Pectoral and Scapular regions, and axilla

Question 1

Which groove does the cephalic vein run in, and by which muscles is it formed?

Answer 1

Deltopectoral groove, formed by pectoralis and adjacent deltoid muscles.

Question 2

Pectoralis major

Answer 2

Proximal: clavicular head: anterior surface of medial half of clavicle.
Sternocostal head: anterior surface of sternum, superior 6 costal cartilages, aponeurosis of external oblique.

Distal: lateral lip of intertubercular sulcus of humerus.

N: Lateral and medial pectoral nerves: clavicular head: C5-C6.
Sternocostal head: C7, C8, T1.

• Adducts and medially rotates humerus, draws scapula anteroinferiorly.
• When acting alone, clavicular head flexes humerus, sternocostal head extends it from the flexed position.

Question 3

Pectoralis minor

Answer 3

Proximal: 3rd-5th ribs near their costal cartilages.
Distal: coracoid process.
N: medial pectoral nerve, C8, T1.
-stabilizes scapulothoracic joint.

Question 4

Subclavius

Answer 4

Proximal: Junction of 1st rib and its costal cartilage.
Distal: middle third of clavicle (inferior surface).
N: nerve to subclavius, C5-C6.
-anchors and depresses clavicle.

Question 5

Serratus anterior

Answer 5

Proximal: External surfaces of lateral parts of 1st to 8th ribs (filipovic said 2nd to 9th).
Distal: anterior surface of medial border of scapula.
N: Long thoracic nerve.
-protracts scapula and holds it against thoracic wall, rotates scapula.

Question 6

Which muscle forms the medial wall of the axilla?

Answer 6

Serratus anterior

Question 7

Which muscle rotates the scapula, elevating its glenoid cavity so the arm can be raised above the shoulder?

Answer 7

Serrated anterior.

Question 8

Trapezius

Answer 8

Proximal: medial third of superior nuchal line, external occipital protuberance, nuchal ligament, spinous processes of C7-T12.

Distal: lateral third of clavicle, acromion and spine of scapula.

N: CNXI (motor), C3-C4 (pain and proprioception).

-Descending part elevates, ascending part depresses, middle part retracts scapula. Descending+ascending parts rotates glenoid cavity superiorly.

Question 9

Latissimus dorsi

Answer 9

Proximal: Spinous processes of T6-T12, rib 8-12 (inferior 3-4 ribs), thoracolumbar fascia, iliac crest.

Distal: floor of intertubercular sulcus of humerus.

N: Thoracodorsal nerve (C6, C7, C8).

-Extends, adducts, and medially rotates humerus, raises body toward arms during climbing.

Question 10

Levator scapulae

Answer 10

Proximal: Posterior tubercles of transverse processes of C1-C4.
Distal: Medial border of scapula superior to root of scapular spine.

N: Dorsal scapular (C4, C5) and cervical nerves (C3, C4).

-Elevates scapula and rotates its glenoid cavity inferiorly by rotating scapula.

Question 11

Rhomboid minor and major

Answer 11

Proximal: Minor: Nuchal ligament, spinous processes of C7 T1.
Major: spinous processes of T2-T5.

Distal: Minor: medial end of scapular spine.
Major: medial border of scapula.

N: Dorsal scapular nerve (C4, C5).

Question 12

Superficial posterior axio-appendicular muscles

Answer 12

Trapezius, Latissimus dorsi

Question 13

Deep posterior axio-appendicular muscles

Answer 13

Levator scapulae, rhomboid minor and major.

Question 14

Scapulohumeral (intrinsic shoulder) muscles

Answer 14

Deltoid, supraspinatus, infraspinatus, teres minor, teres major, subscapularis.

Question 15

Rotator cuff muscles

Answer 15

Supraspinatus, infraspinatus, teres minor, subscapularis. SITS.

Question 16

Deltoid

Answer 16

Proximal: lateral third of clavicle, acromion, and spine of scapula.
Distal: deltoid tuberosity of humerus.

N: Axillary nerve (C5, C6).

• Clavicular part: flexes and medially rotates arm.
• Acromial part: abducts arm.
• Spinal part: extends and laterally rotates arm.

Question 17

Supraspinatus

Answer 17

Proximal: supraspinous fossa of scapula.
Distal: superior facet of greater tubercle of humerus.

N: Suprascapular nerve (C4, C5, C6).
-initiates and assists deltoid in abduction of arm and acts with rotator cuff muscles.

Question 18

Infraspinatus

Answer 18

Proximal: Infraspinous fossa of scapula.
Distal: greater tubercle of humerus.

N: Suprascapular nerve (C5, C6).
-Laterally rotates arm, acts with SITS

Question 19

Teres minor

Answer 19

Proximal: middle part of lateral border of scapula.
Distal: greater tubercle of humerus.

N: Axillary nerve (C5-C6).
-Laterally rotates arm, acts with SITS.

Question 20

Teres major

Answer 20

Proximal: Inferior angle of scapula.
Distal: Intertubercular sulcus of humerus.

N: Lower subscapular nerve (C5, C6).
-Adducts and medially rotates arm.

Question 21

Subscapularis

Answer 21

Proximal: subscapular fossa.
Distal: lesser tubercle of humerus.

N: Upper and lower subscapular nerves (C5, C6, C7).
-medially rotates arm as part of SITS, helps hold head of humerus in glenoid cavity.

Question 22

To initiate movement during the first 15 degrees of abduction of the arm, the deltoid is assisted by which muscle?

Answer 22

Supraspinatus

Question 23

Which of the rotator cuff muscles does not rotate the humerus?

Answer 23

Supraspinatus. It initiates and assists deltoid in the first 15 degrees of abduction.

Question 24

Location and borders of clavipectoral (deltopectoral) triangle

Answer 24

Infraclavicular fossa overlies it. Superiorly: Clavicle. Medially: Pectoralis major. Laterally: Deltoid.

Question 25

Parts of Axillary artery

Answer 25

1st part: medial to pectoralis minor. 2nd part: posterior to pectoralis minor. 3rd part: lateral to pectoralis minor.

Question 26

Branch of 1st part of Axillary artery

Answer 26

This part is enclosed in the axillary sheath. Gives off the superior thoracic artery.

Question 27

Branches of 2nd part of axillary artery

Answer 27

Thoracoacromial and lateral thoracic arteries

Question 28

Branches of 3rd part of axillary artery

Answer 28

Subscapular artery (largest), anterior circumflex humeral and posterior circumflex humeral arteries.