pectoral region

The region on the front of the chest containing structures that connect the upper limb to the anterolateral chest wall; the mammary gland also lies in this region.

Identify the cutaneous nerves and their areas of distribution.

The cervical plexus (C3, C4).

The skin over the upper half of the deltoid and from the clavicle down to the second rib.

Anterior and lateral cutaneous branches of the second to sixth intercostal nerves.

The cervical plexus and intercostal nerves.

Perforating branches of the internal thoracic artery.

The second, third and fourth branches of the internal thoracic artery.

Lateral cutaneous branches of the posterior intercostal arteries.

Cutaneous nerves, mammary gland in females, cutaneous branches from the internal thoracic and posterior intercostal arteries, and platysma.

Origin: first rib at its junction with costal cartilage; insertion: inferior surface of middle third of clavicle; nerve supply: nerve to subclavius (C5, C6); action: draws the clavicle downward and forward, stabilising the sternoclavicular joint.

Nerve to subclavius (C5, C6).

Draws the clavicle downward and forward, stabilising the sternoclavicular joint.

Origin: anterior surfaces of the 3rd, 4th and 5th ribs near their costal cartilages; insertion: medial border and superior surface of the coracoid process of the scapula; nerve supply: medial pectoral nerve (C8, T1); action: stabilises the scapula by drawing it forward and downward.

By drawing the scapula forward and downward, causing protraction and depression of the scapula.

Medial pectoral nerve (C8, T1). Pectoral region-Sharmma(1).pdf

Origin: medial half of clavicle, anterior surface of sternum, costal cartilages of the 1st–6th ribs and aponeurosis of external oblique muscle; insertion: lateral lip of intertubercular sulcus of humerus; nerve supply: lateral pectoral nerve (C5, C6, C7) and medial pectoral nerve (C8, T1); actions: adducts and medially rotates the arm, clavicular part flexes the arm, and sternocostal part extends the arm from a flexed position.

It originates from the medial half of the clavicle, anterior surface of the sternum, costal cartilages of the 1st–6th ribs and aponeurosis of external oblique muscle, and inserts into the lateral lip of the intertubercular sulcus of the humerus. Pectoral region-Sharmma(1).pdf

Lateral pectoral nerve (C5, C6, C7) and medial pectoral nerve (C8, T1).

Adduction and medial rotation of the arm.

Flexes the arm.

Extends the arm from a flexed position.

Origin: external surfaces of the 1st to 8th ribs, sometimes the 9th rib, near their costal cartilages; insertion: anterior surface of the medial border of scapula; nerve supply: long thoracic nerve (C5, C6, C7); actions: protracts the scapula, holds the scapula against the thoracic wall and rotates the scapula upward.

Long thoracic nerve (C5, C6, C7).

It rotates the scapula upward.

Protracts the scapula; holds the scapula against the thoracic wall; rotates the scapula upward. Pectoral region-Sharmma(1).pdf

Serratus anterior.

Pectoralis minor draws the scapula forward and downward, causing protraction and depression; serratus anterior protracts the scapula, holds it against the thoracic wall and rotates it upward.

A fibrous sheet under pectoralis major, situated deep to the clavicular portion of pectoralis major.

It extends from the clavicle above to the axillary fascia below.

The subclavius muscle.

The pectoralis minor muscle.

The investing layer of the deep cervical fascia and the axillary sheath.

To the external intercostal muscle of the upper intercostal spaces.

To the coracoid process.

The suspensory ligament.

To the dome of the axillary fascia.

It helps maintain the dome of the axillary fascia. Pectoral region-Sharmma.pdf

Lateral pectoral nerve; cephalic vein; thoracoacromial artery; lymphatics passing from the breast and pectoral region to the apical group of axillary lymph nodes. Pectoral region-Sharmma(1).pdf

Lateral pectoral nerve.

Cephalic vein.

Thoracoacromial artery.

From the breast and pectoral region to the apical group of axillary lymph nodes.

Weak or loss of adduction and medial rotation of the arm; the clavicular part is more commonly affected.

Forceful abduction and external rotation, for example during weightlifting.

A pectoralis major flap can be used for breast reconstruction and coverage of chest wall defects.

Compression of the brachial plexus and axillary vessels beneath pectoralis minor in the costocoracoid space, causing pain, paraesthesia, coldness and weakness in the upper limb.

It may affect the attachment of pectoralis minor.

A tight or spastic pectoralis minor can cause protraction and anterior tilting of the scapula, contributing to shoulder impingement.

Traction injury, e.g. after axillary lymph node dissection.

Long thoracic nerve (C5–C7) injury.

Winging of the scapula.

Abduction of the arm above 90° and weak forward punching movements.

Scapular upward rotation is affected, resulting in scapular instability and difficulty with overhead activities.

Paralysis of platysma on the same side, causing drooping of the lower lip and angle of the mouth.

Loss of tone leads to neck wrinkles and sagging skin and may be considered in cosmetic and reconstructive procedures.

Compression of the subclavian vein in thoracic outlet syndrome, leading to upper limb swelling and venous congestion.

Fracture of the middle third of the clavicle may injure or detach subclavius; unopposed pull of the sternocleidomastoid causes medial displacement of the medial fragment.

Pectoral nerve injuries may occur during surgery, such as mastectomy or axillary procedures, or after trauma.

Risk of long thoracic nerve injury, which can cause winging of the scapula.

Breast carcinoma, sarcoma or metastatic deposits may involve the pectoral muscles or nerves.

Pectoral fascia can act as a barrier to spread of infection and tumour.