ANATOMY Anatomy of the Forearm, Wrist and Hand 1

Question 1

Describe the bones of the hand

Answer 1

Carpal bones (8 of them in total) make up the wrist joint
Above carpal are 5 metacarpal bones, then phalanges, three on each finger, with the exception of the thumb
Fingers have 3 phalanges: proximal, middle, distal
Thumb has 2 phalanges: proximal, distal
Fingers=digits, thumb = digit 1

Question 2

Label this

Answer 2

Question 3

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Question 4

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Question 5

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Question 6

Answer 6

• ulnar notch = where head of ulnar attaches
• facets for articulation with scaphoid and lunate bones (carpal bones)

Question 7

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Question 8

When the ulnar and radius are joined together, they will be reinforced by…
Also describe the proximal and distal radioulnar joints

Answer 8

When the ulnar and radius are joined together, they will be reinforced by the interosseous membrane
Interosseous membrane is a fibrous joint, that prevents the two bones from going apart. There are apertures on this membrane for interosseous artery and nerve

• proximal radioulnar joint - a pivot joint
• distal radioulnar joint - a pivot joint, articular disc reinforces this joint

Question 9

What are the 8 carpal bones?

Answer 9

Question 10

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Question 11

Describe the:
articular disc, intercarpal joints and wrist joint

Answer 11

The articular disc is fibrous cartilage to reinforce the radio-ulnar joint
Intercarpal joints=synovial plane joints between the carpal bones, augmenting the movements of the radiocarpal joint and increasing range of movement
Wrist joint = radiocarpal joint

Question 12

Does the ulnar contribute to the wrist joint?

Answer 12

Ulnar (condyloid joint) does not actually contribute to the wist joint, instead the articular disc of the distal radio-ulnar joint and the head of the radius do, articulating with the proximal row of carpal bones (minus the pisiform) forming the radiocarpal joint.

Question 13

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Answer 14

Carpometacarpals and intermetacarpals are plane synovial joints
Carpametacarpal of thumb is a saddle joint
Metacarpophalangeal= condyloid joints
Interphalangeal: fingers have a interphalangeal proximal and distal joint (exception of thumb which has one interphalangeal joint). Hinge joints

Question 15

Answer 15

Question 16

What arefour ligamentsof note in the wrist joint?

Answer 16

Palmar radiocarpal: found on the palmar (ant) side of the hand. Apart from increasing stability, it also ensures the hand follows the forearm during supination.
Dorsal radiocarpal: found on the dorsum side of the hand. It contributes to wrist stability + ensures that the hand follows the forearm during pronation.
Ulnar collateral: Runs from the ulnar styloid process to the triquetrum and pisiform. Works in union with the other collateral ligament to prevent excessive lateral joint displacement.
Radial collateral: Runs from the radial styloid process to the scaphoid and trapezium.

Question 17

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Question 18

Describe the actions of the thumb and mcp joints

Answer 18

Question 19

Describe anterior and posterior compartments of the hand

Answer 19

Anterior compartment (flexor-pronator)
- flexors and pronators
- this compartment is all innervated by median nerve (1.5 exceptions)
- medial epicondyle + supracondylar ridge

Posterior compartment (extensor-supinator)
- extensors and supinators
- this compartment is all innervated by radial nerve
- lateral formations

Question 20

Answer 20

Question 21

The muscles in theanterior compartment of the forearmare organised into three layers. Describe these

Answer 21

Superficial: flexor carpi ulnaris, palmaris longus, flexor carpi radialis, pronator teres. All of these muscles have a shared origin- the medial epicondyle of the humerus
Intermediate: flexor digitorum superficialis.
Deep: flexor pollicis longus, flexor digitorum profundus and pronator quadratus.

Question 22

One of the muscles in the superficial anterior compartment of the forearm include the flexor carpi ulnaris. Describe the attachments, actions and innervation of this

Answer 22

Attachments:: flexor carpi ulnaris has 2 origins. The humeral head originates from the medial epicondyle of the humerus with the other superficial flexors, whilst the ulnar head originates from the olecranon of the ulna.

The muscle tendon passes into the wrist and attaches to the pisiform bone, hook of hamate, and base of the 5th metacarpal
Actions:Flexion and adduction at the wrist.
Innervation:Ulnar nerve

Question 23

One of the muscles in the superficial anterior compartment of the forearm include the flexor carpi radialis. Describe the attachments, actions and innervation of this

Answer 23

Attachments:Originates from the medial epicondyle, attaches to the base of metacarpals II and III.
Actions:Flexion and abduction at the wrist
Innervation:Median nerve.

Question 24

One of the muscles in the superficial anterior compartment of the forearm include the palmaris longus. Describe the attachments, actions and innervation of this

Answer 24

This muscle is absent in about 15% of the population.
Attachments:Originates from the medial epicondyle, attaches to the flexor retinaculum of the wrist.
Actions:Flexion at the wrist.
Innervation:Median nerve

Question 25

One of the muscles in the superficial anterior compartment of the forearm include the pronator teres. Describe the attachments, actions and innervation of this

Answer 25

The lateral border of the pronator teres forms the medial border of the cubital fossa **Attachments:** 2 origins, one from the medial epicondyle, and the other from the coronoid process of the ulna. It attaches laterally to the mid-shaft of the radius **Actions:** Pronation of the forearm. **Innervation:** Median nerve.

Question 26

What is the flexor digitorum superficialis?

Answer 26

**flexor digitorum superficialis** is the only muscle of the intermediate compartment. It can sometimes be superficial muscle, but mostly lies between the deep and superficial muscle layers. The **median nerve** and **ulnar artery** pass between its two heads, and then travel posteriorly- so good anatomical landmark in the forearm

Question 27

What are the attachments, actions and innervation of the flexor digitorum superficialis?

Answer 27

**Attachments:** 2 heads – one originates from the medial epicondyle of the humerus, the other from the radius. The muscle splits into four tendons at the wrist, which travel through the carpal tunnel, and attach to the base of the middle phalanx of the four digits. **Actions:** Flexes the metacarpophalangeal joints and proximal interphalangeal joints at the 4 fingers, and flexes at the wrist. **Innervation:** Median nerve.

Question 28

There are three muscles in the deep anterior forearm: - flexor digitorum profundus - flexor pollicis longus - pronator quadratus Describe the flexor digitorum profundus

Answer 28

**Attachments:** Originates from the ulna and associated interosseous membrane. At the wrist, it splits into four tendons, that pass through the carpal tunnel and attach to the distal phalanges of the four fingers. **Actions:** It is the only muscle that can flex the distal interphalangeal joints of the fingers. Also flexes at metacarpophalangeal joints and at the wrist. **Innervation:** The medial half (acts on little + ring fingers) is innervated by the ulnar nerve. The lateral half (acts on middle + index fingers) is innervated by the anterior interosseous branch of the median nerve.

Question 29

There are three muscles in the deep anterior forearm: - flexor digitorum profundus - flexor pollicis longus - pronator quadratus Describe the flexor Pollicis longus

Answer 29

This muscle lies laterally to the flexor digitorum profundus **Attachments:** Originates from the anterior surface of the radius and surrounding interosseous membrane. Attaches to the base of the distal phalanx of the thumb. **Actions**: Flexes the interphalangeal joint and metacarpophalangeal joint of the thumb. **Innervation**: Median nerve (anterior interosseous branch).

Question 30

There are three muscles in the deep anterior forearm: - flexor digitorum profundus - flexor pollicis longus - pronator quadratus Describe the pronator quadratus

Answer 30

A square shaped muscle found deep to the tendons of the flexor digitorum profundus and flexor pollicis longus. **Attachments:** Originates from the ant surface of the ulna and attaches to the ant surface of the radius. **Actions:** Pronates the forearm. **Innervation:** Median nerve (anterior interosseous branch)

Question 31

Label this

Answer 31

Question 32

the carpal tunnel is formed by two layers: a deep carpal arch and a superficial flexor retinaculum. Describe these

Answer 32

**Carpal Arch**: Concave on the palmar side, forming the base and sides of the carpal tunnel. Formed laterally by the scaphoid and trapezium tubercles Formed medially by the hook of the hamate and the pisiform **Flexor Retinaculum**: Thick connective tissue which forms the roof of the carpal tunnel. Bridges the space between the medial and lateral parts of the arch, turning arch into tunnel Spans between the hook of hamate and pisiform (medially) to the scaphoid and trapezium (laterally).

Question 33

What does the carpal tunnel contain?

Answer 33

The carpal tunnel contains a total of 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 34

What is CTS?

Answer 34

Compression of the median nerve within the carpal tunnel can cause carpal tunnel syndrome (CTS).  Causes: thickened ligaments and tendon sheaths. Clinical features: numbness, tingling and pain in the distribution of the median nerve. The pain will usually radiate to the forearm Treat w splint and corticosteriod