Forearm Muscles Anatomy Quiz

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Questions and Answers

What is the distal attachment of the flexor pollicis longus muscle?

Base of proximal phalanx of thumb

Base of distal phalanges of 2nd and 3rd digits

Base of distal phalanx of thumb (correct)

Dorsal aspect of base of 2nd metacarpal

Which muscle is primarily responsible for the flexion of distal phalanges at the distal interphalangeal joints?

Pronator quadratus

Flexor digitorum profundus (correct)

Flexor pollicis longus

Brachioradialis

What nerve innervates the pronator quadratus muscle?

Anterior Interosseous nerve (correct)

Ulnar nerve

Radial nerve

Medial nerve

What type of joint is the elbow joint?

Hinge type synovial joint Signup and view all the answers

What is the muscle action of the extensor carpi radialis brevis?

Extends and abducts the hand at the wrist joint Signup and view all the answers

Which ligaments contribute to the stability of the elbow joint?

Radial collateral and annular Signup and view all the answers

Which muscle originates from the anterior surface of the radius?

Flexor pollicis longus Signup and view all the answers

What is the primary movement allowed by the elbow joint?

Flexion/extension Signup and view all the answers

Which of the following statements about the ligaments of the elbow is false?

The radial collateral ligament attaches to the medial epicondyle. Signup and view all the answers

Which of the following muscles primarily performs weak flexion of the forearm?

Brachioradialis Signup and view all the answers

What structures allow for the pronation and supination of the forearm?

Proximal radioulnar joint and annular ligament Signup and view all the answers

What is the proximal attachment of the pronator quadratus?

Distal quarter of anterior surface of ulna Signup and view all the answers

Which nerve is NOT part of the nerve supply to the elbow joint?

Maxillary nerve Signup and view all the answers

Which muscle action is associated with the extensor carpi radialis longus?

Extends and abducts hand at wrist joint Signup and view all the answers

Which bursa is located between the olecranon and the triceps tendon?

Subtendinous olecranon bursa Signup and view all the answers

What feature is NOT associated with the elbow joint capsule?

It consists of three distinct layers. Signup and view all the answers

What is the primary muscle action of the triceps brachii?

Extension of forearm Signup and view all the answers

Which muscle assists in flexing and adducting the arm?

Coracobrachialis Signup and view all the answers

What nerve innervates the brachialis muscle?

Musculocutaneous and Radial nerves Signup and view all the answers

What is the proximal attachment location of the Anconeous muscle?

Lateral epicondyle of the humerus Signup and view all the answers

Which muscle is primarily responsible for resisting dislocation of the shoulder?

Coracobrachialis Signup and view all the answers

Which muscle action does the brachialis perform?

Flexes the forearm in all positions Signup and view all the answers

What structure separates the forearm's anterior flexor-pronator compartment from the posterior extensor compartment?

Radius and ulna Signup and view all the answers

Which of the following muscles does NOT belong to the superficial layer of the anterior forearm compartment?

Flexor digitorum profundus Signup and view all the answers

What is the innervation of the Flexor Carpi Ulnaris?

Ulnar nerve Signup and view all the answers

Which muscle action is performed by the Flexor Digitorium Superficialis?

Flexes middle phalanges at proximal interphalangeal joints Signup and view all the answers

What is the proximal attachment point of the Ulnar head of the Flexor Carpi Ulnaris?

Olecranon and posterior border of ulna Signup and view all the answers

Which part of the Flexor Digitorium Profundus flexes the distal phalanges of the 4th and 5th digits?

Medial part Signup and view all the answers

What common characteristic do the humeral and ulnar heads of the Flexor Carpi Ulnaris share?

Both insert at the pisiform hook of hamate and 5th metacarpal Signup and view all the answers

What is the distal attachment site for the Flexor Digitorium Superficialis?

Shafts of middle phalanges of medial 4 digits Signup and view all the answers

Which nerve is responsible for the innervation of the Flexor Digitorium Superficialis?

Median nerve Signup and view all the answers

Which action does NOT occur due to the Flexor Carpi Ulnaris?

Extension of fingers Signup and view all the answers

What is the primary action of the abductor pollicis longus muscle?

Abducts and extends the thumb at the carpometacarpal joint Signup and view all the answers

Where is the proximal attachment of the extensor pollicis longus located?

Posterior surface of the middle third of the ulna and interosseous membrane Signup and view all the answers

Which nerve innervates both the abductor pollicis longus and the extensor pollicis longus?

Posterior interosseous nerve Signup and view all the answers

What is the distal attachment of the extensor pollicis brevis?

Dorsal aspect of base of proximal phalanx of the thumb Signup and view all the answers

What is the origin of the median nerve in the forearm?

Union of lateral root and medial root from both lateral and medial cords of the brachial plexus Signup and view all the answers

Which statement about the anterior interosseous nerve is correct?

It originates from the median nerve in the distal part of the cubital fossa. Signup and view all the answers

Which muscle primarily extends the distal phalanx of the thumb at the interphalangeal joint?

Extensor pollicis longus Signup and view all the answers

What is the distal attachment for the abductor pollicis longus?

Base of the first metacarpal Signup and view all the answers

Study Notes

Forearm Muscles

Flexor Digitorum Profundus:
- Distal Attachment: Bases of distal phalanges of 2nd and 3rd digits
- Innervation: Anterior Interosseous nerve from median nerve (C8, T1)
- Action: Flexes distal phalanges 2 and 3 at distal interphalangeal joints
Flexor Pollicis Longus:
- Proximal Attachment: Anterior surface of radius and adjacent interosseous membrane
- Distal Attachment: Base of distal phalanx of thumb
- Innervation: Anterior Interosseous nerve from median nerve (C8, T1)
- Action: Flexes phalanges of the 1st digit
Pronator Quadratus:
- Proximal Attachment: Distal quarter of the anterior surface of the ulna
- Distal Attachment: Distal quarter of the anterior surface of the radius
- Innervation: Anterior Interosseous nerve from median nerve (C8, T1)
- Action: Pronates the forearm, and deep fibers bind the radius and ulna together.
Brachioradialis:
- Proximal Attachment: Proximal two-thirds of the lateral supra-epicondylar ridge of the humerus
- Distal Attachment: Lateral surface of distal end of radius proximal to the styloid process
- Innervation: Radial nerve (C5, C6, C7)
- Action: Relatively weak flexion of the forearm; maximal when the forearm is in a mid-pronated position
Extensor Carpi Radialis Longus:
- Proximal Attachment: Lateral supra-epicondylar ridge of the humerus
- Distal Attachment: Dorsal aspect of the base of the 2nd metacarpal
- Innervation: Radial nerve (C6, C7)
- Action: Extends and abducts the hand at the wrist joint. Active during first clenching.
Extensor Carpi Radialis Brevis:
- Proximal Attachment: Lateral epicondyle of the humerus (common extensor origin)
- Distal Attachment: Dorsal aspect of the base of the 3rd metacarpal
- Innervation: Deep branch of the radial nerve (C7, C8)
- Action: Extends and abducts the hand at the wrist joint

Forearm Joints

Elbow Joint:
- Type: Hinge type synovial joint
- Articulations:
  - Humeroulnar: Articulation between the trochlear notch of the ulna and the trochlea of the humerus
  - Humeroradial: Articulation between the capitulum of the humerus and the head of the radius
- Capsule: Surrounds the joint. Attaches to the humerus at the lateral and medial ends of the capitulum and the trochlea.
- Ligaments:
  - Radial Collateral (LCL): Lateral fan-like ligament. Attaches proximally at the lateral epicondyle of the humerus and distally at the anular ligament of the radius.
  - Annular: Encircles the radial head and holds it in the radial notch of the ulna. (This forms the radio-ulnar joint and allows for pronation and supination of the forearm)
  - Ulnar Collateral (MCL): Medial triangular ligament. Its proximal attachment is the medial epicondyle of the humerus to the olecranon and coronoid process of the ulna. It's made up of three bands: anterior (cordlike, strongest), posterior (fanlike, weakest), oblique (slender, deepens the socket of the trochlea of the humerus).
- Movements: Flexion/extension
- Blood Supply: Anastomosis around the elbow joint
- Nerve Supply: Musculocutaneous, radial, median, and ulnar nerves
- Bursae:
  - Intratendinous Olecranon Bursa: Sometimes present in the tendon of the triceps brachii.
  - Subtendinous Olecranon Bursa: Located between the olecranon and triceps tendon, just proximal to its attachment to the olecranon.
  - Subcutaneous Olecranon Bursa: Located in the subcutaneous connective tissue over the olecranon.
  - Bicipitoradial Bursa: Separates the biceps tendon from the radial tuberosity; also reduces friction.
Proximal Radioulnar Joint:
- Type: Pivot type synovial
- Capsule: Continuous with the elbow joint capsule
- Ligament: Annular: encircles the radial head and holds it in the radial notch of the ulna
- Innervation: Musculocutaneous (C5, C6, and C7)
- Action: Supinates the forearm; Flexes the forearm when supinated. The short head resists dislocation of the shoulder.

Forearm Muscles: Anterior Compartment

Flexor Carpi Ulnaris:
- Humeral Head:
  - Proximal Attachment: Medial epicondyle of humerus (common flexor origin)
  - Distal Attachment: Pisiform, hook of hamate, 5th metacarpal
  - Innervation: Ulnar nerve (C7, C8)
  - Action: Flexes and adducts the hand at the wrist
Flexor Carpi Ulnaris Ulnar Head:
- Proximal Attachment: Olecranon and posterior border of ulna (via aponeurosis)
- Distal Attachment: Pisiform, hook of hamate, 5th metacarpal
- Innervation: Ulnar nerve (C7, C8)
- Action: Flexes and adducts the hand at the wrist
Flexor Digitorum Superficialis:
- Humerus-Ulnar Head:
  - Proximal Attachment: Medial epicondyle (common flexor origin) and coronoid process
  - Distal Attachment: Shafts of middle phalanges of medial four digits
  - Innervation: Median nerve (C7, C8, T1)
  - Action: Flexes middle phalanges at proximal interphalangeal joints of middle four digits; acting more strongly, it also flexes proximal phalanges at metacarpophalangeal joints.
Flexor Digitorum Superficialis Radial Head:
- Proximal Attachment: Superior half of anterior border
- Distal Attachment: Shafts of middle phalanges of medial four digits
- Innervation: Median nerve (C7, C8, T1)
- Action: Flexes middle phalanges at proximal interphalangeal joints of middle four digits; acting more strongly, it also flexes proximal phalanges at metacarpophalangeal joints.

Forearm Muscles: Posterior Compartment

Abductor Pollicis Longus:
- Proximal Attachment: Posterior surface of proximal halves of ulna, radius, and interosseous membrane.
- Distal Attachment: Base of 1st metacarpal
- Innervation: Posterior interosseous nerve (C7, C8); continuation of the deep branch of the radial nerve
- Action: Abducts the thumb and extends it at the carpometacarpal joint
Extensor Pollicis Longus:
- Proximal Attachment: Posterior surface of the middle third of the ulna and interosseous membrane
- Distal Attachment: Dorsal aspect of the base of distal phalanx of the thumb
- Innervation: Posterior interosseous nerve (C7, C8); continuation of the deep branch of the radial nerve
- Action: Extends the distal phalanx of the thumb at the interphalangeal joint, extends the metacarpophalangeal and carpometacarpal joint.
Extensor Pollicis Brevis:
- Proximal Attachment: Posterior surface of the distal third of the radius and interosseous membrane
- Distal Attachment: Dorsal aspect of the base of proximal phalanx of thumb
- Innervation: Posterior interosseous nerve (C7, C8); continuation of the deep branch of the radial nerve
- Action: Extends the proximal phalanx of the thumb at the interphalangeal joint; extends the metacarpophalangeal and carpometacarpal joint.

Forearm Nerves

Median Nerve:
- Origin: Union of the lateral root of the median nerve (C6, C7; lateral cord of brachial plexus) with the medial root (C8, T1) from the medial cord.
- Course in Forearm: Enters the cubital fossa medial to the brachial artery; exits by passing between the heads of the pronator teres; descends in the fascial plane between the flexor digitorium superficialis and profundus. Runs deep to the palmaris longus tendon as it approaches the flexor retinaculum to transverse the carpal plane.
Anterior Interosseous Nerve:
- Origin: Median nerve in the distal part of the cubital fossa
- Course in Forearm: Descends on the anterior aspect of the interosseous membrane with the artery of the same name; between flexor digitorum profundus and flexor palmaris longus, to pass deep to pronator quadratus.
Palmar Cutaneous Branch of the Median Nerve:
- Origin: Median nerve in the middle to distal forearm, proximal to the flexor retinaculum.

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Description

Test your knowledge about the anatomy and functions of forearm muscles including the Flexor Digitorum Profundus, Flexor Pollicis Longus, Pronator Quadratus, and Brachioradialis. This quiz covers their attachments, innervation, and actions. See how well you understand these critical components of upper limb anatomy!