Forearm, Wirst and Hand

Question 1

Anterior Forearm

What are the muscles in the superficial compartment and where do they originate and how are they innervated?

Answer 1

• Pronator Teres
• Flexor Carpi Radialis
• Palmaris Longus
• Flexor carpi ulnaris
  Origin: medial epicondyle of the humerus.
  Innervation: Median nerve except FCU (Ulnar nerve).

Question 2

Pronator Teres;

origin(s), insertion(s), action, innervation.

Answer 2

Origin: 1. medial epicondyle
2. coronoid process of ulna
Insertion: laterally to mid-shaft of the radius
Action: pronation of the forearm.
Innervation: Median nerve.

Question 3

Flexor Carpi Radialis;

origin(s), insertion(s), action, innervation.

Answer 3

Origin: medial epicondyle
Insertion: base of metacarpals II and III
Action: Flexion and abduction at the wrist
Innervation: median nerve

Question 4

Palmaris Longus;

origin(s), insertion(s), action, innervation.

Answer 4

Origin: medial epicondyle
Insertion: flexor retinaculum of the wrist
Action: flexion of wrist
Innervation: median nerve

Question 5

Flexor Carpi Ulnaris;

origin(s), insertion(s), action, innervation.

Answer 5

Origin: 1. medial epicondyle 2. long origin from the ulna
Insertion: pisiform carpel bone
Action: flexion and adduction at the wrist
Innervation: ulnar nerve

Question 6

Anterior Forearm
What is the muscle in the intermediate compartment?
- Origin(s), Insertion(s), Action, Innervation.

Answer 6

Flexor Digitorum Superficialis

Origin: it has 2 heads;
one originates from medial epicondyle and the other from the radius.
Insertion: Muscle splits into 4 tendons at the wrist which travel though the carpel tunnel, and attaches to the middle phalanges of the four fingers.

Action: Flexes the metacarpophalangeal joints and proximal interphalangeal joints at the four fingers, and flexes at the wrist
Innervation: Median nerve.

Question 7

Anterior Forearm

What are the muscles in the deep compartment? How are they innervated?

Answer 7

• Flexor Pollicus Longus
• Flexor Digitorum Profundus
• Pronator Quadratus
  Innervation: mostly median except medial half of FDP

Question 8

Flexor Pollicus Longus;

origin(s), insertion(s), action, innervation.

Answer 8

Origin: Anterior surface of the radius and surrounding interosseous membrane
Insertion: Base of the distil phalanx of the thumb
Action: Flexes interphalangeal joint and metacarpophalangeal joint of the thumb
Innervation: median nerve

Question 9

Flexor Digitorum Profundus;

origin(s), insertion(s), action, innervation.

Answer 9

Origin: Ulna and associated interosseous membrane.
Insertion: At wrist, it splits into 4 tendons that pass through the carpel tunnel and attach to the distil phalanges of the four fingers.

Action: Only muscle able to flex the distil interphalangeal joints. Also flexes at the metacarpophalangeal joints and at the wrist.
Innervation: Medial half (acting on little and ring fingers) - ulnar nerve
Lateral half (acting on middle and index fingers) innervated by median nerve (interosseous branch).

Question 10

Pronator Quadratus;

origin(s), insertion(s), action, innervation.

Answer 10

Origin: Anterior surface of the ulna
Insertion: anterior surface of the radius
Action: Pronation of the forearm
Innervation: Median nerve (interosseous branch)

Question 11

What are the anterior and posterior compartments of the forearm commonly known as?

Answer 11

Anterior - Flexor muscles

Posterior - Extensor muscles

Question 12

What is the general function of the flexor muscles?

Answer 12

Perform flexion at the wrist and fingers, and pronation.

Question 13

What is the general function of the extensor muscles?

Answer 13

Produce extension at the wrist and fingers.

Question 14

ALL of the muscles in the posterior compartment are innervated by which nerve?

Answer 14

The radial nerve.

Question 15

What are the superficial muscles of the posterior forearm?

Answer 15

7 muscles; four of what share a common tendinous origin at the lateral epicondyle.

• Extensor carpi radialis brevis
• Extensor digitorum
• Extensor carpi ulnaris
• Extensor digiti minimi
• Brachioradialis
• Extensor Carpi Radialis Longus
• Anconeus

Question 16

Extensor Carpi Longus and Brevis;

origin(s), insertion(s), action, innervation.

Answer 16

Origin of Longus: Supracondylar ridge
Origin of Brevis: lateral epicondyle
Insertion: Metacarpal bones II and III
Action: Extends and abducts the wrist
Innervation: Radial Nerve

Question 17

Extensor Digitorum;

origin(s), insertion(s), action, innervation.

Answer 17

Origin: Lateral epicondyle
Insertion: Tendon continues into distil part of forearm where it splits into 4 and inserts into the extensor hood of each finger
Action: Extends medial four fingers at the MCP and IP joints
Innervation: Radial nerve

Question 18

Extensor Digiti Minimi;

origin(s), insertion(s), action, innervation.

Answer 18

Lies medially to the extensor digitorum

Origin: Lateral epicondyle
Insertion: W/ the extensor digitorum tendon, into the extensor hood of the little finger
Action: Extends the little fingers and contributes to extension at the wrist
Innervation: Radial nerve

Question 19

Extensor Carpi Ulnaris;

origin(s), insertion(s), action, innervation.

Answer 19

Located on medial aspect.
Origin: Lateral epicondyle
Insertion: base of metacarpal V
Action: Extension and adduction of the wrist
Innervation: Radial Nerve

Question 20

Anconeus;

origin(s), insertion(s), action, innervation.

Answer 20

Situated medially and superiorly in extensor part of forearm.
Origin: lateral epicondyle
Insertion: Posterior and lateral part of olecranon
Action: Extends and stabilises the elbow joint; Abducts the ulna during pronation of the forearm
Innervation: Radial Nerve

Question 21

What are the deep muscles of the posterior forearm? What do they act on?

Answer 21

There are 5.

• Supinator
• Abductor polices longus
• Extensor pollicus brevis
• Extensor polices longus
• Extensor indices

Except the supinator, these muscles act on the thumb and the index finger.

Question 22

Supinator;

origin(s), insertion(s), action, innervation.

Answer 22

It has two heads and the deep branch of the radial nerve passes between them.

Origin: One head from lateral epicondyle and one from posterior surface of the ulna
Insertion: posterior surface of the radius
Action: Supination of the forearm
Innervation: Radial nerve (deep branch)

Question 23

Abductor Pollicis Longus;

location, origin(s), insertion(s), action, innervation.

Answer 23

Location: Immediately distil to the supinator muscle.
Origin: Interosseous membrane and adjacent posterior surfaces of the radius and ulna
Insertion: Lateral side of base of metacarpal I
Action: Abducts the thumb
Innervation: radial nerve (posterior interosseous branch)

*In the hand, the tendon contributes to the lateral border of the anatomical snuffbox

Question 24

Extensor Pollicis Brevis;

location, origin(s), insertion(s), action, innervation.

Answer 24

Location: Medially and deep to the abductor policies longs
Origin: Posterior surface of radius and interosseous membrane
Insertion: the base of the proximal phalanx of the thumb
Action: extends the metacartpophalangeal and carpometacarpal joints of the thumb
Innervation: radial nerve (posterior interosseous branch)

*Contributes to lateral border of anatomical snuffbox

Question 25

Extensor Pollicis Longus; | location, origin(s), insertion(s), action, innervation.

Answer 25

Location: The tendon travels medially to the dorsal tubercle at the wrist, using the tubercle as a pukkey to increase entered force Origin: Posterior surface of the ulna and interosseous membrane Insertion: Distil phalanx of the thumb Action: Extends all joints of the thumb (carpometacarpal, metacarpophalangeal, interphalangeal) Innervation: Radial nerve (posterior interosseous branch) *forms medial border of anatomical snuffbox

Question 26

Extensor Indicis Proprius; | origin(s), insertion(s), action, innervation.

Answer 26

Origin: posterior surface of ulna and interosseous membrane, distil to the extensor pollicis longus Insertion: extensor hood of the index finger Action: extends the finger (allows the index finger to be independent of other fingers during extension) Innervation: radial nerve (posterior interosseous branch)

Question 27

What are the borders of the carpal tunnel?

Answer 27

It is formed by two layers; - Deep carpal arch - Superficial flexor retinaculum

Question 28

What is the carpal arch?

Answer 28

- Concave arch on the palmar side; forms base and sides of tunnel. - Formed laterally by; scaphoid and trapezium tubercles. - Formed medially by; hook of hamate and the pisiform.

Question 29

What is the flexor retinaculum?

Answer 29

- Thick, connective tissue forming room of carpal tunnel. - Turns the arch into a tunnel by bridging medial and lateral parts of the arch. - Originates on lateral side and inserts on medial side of carpal arch.

Question 30

What are the contents of the carpal tunnel?

Answer 30

It contains 9 tendons (surrounded by synovial sheaths) and the median nerve. *The palmar cutaneous branch of the median nerve is given off prior to the carpal tunnel, travelling superficially to the flexor retinaculum.

Question 31

What are the tendons within the carpal tunnel and how are they grouped?

Answer 31

- Tendon of flexor policies longus - 4 tendons of flexor digitorum superficialis - 4 tendons of flexor digitorum profundus The 8 tendons or the flexor digitorum superficialis and profundus are surrounded by a single synovial sheath. *Sheaths allow free movement of tendons.

Question 32

What happens to the median nerve after passing through the carpal tunnel?

Answer 32

It divides into 2 branches - recurrent branch (supplies the thenar muscle group) - palmar digital branch (sensory innervation to palmar skin and dorsal nail beds of lateral 3.5 digits. Also provide motor innervation to lateral 2 lumbricals)

Question 33

How can the muscles acting on the hand be divided?

Answer 33

Extrinsic Muscles; located in the anterior and posterior forearm - they control crude movements and produce a strong grip. Intrinsic Muscles; located within the hand - responsible for fine motor functions of the hand.

Question 34

What are the thenar muscles (generally), where are they and how are they innervated?

Answer 34

- 3 short muscles on the base of the thumb. The muscle bellies produce a bulge (thenar eminence). - Responsible for fine movements of the thumb - Innervated by the median nerve

Question 35

What muscles make up the thenar muscle group?

Answer 35

- Opponens Pollicis - Abductor Pollicis Brevis - Flexor Pollicis Brevis

Question 36

Opponens Pollicis; | location, attachments, actions, innervation.

Answer 36

*Largest of the 3, lies underneath the other two. Origin: Tubercle of trapezium and associated flexor retinaculum. Insertion: lateral margin of metacarpal I (i.e. of the thumb). Action: Opposes the thumb by medially rotating and flexing the metacarpal on the trapezium. Innervation: Median nerve.

Question 37

Abductor Pollicis Brevis; | location, attachments, actions, innervation.

Answer 37

Location: Found anteriorly to opponents policies and proximal to the flexor policies brevis. Origin: Tubercles of scaphoid and trapezium and associated flexor reticulum. Insertion: Lateral side of the proximal phalanx of the thumb. Action: Abducts the thumb Innervation: Median Nerve

Question 38

Flexor Pollicis Brevis; | location, attachments, actions, innervation.

Answer 38

Location: The most distil of the thenar muscles. Origin: Tubercle of the trapezium and from associated flexor retinaculum. Insertion: base of the proximal phalanx of the thumb. Action: Flexes the MCP joint of the thumb. Innervation: Median nerve. *Deep hand is innervated by the deep branch of the ulnar nerve.

Question 39

What are the hypothenar muscles (generally), where are they and how are they innervated?

Answer 39

- Produce the hypothenar eminence; a muscular protrusion on the medial side of the palm at the base of the little finger. - Muscles are similar to thenar muscles in both name and organisation - Innervated by the ulnar nerve.

Question 40

What muscles make up the thenar muscle group?

Answer 40

- Opponens Digiti Minimi - Abductor Digiti Minimi - Flexor Digiti Minimi Brevis

Question 41

Opponens Digiti Minimi; | location, attachments, actions, innervation.

Answer 41

Location: lies deep to the other hypothenar muscles Origin: Hook of hamate and associated flexor retinaculum Insertion: Medial margin of metacarpal V Action: Rotates metacarpal of little finger towards the palm, producing opposition. Innervation: Ulnar nerve.

Question 42

Abductor Digiti Minimi; | location, attachments, actions, innervation.

Answer 42

Location: Most superficial of the hypothenar muscles. Origin: Pisiform and the tendon of the flexor carpi ulnaris. Insertion: Base of the proximal phalanx of the little finger. Action: Abducts little finger. Innervation: Ulnar Nerve.

Question 43

Flexor Digiti Minimi Brevis; | location, attachments, actions, innervation.

Answer 43

Location: lies laterally to the abductor digiti minimi. Origin: Hook of hamate and adjacent flexor retinaculum. Insertion: Base of proximal phalanx of the little finger. Action: Flexes the MCP joint of the little finger. Innervation: Ulnar Nerve.

Question 44

Where are interossei muscles located and what do they do?

Answer 44

- Located between the metacarpals. - Abduction and adduction of fingers - Can be divided into 2 groups; dorsal and palmar interossei.

Question 45

Dorsal Interossei; | location, attachments, actions, innervation.

Answer 45

Location: Most superficial of all dorsal muscles which can be palpated on dorsal of the hand. Number of muscles: 4 Origin: Each originates from lateral and medial surfaces of the metacarpal. Insertion: Into the extensor hood and proximal phalanx of each finger. Action: Abducts the fingers at the MCP joint. Innervation: Ulnar Nerve.

Question 46

Palmar Interossei; | location, attachments, actions, innervation.

Answer 46

Location: Anteriorly on the hand. Number of muscles: 3 Origin: Each originates from a medial or lateral surface of a metacarpal. Insertion: Into the extensor hood and proximal phalanx of the same finger. Action: Adducts the fingers at the MCP joint. Innervation: Ulnar nerve.

Question 47

Palmaris Brevis; | location, attachments, actions, innervation.

Answer 47

Location: Small, thin muscle found very superficially in the subcutaneous tissue of the hypothenar eminence. Origin: Palmar aponeurosis and flexor retinaculum. Insertion: Dermis of the skin on medial margin of the hand Action: Wrinkles skin of hypothenar eminence and deepens curvature of the hand, improving grip. Innervation: Ulnar Nerve

Question 48

Adductor Pollicis; | shape, attachments, actions, innervation.

Answer 48

Shape: Large triangular muscle with two heads. Origin: One head originates from Metacarpal III and the other from the capitate and adjacentt areas of metacarpal II and III. Insertion: Both insert into the base of proximal phalanx of the thumb. Action: Adductor of the thumb. Innervation: Ulnar Nerve.

Question 49

What are the lumbricals and; | attachments, actions, innervation.

Answer 49

- 4 lumbricals, each associated with a finger. Very crucial to finger movement, linking extensor and flexor tendons together. Origin: A tendon of the flexor digitorum profundus. Insertion: they pass dorsally and laterally around each finger and inserts into the extensor hood. Action: Flex at MCP joint and extend at IP joints of each finger. Innervation: Lateral lumbricals (index and middle) - median nerve. Medial lumbricals (little and ring) - ulnar nerve. *Denervation of these muscles is basis for ulnar claw and hand of benediction.