May24 M3-Arm, elbow and cubital fossa

Question 1

movements the forearm can do

Answer 1

• flexion and extension

- pronation and supination (supination = anat position)

Question 2

what nerve innervates the anterior compartment of muscles in the arm and what n. for posterior + function of each compartment + one exception

Answer 2

• anterior = musculocutaneous n. = flexion of arm
• posterior = radial n. = extension of arm
• brachioradialis = posterior compt of arm to anterior of forearm = radial n. = flexion*

Question 3

compartment definition

Answer 3

muscle grouping sharing a closed fascia (CT)

Question 4

number of muscles in ant and post forearm

Answer 4

ant = 3 muscles
post = 1 muscle
+ brachioradialis post arm to anterior forearm

Question 5

compartment syndrome definition + what’s the problem

Answer 5

hematoma or trauma results in muscle swelling and this compresses the vessels going to muscles. get muscle dying. inflammation and pain

Question 6

3 muscles in ant compt of arm

Answer 6

• biceps brachii m.
• coracobrachialis m.
• brachialis m.

Question 7

biceps brachii how many heads and where tendons go on top (origin)

Answer 7

2 heads (biceps)

• tendon of the long head (LATERAL) crosses the glenohumeral joint and goes to SCAPULA
• tendon of short head (MEDIAL) attaches to coracoid process of the SCAPULA

Question 8

biceps brachii insertion

Answer 8

• one tendon on radius (lateral bone forearm)

- an aponeurosis inserts on the ulna (medial bone forearm)

Question 9

names of the aponeurosis of biceps brachii inserting on the ulna

Answer 9

• bicipital aponeurosis

- flat tendon of the biceps brachii m.

Question 10

biceps brachii functions (2) + inn.

Answer 10

• flexion of arm and forearm (crosses glenohumeral joint and elbow joint)
• supination of forearm
• inn = musculocutaneous n.*

Question 11

brachialis m. origin, insertion, function and inn.

Answer 11

• humerus to ulna
• flexion of forearm
• musculocutaneous n.

Question 12

coracobrachialis m. origin, insertion, function and inn.

Answer 12

• scapula to humerus
• flexion of ARM and ADDuction of the arm
• musculocutaneous n.

Question 13

other name for arm

Answer 13

brachium

Question 14

supination and pronation is what movement

Answer 14

pronation = radius crossing over the ulna on top of it
supination = radius back on side (lat) of ulna

Question 15

full training of biceps brachii = what mvmts

Answer 15

• supination of forearm
• flexion of forearm
• arm flexion

Question 16

only muscle in posterior compt of arm + how many heads and tendons

Answer 16

triceps brachii. 3 heads and 3 tendons on top (origin)

Question 17

3 heads (on top) of the triceps brachii m. and where they originate from + location

Answer 17

• long head (medial): from scapula (allows ADDuction)
• lateral head (lateral): from humerus
• medial head (deep between long and lateral heads: from humerus

Question 18

where triceps brachii m. inserts (the 3 heads insert where)

Answer 18

ulna

note: origin was scapula + humerus

Question 19

function and innervation of triceps brachii m.

Answer 19

• extension of the arm (bc of long head) and forearm
• ADDuction of the arm
• radial n.*

Question 20

what brachial artery becomes

Answer 20

• same name all along the humerus
• crosses elbow joint
• after crosses elbow joint, splits in radial a. (lat) and ulnar a. (medial)

Question 21

what cephalic and basilic v become

Answer 21

• cephalic stays lat. and continues in forearm
• basilic stays medial and continues in forearm
• both connect at cubital fossa to form the median cubital vein

Question 22

cubital fossa is what

Answer 22

anterior interior fold of the elbow

Question 23

mechanism to prevent backflow of blood in veins of arm and forearm

Answer 23

valves

competent valve = functioning well

Question 24

how to check if a valve is functional

Answer 24

• ID vein
• put finger on vein and move distally until see a portion of the vein that is white (no blood there proximally valve blocking = one you’re checking and distally your finger is blocking)

Question 25

arteriovenous fistula links what vessels

Answer 25

radial artery and cephalic vein laterally

Question 26

musculocutaneous n. comes from what cord + spinal levels + to what muscles

Answer 26

- from lateral cord - C5,6,7 - to ant compt of arm

Question 27

musculocutaneous n. travels how

Answer 27

- pierces coracobrachialis to go anterior to it | - travels anterior to coracobrachialis, between coracobrachialis and biceps + brachialis m.

Question 28

where radial n is located (don't have to locate in anat lab)

Answer 28

- posterior compt. cut lateral head of triceps | * crosses the triangular interval

Question 29

important concepts in sensory info coming back from limbs

Answer 29

- is cutaneous + non cutaneous (feedback on muscle contraction and length) - in general**, n. innervating a m. also inn. the skin over this m.

Question 30

3 components of the cutaneous innervation of the arm

Answer 30

- axillary n. - radial n. - cutaneous branches of the brachial plexus or of the intercostal nerves (medial brachial and antebrachial cutaneous n.)

Question 31

sensory inn. of axillary n.

Answer 31

skin over deltoid m.

Question 32

sensory inn. of radial n.

Answer 32

skin over triceps brachii m.

Question 33

sensory inn. of musculocutaneous n.

Answer 33

skin over the lateral surface of the FOREARM (not skin over biceps)

Question 34

sensory inn. of cutaneous branches of brachial plexus or of intercostal n. (medial brachial cutaneous n. and antebrachial cutaneous n.)

Answer 34

skin over the biceps

Question 35

shape of the cubital fossa and borders

Answer 35

triangle pointing downwards - lat border = brachioradialis m. - medial border = pronator teres m. - superior border = imaginary line between epicondyles of the humerus

Question 36

most superficial structure in the cubital fossa

Answer 36

median cubital vein

Question 37

3 structures deep to median cubital vein in the cubital fossa

Answer 37

lateral to medial: - biceps tendon (lat) - brachial artery - median nerve (most medial)

Question 38

2 places to feel brachial pulse

Answer 38

- medial surface of biceps (find the brachial a. under the biceps brachii m.) - in the cubital fossa (+ also where you hear if taking manual BP)

Question 39

body landmarks on the surface of the elbow

Answer 39

- lateral and medial epicondyles of the humerus | - olecranon of the ulna

Question 40

what is the funny bone

Answer 40

medial epicondyle of the humerus

Question 41

ulna and radius relation to each other

Answer 41

- parallel in supination - opposite shapes. as you go distally, radius becomes wider but ulna becomes narrower - interosseus membrane between the two bones

Question 42

what's the interosseus membrane between the forearm bones

Answer 42

CT fibers oriented medially and in a proximal-distal direction

Question 43

how the arm absorbs a shock

Answer 43

- hand receives force - force transmitted from hand to RADIUS (wide distally) - radius transfers force to ulna via interosseus membrane - ulna (wider proximally) transfers force to humerus

Question 44

name given to absorption of shock by the arm + most fragile point in the system

Answer 44

- circumvoluted dissipation of force | - wrist to radius transmission is most fragile

Question 45

how humerus, radius and ulna articulate

Answer 45

humerus has 2 surfaces - capitulum (lat) for radius - trochlea for ulna (medial)

Question 46

type of joint the elbow joint is

Answer 46

synovial joint (fluid in it): for more movement and less friction

Question 47

structures supporting the elbow joint

Answer 47

- capsule (around the joint) - radial collateral ligament (lat epicondyle of humerus to radius) - ulnar collateral ligament (medial epicondyle of humerus to ulna) - annulus ligament (circle around the 3 bones at their articulation + gives a hole for the radius to fit in)

Question 48

2 important structures (supporting structures) in pronation and supination

Answer 48

- annular ligament allows radius ROTATION ON THE SURFACE OF THE HUMERUS (capitulum) in pronation-supination - interosseus membrane prevents radius dislocation during pronation-supination

Question 49

ulna movement in pronation-supination

Answer 49

doesn't move at all. well articulated with humerus

Question 50

why the ulna doesn't move in pronation-supination, is well articulated with the humerus and can only do flexion-extension

Answer 50

the ulna wraps around the humerus (**and not the opposite**). - interior part wrapping around = coronoid process of the ulna - exterior part wrapping around = olecranon of the ulna

Question 51

what's a pulled elbow

Answer 51

- a dislocation of the radius from the annular ligament - dislocation of arm downwards - can happen in children held in the air by their hands (more likely in children bc their annular ligament is loose)

Question 52

clinical case: 1. rupture of biceps tendon on right side (right upper extremity) 2. no fractures or dislocation 3. swelling and pain 4. numbness on lateral surface of right forearm 5. diminished radial pulse on the right upper extremity 6. weakness on elbow flexion * *Q: how do you account for the symptoms**: compt syndrome affecting median or ulnar or radial or musculocutaneous n. ?

Answer 52

compartment syndrome affecting the musculocutaneous nerve