MED 2160 Upper Limb 2 Quiz

Movement Terminology

• Flexion/Extension: Key movements at elbow, wrist, and hand joints.
• Abduction/Adduction: Movements of digits away from or towards the midline of the hand.
• Supination/Pronation: Rotational movements of the forearm; supination turns the palm up, while pronation turns it down.
• Radial/Ulnar Deviation: Radial deviation moves the wrist towards the thumb, while ulnar deviation moves it towards the little finger.

Compartments of the Arm

• Anterior Compartment:
  • Action: Primary flexors of the elbow and shoulder.
  • Innervation: Musculocutaneous nerve.
  • Major muscle: Biceps brachii, which also supinates the forearm.
• Posterior Compartment:
  • Action: Primary extensors of the elbow and shoulder.
  • Innervation: Radial nerve.
  • Major muscle: Triceps brachii.

Compartments of the Forearm

• Anterior Compartment:
  • Action: Flexion at the wrist and digits, pronation of the forearm.
  • Innervation: Median and ulnar nerves.
• Posterior Compartment:
  • Action: Extension at the wrist and digits, supination of the forearm.
  • Innervation: Radial nerve.
  • Notable muscle: Brachioradialis, which assists with elbow flexion.

Muscles of the Hand

• Intrinsic Muscles:
  • Action: Fine motor control, abduction/adduction of digits.
  • Innervation: Median and ulnar nerves.
  • Major groups: Thenar (controls thumb) and Hypothenar (controls pinky), Lumbricals (flex MCP joints, extend IP joints), Interossei (abduct/adduct digits).

Limb Function: Muscle Attachment Points and Leverage

• First Class Levers: Efficient mechanical systems where load is balanced on both sides of the fulcrum.
• Third Class Levers: Inefficient but allows for greater range of motion and speed; common in muscles like the biceps.

Surface Anatomy of the Arm

• Humerus: Largest bone; features include the head, anatomical neck, tubercles, and epicondyles.
• Radial and Ulnar articulation: Allow for pronation/supination; primary wrist functions involve the radius.

Osteology of the Arm

• Humerus:
  • Head articulates with glenoid fossa.
  • Greater and lesser tubercles serve as muscle attachment sites.
• Radius and Ulna:
  • Radius: Head, radial tuberosity, and styloid process critical for wrist joint movement.
  • Ulna: Trochlear notch for humerus, olecranon for triceps attachment.

Anatomy of the Hand

• Carpal Bones: 8 total, arranged in two rows; form carpal tunnel for tendons and median nerve.
• Metacarpals: Five bones corresponding to fingers, important for hand function and dexterity.

Fascial Layers

• Fascial Components: Surround muscles; brachial and antebrachial fascia divide compartments of the arm and forearm.
• Retinacula: Thickened fascial bands that stabilize tendon positions at the wrist.
• Palmar Fascia: Contains palmar aponeurosis, anchoring skin and helping with grip.

Neurovascular Supply

• Musculature in the upper limb is innervated by specific branches of the brachial plexus, reflecting the compartments formed by fascial layers.### Anterior Arm Muscles
• Biceps Brachii: Composed of short (medial) and long (lateral) heads; attaches to the coracoid process and supraglenoid tubercle, respectively; primarily flexes the elbow and shoulder.
• Coracobrachialis: Located in the superomedial arm; flexes the glenohumeral joint; attaches to the coracoid process and middle third of the humerus.
• Brachialis: Deep to biceps; the primary muscle for elbow flexion in all positions; attaches to the humerus and inserts into the ulna.

Posterior Arm Muscle

• Triceps Brachii: Only muscle in the posterior compartment; consists of lateral, long, and medial heads; primarily extends the elbow and assists in shoulder extension.

Anterior Forearm Muscles

• Superficial Layer: Includes pronator teres, flexor carpi radialis, palmaris longus, and flexor carpi ulnaris; these originate from the medial epicondyle.
• Flexor Carpi Radialis/Ulnaris: Flexes the wrist and contributes to radial/ulnar deviation.
• Palmaris Longus: Flexes wrist and tenses palmar aponeurosis if present.
• Flexor Digitorum Superficialis: Flexes digits 2-5 and the wrist; has four tendons passing through the carpal tunnel.
• Deep Layer: Contains flexor pollicis longus, flexor digitorum profundus, and pronator quadratus; these flex digits and the wrist with the pronator quadratus being the prime mover for forearm pronation.

Posterior Forearm Muscles

• Superficial Layer: Includes brachioradialis, extensor carpi radialis (longus and brevis), extensor digitorum, extensor digiti minimi, extensor carpi ulnaris, and anconeus.
• Brachioradialis: Functions as a “flexor wannabe”; flexes elbow in a neutral hand position.
• Extensor Muscles: Extend the wrist and digits; the extensor digiti minimi provides independent extension for the pinky.
• Deep Layer: Contains supinator, abductor pollicis longus, extensor pollicis (brevis and longus), and extensor indicis; aids in extending the wrist and thumb movements.

Intrinsic Hand Muscles

• Thenar Muscles: Form a lateral eminence; control thumb movements, including opposition.
• Hypothenar Muscles: Medial eminence over the 5th metacarpal; responsible for pinky movements.
• Adductor Pollicis: Deep muscle responsible for thumb adduction.
• Lumbricals: Flex metacarpophalangeal joints while extending interphalangeal joints of digits 2-5.
• Interossei: Assist in abduction and adduction of fingers; notably, the first dorsal interosseous is more robust due to the non-adjacency of the first metacarpal.

Nerves and Vessels

• Forearm Nerves: Radial, ulnar, and median nerves; accompany brachial artery branches.
• Ulnar Canal: The ulnar artery and nerve enter through Guyon’s canal; supplies blood to superficial palmar arch.
• Median Nerve: Innervates thenar muscles and first two lumbricals; enters the hand via the carpal tunnel.

Pronation and Supination

• Pronation: Weaker movement involving the pronator teres and quadratus; distal end of the radius rotates around the ulna.
• Supination: Stronger movement facilitated by the biceps brachii; occurs most effectively when the forearm is flexed.

Humerus Anatomy

• Key structures include the head, bicipital groove, medial/ lateral epicondyle, and others relevant for muscle attachment and joint function.

Muscle Insertions in the Hand

• Identify insertions for flexor carpi ulnaris, flexor carpi radialis, flexor digitorum superficialis, flexor pollicis longus, and flexor digitorum profundus in the palm for a comprehensive understanding of their functions.### Muscles of the Antebrachium: Flexors & Extensors

• Pronator Teres

  • Origin: Medial epicondyle of humerus (humeral head) and coronoid process of ulna (ulnar head)
  • Insertion: Middle of lateral radius
  • Action: Pronation of forearm
  • Innervation: Median nerve

• Flexor Carpi Ulnaris

  • Origin: Medial epicondyle of humerus (humeral head) and olecranon + proximal posterior ulna (ulnar head)
  • Insertion: Pisiform and base of 5th metacarpal
  • Action: Flexion and ulnar deviation of wrist
  • Innervation: Ulnar nerve

• Palmaris Longus

  • Origin: Medial epicondyle of humerus
  • Insertion: Palmar aponeurosis and bases of proximal phalanges
  • Action: Flexion of wrist
  • Innervation: Median nerve

• Flexor Carpi Radialis

  • Origin: Medial epicondyle of humerus
  • Insertion: Base of 2nd and 3rd metacarpals
  • Action: Flexion and radial deviation of wrist
  • Innervation: Median nerve

• Flexor Digitorum Superficialis

  • Origin: Medial epicondyle of humerus, coronoid process of ulna, anterior surface of radius
  • Insertion: Middle phalanges of digits 2-5
  • Action: Flexion of wrist and digits at PIP joints
  • Innervation: Median nerve

• Pronator Quadratus

  • Origin: Distal anteromedial ulna
  • Insertion: Distal anterolateral radius
  • Action: Pronation of forearm
  • Innervation: Median nerve

• Flexor Pollicis Longus

  • Origin: Anterior surface of radius and interosseous membrane
  • Insertion: Base of distal phalanx of digit I (thumb)
  • Action: Flexion of thumb at IP joint
  • Innervation: Median nerve

• Flexor Digitorum Profundus

  • Origin: Anterior surface of ulna and interosseous membrane
  • Insertion: Distal phalanges of digits 2-5
  • Action: Flexion of wrist and digits at DIP joints
  • Innervation: Median nerve (digits 2-3) and ulnar nerve (digits 4-5)

Muscles of the Antebrachium: Extensors

• Extensor Carpi Radialis Longus

  • Origin: Lateral supracondylar ridge and lateral epicondyle of humerus
  • Insertion: Base of 2nd metacarpal
  • Action: Extension and radial deviation of wrist
  • Innervation: Radial nerve

• Extensor Carpi Radialis Brevis

  • Origin: Lateral epicondyle of humerus
  • Insertion: Base of 3rd metacarpal
  • Action: Extension of wrist
  • Innervation: Deep branch of radial nerve

• Extensor Digitorum

  • Origin: Lateral epicondyle of humerus
  • Insertion: Extensor expansion of digits 2-5
  • Action: Extension of wrist and digits at MCP joints
  • Innervation: Deep branch of radial nerve

• Extensor Digiti Minimi

  • Origin: Lateral epicondyle of humerus
  • Insertion: Extensor expansion of digit 5
  • Action: Extension of 5th digit at MCP joint
  • Innervation: Deep branch of radial nerve

• Extensor Carpi Ulnaris

  • Origin: Lateral epicondyle of humerus (humeral head) and proximal posterior ulna (ulnar head)
  • Insertion: Base of 5th metacarpal
  • Action: Extension and ulnar deviation of wrist
  • Innervation: Deep branch of radial nerve

• Supinator

  • Origin: Lateral epicondyle of humerus and radial collateral ligaments, annular ligament, crest of ulna
  • Insertion: Lateral radius
  • Action: Supination of forearm
  • Innervation: Deep branch of radial nerve

• Extensor Indicis

  • Origin: Posterior ulna and adjacent interosseous membrane
  • Insertion: Extensor expansion of digit 2
  • Action: Extension of wrist and digit 2 at MCP joint
  • Innervation: Deep branch of radial nerve

• Abductor Pollicis Longus

  • Origin: Posterior surfaces of radius and ulna
  • Insertion: Base of 1st metacarpal
  • Action: Abduction and radial deviation of thumb
  • Innervation: Deep branch of radial nerve

• Extensor Pollicis Brevis

  • Origin: Posterior radius and interosseous membrane
  • Insertion: Base of proximal phalanx of digit I
  • Action: Extension of thumb at MCP joint
  • Innervation: Deep branch of radial nerve

• Extensor Pollicis Longus

  • Origin: Middle posterior ulna and interosseous membrane
  • Insertion: Base of distal phalanx of digit I
  • Action: Extension of thumb at IP joint and radial deviation of wrist
  • Innervation: Deep branch of radial nerve

Anatomy of the Radius and Ulna

• Proximal Radio-Ulnar Joint: Articulates at the elbow, allowing forearm rotation
• Distal Radio-Ulnar Joint: Located at the wrist, connects the distal ends of radius and ulna
• Structures of Radius: Includes head, neck, radial tuberosity, and styloid process
• Structures of Ulna: Includes olecranon process, coronoid process, trochlear notch, and ulnar head