Answer Guide for the Back and Upper Limb Main Essays - September 30, 2011

Note. The following is a guide to answering the questions and is not the "answer."

Finger Movements

A 50 year-old professional athlete fell on his outstretched hand and fracture the hook of the hamate bone. A bone fragment invaded the Tunnel of Guyon and severed the deep branch of the ulnar nerve. The four digits on the ulnar side have the appearance of a “claw hand.” He has lost his ability for fine movements of these fingers. Discuss the joints, ligaments, fascial specializations, tendon insertions, vasculature, and innervations of the medial four digits of the hand. Account for the refined movements of flexion relative to extension. (12 pts)

Joints, Ligaments, Fascial Specializations, and Tendon Insertions

  • Metacarpophalangeal joint
    • Head of metacarpal and base of proximal phalanx
  • Proximal interphalangeal joint
    • Head of proximal phalanx and base of middle phalanx
  • Distal interphalangeal joint
    • Head of middle phalanx and base of distal phalanx

Ligaments

  • Collateral ligaments at metacarpophalangeal and interphalangeal joints
  • Palmar plates (ligaments) on the anterior aspect of each finger joint
  • Deep transverse metacarpal ligament continuous with palmar plate of the metacarpophalangeal joint

Fascial Specializations - Extensor Hood

  • Broad expansion of fibrous sheet on the dorsum of the ulnar 4 digits
  • Central slip to the base of the middle phalanx
  • Lateral bands extend to the base of the distal phalanx
  • Tethers the extensor and intrinsic muscles that insert by way of the extensor hood

Tendon Insertions, Actions, and Innervations on the Posterior Sides of the Digits

  • Second digit (index finger)
    • Extensor indicis
      • Insertion: base of distal two phalanges by way of extensor hood
      • Innervation: posterior interosseous nerve
      • Action: extends MP and IP joints
    • Extensor digitorum
      • Insertion: base of distal two phalanges by way of extensor hood
      • Innervation: deep radial nerve
      • Action: extends MP and IP joints
    • First lumbrical
      • Insertion: base of distal two phalanges by way of extensor hood
      • Innervation: median nerve
      • Action: flexes MP and extends IP joints
    • First dorsal interosseous
      • Insertion: base of distal two phalanges by way of extensor hood
      • Innervation: ulnar nerve
      • Action: abduction; flexes MP and extends IP joints
    • First palmar interosseous
      • Insertion: base of distal two phalanges by way of extensor hood
      • Innervation: ulnar nerve
      • Action: adduction; flexes MP and extends IP joints
  • Third digit (middle finger)
    • Extensor digitorum - base of distal two phalanges by way of extensor hood
      • Insertion: base of distal two phalanges by way of extensor hood
      • Innervation: deep radial nerve
      • Action: extends MP and IP joints
    • Second lumbrical
      • Insertion: base of distal two phalanges by way of extensor hood
      • Innervation: median nerve
      • Action: flexes MP and extends IP joints
    • Second dorsal interosseous
      • Insertion: base of distal two phalanges by way of extensor hood
      • Innervation: ulnar nerve
      • Action: abduction; flexes MP and extends IP joints
    • Third dorsal interosseous
      • Insertion: base of distal two phalanges by way of extensor hood
      • Innervation: ulnar nerve
      • Action: abduction; flexes MP and extends IP joints
  • Fourth digit (ring finger)
    • Extensor digitorum
      • Insertion: base of distal two phalanges by way of extensor hood
      • Innervation: deep radial nerve
      • Action: extends MP and IP joints
    • Third lumbrical
      • Insertion: base of distal two phalanges by way of extensor hood
      • Innervation: ulnar nerve
      • Action: flexes MP and extends IP joints
    • Second palmar interosseous
      • Insertion - base of distal two phalanges by way of extensor hood
      • Innervation: ulnar nerve
      • Action: adduction; flexes MP and extends IP joints
    • Fourth dorsal interosseous
      *Insertion
      base of distal two phalanges by way of extensor hood
      • Innervation: ulnar nerve
      • Action: abduction; flexes MP and extends IP joints
  • Fifth digit (little finger)
    • Extensor digitorum
      • Insertion: base of distal two phalanges by way of extensor hood
      • Innervation: deep radial nerve
      • Action: extends MP and IP joints
    • Fourth lumbrical
      • Insertion: base of distal two phalanges by way of extensor hood
      • Innervation: ulnar nerve
      • Action: flexes MP and extends IP joints
    • Third palmar interosseous
      • Insertion: base of distal two phalanges by way of extensor hood
      • Innervation: ulnar nerve
      • Action: adduction; flexes MP and extends IP joints
    • Abductor digiti minimi
      • Insertion: medial aspect of the base of the proximal phalanx
      • Innervation: ulnar nerve
      • Action: abduction;

Tendon Insertions, Actions, and Innervations on the Palmar Side

  • Flexor digitorum superficialis
    • Insertion: tendons splits to insert of the palmar sides of the middle phalanx of the medial four digits
    • Flexor digitorum longus tendon passes deep (posterior) to the bifurcation of the flexor digitorum superficialis tendon
      • Tendon synovial sheath reduces friction
    • Action at the digits: flexes the MP and proximal IP joints
    • Innervation: median nerve
  • Flexor digitorum profundus
    • Insertion: base of distal phalanx on the medial four digits
    • Innervation: Ulnar two tendon heads by ulnar nerve; medial two tendon heads by anterior interosseous nerve
    • Action: uniquely flexes the distal IP joint
  • Flexor digiti minimi brevis
    • Insertion: base of the proximal phalanx
    • Innervation: ulnar nerve
    • Action: flex the MP joint

Vasculature Including Lymphatic Drainage and Synovial Anatomy

  • Dorsal digital arteries
  • Palmar digital arteries
  • Tendons served by the vincula tendina
  • The little finger tendon sheath may communicate across the palm (spread of infection)
  • Lymphatic vessels follow superficial venous pathways and deep arterial pathways to axillary nodes (basilic venous pathway) and infraclavicular nodes (cephalic venous pathway).
    • Note: Lymph does not drain into the veins that indicate the pathways of lymphatic vessels.

Cutaneous Innervation

  • Palmar side
    • Superficial branch of ulnar nerve for the medial 1.5 digits
    • Median nerve for the radial 3.5 fingers (including thumb)
    • Palmar digital nerves wrap posterior at the distal digits to innervate the nail beds
  • Dorsal side
    • Superficial branch of the radial nerve crosses tendon of extensor pollicis longus to radial 3.5 fingers
    • Dorsal branch of ulnar nerve to ulnar 1.5 fingers
    • Dorsal digital nerves do not extend to the nail beds

Refined Movement

  • The lumbricals and interossei retard flexion (extend) at the IP joints while flexing the MP joint and, thus, allow for a "graceful" grasp.
  • The extensors are tethered by the extensor hood and, thus, extension is not refined.
  • The long and short flexors act independently at each digit with regard to the distal IP joint
  • Fine motor movement requires precise sensory feedback

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Scapular Region and Shoulder Joint

A 45 year-old female comes to your office with persistent right shoulder pain. She states she states she has recently begun a weight-training program. The morning after increasing the weight for her military press she noted that her shoulder was painful. She felt that she may have slept on it in the wrong position. The shoulder has not improved and she now has difficulty raising her arm above her head. On physical exam, her "oil can" test is positive. She has difficulty abducting her right arm above her shoulder. She cannot hold her right arm up when resistance is applied during abduction. Review the anatomy of the scapular region and shoulder joint. Include bones, articular surfaces, cavities, capsules, ligaments, contents, muscles, movements and limitations of movement, vasculature, innervation, relationships to surrounding structures, and lymphatic drainage. (12 pts)

Scapular Region

  • The scapula is a highly movable structure that makes up the bulk of the pectoral girdle.
  • Abduction from approximately 90 degrees to 180 degrees is largely accounted for by scapular movement (upward rotation).
  • A rich anastomotic network centered in the infraspinous fossa provides an arterial shunt across much of the axillary artery.
  • The scapula hosts the proximal component of the glenohumeral joint.
  • Positioning of the upper limb is largely dependent upon the anatomy of the scapular region
Bones, Muscles and Movements
  • Medial border
    • Rhomboideus minor
    • Rhomboideus major
    • serratus anterior
  • Superior Angle
    • Levator scapulae
  • Inferior Angle
    • Serratus anterior
  • Lateral border
    • Teres major
  • Supraspinous fossa
    • Supraspinatous
  • Infraspinous fossa
    • Infraspinatous
    • Teres minor
  • Spine of the scapula
    • Upper fibers of trapezius
    • Lower fibers of trapezius
  • Acromion
    • Trapezius
    • Deltoid
    • Coracoacromial ligament and arch
  • Subscapular fossa
    • Subscapularis
  • Corocoid Process
    • Pectoralis minor
    • Coracobrachialis
    • Short head of biceps
  • Glenoid fossa
    • Proximal articulation for glenohumeral joint
  • Supraglenoid tubercle
    • Long head biceps
  • Infraglenoid tubercle
    • Long head triceps
Vascularization and Scapular anastomosis
  • Transverse cervical artery
  • Suprascapular artery
  • Dorsal scapular artery
  • Posterior intercostal arteries
  • Circumflex scapular artery
Innervation
  • Suprascapular nerve
  • Accessory nerve
  • Axillary nerve
  • Dorsal scapular nerve
  • Medial and Lateral pectoral nerves
  • Upper, middle, and lower subscapular nerves
  • Musculocutaneous nerve
  • Long thoracic nerve - winging
Relationships
  • Superior transverse scapular ligament and scapular notch
    • Suprascapular nerve passes through osseofibrous foramen
    • Suprascapular artery passes superior to the superior transverse scapular ligament
  • Circumflex scapular artery in the triangular space
  • Posterior cord anterior to subscapularis
  • Subscapular fossa is part of posterior wall of axilla
  • Coracoacromial arch is superior support for glenohumeral joint
Lymphatic drainage
  • Posterior - intercostal nodes
  • Anterior - axillary nodes

Rotator Cuff*

  • The rotator cuff, celebrated for its role in lateral rotation, mediates lateral rotation, medial rotation, 15 deg of abduction, and weak adduction.
  • The tendon of supraspinatus is particularly vulnerability to tearing due to the restricted space between it and the acromion.
Bones: Scapula and Humerus
  • Glenoid fossa
  • Acromion
  • Corocoid process
Muslces
  • Supraspinatus
  • Infraspinatus
  • Teres minor
  • Subscapularis
Movements
  • Abduction: 15 deg by supraspinatus
  • Adduction: weak by teres minor
  • Lateral rotation: infraspinatus and teres minor
  • Medial rotation: subscapularis
Vascularization
  • Scapular anastomosis av
  • Shoulder anastomosis av
  • Anterior humeral circumflex av
  • Posterior humeral curcumflex av
  • Subscapular av
Innervation
  • Suprascapular nerve
  • Axillary nerve
  • Upper and lower subscapular nerves
Relationships
*Subacromial bursa and arch
  • Tendon of the long head of the biceps
Lymphatic drainage
  • Axillary nodes
  • Cervical nodes
Clinical Significance
  • Rotator cuff tear - supraspinatus

Shoulder Joint

  • General Comment
    • Extremely Unstable - "Golf ball and Tee"
Bones
  • Glenoid Fossa and Humerus
Articular surfaces
  • Glenoid fossa - cartilage
  • Head of humerus - cartilage
  • Glenoid labrum
Cavities
  • Synovial joint cavity
  • Subacromial Bursa
Capsules and ligaments
  • Fibrous joint capsule
  • Glenohumeral ligaments
  • Musculocutaneous Cuff (rotator Cuff)
Contents
  • Biceps tendon
Muscles
  • Rotator Cuff, Deltoid
  • Pectoralis major, teres major, latissimus dorsi
  • coracobrachialis, long and short head of biceps, long head of triceps
Movements
  • Medial rotation
  • Lateral rotation
  • Abduction
  • Adduction
  • Flexion
  • Extension
Limitations of movement
  • Glenohumeral ligaments
  • Antagonistic muscles
  • Coracoacromial arch and greater tubercle of humerus
Vascularization
  • Anterior and Posterior humeral circumflex arteries
  • Deltoid and acromial branches of thoracoacromial trunk
  • Suprascapular artery and Circumflex scapular artery
  • Ascending branch of profunda brachii
Innervation
  • Axillary Nerve
  • Upper lateral cutaneous nerve of arm
  • Hilton's law - Axillary, suprascapular, and lower subscapular nerves
  • Hilton's law continued - musculocutaneous, radial, median, and ulnar nerves
Relationships
  • Coracoacromial arch
  • Long head biceps tendon
  • Clavical
  • Coracoid process
Lymphatic drainage
  • Axillary nodes
Shoulder injury and dislocation
  • Traction injury of axillary nerve
  • Clinical test for upper lateral cutaneous nerve

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Elbow Region and Cubital Fossa

A 35 year-old female tennis player complains of tenderness on the outer bony part of the elbow. She reports morning stiffness of the elbow with persistent aching and pain when the fingers and wrist are extended. Review the anatomy of the elbow region and cubital fossa. Include bones, articular surfaces, cavities, capsules, ligaments, contents, boundaries, muscles, movements and limitations of movement, vasculature, innervation, relationships to surrounding structures, and lymphatic drainage. (12 pts)

General comment

  • Humeroulnar joint - hinge joint
  • Humeroradial joint
  • Proximal radioulnar joint
  • Synovial joint cavity - synovial membrane continuous with elbow and radioulnar joint

Bones, Articular Surfaces, and Synovial Cavity

  • Humeral trochlea and ulnar trochlear notch - elbow joint
  • Capitulum and radial head - humeroradial joint
  • Head of radius and radial notch of ulnar - proximal radioulnar joint

Capsules and Ligaments

  • Ulnar collateral ligament - medial epicondyle to olecranon and coronoid process
  • triangular, anterior, intermediate, and posterior fibers
  • radial collateral ligament - lateral epicondyle to annular ligament and to supinator crest
  • Annular ligament - secures radial head to the ulnar notch, blends with radial collateral ligament

Boundaries and Contents of Cubital Fossa

  • Boundaries
    • Superior: line across humeral epicondyles
    • Inferior: crossing of pronator teres and brachioradialis
    • Anterior: bicipital aponeurosis
    • Posterior: brachialis, supinator, and tendon of the biceps
    • Lateral: brachioradialis
    • Medial: pronator teres
  • Contents - medial to lateral
    1. inferior ulnar collateral artery
    2. anterior recurrent ulnar artery
    3. median nerve
    4. brachial artery splitting to ulnar and radial arteries
    5. tendon of the biceps
    6. lateral cutaneous nerve of forearm
    7. radial nerve, superficial and deep branches
    8. radial collateral artery
    9. radial recurrent artery

Muscles, Movements, and Limitations of Movement

  • Flexion
    • Anterior compartment of arm - biceps, brachialis, and brachioradialis
    • Flexor origin from medial humeral epicondyle
    • Pronator teres
    • Coronoid process and coronoid fossa - stability of flexion
  • Extension
    • Posterior compartment of arm - triceps and anconeus
    • Flexor origin from medial humeral epicondyle
    • Olecranon and olecranon fossa - stability on extension

Vasculature and Innervation

  • elbow anastomosis- relationships to epicondyles and to adjacent muscles
  • Hilton's law - musculocutaneous, median, ulnar, and radial nerves
  • Cutaneous nerves
    • Lower lateral cutaneous of arm, posterior cutaneous nerve of arm
    • posterior cutaneous nerve of forearm
    • Medial and lateral cutaneous nerves of the forearm

Relationships

  • biceps aponeurosis
  • median cubital vein, venipuncture
  • elbow (cubital) anastomosis
  • lateral cutaneous nerve of forearm
  • ulnar groove and nerve

Lymphatic Drainage

  • Supratrochlear nodes, axillary etc.

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Topic revision: r1 - 09 Oct 2011, UnknownUser
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