MSK 1.1 - Pectoral Region, Axilla And Brachial Plexus Flashcards
What are the 5 origin points of the pectoralis major?
- Medial half of clavicle
- Manubrium
- Body of sternum
- Costal cartilage of ribs 1-6
- Anterior layer of rectus sheath
Where is the insertion point of the pectoralis major?
Crest of greater tubercule of humerus
What is the nerve supply of the pectoralis major?
- Medial and lateral pectoral nerves
- Brachial plexus (C5, T1)
What are the actions of the pectoralis major?
Adduction, medial rotation and Flexion of the humerus
What is the shape and size of the pectoralis minor?
Small and triangular
What are the origin points of the pectoralis minor?
Ribs 3,4 and 5
What is the insertion point of the pectoralis minor?
Coracoid process of the scapula
What is the nerve supply of the pectoralis minor?
Medial and lateral pectoral nerves (C6, T1)
What is the action of the pectoralis minor?
Pulls scapula medially, forwards and downwards
What is the shape and size of the serratus anterior?
Fan shaped and small
What are the origin points of the serratus anterior?
- Superior section = 1st and 2nd ribs
- Intermediate section = 2nd and 3rd ribs
- Inferior section = 4th and 9th ribs
What is the insertion point of the serratus anterior?
Medial margin of the costal surface of scapula
What is the nerve supply of the serratus anterior?
- Long thoraic nerve
- Brachial plexus (C5-C7)
What are the actions of the serratus anterior?
- Superior external rotation of scapula which moves scapula internally and forward therefore lowering the arm
- Lifts ribs
What is the axilla and where is it located?
- Pyramidal shaped space
- Underneath shoulder and between thorax and upper limb
What makes up the medial border of the axilla?
- Rib
- Serratus Anterior
What makes up the anterior border of the axilla?
- Pectoralis major
- Pectoralis minor
What makes up the lateral border of the axilla?
Intertubecular grooves of humerus
What makes up the posterior border of the axilla?
- Scapula
- Subscapularis
- Latissimus Dorsi
- Teres major
What does the axilla contain? (6)
- Cords of brachial plexus
- Axillary vein and artery
- Short head of biceps brachi
- Coracobrachialis
- Tendons of muscles attaching to scapula
- Axillary lymph nodes
What is the order of sections in the brachial plexus?
- Branches
- Cords
- Divisions
- Trunks
- Roots
(BIG COCKS DO TOUCH RIGHT)
What is the order of nerves in the brachial plexus?
- Musculocutaneous
- Axillary
- Radial (behind median)
- Median
- Ulnar
MARMU
Where does the Musculocutaneous nerve originate?
C5, C6, C7 (cervical)
Where does the Axillary nerve originate?
C5, C6 (cervical)
Where does the median nerve originate?
C5 - T1 (cervical to thoraco)
Where does the radial nerve originate?
C5 - T1 (cervical to thoraco)
Where does the ulnar nerve originate?
C8, T1 (cervical, thoraco)
What does the Musculocutaneous nerve innervate? (3)
- Biceps brachi
- Brachialis
- Coracobrachialis
(The BBC)
What does the Axillary nerve innervate? (2)
- Deltoid
- Regimental badge (area of skin)
What does the median nerve innervate? (1)
Lumbricals of the hand
What does the radial nerve innervate? (4)
- Skin in posterior forearm
- Dorsal surface of lateral palm
- Triceps brachi
- Majority of extensor muscles
What does the ulnar nerve innervate? (1)
The muscles of the hand
What are the three sections of the cords?
- Lateral
- Posterior
- Medial
Which nerves branch from the lateral section of the cords?
- medial and lateral pectoral nerves
Which nerves branch from the posterior section of the cords?
There are three:
- middle = thoracodorsal nerve
- outer = upper and lower subscapular nerves
What are the nerves that branch from the medial section of the cords?
There are three, read right to left:
- medial and lateral pectoral nerves
- medial cutaneous nerve of the arm
- medial cutaneous nerve of the forearm
What are the three sections of the trunks of the brachial plexus?
- superior (C5 and C6)
- middle (C7)
- inferior (C8 and T1)
Which nerves branch of the superior section of the trunks?
- Suprascapular
- Nerve to subclavius
What is Erb’s Palsy and how is it caused?
- Damage to roots C5 and C6 due to too big of an angle increase between neck and shoulder
- Upper brachial plexus injury
What are the effects of Erb’s palsy?
- ‘Waiter’s tip’
- Loss of sensation on anterior arm
What is klumpke’s palsy and how is it caused?
- Damage to nerves from T1 root upwards due to excessive abduction
- Lower brachial plexus injury
What are the effects of klumpke’s palsy?
- Paralysis of small muscles in hand
- Sensory loss on medial side of arm
What is the shape of the pectoralis major?
Large and triangular
