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Questions and Answers

Which muscle is NOT supplied by the radial nerve?

Brachialis

Anconeus

Triceps

Biceps brachii (correct)

What is the primary function of the superficial branch of the radial nerve?

Motor supply to the triceps muscle

Sensory supply to the distal phalanges of the fingers

Motor supply to forearm flexors

Sensory supply to the dorsal surface of the hand (correct)

What is a common deformity associated with radial nerve injury?

Ape thumb deformity

Simian line

Claw hand

Wrist drop (correct)

Which statement correctly describes the path of the radial nerve in the forearm?

It pierces the supinator muscle Signup and view all the answers

Which nerve is responsible for supplying the skin of the back of the arm?

Posterior cutaneous nerve of the arm Signup and view all the answers

Which muscle is part of the thenar eminence responsible for thumb opposition?

Opponens pollicis Signup and view all the answers

What is the primary action of the lumbrical muscles of the hand?

Flexion at the MCP joint and extension at the interphalangeal joints Signup and view all the answers

Which nerve primarily supplies the abdominal region of the thenar eminence?

Median nerve Signup and view all the answers

Which muscle functions to abduct the little finger?

Abductor digiti minimi Signup and view all the answers

What does the acronym 'PAD' refer to in relation to the palmar interossei?

Palmar Adduction of Digits Signup and view all the answers

What injury is most likely associated with musculoskeletal issues relating to the musculocutaneous nerve?

Inability to flex the elbow Signup and view all the answers

Which nerve is responsible for innervating the deltoid and teres minor muscles?

Axillary nerve Signup and view all the answers

What is a common clinical sign associated with injury to the ulnar nerve?

Claw hand deformity Signup and view all the answers

What is the function of the lateral cutaneous nerve of the arm?

It carries sensation from the skin over the deltoid muscle. Signup and view all the answers

Which structure is the palmar cutaneous branch of the median nerve associated with?

It arises proximal to the flexor retinaculum. Signup and view all the answers

Which of the following nerves does NOT provide branches in the arm?

Ulnar nerve Signup and view all the answers

What is the location of the ulnar nerve in relation to the axillary artery in the arm?

Medial to the axillary artery. Signup and view all the answers

What does the recurrent nerve supply at the wrist?

Thenar muscles. Signup and view all the answers

Which statement correctly describes a characteristic of carpal tunnel syndrome concerning the median nerve?

It does not affect the palmar cutaneous branch. Signup and view all the answers

What does the deep branch of the ulnar nerve provide innervation to?

All the interossei muscles. Signup and view all the answers

At what position is the ulnar nerve particularly susceptible to injury at the wrist?

Superficial to the flexor retinaculum. Signup and view all the answers

Study Notes

Hand Muscles

Thenar eminence muscles:
- Abductor pollicis brevis: Abducts thumb.
- Flexor pollicis brevis: Flexes thumb at metacarpophalangeal (MCP) joint.
- Opponens pollicis: Opposes thumb.
- Adductor pollicis: Adducts thumb.
Hypothenar eminence muscles:
- Abductor digiti minimi: Abducts little finger.
- Flexor digiti minimi: Flexes little finger at MCP joint.
- Opponens digiti minimi: Opposes little finger.
- Palmaris brevis: Superficial muscle under the skin; helps grip by making the hypothenar eminence prominent; improves grip.
Lumbricals:
- 4 small muscles, originating from the tendon of flexor digitorum profundus.
- Nerve supply: First and second by median nerve; third and fourth by ulnar nerve.
- Action: Flexion at MCP joint and extension at interphalangeal joints (writing position).
Interossei:
- 4 small muscles between the metacarpal bones.
- Dorsal interossei: Bipinnate; origin metacarpal bones; nerve supply: Ulnar nerve; action: Abduction of fingers.
- Palmar interossei: Nerve supply: Ulnar nerve; action: Adduction of fingers.

Movements of the Thumb

Abduction and adduction: Occur in a plane perpendicular to the other four fingers
Extension and flexion: Occur in a plane parallel to the other four fingers

Nerve Injuries - Upper Limb

Brachial plexus injuries:
- Winging of scapula: Associated with musculocutaneous nerve injury.
Musculocutaneous nerve:
- From lateral cord (C5, 6, 7).
- Penetrates coracobrachialis muscle.
- Passes between biceps brachii and brachialis muscles.
- Supplies coracobrachialis, biceps, and brachialis muscles.
- Supplies the skin of the lateral forearm.
Axillary nerve:
- From the posterior cord of the brachial plexus.
- Exits axilla through quadrangular space.
- Related to the surgical neck of the humerus.
- Innervates deltoid and teres minor muscles.
- Supplies the skin over the deltoid muscle.
Median nerve:
- Arm: Lateral to the axillary artery and anterior to the elbow joint.
- Forearm: Passes between the two heads of the pronator teres muscle; then on the deep surface of the flexor digitorum superficialis.
- Hand: Enters the palm by passing through the carpal tunnel.
- Branches: No branches in the arm. In the forearm, branches supply the pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis muscles, the elbow joint, and the anterior interosseous nerve.
- Palmar cutaneous branch: Superficial to flexor retinaculum.
- Hand: Supplies the first and second lumbricals, and all thenar muscles except the adductor pollicis.
Palmar cutaneous branch:
- Arises proximal to the flexor retinaculum.
- Supplies the lateral 2/3 of the palm.
- Not affected in carpal tunnel syndrome.
Ulnar nerve:
- Arm: Medial to the axillary artery, passes posterior to the medial epicondyle of the humerus.
- Forearm: Passes between the two heads of the flexor carpi ulnaris muscle, then between the flexor carpi ulnaris and the flexor digitorum profundus.
- Wrist: Lies lateral to the tendon of flexor carpi ulnaris and superficial to the flexor retinaculum.
- Branches: No branches in the arm. In the forearm, branches supply the flexor carpi ulnaris and the medial 1/2 of the flexor digitorum profundus.
- Palmar branch: Supplies skin of the medial 1/3 of the palm.
- Dorsal branch: Supplies the skin of the medial 1/3 of the dorsal surface of the hand and the medial 1 1/2 fingers.
- Hand:
  - Superficial branch: Supplies the palmaris brevis muscle and the skin on the palmar surface of the medial 1 1/2 fingers.
  - Deep branch: Supplies all interossei, adductor pollicis, and the two medial lumbricals.
Radial nerve:
- Arm: Accompanies the profunda brachii artery in the lower triangular space; crosses the radial groove; appears in the forearm between the brachialis and brachioradialis muscles.
- Forearm: Divides into deep (motor) and superficial (cutaneous) branches; the deep branch pierces the supinator to enter the back of the forearm.
- Branches:
  - Axilla: Muscular branches to the triceps.
  - Posterior cutaneous nerve of the arm: Supplies the skin of the back of the arm.
  - Arm: Muscular branches to the triceps and anconeus; lower lateral cutaneous nerve of the arm (supplies the skin over the anterolateral aspect of the lower part of the arm); posterior cutaneous nerve of the forearm (supplies the skin of the back of the forearm).
  - Forearm: Emerges between the two heads of the supinator as posterior interosseous nerve and supplies the remaining extensor muscles of the forearm.
  - Superficial branch: Supplies the lateral 2/3 of the dorsal surface of the hand and the dorsal surface of the lateral 3 1/2 fingers, except the distal phalanges (supplied by the median nerve).