The axilla and brachial plexus Flashcards
Week 1
Medial border of the axillary region =
Serratus anterior muscles
Posterior border of the axillary region =
Subscapularis, teres major and latissimus dorsii
Anterior border of the axillary region =
Pectoral muscles (pectroalis major, pectoralis minor, subclavius)
What forms the apex of the axilla
Lateral border of 1st rib, superior border of the scapula, posterior border of clavicle
Contents of the axilla:
- Axillary artery
- Axillary vein
- Brachial plexus
- Axillary lymph nodes
- Biceps brachii (short head) and Coracobrachialis
Axillary lymph node groups:
Lateral, subscapular, pectoral, cental, apical
Which type of rami does the brachial plexus include?
Ventral/anterior rami of C5-T1
Roots of brachial plexus:
C5-T1
Read that damn cadavar book
Roots, trunks, divisions, cords, branches
Superior trunk =
C5 + C6
Middles trunk =
C7
Inferior trunk =
C8 + T1
Trunks split into…
Anterior and posterior divisions
Lateral cord =
Anterior division of superior trunk + Anterior division of middle trunk
Posterior cord =
Posterior divisions of superior, middle and inferior trunks
Medial cord =
The anterior division of the inferior trunk
Anterior divisions supply which types of muscle?
Flexors and adductors
Posterior divisions supply which type of muscles?
Extensors and abductors
Cords:
Lateral, posterior, medial
Lateral cord splits into which branches?
Musculocutaneous
Median
Posterior cord splits into which branches?
Axillary
Radial
Medial cord splits into which branches?
Median
Ulnar
Which 2 nerves supply the majority of extensors and abductors?
Axillar and radial nerves
Which 3 nerves supply the majority of flexors and adductors?
Musculocutaneous
Median
Ulnar
The anterior nerves ‘supply in the order they are derived’ for the most part - what does this mean?
Musculocutaneous = arm Median = forearm Ulnar = hand
What does the musculocutaneous nerve supply?
Flexors of the upper arm: coracobrachialis, brachialis, biceps brachii
Sensory = lateral half of the anterior forearm
What does the axillary nerve supply?
Teres minor and deltoid muscles, superior lateral cutaneous nerve of arm (sargent’s stripes)
What does the median nerve supply?
Anterior compartment flexors of forearm and hand (radial side)
Sensory = Palmar cutanous branch, lateral 3 and a half fingers on palmar surface of hand.
What does the radial nerve supply?
Triceps brachii and muscles in posterior compartment of forearm (mostly extensors of the wrist and fingers),
Sensory = posterior aspect of arm and forearm, posteroateral aspect of hand.
What does the ulnar nerve supply?
Innervates muscles of the hand, 2 muscles in forearm = flexors carpi ulnas and medial half of flexor digitorum profundus
Sensory = Anterior and posterior surfaces of the medial one and half fingers and associated palm area
What would happen to a patient with a radial nerve injury?
- Wrist drop (weakness of extensors)
- Loss of sensation over dorsal web between thumb and index finger
Dermatome =
Area of skin supplies by a single spinal nerve
Myotomes =
Group of muscles that a single spinal nerve innervates
Shoulder myotomes
Abduct and laterally rotate = C5
Adduct and medially rotate = C6, 7, 8
Elbow myotomes
Flex = C5, 6 Extend = C7, 8
Forearm myotomes
Pronate and supinely = C6
Wrist myotomes
Flex and extend = C6, 7
Fingers and thumb myotomes
Flex and extend = C7, 8
Hand intrinsic muscles (fine movement) = T1
Example of upper brachial plexus injury
Erb’s palsy
Erb’s palsey
Upper myotomes and dermatomes affected.
Tear of C5 nerve root.
Loss of sensation over lateral arm, loss of muscles of shoulder.
Example of lower brachial plexus injury
Klumpke’s paresis
Klumpke’s paresis
Tear to lower roots of brachial plexus.
All fine movement of hands is lots, sensation over medial side of forearm lost.
