Biology Chapter 1: Body Structure

Chapter 1 - Structure

• The body is made up of 4 primary types of tissues:
  • Connective tissue (bone, cartilage, and soft tissue)
  • Muscle tissue (skeletal muscle, cardiac muscle, and smooth muscle)
  • Nerve tissue (neurons and neuroglia)
  • Epithelial tissue (respiratory, gastrointestinal, urinary, and reproductive systems)
• Long bones:
  • Framework for the body
  • Enable body movement
  • Composed of diaphysis (shaft) and two epiphyses (prominences)
  • Grows from the epiphyseal plates (growth plate)
  • Bone cells produced by periosteum
  • Protected from wear and tear by articular cartilage
• Wolff's Law:
  • Bones respond to stress
  • Bones are constantly undergoing a remodeling process
  • Osteoclasts - bone breakdown
  • Osteoblasts - bone formation
  • Mechanical stress →↑ Osteoblasts →↑ Bone formation
  • Physical activity →↑ Bone formation

Skeletal Muscle

• Ability to produce force and movement
• Four properties of skeletal muscle:
  • Extensibility (ability of muscle to be stretched)
  • Elasticity (ability of muscle to return to its original length)
  • Contractility (ability of muscle to shorten and develop tension)
  • Excitability (ability of muscle to be sensitive or responsive to chemical, electrical, or mechanical stimuli)
• Types of Contraction:
  • Concentric contraction (shortening of a muscle against resistance)
  • Eccentric contraction (lengthening of a muscle under tension)
  • Isometric contraction (tensing of a muscle without movement at the joint)

Chapter 2 - Movement

• Anatomical Locations:
  • Superior (above or higher than another structure)
  • Inferior (below or lower than another structure)
  • Lateral (farther away from the midline of the body than another structure)
• Volar:
  • The downside or bottom aspect of a structure
  • Palmar aspect of the wrist or hand
• Pronation:
  • Turning of the forearm toward the body, resulting in the volar (palmar surface of the hand facing the body)
• Supination:
  • Turning the forearm outward and palm upward from the pronated position
• Planes:
  • Sagittal plane (passes from the front through the back, creating a left and right side)
  • Horizontal plane (passes through the body horizontally, creating top and bottom segments)
  • Frontal plane (passes from one side to the other, creating a front side and a back side)
• Fundamental Movements:
  • Flexion (reduction of the joint angle)
  • Extension (increase of the joint angle)
  • Abduction (movement away from the midline of the body)
  • Adduction (movement toward the midline of the body)
  • External rotation (rotation of a limb away from the midline of the body)
  • Internal rotation (rotation of a limb toward the midline of the body)
  • Circumduction (orderly combination of shoulder movements, tracing a circle with the hand and a cone with the arm)

Chapter 3 - The Shoulder

• Bones of the Shoulder Girdle:
  • Clavicle and scapula
  • Position the shoulder joint to accommodate movement
• Ligaments of Shoulder Girdle:
  • Three ligaments for the sternoclavicular joint
  • Sternoclavicular ligament (stabilizes the sternoclavicular articulation)
  • Costoclavicular ligament (secures the sternal end of the clavicle to the first rib)
  • Interclavicular ligament (secures ends of both clavicles into the sternum)
• Movements of the Shoulder Girdle:
  • Elevation (upward movement of the scapula in the frontal plane)
  • Depression (downward movement of the scapula in the frontal plane)
  • Abduction (upward rotation and lateral tilt of the scapula)
  • Adduction (downward movement of the glenoid of the scapula)
• Anterior Muscles of the Shoulder Girdle:
  • Pectoralis minor (originates from the 3rd, 4th, and 5th ribs, inserts on the coracoid process of the scapula)
  • Serratus anterior (originates from the anterior lateral aspects of the upper nine ribs, inserts on the anterior surface of the vertebral border of the scapula)
• Scapulohumeral Rhythm:
  • Phases of movement
  • Early phase (0~30° of abduction): primarily involves movement at the glenohumeral joint with minimal scapular movement
  • Mid-phase (30~90° of abduction): involves both the glenohumeral and scapulothoracic joints with increasing scapular upward rotation
  • Late phase (90~180° of abduction): continues glenohumeral movement by scapular rotation and elevation

Chapter 4 - The Elbow and Forearm

• Bones of the Elbow and Forearm:
  • Three main fossae on the distal humerus
  • Coronoid fossa (located on the anterior aspect of the distal humerus, involved in full flexion of the elbow joint)
  • Radial fossa (located on the anterior aspect of the distal humerus, involved in full flexion of the elbow joint)
  • Olecranon fossa (located on the posterior aspect of the distal humerus, involved in full extension of the elbow joint)
• Ligaments of the Elbow and Forearm:
  • Ulnar collateral ligament (runs along the medial side of the elbow, prevents excessive valgus stress)
  • Oblique cord ligament (runs from the lateral aspect of the ulna to the radial tuberosity on the radius, stabilizes the proximal radioulnar joint and limits separation between the radius and ulna)
• Anterior Muscles of the Elbow:
  • Brachialis (originates on the middle of the anterior shaft of the humerus, inserts on the coronoid process of the ulna, involved in flexion of the elbow joint)
  • Brachioradialis (originates from the lateral epicondyle of the humerus, inserts on the radial styloid process, involved in flexion of the elbow joint)
• Posterior Muscles of the Elbow:
  • Triceps brachii (originates from the infraglenoid tubercle of the scapula, involved in extension of the elbow joint)

Anatomical Locations

• Superior: a location above or higher than another structure (e.g., the head is superior to the chest)
• Inferior: a location below or lower than another structure (e.g., the chest is inferior to the head)
• Lateral: a location farther away from the midline of the body than another structure (e.g., the arms are lateral to the spinal column)
• Volar: the downside or bottom aspect of a structure (e.g., the volar aspect of the wrist or hand is referred to as the palmar aspect)
• Pronation: the turning of the forearm toward the body, resulting in the volar (palmar surface of the hand) facing the body
• Supination: the turning of the forearm outward and palm upward from the pronated position

Planes

• Three planes:
  • Sagittal plane: passes from the front through the back, creating a left and right side
  • Horizontal plane: passes through the body horizontally, creating top and bottom segments
  • Frontal plane: passes from one side to the other, creating a front side and a back side

Fundamental Movements

• In the sagittal plane:
  • Flexion: a reduction of the joint angle
  • Extension: an increase of the joint angle
• In the frontal plane:
  • Abduction: a movement away from the midline of the body
  • Adduction: a movement toward the midline of the body
• In the horizontal plane:
  • External rotation: the rotation of a limb away from the midline of the body
  • Internal rotation: the rotation of a limb toward the midline of the body
• Circumduction: the orderly combination of shoulder movements, producing a circular motion

Kinetic Chain

• The interconnected system of body segments, joints, and muscles during movement
• Two types of kinetic chains:
  • Closed kinetic chain (CKC): the distal segment of the chain is fixed or attached to an object (e.g., floor, wall, or ground)
  • Open kinetic chain (OKC): the distal segment of the chain is free to move in space

The Shoulder

• Bones of the shoulder girdle:
  • Clavicle: a long, slender, S-shaped bone that attaches to the sternum at the medial end and the scapula at the lateral end
  • Scapula: facilitates movement of the shoulder joint
• Ligaments of the shoulder girdle:
  • Three ligaments for the sternoclavicular joint: sternoclavicular ligament, costoclavicular ligament, and interclavicular ligament
• Movements of the shoulder girdle:
  • Elevation: upward movement of the scapula in the frontal plane
  • Depression: downward movement of the scapula in the frontal plane
  • Abduction: upward rotation and lateral tilt of the scapula
  • Adduction: downward movement of the glenoid of the scapula

Anterior Muscles of the Shoulder Girdle

• Pectoralis minor: originates from the 3rd, 4th, and 5th ribs and inserts on the coracoid process of the scapula, responsible for downward rotation or adduction of the shoulder girdle
• Serratus anterior: originates from the anterior lateral aspects of the upper nine ribs and inserts on the anterior surface of the vertebral border of the scapula, responsible for upward rotation and lateral tilt of the shoulder girdle

Scapulohumeral Rhythm

• Phases of movement:
  • Early phase (0-30° of abduction): primarily involves movement at the glenohumeral joint with minimal scapular movement
  • Mid-phase (30-90° of abduction): involves both the glenohumeral and scapulothoracic joints with increasing scapular upward rotation
  • Late phase (90-180° of abduction): continues glenohumeral movement by scapular rotation and elevation

The Elbow and Forearm

• Bones of the elbow and forearm:
  • Three main fossae on the distal humerus: coronoid fossa, radial fossa, and olecranon fossa
• Ligaments of the elbow and forearm:
  • Ulnar collateral ligament: runs along the medial side of the elbow and prevents excessive valgus stress
  • Oblique cord ligament: runs from the lateral aspect of the ulna to the radial tuberosity on the radius and stabilizes the proximal radioulnar joint
• Anterior muscles of the elbow:
  • Brachialis: originates on the middle of the anterior shaft of the humerus and inserts on the coronoid process of the ulna, responsible for flexion of the elbow joint
  • Brachioradialis: originates from the lateral epicondyle of the humerus and inserts on the radial styloid process, responsible for flexion of the elbow joint
• Posterior muscles of the elbow:
  • Triceps brachii: originates from the infraglenoid tubercle of the scapula, posterior surface of the humerus, and inserts on the olecranon process of the ulna, responsible for extension of the elbow joint

Muscles of the Forearm

• Supinator: originates on the ulna and inserts on the radius at the proximal ends of the bones on the posterior aspect, responsible for supination of the forearm
• Biceps brachii: when the forearm is in pronation, responsible for lateral rotation of the forearm