Human Anatomy & Physiology II: Review of Skeletal, Muscular, and Nervous Systems

Chapter 6: Bones & Skeletal Tissues

Overview of Skeletal Cartilages

The human skeleton is initially made up of cartilages and fibrous membranes, which are replaced by bone during development. Cartilage remains in areas where flexibility is needed.

• Hyaline cartilage: Most abundant; provides support, flexibility, and resilience. Found in articular surfaces, costal cartilages, respiratory tract, and nasal cartilage.

• Elastic cartilage: Contains more elastic fibers; found in the external ear and epiglottis.

• Fibrocartilage: Highly compressible with great tensile strength; found in intervertebral discs and menisci of the knee.

Functions of the Skeletal System:

• Support

• Protection

• Movement

• Mineral and growth factor storage

• Blood cell formation (hematopoiesis)

• Triglyceride (fat) storage

• Hormone production

Classification of Bones:

• Long bones (e.g., femur, humerus)

• Short bones (e.g., carpals, tarsals)

• Flat bones (e.g., sternum, skull)

• Irregular bones (e.g., vertebrae, hip bones)

Structure of a Typical Long Bone:

• Diaphysis: Shaft, composed of compact bone surrounding a medullary cavity.

• Epiphyses: Ends of the bone, mostly spongy bone covered by compact bone.

• Periosteum: Double-layered membrane covering the bone except at joint surfaces.

• Endosteum: Membrane lining the medullary cavity.

Cells of Bone Tissue:

• Osteogenic cells: Stem cells in periosteum and endosteum.

• Osteoblasts: Bone-forming cells.

• Osteocytes: Mature bone cells maintaining bone matrix.

• Osteoclasts: Bone-resorbing cells.

Example: The femur is a long bone that supports body weight and facilitates movement.

Chapter 7: The Skeleton

Axial and Appendicular Skeleton

The skeleton is divided into two main regions:

• Axial skeleton: Skull, vertebral column, and thoracic cage.

• Appendicular skeleton: Limbs and girdles (pectoral and pelvic).

Major Bones and Landmarks:

• Skull: Cranial and facial bones

• Vertebral column: Cervical, thoracic, lumbar vertebrae, sacrum, coccyx

• Thoracic cage: Sternum, ribs

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

• Lower limb: Femur, tibia, fibula, tarsals, metatarsals, phalanges

Example: The scapula (shoulder blade) is part of the appendicular skeleton and provides attachment for muscles that move the arm.

Chapter 8: Joints

Classification and Structure of Joints

Joints, or articulations, are sites where two or more bones meet. They are classified by structure and function.

• Structural classification:

  • Fibrous joints (e.g., sutures of the skull)

  • Cartilaginous joints (e.g., intervertebral discs)

  • Synovial joints (e.g., knee, elbow)

• Functional classification:

  • Synarthroses (immovable)

  • Amphiarthroses (slightly movable)

  • Diarthroses (freely movable)

General Structure of Synovial Joints:

• Articular cartilage

• Joint (synovial) cavity

• Articular capsule

• Synovial fluid

• Reinforcing ligaments

• Nerves and blood vessels

Types of Synovial Joints:

• Plane

• Hinge

• Pivot

• Condyloid

• Saddle

• Ball-and-socket

Example: The knee joint is a hinge synovial joint that allows flexion and extension of the leg.

Chapter 9: Muscles and Muscle Tissue

Overview of Muscle Types and Functions

Muscle tissue is essential for movement, posture, and heat production. There are three types of muscle tissue:

• Skeletal muscle: Voluntary, striated, attached to bones for movement.

• Cardiac muscle: Involuntary, striated, found only in the heart.

• Smooth muscle: Involuntary, non-striated, found in walls of hollow organs.

Functions of Muscle Tissue:

• Movement of bones or fluids

• Maintaining posture and body position

• Stabilizing joints

• Heat generation

Microscopic Anatomy of Skeletal Muscle:

• Muscle fiber (cell)

• Myofibrils (contain sarcomeres, the contractile units)

• Sarcolemma (muscle cell membrane)

• Sarcoplasmic reticulum (stores calcium)

Example: Biceps brachii is a skeletal muscle responsible for flexing the forearm.

Chapter 10: The Muscular System

Major Muscles and Muscle Actions

The muscular system consists of skeletal muscles that produce movement by acting on the skeleton. Muscles are named based on location, shape, size, direction of fibers, number of origins, location of attachments, and action.

• Prime mover (agonist): Main muscle responsible for movement.

• Antagonist: Opposes or reverses a movement.

• Synergist: Assists the prime mover.

• Fixator: Stabilizes the origin of the prime mover.

Example: During elbow flexion, the biceps brachii is the prime mover, and the triceps brachii is the antagonist.

Chapter 11: Fundamentals of the Nervous System and Nervous Tissue

Overview of Nervous System Structure and Function

The nervous system is the master control and communication system of the body. It is divided into:

• Central nervous system (CNS): Brain and spinal cord

• Peripheral nervous system (PNS): Cranial and spinal nerves

Functions:

• Sensory input

• Integration

• Motor output

Cells of Nervous Tissue:

• Neurons: Excitable cells that transmit electrical signals

• Neuroglia: Supporting cells

Example: Sensory neurons carry information from the skin to the CNS.

Table: Types of Skeletal Cartilage

Type	Location	Function
Hyaline	Articular surfaces, costal cartilages, nose, trachea	Support, flexibility, resilience
Elastic	External ear, epiglottis	Maintains shape, flexibility
Fibrocartilage	Intervertebral discs, menisci	Strength, shock absorption

Table: Types of Synovial Joints

Type	Movement	Example
Plane	Gliding	Intercarpal joints
Hinge	Flexion/Extension	Elbow, knee
Pivot	Rotation	Proximal radioulnar joint
Condyloid	Flexion/Extension, Abduction/Adduction	Wrist
Saddle	Flexion/Extension, Abduction/Adduction	Thumb (carpometacarpal joint)
Ball-and-socket	All axes, rotation	Shoulder, hip