Pectoral Regions

Winging of the Scapula:

Damage to the Long Thoracic Nerve occurs, the Serratus Anterior muscle will become paralyzed. When pushing the affected limb, the scpula is no longer held against the rib cage, and protrudes out of the back. It is said to have a 'winged' appearance.

Pectoralis Major Attachments:

Distal attachment of both heads is into the intertubebular sulus of the humerus. Proximal attachment of the clavicular head is the anterior surface of the medial half of the clavicle. The sternocostal head ataches proximally to the anterior surface of the sternum, the superior six costal cartilages and the aponeurosis of the external oblique.

What action does the clavicular head of pectoralis major perform on the shoulder?

Flexion *Also helped by some anterior fibres of the deltoid muscle

Serratus Anterior:

Found more laterally in the chest and, forms the medial wall of the axilla.

Pectoralis Minor Innervation:

Medial pectoral nerve, c8-t1

Pectoralis Minor:

Much smaller than the pectoralis major, and lies posterior to it. With the pectoralis major, it forms part of the anterior wall of the axilla.

What is the main action of the serratus anteriro?

Rotating the scapula *Allows the arm to be raised over 90 degrees

Subclavius Muscle:

Small muscle, lying directly under the clavicle and running horizontally. It affords some minor protection to the underlying neurovascular structures, in the case of claviclular fractures.

Pectoralis Minor Function:

Stabilizes the scapula by drawing it anteroinferiorly against the thoracic wall.

Serratus Anterior Function:

The main action of the serratus anterior is to rotate the scapula, allowing the arm to be raised over 90 degrees. It also holds the scapula against the ribcage - this is particularly useful when upper limb reaches anteriorly (e.g punching).

Pectoralis Major:

This a large, fan shaped muscle, and is the most superficial muscle in the pectoral region. It also makes up most of the anterior wall of the axilla. It is composed of a sternal and a clavicular head.

Damage to the Long Thoracic Nerve:

Trauma to the shoulder, repetitive movements involving the shoulder or by structures becoming inflamed and pressing on the nerve. Go

Pectoralis Major Function:

Adducts and medially rotates the humerus, and draws the scapular anteroinferiorly. On its own the clavicular head flexes the humerus , and the sternocostal head extends it.

Subclavius Function:

Anchors and depresses the clavicle

Where on the scapula does pectoralis minor attach?

Corocoid process

Subclavius Attachment:

It originates from the junction of the 1st rib and its costal cartilage, inserting into the inferior surface of the middle third of the clavicle.

Pectoralis Major Innervation:

Lateral and medial pectoral nerves. Clavicular head is innervated by c5-c6 and the sternocostal head is innervated by c7-t1.

Serratus Anterior Innervation:

Long thoracic nerve

Injury to which nerve can cause winging of the scapula?

Long thoracic nerve *Supplies serratus anterior

Which wall of the axilla does serratus anterior form?

Medial *Found on the outer aspect of the ribcage

What is the innervation of pectoralis major?

Medial and lateral pectoral nerves

Subclavius Innervation:

Nerve to subclavius (c5, c6)

Pectoralis Minor Attachment:

Pectoralis minor originates from the 3rd-5th ribs, and inserts into the coracoid process of the scapula.

Where is pectoralis minor located in comparison to pectoralis major?

Posterior

Serratus Anterior Attachment:

The muscle consists of several strips, which originate from ribs 2-8. They attach to the costal (rib facing) surface of the medial border of the scapula.

3 muscles that lie in the pectoral region and exert a force on the upper limb?

pectoralis major, pectoralis minor, and serratus anterior