Muscles of Upper limb Flashcards
What muscles act accessory muscles of respiration
Pectoralis major, minor, serratus anterior
(increases vol. of thoracic cavity)
Important landmark of Brachial plexus
Coracobrachialis
Muscles in Pectoral Region
Pectoralis Major (superficial)
Pectoralis Minor (deep to ↑)
Serratus Anterior (deep to ↑)
Subclavius
O, I, A, Inv for Pectoralis Major
O: Sternal head, Clavicular head
I: Intertubercular sulcus
A: Arm adduction, medial rotation, draw scapula anteroinferiorly
Inv: Lateral (C5-7) & Medial pectoral nerves (C8-T1)
O, I, A, Inv for Pectoralis Minor
O: 3’rd-5th ribs
I: Coracoid process
A: Draw scapula anteroinferiorly (stabilises)
Ins: Medial pectoral nerve (C8-T1)
O, I, A, Inv for Serratus anterior
O: 1’st-8th ribs
I: Scapula
A: Rotates scapula (arm raised above 90°)
Inv: Long thoracic nerve (C5-7)
O, I, A, Inv for Subclavius
O: 1’st rib
I: Clavicle
A: Anchors clavicle
Inv: Nerve to subclavius
O, I, A, Inv for Coracobrachialis
O: Coracoid process
Insertion: Humerus
A: Elbow flexion, weak adduction
Inv: Musculocutaneous nerve (C5-7)
O, I, A, Inv for Deltoid
O: Clavicle, Scapula
I: Deltoid tuberosity
A: (Ant.) Arm flexion, medial rotation, (Mid.) abduction (15-90°), (Post.) Arm extension, lateral rotation
Inv: Axillary nerve (C5, C6)
What happens when the long thoracic nerve is damaged and what are the causes of this
Serratus anterior is paralysed.
Winged scapula deformity -medial border of the scapula is no longer held against the chest wall and protrudes posteriorly
Cause: Trauma
e.g.) Surgical trauma: Mastectomy with axillary clearance
Blunt trauma: Sudden depression of the shoulder girdle
The axillary borders
Apex: Lateral border of the first rib
Base: Axillary fascia
Lateral wall: Intertubercular sulcus of the humerus
Medial wall: Serratus anterior, ribs, intercostal muscles
Anterior wall: Pectoralis major, minor, subclavius
Posterior wall: Subscapularis, teres major, latissimus dorsi
Contents of the axilla
Axillary artery
Axillary vein
Cords of the brachial plexus
Intercostobrachial nerve
Axillary lymph node
Three routes by which structures leave the axilla
- Inferiorly and laterally, into the upper limb
- Quadrangular space (axillary nerve, posterior circumflex artery pass)
- Clavipectoral triangle (cephalic vein enters, medial & lateral pectoral nerves leave)
Lymph nodes of the axilla
A nterior (pectoral) group
P osterior (subscapular) group
I nfraclavicular (deltopectoral) group
C entral group
A pical group
L ateral group
Causes of Axillary lymphadenopathy
Infection of upper limb (causes lymphangitis)
Infection of the pectoral region & breast
Metastases from breast cancer
Leukaemia/lymphoma
Metastases from malignant melanoma in upper limb
What nerves are at risk of damage during axillary lymph node dissection
Thoracic nerve
Thoracodorsal nerve (supply to latissimus dorsi)
The five main vessels that the arterial supplied to the upper limb
Subclavian artery
Axillary artery
Brachial artery
Radial artery
Ulnar artery
Main branches of the Axillary artery
First part (proximal to pectoralis minor):
Superior thoracic artery
Second part (posterior to pectoralis minor):
Thoracoacromial artery, Lateral thoracic artery
Third part (distal to pectoralis minor):
Subcapsular artery, anterior&posterior circumflex humeral artery
What does the anterior and posterior circumflex humeral arteries form
Anastomotic network
(can be damaged in fractures of this region)
Where is the second most common site for avascular necrosis to occur
Head of humerus
Main branches of the Axillary vein
First part (above pectoralis minor): Cephalic vein
Second part (posterior to pectoralis minor):
Thoracoacromial vein, Lateral thoracic vein
Third part (distal to pectoralis minor):
Subcapsular vein, anterior&posterior circumflex humeral vein
Where does the axillary vein drain deoxygenated blood from
Arm
Axilla
Superolateral chest wall
