Lecture 14 - Musculoskeletal 3

Question 1

what are the three parts of the deltoid?

Answer 1

anterior, posterior and middle fibres

Question 2

what is the origin and insertion of the entire deltoid?

Answer 2

origin: the anatomical horseshoe
- anterior = clavicle, posterior fibres = scapula
insertion: the deltoid tuberosity of the humerus

Question 3

what is the primary movement of the deltoid’s anterior fibres?

Answer 3

flex the shoulder
internal rotator of the humerus

Question 4

what is the primary movement of the deltoid’s posterior fibres?

Answer 4

extend the shoulder (pulls humerus backwards)
externally rotates arm

Question 5

what is the primary movement of the deltoid’s middle fibres and entire deltoid?

Answer 5

abducts humerus/arm, but does depend of where arm is and which fibres are activated

Question 6

how do the anterior and posterior fibres of the deltoid relate to each other?

Answer 6

they are antagonists in rotation and flexion/extension.
but flexing them at the same time can cause adduction of the humerus at anatomical position, and assist in further abduction when arms are lifted

Question 7

how does the supraspinatus assist in abduction?

Answer 7

the middle fibres of the deltoid would try to pull up on the humerus. The corcoacromial arch prevents this, so the supraspinatus starts abduction to take the humerus far enough away from your body so the middle fibres can start to contract

Question 8

what is the origin and insertion of the teres major?

Answer 8

origin: inferior angle of the posterior scapula just below the teres minor
insertion: medial lip of the intertubercular groove on the anterior humerus
- goes from posterior side of body to anterior like lat dorsi

Question 9

what is the primary movement of the teres major?

Answer 9

adductor of the shoulder
also an internal/medial rotator

Question 10

what does a teres mean

Answer 10

the muscle is circular or round when cut in cross-section

Question 11

what muscles form the anterior and posterior fold of the armpit?

Answer 11

anterior = pectoralis major
posterior = latissimus dorsi and teres major

Question 12

what is the origin and insertion of the coracobrachialis?

Answer 12

origin: coracoid process
insertion: medial side of humerus (opposite the deltoid tuberosity)

Question 13

what is the primary movement of the coracobrachialis?

Answer 13

adduction of shoulder

Question 14

what is the insertion of the pectoralis major and what is its significance to the arm?

Answer 14

lateral lip of the intertubercular groove
- hold tendon of the biceps brachii in place

Question 15

what do all components of a compartment share?

Answer 15

the same nerve supply, drained by the same vein and lymphatics

Question 16

at what point in the arm can we begin to form compartments?

Answer 16

just under the insertion of the deltoid (deltoid tubercle) and the coracobrachialis, the lateral and medial intermuscular septa begin.

Question 17

describe the comparment of the arm at the mid humerus (1)

Answer 17

there is a flexor compartment with 3 muscles and an extensor compartment with 1 muscle. these two are separated by the humerus and the lateral and medial intermuscular septa

Question 18

true or false, the origin of muscles can be an intermuscular septum

Answer 18

true

Question 19

what is the primary movement of the brachialis?

Answer 19

main elbow flexor

Question 20

what is the origin and insertion of the brachialis?

Answer 20

origin is the anterior surface of the distal humerus (including intermuscular septa)
insertion is the tuberosity of the ulna

Question 21

why do the long muscles of the hands and fingers attach to the side of the elbow/humerus?

Answer 21

• long muscles account for large range of motion and stronger movements
• It keeps the forearm compact, allowing the long tendons to run down the forearm into the hand without bulky muscle mass getting in the way of fine motor control.
  In short: power at a distance with precision at the fingertips! 💪✋

Question 22

how does muscle attachment on the elbow for hand movement change the structure of the upper arm/elbow compartment?

Answer 22

the lateral and medial intermuscular septa split to create another compartment on each side, where the muscles for hand movement can attach
- medial and lateral compartments created as well as flexor and extensor compartments for the common tendons

Question 23

where do the majority of the muscles of the forearm originate?

Answer 23

on the lateral and medial epicondyles of the humerus/elbow via a common tendon

Question 24

the lateral epicondyle shares a common __________ tendon of the forearm, and the medial epicondyle shares a common _________ tendon of the forearm

Answer 24

extensor, flexor

Question 25

where does the common extensor tendon go/occupy?

Answer 25

from the lateral side of the humerus around to the posterior side of the forearm.

Question 26

where does the common flexor tendon go/occupy?

Answer 26

from the medial side of the humerus around to the anterior side of the forearm.

Question 27

what are the three muscles of the flexor compartment of the upper arm?

Answer 27

- biceps brachii - brachialis - coracobrachialis

Question 28

what originates from the medial and lateral compartments OTHER than the common tendons?

Answer 28

medial: pronator teres on the supracondylar ridge lateral: Brachioradialis and ECRL (extensor carpi radialis longus)

Question 29

what muscle forms the extensor compartment of the upper arm?

Answer 29

the triceps brachii

Question 30

what is the primary movement of triceps brachii?

Answer 30

elbow extensor

Question 31

what are the two origins and two insertions of the biceps brachii?

Answer 31

long head origin: supraglenoid tubercle short head origin: coracoid process insertion 1: bicipital aponeurosis (not a bony insertion) insertion 2: radial tuberosity (bump on inside of radius)

Question 32

what is the primary movement of biceps brachii?

Answer 32

supinator (towards holding bowls of soup from spilt soup = supination) and then elbow flexor = pulls the radius back over the ulna to anatomical position

Question 33

what is the primary movement of brachialis?

Answer 33

main elbow flexor

Question 34

what is the origin and insertion of the brachialis?

Answer 34

origin: anterior surface of distal humerus insertion: tuberosity of the ulna

Question 35

how does supernation happen in terms of forearm bones?

Answer 35

the distal end of the radius crosses over the top of the ulna as the proximal end rotates against the humerus, and this brings the hand with it

Question 36

random function of the tendon of the long head biceps tendon?

Answer 36

keeps the humerus against the glenoid as the humerus rotates

Question 37

what is a problem with the biceps long head as we get older?

Answer 37

osteophytes can cause rupturing of the long head biceps - worn down tendon

Question 38

which nerve innervates all three muscles of the anterior flexor compartment?

Answer 38

the musculocutaneous nerve

Question 39

what are the head of the triceps?

Answer 39

lateral, medial, long heads

Question 40

what is the insertion of the triceps heads?

Answer 40

olecranon of the ulna

Question 41

what is the forearm muscle that assists triceps in elbow extension?

Answer 41

anchoneus lateral epicondyle -> back of the ulna

Question 42

what are shunt muscles?

Answer 42

prevent unwanted inferior movement/dislocation of the humeral head at the shoulder joint during loading (e.g carrying a heavy item). but they are not shortening

Question 43

what are the shunt muscles of the arm?

Answer 43

deltoid short head biceps coracobrachialis long head triceps