13 - Pectoral Region and Axilla Flashcards
What is the origin, insertion, innervation of pectoralis major?
- Triangle with a sternal and clavicular head
- Clavicular head originates at medial clavicle and sternocostl head originates at anterior sternum, upper six costal cartilages and aponeurosis of external oblique muscle
- Inserts to intertubercular sulcus of humerus
- Medial pectoral nerve (C8-T1 from medial cord) and lateral pector nerve (C5 - C7 from lateral cord)
What actions does the pectoralis major have?
- Adducts humerus if arm abducted at shoulder
- Flex humerus if start in anatomical position
- Medially rotates humerus if externally rotated
What is the origin, insertion and nerve supply of pectoralis minor?
- Origin on 3rd to 5th ribs near costochondral junction
- Inserts onto coracoid process of scapula
- Medial pectoral nerve (C8 - T1)
What actions does the pectoralis minor have?
Stabilises scapula by drawing it anteroinferiorly against thoracic wall
What is the origin, insertion, innervation and action of serratus anterior?
- Holds medial border of scapula against ribcage
- Rotates medial border of scapula so glenoid cavity rotates upwards
- Nerve is C5-C7 from anterior rami of spinal nerves
What does this indicate?
- Winging of scapula
- Long thoracic nerve damage as serratus anterior is no longer holding medial border of scapula to ribcage
- Trauma, surgery, heavy backpack on shoulder girdle
What muscles can act as accessory muscles for breathing and when would this occur?
- Serratus anterior, pectoralis minor and major
- High metabolic demaind or in respiratory disease so even further increased volume of thorax
What is the origin, insertion, nerve supply and action of corachobrachialis?
- Deep to biceps brachii
- Nerve C5-C7 from lateral cord of brachail plexus
What is the origin, insertion, innervation and actions of subclavius?
- Origin: Junction of 1st rib and costal cartilage
- Insertion: Inferior surface of middle third of clavicle
- Actions: Anchors and depresses clavicle, protects neurovascular structures
- Innervation: Nerve to subclavius
What is the origin, insertion, actions and innervation of the deltoid muscle?
- Axillary nerve is C5 and C6 from posterior trunk
- Middle fibres take over from supraspinutus
- Anterior medially rotate arm at shoulder
- Posterior laterally rotate arm at shoulder
How do you remember the different sections of the brachial plexus?
What is the axilla and it’s borders?
- Pyramidal space at junction between upper limb and thorax
- Provides passageway for neurovascular and muscular structures
- Size and shape of axilla varies with degree of arm abduction, when fully abducted fascia are taught and axilla contents compressed on proximal humerus
What are the contents of the axilla?
What are the three routes that structures leave the axilla?
- Inferiorally and laterally into upper limb
- Quadrangular space to posterior arm and shoulder (axillary nerve and PCHA from axillary vein)
- Clavipectoral triangle (cephalic vein and medial and lateral pectoral nerves)
Draw on the axillary lymph nodes and state what drainage they recieve.
- A: pectoral group. Lower border of pec minor recieving from lateral breast and anterolateral abdominal wall from umbilicus
- P: subcapsular group. in front of subcapsularis recieving from superficial from back to iliac crest
- L: Medial side of axillary vein recieving from most of upper limb apart from lateral
- C: Centre of axilla within fat recieving from A, P and L
- I: deltopectoral group between deltoid and pecs, recieving from lateral hand, forearm and arm
- A: apex of axilla at lateral first rib recieving vessels from all other axillary nodes
How do the axilla lymphatics join and return with the venous system?
- Drain to apical node
- Efferent apical vessels converge to form subclavian lymphatic trunk
- Right subclavian continues to form right lymphatic duct to drain into right venous triangle
- Left subclavian drains directly into thoracic duct at left venous angle
Why may you have axillary lymphadenopathy?
- Infection of upper limb (can be lymphangitis)
- Infections of pectoral and breast
- Metastases from breast cancer
- Leukaemia or lymphoma
- Metastases from malignant melanoma
What does lymphangitis appear as?
- Inflammation of lymph vessels
- Red, warm tender streaks visible in upper limb
What are the risks of axillary lymph node dissection?
- Lymphoedema
- Long thoracic nerve or thoracodorsal nerve damage
What are the three surgical levels of axillary lymph nodes?
What is the course of the axillary artery?
- Subclavian artery entering the lateral border of first rib becomes axillary
- Zones in relation to pec minor and branches
1 - Superior thoracic artery
2 - Thoracoacromial and lateral thoracic
3 - Subscapular, anterior and posterior circumflex humeral
What is the course of the axillary vein?
- Inferior border of teres major from brachial veins and basilic vein
- Travels medially to the axillary artery and joins with subclavian vein at lateral border of first rib
- 3 zones depending on where to pec minor and same branches in 2 and 3 as arteries. Zone 1 has cephalic vein
What are the superficial veins of the upper limb?
Cephalic (pre-axial) and Basillic (post-axial border) in subcutaneous tissue
What is the course of the basilic vein?
- From dorsal venous network of hand and ascends medial along limb
- At inferior teres major it moves deep and combines with brachial veins from deep venous system to form axillary vein
What is the course of the cephalic vein?
- From dorsal venous network of hand and ascends anterolateral, passing anteriorly at elbow
- At shoulder travels between deltoid and pec major and enters axilla via clavipectoral where drains in axillary vein
How are the cephalic and basilic veins connected?
At the elbow by medial cubital vein
