vertebral column, rib cage, and sternum (central axis of the body).

• Appendicular skeleton: Pectoral girdle, upper limbs, pelvic girdle, and lower limbs (appendages).

Skull and Facial Bones

• Cranium: Frontal, parietal, temporal, ethmoid, sphenoid, occipital bones.

• Facial bones: Mandible, maxilla, zygomatic, vomer, palatine, nasal, lacrimal bones.

Vertebral Column

• Cervical (C1–C7): Neck region

• Thoracic (T1–T12): Chest region

• Lumbar (L1–L5): Lower back

• Sacrum: Base of the spine

• Coccyx: Tailbone

Rib Cage

• True ribs (1–7): Attach directly to the sternum

• False ribs (8–10): Attach indirectly to the sternum

• Floating ribs (11–12): Do not attach to the sternum

Appendicular Skeleton

• Pectoral girdle: Clavicle and scapula

• Upper extremity: Humerus, radius, ulna, carpals, metacarpals, phalanges

• Pelvic girdle: Ilium, ischium, pubis

• Lower extremity: Femur, patella, tibia, fibula, tarsals, metatarsals, phalanges

Joints (Articulations)

• Definition: Joints are locations where two or more bones meet.

• Types of joints:

  • Synovial joints: Freely movable (e.g., knee, shoulder); contain synovial fluid and are stabilized by ligaments and sometimes menisci or bursae.

  • Cartilaginous joints: Slightly movable, bones joined by cartilage (e.g., pubic symphysis).

  • Fibrous joints: Immovable, bones joined by fibrous tissue (e.g., skull sutures).

Bone Pathology and Fractures

Common Fracture Types

• Transverse: Straight across the bone

• Oblique: Angled fracture

• Spiral: Twisting force causes a spiral break

• Greenstick: Incomplete break, common in children

• Comminuted: Bone is shattered into several pieces

Bone Diseases

• Osteogenic sarcoma: Malignant bone tumor, often seen in long bones.

• Osteopenia and osteoporosis: Conditions of decreased bone density, increasing fracture risk.

Spinal Pathology

• Herniated disk: Protrusion of intervertebral disk, may compress spinal nerves.

• Abnormal curvatures: Kyphosis (humpback), lordosis (swayback), scoliosis (lateral curvature).

Muscular System

General Structure and Function

• Muscles: Organs composed of bundles of muscle fibers that contract to produce movement.

• Functions: Movement, posture, heat production, and stabilization of joints.

• Types of muscle tissue: Skeletal (voluntary), smooth (involuntary), cardiac (involuntary).

Skeletal Muscle Anatomy and Actions

• Origin: Less movable attachment point of a muscle.

• Insertion: More movable attachment point.

• Action: The movement produced by muscle contraction.

• Antagonistic pairs: Muscles often work in pairs with opposite actions (e.g., biceps and triceps).

Key Medical Terminology

Combining Forms, Prefixes, and Suffixes

• Oste/o: Bone

• Arthr/o: Joint

• My/o, myos/o: Muscle

• -algia: Pain

• -itis: Inflammation

• -centesis: Surgical puncture to remove fluid

• -ectomy: Surgical removal

• Hyper-: Excessive

• Poly-: Many

Selected Pathology Terms

• Osteoarthritis: Inflammation of bones and joints

• Kyphosis: Abnormal posterior curvature of the thoracic spine

• Myorrhexis: Rupture of muscle

• Polymyositis: Inflammation of many muscles

Selected Diagnostic and Therapeutic Terms

• Myelography: X-ray imaging of the spinal cord

• Arthroscopy: Visual examination of a joint using an endoscope

• Arthrocentesis: Puncture of a joint to remove fluid

• Bursectomy: Surgical removal of a bursa

Summary Table: Types of Joints

Type of Joint	Movement	Example
Synovial	Freely movable	Knee, shoulder
Cartilaginous	Slightly movable	Pubic symphysis
Fibrous	Immovable	Skull sutures

Conclusion

Mastery of musculoskeletal system terminology, anatomy, and pathology is foundational for medical terminology students. Understanding the structure and function of bones, joints, and muscles, as well as the language used to describe their conditions and treatments, is essential for effective communication in healthcare settings.