Lab 1 - Module 2: Axilla - Page 1 of 8

READINGS:

Gray's Anatomy for Students (Fourth Edition): Pages: 710-738

CASE REPORT Continued:

A sentinel lymph node biopsy refers to a biopsy of the lymph node in which cancer cells are most likely to spread to first. Based on the location of the mass in this patient [insert picture that indicates the quadrants of the breast] the most likely lymph node(s) involved first would be pectoral nodes. In some cases, a complete axillary lymph node dissection will be performed. In these instances, it is imperative that the surgeon understand the anatomy of the Axilla and the neurovascular structures within.

Axilla

The Axilla (arm pit) is a pyramid shaped space that provides a passageway for nerves and vessels of the trunk to reach the upper limb.

The Medial Wall of the Axilla is formed by the upper ribs, intercostal muscles, and serratus anterior muscles.

Rotate to a right lateral view of the thoracic cage and identify the the components of the apex of the axilla which is formed by the convergence of the bones in its three major walls; clavicle in the anterior wall, scapula in the posterior wall, and the first rib in the medial wall. This convergence creates an opening at the apex called the cervicoaxillary canal through which the major nerves and vessels pass. Identify the following structures:

Clavical

Scapula

First rib

Add the intercostal muscles.

Add the serratus anterior muscles.

Origin - lateral surfaces of the upper 8- 9 ribs and deep fascia overlying the related intercostal spaces.

Insertion - costal surface of the medial border of the scapula.

Innervation - long thoracic nerve (C5,C6, C7).

Action -

Blood supply -

Rotate the cadaver to visulaize this muscle.

The Posterior Wall of the Axilla is formed by the scapula and subscapularis, latissimus dorsi and the teres major muscles.

Add the subscapularis muscles.

Origin - medial two thirds of the subscapular fossa.

Insertion - lesser tubercle of the humerus.

Innervation - upper and lower subscapular nerves (C5,C6, C7).

Action -

Blood supply -

Rotate the cadaver to visulaize this muscle.

Add the teres major muscles.

Origin - elongated oval area on the posterior surface of the inferior angle of the scapula.

Insertion - medial lip of the intertubecular sulcus on the anterior surface of the humerus.

Innervation - lower subscapular nerves (C5,C6, C7).

Action -

Blood supply -

Rotate the cadaver to visulaize this muscle.

Add the latissimus dorsi muscles.

Origin - spinous processes of the lower six thoracic vertebrae and related spinous liagments.

Insertion - lesser tubercle of the humerus.

Innervation - thoracodorsal nerve (C6,C7, C8).

Action -

Blood supply -

Rotate the cadaver to visulaize this muscle.

Add the humerus and see how each of these muscles insert into the humerus.

The Lateral Wall of the Axilla is formed by the humerus and the coracobrachialis muscles.

Add the coracobrachialis muscles.

Origin - apex of the coracoid process.

Insertion - linear roughing on the medial midshaft of the humerus.

Innervation - musculocutaneousnerves (C5,C6, C7).

Action -

Blood supply -

Rotate the cadaver to visulaize this muscle.

The Anterior Wall of the Axilla is formed by the clavical, pectoralis minor and the pectoralis major muscles.

Add the pectoralis minor muscles.

Origin - anterior surfaces and superior borders of ribs III to V.

Insertion - coracoid process of the scapula.

Innervation - medial pectoral nerves (C8,T1).

Action -

Blood supply -

Rotate the cadaver to visulaize this muscle.

Add the pectoralis major muscles.

Origin - clavicular head - anterior surface of the medial half of the clavicle, sternocostal head - anterior surface of the sternum; first seven cartilages; sternal end of the 6th rib.

Insertion - lateral lip of intertubercular sulcus of the humerus.

Innervation - medial and lateral pectoral nerves: clavicular head (C5,C6); sternocostal head (C6,C7, C8, T1).

Action -

Blood supply -

Rotate the cadaver to visulaize this muscle.

	Identify the opening at the axillary apex called the cervicoaxillary canal through which the major nerves and vessels pass. Rotate the cadaver to build a better understanding of this canal.
	The axilla contains large important nerves – branches of the brachial plexus, which pass from the neck to supply the upper limb. The axilla also contains axillary vessels as well as several groups of axillary lymph nodes. These all pass through the cervicoaxillary canal.