Pectoral Region, Axilla Flashcards
What is the Pectoral Region and how many muscles does it contain?
Name them
A region on the anterior chest wall
Pectoralis Major (Most superficial)
Pectoralis Minor
Serratus Anterior
Subclavius
Describe the Origins and Insertion of Pectoralis Major
Clavicular Head: Anterior surface of Medial clavicle
Sternacostal head: Anterior surface of sternum, Upper 6 costal cartilages, Aponeurosis of externa oblique muscle
Insertion: Intertubucular sulcus (Clavicular head inserts inferior)
What are the Actions and Innervations of Pectoralis Major
Actions;
- Medial rotation (Both heads)
- Adduction (Sternocostal head)
- Flexion (Clavicular head)
Interactions;
- Medial Pectoral Nerve
- Lateral Pectoral Nerve
Describe the Origin, Insertion, Action and Innervation of Pectoralis Minor
Origin: Ribs 3-5
Inserts: Coracoid process of scapula
Action: Stabilises scapula (draws it anterioinferiorly)
Innervation: Medial Pectoral Nerve
Describe the Origin, Insertion, Action and Innervation of Serratus Anterior
Origin: Lateral aspects of ribs 1-8/9
Insertion: Costal surface of medial border of scapula
Action: Rotates scapula so that arm can be raised over 90 degrees
Innervation: Long thoracic nerve
Describe the Origin, Insertion, Action and Innervation of Coracobrachialis
(Deep to Biceps Brachii)
Origin: Coracoid process of scapula
Insertion: Medial side of numeral shaft
Action: Shoulder Flexion, Arm Adduction
Innervation: Musculocutaenous nerve
Describe the Origin, Insertion, Action and Innervation of Subclavius
(Directly underneath clavicle)
Origin: Junction of 1st rib and its costal cartilage
Insertion: Inferior surface of middle third of clavicle
Action: Anchors and depresses the clavicle
Innervation: Nerve to subclavius
Describe the Origins and Insertion of Deltoid (3 parts)
Anterior fibres: Lateral third of anterior of clavicle
Middle fibres: Acromion of scapula
Posterior fibres: Spine of scapula
Insertion: Deltoid tuberosity on lateral surface of humerus
Describe the Actions and Innervation of Deltoid (3 parts)
Innervation: Axillary nerve
Actions;
Anterior fibres- Flexion, Medial rotation of arm
Middle fibres- Abduction of arm (From 15 to 90 degrees)
Posterior fibres- Extension, Lateral rotation of arm
What is the Axilla?
What does it act as?
A pyramidal space that lies underneath the shoulder joint, at the junction of the upper arm and thorax.
It acts as a passageway for neurovascular and muscular structures
What are the 6 borders of the Axilla
Apex
Base
Lateral Wall
Medial Wall
Anterior Wall
Posterior Wall
What structures form the Apex and Base of the Axilla
Apex: Lateral border of 1st rib, Superior border of scapula, Posterior border of clavicle
Base: Axillary fascia and skin
What structures form the Lateral and Medial walls of the Axilla
Lateral Wall: Intertubcular groove of humerus
Medial Wall: Serratus Anterior, Ribs, Intercostal Muscles
What structures form the Anterior and Posterior walls of the Axilla
Anterior Wall: Pectoralis Major, Minor and Subclavius
Posterior Wall: Teres major, Latissimus Dorsi, Subscapularis
How is Axilla affected when arm is fully abducted
Axillary fascia (Base) becomes taught and axillary contents are compressed against proximal humerus
Name 6 important contents of the Axilla
- Axillary arteries (and branches)
- Axillary vein
- Brachial plexus (Cords and branches)
- Axillary lymph nodes
- Biceps brachial and Coracobrachialis
- Intercostobrachial nerve
What are the 3 main routes through which structures can leave the Axilal
- Inferolaterally into upper limb
- Via the Quadrangular space
- Via the Clavipectoral/ Deltopctoral triangle
Name 2 structures that pass through Quadrangular Space
Axillary nerve
Posterior Circumflex Artery
What is the Deltopectoral/ Clavipectoral triangle
Name 3 structures that pass through
Opening in anterior wall of Axilla, bound by Pectoralis Major, Deltoid and Clavicle
- Cephalic vein (Enters)
- Medial Pectoral Nerve (Leaves)
- Lateral Pectoral Nerve (Leaves)
What is the Axillary Artery?
What is the Axillary Vein?
Artery- Main artery supplying the upper limb
Vein- Main vein draining the upper limb (Contributions from Cephalic and Basilic veins)
What do the Axillary Lymph Nodes do?
What is their clinical significance?
Filter lymph that has been drained from the upper arm and pectoral region
ALN enlargement is a non-specific indicator of breast cancer (75% of lymph from breasts is filtered by ALNs)
What are the 6 groups of lymph nodes in the Axilla
APICAL
- Anterior/ Pectoral (Behind Pec Major, Lower border of Pec Minor)
- Posterior (Anterior to Subscapularis)
- Infraclavicular (In groove between Deltoid and Pec Major)
- Central (Centre of axilla within axillary fat)
- Apical (Apex of axilla)
- Lateral (Medial side of axillary vein)
The Central and Apical groups of Axillary Lymph Nodes receive lymph from where?
Central: From Lateral, Posterior, Anterior lymph nodes
Apical: From all other axillary nodes
Outline the lymph pathway after it reaches the Apical group of Axillary Lymph Nodes
- Efferent vessels from Apical Nodes converge-> Subclavian Lymphatic Trunk
- Right subclavian trunk continues-> Right lymphatic duct-> Right Venous Angle (Junction of Subclavian and Internal Jugular Veins)
- Left subclavian trunk drains into Thoracic Duct-> Left Venous Angle
