SEM401: Extremities

• Shoulder Complex


  • One of the most mobile segments in the human body
  • 0-180 degrees
  • Mobility is provided by 6 moving areas (Joints)
• Joints in the Shoulder Complex

  • True Joints
  • False Joints
• True Joints

  True bone to bone contact

  
• False Joints


  • Space only
  • Aka Functional Joint
• True Joints in the Shoulder Complex

  • Sternoclavicular Joint – Only connection to the axial skeleton
  • Acromioclavicular Joint
  • Glenohumeral Joint – Most important true joint that provides the greatest mobility (ball and socket joint)

  
• False Joints in the Shoulder Complex

  • Bicipital Groove
  • Subacromial Joint – Below or under the acromion process of the scapula
  • Scapulothoracic Joint – Between the scapula and the posterior thorax because there are muscles between, most important false joint

  
• Scapulohumeral Rhythm


  • Ratio of Glenohumeral to Scapulothoracic – 2:1
  • For every 3 degrees of motion, 2 degrees come from the Glenohumeral and 1 degree comes from the Scapulothoracic
  • Whole part will be divided by 3, then disseminate
• Clavicle


  • A long slender bone that lies horizontally at the root of the neck
  • Most commonly fractured bone in the human body
  • S-shaped bone
  • Middle 2/3 is convex anteriorly and concave posteriorly
  • Lateral 1/3 is concave anteriorly and convex posteriorly

  
• Mechanisms of Clavicular Fracture

  • Fall on outstretched hand (FOOSH) – Protective mechanism when you fall with your hand raised
  • Fall on Shoulder (FOS) – Most common in geriatric patients due to delayed reaction time
  • Medially directed blow to the shoulder – Either you are dynamic or static, e.g. you hit the floor or get hit by a truck, most common in contact sports
• Complete Clavicular Fracture

  • Painful and guards the muscle around the muscle
  • Medial fragments will be tilted superiorly by SCM
  • Lateral fragments will be pulled medially by pectoralis major muscle and downward by the force of gravity
  • Only connection of the shoulder to the axial skeleton is the SC Joint

  
• Costoclavicular Space

  • Seen between the clavicle and the 1st rib
  • Damaged during Complete Clavicular Fracture
  • Immediate management is surgery
  • Structures passing through: Subclavian artery, Brachial Plexus

  
• Incomplete Clavicular Fracture Management

  • Figure of 8 Bandaging technique
  • Horizontally
  • Put at the back
  • The goal is to retract the shoulder while allowing the clavicle to heal

  
• Scapula

  • Flat, triangular bone that lies on the posterior thoracic wall between the second (T2) and seventh ribs (T7)
  • Important to palpate spinous process to know the corresponding vertebral column

  
• Parts of the Scapula

  • Acromion Process
  • Coracoid process
  • Spine of the Scapula
  • Glenoid Fossa (lady gaga)
• Acromion Process


  • Summit of the shoulder (pinakamataas)
  • PLS orientation: Posterior, Lateral, Superior
  • Types: I - Flat, II - Curved (most common), III - Hooked (most common but angulated, associated with impingement syndrome), IV - Upturned (very rare)

  
• Coracoid Process

  • Orientation: Anterior and Superior
  • Ligament that connects coracoid process to the Acromion process – Coracoacromial ligament, prevents superior translation of the humerus

  
• Spine of the Scapula

  • Extension of the Acromion process medially
  • To locate the structures above and below because it is fossae: Above - Supraspinous fossa, Below - Infraspinous fossa, Anterior - Subscapular fossa

  
• Glenoid Fossa


  • Located at the lateral portion of the scapula
  • Shallow cavity
  • Accessory structure to enhance the depth of the fossa – Glenoid labrum, maintains negative intra-articular pressure (suction)
• Humerus

  • Humeral Head - Forms 1/3 of a sphere, intracapsular
  • Anatomical Neck - End attachment of the shoulder joint capsule
  • Surgical Neck - More prone to fracture because nearer to the humeral shaft, Axillary nerve most commonly damaged
  • Greater Tuberosities - Lateral, palpation in internal rotation, muscle attachment of rotator cuff muscles
  • Lesser Tuberosities - Medial, palpation in external rotation, muscle attachment of subscapularis
  • Bicipital Groove - Between the 2 tuberosities, long head of the biceps passes through, Transverse Humeral Ligament contains the long head
  • Spiral Groove - Posterior, Radial Nerve/Musculospiral Nerve passes through, prone to fracture which can damage the nerve

  
• True Joints in the Upper Extremity

  • Sternoclavicular Joint - Saddle/Sellar joint, 3 degrees of freedom
  • Acromioclavicular Joint - Synovial plane joint, 3 degrees of freedom
  • Glenohumeral Joint - Synovial ball and socket/Spheroidal/Universal joint, 3 degrees of freedom
  • Elbow - Humeroulnar and Humeroradial joints, Modified Hinge/Ginglymus joints

  
• Elbow Joints

  • Humeroulnar - Modified Hinge/Ginglymus, 1 degree of flexion/extension
  • Humeroradial - Modified Hinge/Ginglymus, 1 degree of flexion/extension

  
• Elbow Flexors


  • Brachialis - Origin: Anterior midshaft of humerus, Insertion: Ulna, Chief elbow flexor, Innervated by Musculocutaneous nerve
  • Biceps Brachii - Origin: Supraglenoid tubercle (long head), Coracoid process (short head), Insertion: Radial tuberosity, Strong flexor during forearm supination, Innervated by Musculocutaneous nerve
  • Brachioradialis - Origin: Lateral supracondylar ridge, Insertion: Radius, Flexes elbow but belongs to extensor group, Innervated by Radial nerve
• Elbow Extensors


  • Triceps Brachii - Origin: Infraglenoid tubercle (long head), Posterior humeral shaft (medial and lateral heads), Insertion: Olecranon process of ulna
  • Anconeus - Small muscle, Assists elbow extension and stabilizes forearm rotation
• Finger Flexion


  • Prime mover: Finger flexors
  • Synergist: Wrist extensors
  • Unwanted action: Wrist flexion
• Forearm Rotators


  • Pronator Teres - Strongest pronator, Weak elbow flexor, Has humeral and ulnar heads, Crosses at the elbow, Affected by elbow position
  • Pronator Quadratus
• Proximal and Distal Radioulnar Joints

  • Proximal - Pivot/Trochoid joint, 1 degree of pronation/supination
  • Distal - Pivot/Trochoid joint, 1 degree of pronation/supination

  
• Proximal Radioulnar Joint Ligament

  Annular Ligament - Forms 4/5 of a ring, involved in Nursemaid's elbow (Dislocation)
• Distal Radioulnar Joint Ligament


  Radioulnar Ligament - Prevents diastasis (Separation of radius and ulna in their distal end)

  
• Anconeus


  Small muscle
• Anconeus


  • Assists elbow extension and it acts as a stabilizer during forearm rotation
  • Counteracts elbow flexion from the biceps brachii during forearm supination
  • Synergists in forearm supination (identical action opposes the equal action of the prime mover)
• Finger flexion


  • Prime mover: Finger flexors
  • Synergist: Wrist extensors
  • Unwanted action: Wrist flexion
• Proximal Radioulnar joint


  • Pivot / Trochoid type
  • Radial Head + Radial Notch articulation
  • Annular Ligament - Forms 4/5 of a ring and involved in Nursemaid's elbow (Dislocation)

  
• Distal Radioulnar joint


  • Pivot / Trochoid type
  • Ulnar head + Ulnar Notch articulation
  • Radioulnar Ligament - Prevents diastasis (Separation of radius and ulna in their distal end)

  
• Radioulnar joint kinematics


  1 degree during pronation and supination
• Pronator Teres


  • Strongest pronator
  • Weak elbow flexor
  • Has humeral head and ulnar head
  • Crosses at the elbow
  • Affected by elbow position
• Pronator Quadratus


  • Chief pronator muscle
  • Remains unaffected in any other joints position
• Biceps brachii


  • Strongest supinator
  • If the elbow is flexed to 90 degrees, it is 4x more effective
  • If the elbow is extended, it is 2x as effective
• Supinator


  • MMT Isolation: Terminal elbow flexion
  • Because the biceps is near its active insufficiency
• Osseous parts of the carpals

  • Scaphoid
  • Lunate
  • Triquetrum
  • Pisiform
  • Trapezium
  • Trapezoid
  • Capitate
  • Hamate

  
• Scaphoid


  • Navicular of hand
  • Most commonly fractured carpals
  • Floor anatomic snuffbox
  • Lateral boundary: APoL, ExPoB
  • Medial boundary: EPoL (Radial artery passes through)
  • Manifests after 1-2 weeks
  • Forms the Radiocarpal joint articulation