Lecture 6: The Arm (and cubital fossa)

Question 1

What are the 3 muscles that go from the pec girdle to the humerus

Answer 1

Deltoid, Teres Major and Coracobrachialis

Question 2

Describe the innervation, origin and insertion of the deltoid

Answer 2

N: axillary nerve
O: anatomical horseshoe (spine of scapula, acromion and clavicle)
I: deltoid tuberosity on the humerus

Question 3

Describe the primary movement of the 3 section fibres of the deltoid

Answer 3

Ant fibres: flex the shoulder and internally rotate the arm
Mid fibres: adduct the arm
Post fibres: extend the shoulder, and externally rotate the arm.

Ant and Post fibres together help to adduct the arm or further adduct the arm from t pose

Question 4

Describe the innervation, origin and insertion of Teres major

Answer 4

N: Lower scapular nerve
O: inferior angle and lateral border of the scapula
I: medial lip of the intertubercular groove

Question 5

What are the primary movements of Teres major

Answer 5

• Internal rotation of the arm

- Extension of shoulder

Question 6

Describe the innervation, origin and insertion of Coracobrachialis

Answer 6

N: Musculocutaneous nerve
O: Coracoid
I: medial side of the humerus opposite deltoid tuberosity

Question 7

What are the primary movements of coracobrachialis

Answer 7

• adduction of the shoulder

Question 8

Describe the muscles found in the upper anterior face of the arm from the head of humerus to the start of the intermuscular septa in relation to bone structures on the humerus

Answer 8

At the proximal end of the humerus, there is a greater tubercle (lat) and lesser tubercle and intertubercular groove in the middle.
3 muscles attach there
- Pectoralis major on the lateral lip,
-Teres major on the medial lip and
-Lat Dorsi on the floor of the interbecular groove.

Just below that is there is the insertion of deltoid- the deltoid tuberosity on the lateral side opposite on the medial side is the insertion of coracobrachialis muscle

Question 9

How is the anterior/ flexor compartment divided from the posterior extensor compartment? and where are these boundaries attached

Answer 9

Medial and lateral intermuscular septa which are attached divides them into compartments and attaches distally to medial and lateral supracondylar ridges of the humerus- continuous with deep fascia, whilst fading out in the proximal part of the arm.

Question 10

Describe the muscles found in the lower anterior compartment of the arm

Answer 10

There is brachialis which fills up anterior compartment- from lateral to medial septa.
There is the lower part of biceps brachi which passes over superior to brachialis to its insertion

Question 11

At the level of the epicondyles, how is the muscle compartments of the arm/ forearm organised.

• what action muscles are there and where are they attaching to
• what compartment will they become on the forearm

Answer 11

There is now a lateral and medial compartment. (4 all together).

• Lateral compartment = common muscle origin of the extensor/ sup muscles of forearm.

Attaches from the lateral epicondyle and will become posterior compart of forearm.

• Medial compartment = common muscle origin of flexor/ pro muscles of the forearm.

Attaches from the medial epicondyle
Contains common flexor origin which will become the anterior compart of forearm

Question 12

What is the nerves are in the anterior, posterior, lateral and medial compartments at the level of the epicondyles ( just above cubital fossa)

Answer 12

Ant: musculocutaneous
Post: radial nerve
Lat: radial nerve
Med: ulnar/ median nerve

Question 13

What muscles of the forearm have their origin outside of the common tendons at the epicondyles. (from proximal to distal, belonging to extensor and flexor compt of forearm)

Answer 13

Lat/later extensor: Brachioradialis and ECRL

Med/ later flexor: Protanor teres from the supra condyle ridge

Question 14

What muscles are considered to be in the anterior/ flexor compartment of the arm from superficial to deep ? and what is their common innervation

Answer 14

Biceps brachii, Brachialis
Coracobrachialis.

N: musculocutaneous nerve

Question 15

Describe origin and insertion of biceps brachii

Answer 15

Origin of long head is the supraglenoid tubercle
Origin of the short head is the coracoid

Insertion of biceps brachi is bicipital aponeurosis which lies to the medial direction around the cubital fossa, and the radial tuberosity (more lateral than aponeurosis).

Question 16

Describe the primary movements of biceps brachii

Answer 16

Supinator and elbow flexor

Question 17

Describe origin and insertion of brachialis

Answer 17

O: anterior surface of the distal humerus including the intermuscular septa

I: Tuberosity of the ulnar (middle of two forearm bones)

Question 18

Describe the primary movements of brachialis

Answer 18

main elbow flexor

Question 19

What muscles are found from the pectoral girdle to the forearm

Answer 19

Biceps brachii and Triceps brachii - long head

Question 20

What muscles are found from the arm to the forearm

Answer 20

Brachialis and triceps : lateral and medial head

Question 21

What muscle makes up the posterior compartment of the arm

Answer 21

Triceps brachii

Question 22

Describe the innervation, origin and insertion of triceps brachii

Answer 22

N: radial nerve

Triceps Brachii has 3 heads, (long, medial and lateral).

• Long head O: infraglenoid tubercle.
• Medial and lateral head O: back of the humerus

Insertion: olecranon (back of the ulna)

Question 23

What is the position of the muscle belly of long head of triceps brachii in relation to teres maj and min

Answer 23

It passes between them, with the major in front and the minor behind

Question 24

What is the muscle considered an extension of triceps and where is it

Answer 24

A small forearm muscle attached to the lateral epicondyle is the Anconeous which helps the extension of triceps

Question 25

What are the “shunt muscles” of the arm and what does this mean

Answer 25

These are the deltoid, short head biceps, coracobrachialis and long head triceps. These help to prevent unwanted inferior movement of the humeral head at the shoulder during load carrying.

Question 26

Describe the path of the median nerve from origin to its entry at the cubital fossa

Answer 26

Follows closely the axillary/brachial artery on the lateral side of it, underneath the biceps brachi and enters the cubital fossa on the medial side of the brachial artery next to the medial intermuscular septa on other side lies basilic vein

Question 27

Describe the path of the ulnar nerve from origin to its entry at the cubital fossa

Answer 27

Starts most medial and follows axillary/brachial artery down until 2/3 way down when it goes to the posterior compartment behind the intermuscular septum with the superior ulnar collateral artery, so slightly in front of the triceps brachii before going back to the anterior side of the forearm after the medial epicondyle

Question 28

Describe the path of the musculocutaneous nerve from origin to its entry at the cubital fossa

Answer 28

starts most lateral with a branch going to coracobrachialis, travels between brachialis and biceps brachii, ends up entering the cubital fossa in between those muscles on the lateral side of anterior compartment b

Question 29

Describe the path of the radial nerve from origin to its entry at the cubital fossa

Answer 29

Starts behind the axillary artery on top of pec major and then goes in the triangular interval (radial groove) under teres major and in the gap between long head of triceps and medial head. Travels down the posterior compartment before entering the lateral intermuscular septa and ending up in the lateral posterior compartment of the cubital fossa under the brachioradialis. Later goes to the anterior side of lateral epicondyle

Question 30

Describe the path of the axillary nerve from origin to its end

Answer 30

starts off behind the axillary artery, branching first before the radial nerve and crosses to the posterior side through the quadrangular space to go back out to the lateral skin of the shoulder area

Question 31

Describe the 3 spaces at the posterior view of shoulder/arm formed by what 3 muscles

Answer 31

Teres minor and major run parallel from scapula to humerus at sort of right angle to the long head of triceps brachi just going down the humerus.
There is a triangular space between teres minor and maj containing circumflex scapular artery
There is quadrangular space between all three which contains the axillary nerve and posterior circumflex humeral artery (and vein)
There is a triangular interval under teres major and next to long head of triceps brachii long head which contains radial nerve and profunda brachii artery.

Question 32

Describe the main arterial supply of the arm to cubital fossa

Answer 32

Starts off as axillary artery which becomes brachial artery after it passes Teres major. At this point there is also the branch of the profunda brachii artery.
Continues down medial side going to the centre point at the cubital fossa where it splits to the radial artery and ulnar artery. They give off recurrent (ascending) branches which anastomose with descending branches from the profunda and brachial arteries to provide a network around the elbow

Question 33

Describe the superficial veins at the cubital fossa

Answer 33

On the lateral side the cephalic vein continues down and on the medial side is the basilic vein. Connecting these two is the median cubital vein from which the median antebrachial vein may be present

Question 34

Describe the boundaries of the cubital fossa

Answer 34

The imaginary line between the lateral and medial epicondyles of humerus forms upper border. The medial boundary is from pronator teres . The lateral boundary is by brachioradialis. the roof is by the deep fascia of the forearm and the floor by brachialis