Ch.38 Pectoral Region

Pectoralis major action

Clavicular part: Flexion of the arm at the shoulder joint Sternocostal part: Adduction and medial rotation of the arm at the shoulder joint

Pectoralis major origin

Clavicular part: medial half of the clavicle Sternocostal part: sternum and first 6 costal cartilages

What is another name for clavipectoral fascia?

Coracoclavicular fascia

Pectoralis minor insertion

Coracoid process of the scapula

Subclavius action

Depression of the clavicle

What would damage to the long thoracic nerve and/or serratus anterior cause?

This would result in a patient's difficulty with raising their upper limb above the horizontal and would also result in winged scapula.

Pectoralis minor action

Depression of the scapula

Subclavius insertion

Inferior surface of the clavicle

Where is the clavipectoral fascia?

It lies both superficial and deep to the muscle that unites at both edges of the muscle, thereby forming a compartment for the muscle. It continues from the lower margin of pectoralis minor inferiorly to the axillary fascia, which forms the floor of the axilla (suspensory ligament of the axilla). It continues from the upper margin of pectoralis minor superiorly as a tough layer of fascia that splits around the subclavious muscle and attaches to the clavicle.

Serratus anterior origin

Ribs 1-8

Pectoralis minor origin

Ribs 2-5

How does serratus anterior allow the humerus to be abducted above the horizontal?

When the upper limb is abducted, the greater tubercle of the humerus approximates the acromion. When the abducted arm reaches the horizontal, serratus anterior contracts, moving the inferior angle laterally. This rotates the entire scapula so that the acromion moves medially out of the way of the great tubercle of the humerus.

What is the costocoracoid membrane pierced by?

Cephalic vein, thoracoacromial trunk, lateral pectoral nerve (VAN)

Pectoralis minor innervation

Medial pectoral nerve

Pectoralis major insertion

Crest of the greater tubercle of the humerus

Pectoralis major innervation

Lateral pectoral nerve Medial pectoral nerve

Serratus anterior innervation

Long thoracic nerve

Subclavius innervation

Nerve to subclavius

Serratus anterior insertion

Superior angle, medial border, and inferior angle of the costal surface of the scapula

Subclavius origin

Junction of the first rib and its costal cartilage

What is clavipectoral fascia?

The fascia and its extensions that surround the pectoralis minor muscle

Costocoracoid membrane

The part of the clavipectoral fascia between the upper margin or pectoralis minor and the subclavius; laterally it reaches to the coracoid process and medially it reaches to the first costal cartilage

Serratus anterior action

Upward rotation of the scapula (inferior angle rotates laterally), holds the scapula against the thoracic cage, and protraction of the scapula