Exercise Science 4

Musculoskeletal System: Upper Extremity

Chapter Overview

  • Instructor: Nicole Mendola, MS, RCEP, C-EP, GEI, EIM III
  • Focus: The structure and function of the musculoskeletal components of the upper extremity, including bones, joints, and muscles of the shoulder, elbow, and wrist/hand.

Objectives

  • Discuss the bones, joints, and muscles of the upper body, specifically:
    • Shoulder
    • Elbow
    • Hand/wrist/fingers
  • Identify the origin and insertion points of muscles
  • Analyze the direction of pull and joint actions of muscles

Joint Action

  • Mechanics of Muscle Contraction:
    • Skeletal muscles produce force that is transferred to tendons, which then pull on bones and other structures.
    • Most muscles cross joints, contracting to pull one of the articulating bones toward the other.
  • Definitions:
    • Origin: The attachment point of a muscle that is more stationary and proximal.
    • Insertion: The attachment point of a muscle that is more mobile and distal.

Shoulder Anatomy

  • Structure:
    • Multi-joint structure providing a connection between the thoracic cage and the upper extremity.
    • High degree of mobility but unstable; stability is provided by muscles, ligaments, and joint capsules.
Shoulder Bones

  • Humerus:

    • The major bone of the arm.
    • Key Features:
    • Humeral head articulates with the glenoid fossa of scapula.
    • Greater and lesser tubercles serve as muscle attachment sites.

  • Scapula:

    • A large triangular bone located posteriorly in the thoracic cage, between ribs 2 and 7.
    • Glenoid Fossa: Faces anterolaterally to accommodate the humeral head.
    • Acromion Process: Situated at the superior aspect, it articulates with the clavicle.

  • Clavicle:

    • Runs obliquely to connect the upper extremity to the axial skeleton.
    • Functions:
    • Provides protection for the "brachial plexus" nerve bundle and vasculature supplying the upper extremity.
    • Supports the weight of the humerus and maintains the position of scapula and humerus.

Shoulder Joints

  • Complex Structure: Four joints including:
    • Glenohumeral Joint:
    • Type: Ball and socket; the most freely movable joint in the body.
    • Acromioclavicular Joint:
    • Type: Synovial joint.
    • Sternoclavicular Joint:
    • Type: Saddle synovial joint; allows movements in synchronization with other shoulder joints.
    • Provides the only bony connection between the humerus and axial skeleton.
    • Scapulothoracic Joint:
    • Not a true joint; considered a physiological joint.

Planes of Motion

  • There are three primary planes of motion:
    • Sagittal Plane: Divides the body into right and left halves.
    • Frontal Plane: Divides the body into anterior (front) and posterior (back) sections.
    • Transverse Plane: Divides the body into superior (upper) and inferior (lower) halves.

Shoulder Joint Movements

  • Movements at the Glenohumeral Joint:
    • Abduction/Adduction: Occurs in the frontal plane.
    • Flexion/Extension: Occurs in the sagittal plane.
    • Internal/External Rotation: Occurs in the transverse plane.
    • Horizontal Abduction/Adduction: Occurs in the transverse plane.
    • Circumduction: A conical movement encompassing all the above.
Glenohumeral Movement Visualization

  • Movements Illustrated:

    • Abduction
    • Adduction
    • Circumduction
    • Flexion
    • Extension
    • Horizontal Abduction
    • Horizontal Adduction
    • Internal Rotation
    • External Rotation

  • Movements at the Scapulothoracic Joint:

    • Internal/External Rotation: Transverse.
    • Retraction/Protraction: Frontal.
    • Elevation/Depression: Frontal.
    • Anterior/Posterior Tilting: Sagittal.
Scapulohumeral Rhythm
  • This refers to the coordinated movement of the glenohumeral joint and scapulothoracic joint during arm elevation.
  • Mechanism: For every 3 degrees of elevation of the arm, 2 degrees occur at the glenohumeral joint and 1 degree at the scapulothoracic joint.

Shoulder Muscles

  • Muscles of the Shoulder:
    • Functionality:
    • Muscles directly moving the arm are categorized separately from those stabilizing the shoulder girdle.
Anterior Shoulder Muscles

  • Pectoralis Major:

    • Origin: ?
    • Insertion: ?
    • Actions:
    • Adduction
    • Horizontal Adduction
    • Internal Rotation of Humerus

  • Subscapularis:

    • Origin: ?
    • Insertion: ?
    • Actions:
    • Flexion
    • Adduction
    • Horizontal Adduction
    • Internal Rotation of Humerus

  • Coracobrachialis:

    • Origin: ?
    • Insertion: ?
    • Action:
    • Internal Rotation of Humerus

  • Biceps Brachii:

    • Origin: ?
    • Insertion: ?
    • Action:
    • Flexion
Superior Shoulder Muscles
  • Deltoid:
    • Anterior Head:
    • Origin: ?
    • Insertion: ?
    • Actions:
      • Flexion
      • Horizontal Adduction
      • Internal Rotation
    • Middle Head:
    • Origin: ?
    • Insertion: ?
    • Action:
      • Abduction
      • Horizontal Abduction
    • Posterior Head:
    • Origin: ?
    • Insertion: ?
    • Actions:
      • Extension
      • External Rotation of Humerus
Inferior Shoulder Muscles

  • Latissimus Dorsi:

    • Origin: ?
    • Insertion: ?
    • Actions:
    • Extension
    • Internal Rotation
    • Adduction of Humerus

  • Teres Major:

    • Origin: ?
    • Insertion: ?
    • Actions:
    • Extension
    • Internal Rotation
    • Adduction of Humerus

  • Triceps Brachii (Long Head):

    • Origin: ?
    • Insertion: ?
    • Action:
    • Adduction
Rotator Cuff Muscles
  • Components and Actions:
    • Supraspinatus:
    • Action: Abduction
    • Infraspinatus:
    • Action: External Rotation
    • Teres Minor:
    • Action: External Rotation
    • Subscapularis:
    • Actions:
      • Flexion
      • Adduction
      • Horizontal Adduction
      • Internal Rotation of Humerus
    • Origins and Insertions:
    • Not fully defined in the notes.
Shoulder Girdle Muscles

  • Anterior Muscles:

    • Pectoralis Minor:
    • Origin: ?
    • Insertion: ?
    • Actions:
      • Protraction
      • Downward Rotation
      • Depression of Scapula
    • Serratus Anterior:
    • Origin: ?
    • Insertion: ?
    • Action:
      • Protraction of Scapula
    • Subclavius:
    • Origin: ?
    • Insertion: ?
    • Action:
      • Stabilizes Sternoclavicular Joint

  • Posterior Muscles:

    • Levator Scapulae:
    • Origin: ?
    • Insertion: ?
    • Action:
      • Elevation
      • Downward Rotation of Scapula
    • Rhomboids:
    • Origin: ?
    • Insertion: ?
    • Actions:
      • Retraction
      • Downward Rotation
      • Elevation of Scapula
    • Trapezius:
    • Origin: ?
    • Insertion: ?
    • Actions:
      • Elevation
      • Retraction
      • Depression of Scapula

Elbow Anatomy

  • Bones:
    • Humerus, Radius, and Ulna
Elbow Joints
  • Compound synovial joint comprising two key articulations:
    • Humeroulnar Joint:
    • Articulation between the distal humerus and proximal ulna.
    • Humeroradial Joint:
    • Articulation between the distal humerus and proximal radius.
    • Proximal Radioulnar Joint:
    • Articulation of the proximal radius with the proximal ulna.
Elbow Ligaments
  • Ulnar (Medial) Collateral Ligament:
    • Connects the humerus with the ulna.
  • Radial (Lateral) Collateral Ligament:
    • Connects the humerus with the radius.
  • Annular Ligament:
    • Connects the radius with the ulna.
Elbow Movements
  • Movement Types:
    • The elbow primarily operates as a hinge joint that allows flexion and extension in the sagittal plane.
    • Range of Motion (ROM):
    • Flexion: 145° to 150°
    • Additional Movements:
    • Supination
    • Pronation
Anterior Elbow Muscles

  • Biceps Brachii:

    • Origin: ?
    • Insertion: ?
    • Actions:
    • Supination
    • Flexion of Elbow

  • Brachialis:

    • Origin: ?
    • Insertion: ?
    • Action:
    • Flexion of Elbow

  • Brachioradialis:

    • Origin: ?
    • Insertion: ?
    • Action:
    • Flexion of Elbow
Posterior Elbow Muscles
  • Triceps Brachii:
    • Origin: ?
    • Insertion: ?
    • Action:
    • Extension
  • Anconeus:
    • Aids in stability.

Wrist, Hands, and Fingers Anatomy

  • Total Bones: 29 bones including:
    • Distal Ulna
    • Distal Radius
    • 8 Carpals
    • 5 Metacarpals
    • 14 Phalanges
Carpal Bones Arrangement
  • Carpals: Small, oddly shaped bones arranged in two rows.
    • Proximal Row (Lateral to Medial):
    • Scaphoid (Navicular), Lunate, Triquetrum, Pisiform
    • Distal Row (Lateral to Medial):
    • Trapezium, Trapezoid, Capitate, Hamate
  • Each digit has three phalanges except the thumb, which has two.
Wrist Joints
  • Primary Wrist Joint:
    • Radiocarpal Joint:
    • Type: Condyloid (Ellipsoidal) joint, connecting the distal radius with the proximal carpal bones (Scaphoid, Lunate, Triquetrum).
    • Midcarpal Joint:
    • Articulation between proximal and distal rows of carpal bones.
    • Distal Radioulnar Joint:
    • Type: Pivot joint allowing supination and pronation.
Wrist Movements
  • The wrist allows for various movements:
    • Flexion: 70° to 90° in the sagittal plane
    • Extension: 65° to 85° in the sagittal plane
    • Abduction: 15° to 25° in the frontal plane
    • Adduction: 25° to 40° in the frontal plane
    • Circumduction of the wrist is also possible through combined actions of radioulnar and midcarpal joints.
Anterior Wrist and Hand Muscles
  • Wrist Flexors:
    • Flexor Carpi Radialis:
    • Action: Abduction
    • Flexor Carpi Ulnaris:
    • Action: Adduction
    • Flexor Digitorum Superficialis:
    • Action: Flexion of Phalanges
    • Palmaris Longus:
    • Action: ?
Posterior Wrist and Hand Muscles
  • Wrist Extensors:
    • Extensor Carpi Radialis Longus:
    • Action: Abduction
    • Extensor Carpi Radialis Brevis:
    • Action: Abduction
    • Extensor Digitorum:
    • Action: Extension of Phalanges
    • Extensor Digiti Minimi:
    • Action: Extension of Phalanges
    • Extensor Carpi Ulnaris:
    • Action: Adduction