MSK - forearm

Question 1

Bones of the forearm - name them

Answer 1

radius (thumb side) + ulna

Question 2

describe the radius

Answer 2

head, neck, radial tuberosity

Question 3

describe the ulna

Answer 3

coronoid process, olecranon, ulnar tuberosity, ulnar notch, head

Question 4

name the compartments of the forearm

Answer 4

anterior (superficial, intermediate and deep) and posterior (superficial and deep)

Question 5

what do the anterior compartment muscles generally do?

Answer 5

flex wrist or fingers

Question 6

what do the posterior compartment muscles generally do?

Answer 6

extend wrist or fingers

Question 7

in genearal, what innervates the anterior forearm muscles?

Answer 7

median nerve

Question 8

what innervates all the posterior compartment forearm muscles?

Answer 8

radial nerve

Question 9

name the muscles of the anterior, suprficial compartment + innervations (4)

Answer 9

all originate from the common flexor origin (medial epicondyle of humerus). 1) pronator teres (median). 2) flexor carpi radialis (median). 3) palmaris longus (median). 4) flexor carpi ulnaris (ULNAR)

Question 10

name the muscles of the anterior, intermediate compartment and innervation (1)

Answer 10

flexor digitorum superficialis (medial)

Question 11

name the muscles of the anterior, deep compartment and innervation (3)

Answer 11

flexor digitorum profundus (ULNAR), flexor pollicis longus (median) , pronator quadratus (median)

Question 12

name the muscles of the posterior, superficial compartment and innevation (5)

Answer 12

all originate from the common extensor origin (lateral epicondyle of humerous), and all are innervated by the RADIAL NERVE. 1) extensor carpi ulnaris, 2) extensor digitorum, 3) extensor digiti minimi, 4) extensor radialis brevis, 5) extensor radialis longus

Question 13

name the muscles of the posterior, deep compartment and innervation (5)

Answer 13

All are innervated by the RADIAL nerve. 1) supinator, 2) abductor pollicis longus, 3) extensor pollicis longus, 4) extensor pollicis brevis, 5) extensor indicis

Question 14

** what is so special about the flexor digitorum superficialis and flexor digitorum profundus?

Answer 14

FDP pierces FDS (profundus inserts into distal phalanges of fingers 2-5, superficialis only inserts into middle phalanges)

Question 15

what form the borders of the anatomical snuffbox?

Answer 15

tendons of the 1) extensor pollicis longus, and 3_ extensor pollicis brevis

Question 16

note: anything that is called “longus” and inserts into a finger probably inserts into what part of the finger?

Answer 16

distal phalanges/phalanx

Question 17

anything that is called “brevis” and inserts into a finger probably inserts into what part of the finger?

Answer 17

middle phalanges/phalanx

Question 18

Arteries of the forearm 1(the 4 branches of the brachial artery)

Answer 18

brachial artery –> radial recurrent + ulnar recurrent, and radial artery +ulnar artery

Question 19

arteries of the forearm 2 (arches of the ulnar and radial arteries)

Answer 19

radial artery (primarily) –> deep palmar arch, ulnar artery (primarily) –> superficial palmar arch

Question 20

arteries of the forearm 3 (a note on the branches of the ulnar artery)

Answer 20

ulnar artery –> common interosseus artery –> anterior + posterior interosseus arteries

Question 21

Generally speaking, describe the path of the main nerves of the arm + forearm (musculocutaneous, median, ulnar, radial)

Answer 21

musculocutaneous lives in the arm, you’ll see it on the anterior side high up in the arm before the elbow. MEDIAN and ULNAR supply the anterior compartment of the forearm, and median runs right down the center of the ant forearm, passing over the brachial artery just before it branches into the radial and ulnar arteries. Ulnar is visible on the anterior side, runnning from just behind the medial epicondyle (remember FUNNYBONE) down along the ulnar side of the arm. RADIAL supplies the entire posterior compartment, and is sneaky - it emerges and wraps around the lateral side of the anterior arm, just where you would think the musculocutaneous should be.

Question 22

cutaneous innervation of theforearm

Answer 22

lateral cutaneous nerve (musculocutaneous), medial cutaneous nerve (medial chord), posterior cutaneous nerve (radial)

Question 23

there are 3 articulations in the elbow joint capsule… name them

Answer 23

1) humeroulnar, 2) humeroradial (HINGE JOINTS), and 3) proximal radioulnar joint (PIVOT JOINT)

Question 24

name the 2 “Dents” in the humerus that allow the elbow to flex

Answer 24

radial fossa and coronoid fossa (for coronoid process of ulna)

Question 25

what is the posterior “dent” in the humerus that allows the elbow to extend?

Answer 25

olecranon fossa (for olecranon of ulna)

Question 26

The elbow is a hinge joint… what does this mean? (hint: collateral ligaments)

Answer 26

it has thickened collateral ligaments to prevent side-side slippage: radial collateral ligament + ulnar collateral ligament.

Question 27

What are the 3 ligaments of the elbow joint

Answer 27

radial collateral ligament, ulnar collateral ligament, joint capsule

Question 28

what mvts can the elbow (humeroradial and humeroulnar) joint do? (hint, elbow is a hinge joint)

Answer 28

flexion + extension

Question 29

how do you identify which bone is the ulna and which is the radius?

Answer 29

look for a skinny head (radius), coronoid process (ulna), olecranon (ulna), prominent tuberosity (probably the radial tuberosity), which one is covered by more ligaments (probably the radius in the radioulnar joint)

Question 30

describe the proximal radioulnar joint

Answer 30

head of radius is wrapped in an annular ligament, attaching it to the ulna’s radial notch in a PIVOT JOINT. Can dislocate/become pulled in children.

Question 31

what mvts can the proximal radioulnar joint do?

Answer 31

rotation of the radius within the annular ligament (pronation/supination)

Question 32

describe the distal radioulnar joint

Answer 32

ulnar head is attached to the radius’ ulnar notch via a Triangular Fibrocartilaginous Disc (TFD). A synovial joint which allows pronation in combination with the proximal radioulnar pivot joint

Question 33

what are 2 examples of a pivot joint (enabling rotation) in the body?

Answer 33

atlantoaxial joints (dens/anterior arch + 2 lateral mass/shoulder joints) + proximal radioulnar joint