Elbow, Posterior Forearm, and Wrist

Question 1

what makes up the elbow joint

Answer 1

the elbow joint is actually made from 3 separate joints

• humeroulnar joint
• humeroradial joint
• proximal radioulnar joint

Question 2

humeroulnar joint

Answer 2

this is the joint between the humerus and the ulna within the elbow

-the junction between the trochlear notch of ulna and the trochlea of humerus

Question 3

humeroradial joint

Answer 3

this is the joint between the humerus and the radius within the elbow

the joint between the head of the radius and the capitulum of the humerus

Question 4

proximal radioulnar joint

Answer 4

a synovial joint that connects the proximal ends of the radius and ulna.

• In this joint, the circumferent head of radius is placed within the ring formed by the radial notch of ulna and the annular ligament –> makes this joint a pivot joint

Question 5

annular ligament

Answer 5

this is a ligament that surrounds the radius, holding it tight to the ulna which still allowing it to rotate on the ulna with pronation and supination

-this is within the proximal radioulnar joint

Question 6

radial collateral ligament

Answer 6

• this is a short and narrow fibrous band that is less distinct that the ulnar collateral ligament
• this is on the radial side of the humeroulnar joint
• works with the ulnar collateral ligament to prevent abduction and adduction at the joint

Question 7

ulnar collateral ligament

Answer 7

• runs along the inner side of the elbow
• this is on the ulnar side of the humeroulnar joint
• works with the radial collateral ligament to prevent abduction and adduction at the joint

Question 8

distal radioulnar joint

Answer 8

the distal articulation between the radius and ulna.

The ulna is smaller distally while the radius is larger

Question 9

radiocarpal joint

Answer 9

between the radius and carpal bones. The ulna does not articulate directly with the first row of carpal bones in the lower hand

Question 10

midcarpal joint

Answer 10

synovial gliding joints between the proximal and distal rows of carpal bones

Question 11

intercarpal joint

Answer 11

synovial plane joints that connect the carpal bones

Question 12

carpometacarpal joints

Answer 12

between the distal carpals and the metacarpals

Question 13

extensor carpi radialis longus

Answer 13

• On the radial side of the forearm
• deep to the brachioradialis
• has a longer tendon and is just superficial and lateral to the extensor carpi radialis brevis

Action:Extends wrist, abducts hand

origin: Lateral distal humerus
insertion: Base of 2nd metacarpal
innervation: Radial nerve

Question 14

extensor carpi radialis brevis

Answer 14

• On the radial side of the forearm
• deep to the brachioradialis
• has a shorter tendon and is just deep to the extensor carpi radialis longus

action:Extends wrist, abducts hand
origin:Lateral epicondyle of humerus
insertion:Base of metacarpal III
Innervation: Radial nerve

Question 15

radial deviation

Answer 15

abduction of the wrist

Question 16

extensor carpi ulnaris

Answer 16

action: Extends wrist, adducts hand
origin: Lateral epicondyle of humerus
insertion: Base of 5th metacarpal
Innervation: Radial nerve

Question 17

ulnar deviation

Answer 17

adduction of the wrist

Question 18

extensor digitorum

Answer 18

Note that there is only one extensor digitorum muscle, so there is no other descriptor in the name

action: Extends wrist, 2nd–5th MP joints, PIP joints, & DIP joints
origin: Lateral epicondyle of humerus
insertion: Distal & middle phalanges of digits 2–5

Innervation: Radial nerve

Question 19

juncturae tendinae.

Answer 19

angled dense connective tissue connecting the tendons of the extensor digitorum in the hand

• functions to coordinate and distribute force across the extensor tendons

Question 20

extensor digiti minimi

Answer 20

just medial to the extensor digitorum and is lateral to the extensor carpi ulnaris

allows you to you can extend your 5th digit much farther while the others are flexed

action: Extends wrist, MP, and PIP joints of finger 5

origin:Lateral epicondyle of humerus
insertion:Proximal phalanx of finger 5
Innervation: Radial nerve

Question 21

extensor indicis

Answer 21

deep to the extensor digitorum
medial to the extensor pollicis longus

allows you to extend your 2nd digit (pointer finger) while flexing your other digits

action: Extends MP, PIP, and DIP joints of finger 2
origin: Posterior ulna
insertion: 2nd finger

Innervation:Radial nerve

Question 22

supinator

Answer 22

• this is a deep muscle in the posterior arm
• is deep and more difficult to find, but it can be observed running from the lateral epicondyle to the shaft of the radius.
• this is just distal to the elbow

action:Supinates forearm
origin:Lateral epicondyle of humerus & proximal ulna
insertion: Anterolateral radius
Innervation: Radial nerve

Question 23

abductor pollicis longus

Answer 23

• a deep muscle in the forearm
• this is on the lateral side and wraps around the tendons of the extensor carpi radialis longus and brevis
• this is lateral to the extensor pollicis brevis

action:Abducts thumb
origin:Proximal radius and ulna
insertion:Lateral 1st metacarpal
Innervation:Radial nerve

Question 24

extensor pollicis brevis

Answer 24

• a deep muscle of the forearm
• it’s tendon sits between the abductor pollicis longus and extensor pollicis longus tendons
• this is on the lateral side and wraps around the tendons of the extensor carpi radialis longus and brevis
• this is just medial to the abductor pollicis longus

action:Extends MP joints of thumb
origin:Posterior radius
insertion: thumb
Innervation:Radial nerve

Question 25

extensor pollicis longus

Answer 25

• a deep muscle of the forearm
• just lateral to the extensor indicis muscle

action:Extends MP and IP joints of thumb
origin:Posterior ulna
insertion: thumb
Innervation:Radial nerve

Question 26

extensor retinaculum

Answer 26

this is the dense connective tissue running over the extensor tendons
- this holds the extensor tendons in place and provided a mechanical advantage with extension