Lecture 15 - Forearm and Hand 1

Question 1

How many carpal, metacarpal and phalanx bones are there in the hand?

Answer 1

8 Carpal bones

5 Metacarpal bones

14 Phalanges (2 in thumb, 3 in other fingers)

Question 2

Describe the arrangement of the 8 carpal bones

Answer 2

The carpal bones are arranged into a proximal and distal row, with there being 4 bones in each row

Question 3

What are the 4 bones in each of the proximal and distal row of the carpal bones?

Answer 3

Proximal: Scaphoid, Lunate, Triquetral, Pisiform

Distal: Trapezium, Trapezoideum, Capitate, Hamate

Question 4

What kind of joint is the wrist joint?

Answer 4

It’s an Ellipsoid joint, which is biaxial allowing for flexion, extension, adduction and abduction

Question 5

What bones form the midcarpal joint, and what function does this joint have?

Answer 5

Midcarpal joint is formed by the proximal and distal row of carpals.

This joint increases the range of flexion/extension of the carpus.

Question 6

Describe the naming system for the wrist (sides and aspects)

Answer 6

Question 7

What is the origin of Flexor carpi ulnaris, and flexor carpi radialis, and where do they insert?

Also, what movement do they perform on the wrist joint?

Answer 7

They both originate at the medial epicondyle of humerus.

Flexor carpi ulnaris inserts into the base of the 5th metacarpal, whilst Flexor carpi radialis inserts into the base of metacarpals 2 and 3.

They both flex and abduct the wrist joint.

Question 8

What muscles flexes both the interphalangeal amd metacarpophalangeal joints of the thumb?

Answer 8

Flexor pollicis longus

Question 9

What muscle flexes both the interphalangeal and metacarpophalangeal joints of the index, middle, ring, and little fingers of the hand?

Answer 9

Flexor digitorum profundas

Question 10

What are the extensors of the wrist in the posterior compartment of the forearm? And where do these originate?

Answer 10

Extensor carpi radialis longus

Extensor carpi radialis brevis

Extensor carpi ulnaris

They originate from the lateral epicondyle of the humerus

Question 11

Where does the Extensor carpi radialis brevis insert?

Answer 11

Base of metacarpals 2 and 3

Question 12

Where does extensor carpi radialis longus insert?

Answer 12

Base of metacarpal 2

Question 13

Where does extensor carpi ulnaris insert?

Answer 13

Base of metacarapl 5

Question 14

Which muscles peform wrist flexion?

Answer 14

Flexor carpi radialis

Flexor carpi ulnaris

Question 15

Which muscles perform wrist extension?

Answer 15

Extensor carpi radialis longus and brevis

Extensor carpi ulnaris

Question 16

How can the muscles of the wrist work together?

Answer 16

They act in pairs, with one being the agonist and the other an antagonist. And they also act as synergists to cancel out unwanted movement.

Question 17

Which muscles which move the wrist are found on the ulnar side of the forearm?

Answer 17

Flexor carpi ulnaris

Extensor carpi ulnaris

Question 18

Which muscles which move the wrist are found on the radial side of the forearm?

Answer 18

Flexor carpi radialis

Extensor carpi radialis longus

Extensor carpi radialis brevis

Question 19

Describe the carpometacarpal joints (CMJ)

Also include which ones have a greater, and smaller ROM

Answer 19

The carpometacarpal joints consists of a series of four medial plane joints.

There is a greater range of movement for the CMJ with metacarpals 4 and 5

There is less movment than CMJ at metacarpals 2 and 3 (with index and middle finger)

Question 20

What kind of joint is the carpometacarpal joint of metacarpal 1?

Answer 20

This is the thumb joint. Its a saddle joint between trapezium and metacarpal 1.

This joint allows flexion, extension, adduction, abduction and opposition.

(this joint commonly becomes osteoartritic)

Question 21

How is the thumb set? As in, what position does the thumb have to be in in order for the palmar surface to be facing anteriorly?

Answer 21

The thumb is set at 90 degrees to the plane of the palm.

Question 22

Describe how flexion, extension and abduction and adduction would look like for the thumb

Answer 22

Flexion of thumb draws it across hand, opposite is extension.

Abduction pulls thumb away from plane of hand, opposite of this is adduction

Opposition is just touching the tips of the other four fingers with the thumb

Question 23

Describe the metacarpophalangeal joints

Answer 23

They are biaxial (ellipsoidal joints) allowing for:

Flexion, extension, abduction and adduction

Question 24

How many interphalangeal joints are there? And also, describe this joint.

Answer 24

There are two in each finger, and one in the thumb. Proximal is the proximal interphalangeal joint, and distal is the distal interphalangeal joint.

These are hinge joints, which allow for flexioin and extension

Question 25

Flexion of the MCP and IP joints allows for what kind of grip?

Answer 25

Hook/power grip

Question 26

Flexion of the MCP and extension of IP joints allows for what kind of grip?

Answer 26

Precision grip

Question 27

What are the extrinsic muscles of the thumb?

Answer 27

Flexor pollicis longus

• Lateral side of forearm
• Attaches to base of distal phalanx

Extensor pollicis longus and brevis

• Oblique bellies
• Attach to base of proximal (EPB) and distal (EPL) phalanges

Abductor pollicis longus

• Adjacent to EPB
• Attaches to base of metacarpal 1
  *

Question 28

What anterior and posterior tendons make up the anatomical snuff box?

Answer 28

Anteriorly then tendons are of:

• Extensor pollicis brevis
• Abductor pollicis longus

Posteriorly the tendon of

• Extensor pollicis longus

Question 29

Which artery runs through the snuff box?

Answer 29

Radial artery

Question 30

What are the intrinsic muscles of the thumb?

Answer 30

Thenar eminence, made up of three muscles (all inneravted by the median nerve)

• Flexor pollicis brevis
• Abductor pollicis brevis
• Opponens pollicis (helps more with opposition)

Adductor pollicis (innervated by the ulnar nerve)

Question 31

Describe the location of flexor pollicis brevis, and where it inserts

Answer 31

It is on the medial side of thenar eminence, and it inserts into proximal phalanx

Question 32

Describe the location of Abductor pollicis brevis, and where it inserts

Answer 32

Lateral side of thenar eminence, inserts into proximal phalanx

Question 33

Describe the location of Opponens pollicis, and where it inserts

Answer 33

Inserts into lateral border and lateral part of the front of the shaft of metacarpal 1

Question 34

Describe the location, structure and insertion of adductor pollicis

Answer 34

Adductor pollicis comes off the capitate and 3rd metacarpal and inserts into the base of the proximal phalanx of thumb

It arises by two heads, an oblique head and a transverse head

Question 35

What are the extrinsic flexors of the fingers?

Answer 35

Flexor digitorum superficialis (FDS)

Flexor digitorum profundus (FDP)

Both originate from the medial epicondyle

Question 36

What is the origin and insertion for flexor digitorum superficialis?

Answer 36

Originates at the humeroulnar and radial heal, and inserts into the proximal phalanges (and also basees of middle phalanges)

Question 37

What is the origin of flexor digitorum profundas?

Answer 37

Arises from anterior ulnar and interosseseous membrane, and inserts into the base of the distal phalanges