Shoulder muscles, their fascias and the axillary fossa

Question 1

Shoulder muscles

Answer 1

• Encircle shoulder joint
• Start from shoulder-blade and clavicle
• Attach to the proximal end of the humerus
• Subscapularis
• Supraspinatus
• Infraspinatus
• Teres minor
• Teres major
• Deltoid

Question 2

Subscapularis

Answer 2

• Origin: facies costalis scapulae
• Runs laterally
• Insertion: tuberculum minus humeri
• Innervation: subscapular nerve (from the brachial plexus)
• Function: humeral pronation

Question 3

Supraspinatus

Answer 3

• Origin: fossa supraspinata
• Runs laterally
• Inesrtion: superior part of tuberculum majus humeri
• Innervation: suprascapular nerve (brachial plexus)
• Function: humeral supination and abduction

Question 4

Infraspinatus

Answer 4

• Origin: fossa infraspinata
• Runs laterally
• Grows together with inferior part of the shoulder joint capsule
• Insertion: middle part of tuberculum majus humeri
• Innervation: suprascapular nerve (from the brachial plexus)
• Function: humeral supination

Question 5

Teres minor

Answer 5

• Origin: lateral margin of the scapula
• Insertion: inferior margin of infraspinatus and the inferior portion of the tuberculum majus humeri
• Grows together with dorsal side of joint capsule
• Innervation: axillary nerve (from the brachial plexus)
• Function: humeral supination

Question 6

Teres major

Answer 6

• Origin: inferior angle of the scapula
• Runs ventrolaterally
• Insertion: crista tuberculi minoris
• Innervation: subscapular nerve (from the brachail plexus)
• Function: adduction, extension and humeral pronation

Question 7

Deltoideus

Answer 7

• Origin: acromial part of clavicle, acromion and spina scapulae
• Muscle fibres descend distally
• Insertion: deltoid tuberosity of the humerus
• Bursa subdeltoidea is inserted below the muscle in the area of the tuberculum majus of the humerus
• Innervation: axillary nerve (from the brachial plexus)
• Function: abduction, anterior part of the muscle - anteflexion, posterior part of the muscle - dorsiflexion in humeral joint

Question 8

Deltoideopectoral triangle

Answer 8

• Borders:

1. Superiorly - clavicle
2. Medially - pectoralis major
3. Laterally - deltoideus

• Cephalic vein runs through it
• Subclavian vessels can be accessed deep to it
• On the body surface it’s seen as the infraclavicular fossa

Question 9

Rotator cuff

Answer 9

• Anteriorly: subscapularis
• Posteriorly: supraspinatus, infraspinatus and teres minor

Question 10

Fasciae of the shoulder

Answer 10

• Fascia deltoidea - thin superficial fascia covering the deltoideus, passing to the fascia superficialis of the trunk and upper extremity
• Fascia supraspinata - strong fascia, covering the supraspinatus, and attaches itself to margins of the fossa supraspinata
• Fascia infraspinata - bridges fossa infraspinata and covers the infraspinatus
• Fascia subscapularis - thin fibrous membrane, attaches to the scapular margins and covers the subscapularis

Question 11

Axillary fossa

Answer 11

• Floor - axillary fascia (correction for the picture)
• Quadrangular pyramid with the apex inverted proximally
• Lower posterior boundary is called the posterior axillary fold and this is a compound structure consisting of the latissimus dorsi and teres major muscles
• Anterior boundary is called the anterior axillary fold and this is rounded in shape and formed by the lower border of the pectoralis major
• Contents: axillary vessels, brachial plexus and adipose tissue (inside of which there are many axillary lymph nodes)

Question 12

Humerotricipital foramen (quadrangular foramen)

Answer 12

• Borders:

1. Superiorly: subscapularis and teres minor
2. Inferiorly: teres major
3. Medially: long head of the triceps
4. Laterally: surgical neck of the humerus

• Contents: axillary nerve and the posterior circumflex humeral artery
• Split from the omotricipital foramen by the long head of the triceps

Question 13

Omotricipital foramen (triangular)

Answer 13

• Triangular shape
• Borders:

1. Superiorly: teres minor
2. Laterally: long head of the triceps
3. Inferiorly: teres major

• Contents: scapular circumflex vessels