What is the embryological basis for limb nerve supply?
- limb buds grow from lateral strip supplied by lateral branches of anterior rami
- plexuses formed by anterior and posterior divisions to supply muscles and skin
- posterior: extensor muscles and skin
- anterior: flexor muscles and skin
What are the markers of the preaxial and postaxial border in the upper limb?
preaxial: cephalic
postaxial: basilic
What is an example of a flexor muscle supplied by an extensor compartment nerve? Why is this?
- lateral portion of brachialis (radial nerve)
- muscle develops in extensor compartment of fetal limb, but is in flexor compartment functionally as adult so brings its nerve supply with it
Describe the course of the anterior axillary line and posterior axillary line.
p 30 fig 1.16
sternal angle to 2nd costal cartilage, down front of limb to wrist
from vertebra prominens to insertion of deltoid muscle
Where are the origins/insertions of pectoralis major?
- clavicular head: medial half of anterior clavicle
- sternocostal head: lateral part of anterior sternum/manubrium/external oblique, upper attachment of rectus abdominis, upper 6 costal cartilages
- insert: trilaminar into bicipital groove fig 2.1
note lowermost fibres of sternocostal origin twist upwards deep to manubrial fibres
What is the nerve supply and best way to test pectoralis major?
p. 70
NS: medial and lateral pectoral nerves (from medial and lateral cords)
only muscle of upper limb to be supplied by all 5 segments of brachial plexus
- C5,6 clavicular head
- C7, 8 T1 sternocostal part
TEST
- abduct arm to 90 degree and push forward against resistance
- abduct to 60 degrees and adduct against resistance
What is the origin and insertion of pectoralis minor?
What is its relation to the axillary artery and cords of the brachial plexus?
- arises from 3rd, 4th, 5th ribs (not costal cartilage)
- inserts into medial border and upper surface of coracoid process
UNDERNEATH:
- divides axillary artery
- cords of brachial plexus deep
What are the 3 parts of the axillary artery and its relations at each stage to elements of the brachial plexus? What are the relevant surface markings?
1st (above pec minor):
2nd (behind pec minor): part clasped by 3 cords of plexus
3rd (below pec minor): clasped by 2 heads of median nerve in anatomical position
SURFACE MARKINGS
- curved line from middle of clavicle, below coracoid process to groove behind coracobrachialis
What is the nerve supply and action of pectoralis minor?
NS: pectoral nerves (C6, 7, 8) (medial and lateral)
assists in protraction of scapula
What are the boundaries of the clavipectoral fascia?
What structures does it enclose?
What structures pierce it?
fig 2.3
- superiorly from the clavicle (not physically continuous above with investing layer of deep cervical fascia)
- medially from the costochondral joints
- superolaterally from the coracoid process.
- turns into suspensory ligament of axilla below pec minor
https: //www.earthslab.com/wp-content/uploads/2017/06/060717_0233_FasciaePact1.jpg
CONTENTS
- subclavius
- pec minor
- ribs
CALL : pierces above pec minor
- Cephalic vein
- thoracoAcromial artery
- Lateral pectoral nerve
- Lymphatics
What are the branches of the axillary artery?
1st part: 1
- superior thoracic artery
2nd part :2
- lateral thoracic
- thoracoacromial
3rd part: 3
- subscapular
- anterior circumflex humeral
- posterior circumflex humeral
What are the boundaries of the axilla?
FLOOR: axillary fascia
ANTERIOR: pec maj, pec min, subclavius, clavipectoral fascia
POSTERIOR: subscapularis and teries major
MEDIAL: serratus anterior
LATERAL LIMIT: intertubercular groove
LOWER LIMIT: 4th rib
What are the muscles of the hand that ARE NOT supplied by the ulnar nerve
hand muscles not supplied by ulnar nerve
MEAT : median
L: laterral two lumbricals
O: opponens pollicis
A: abductor pollicis brevis
F: flexor pollicis brevis
Structures that are in flexor retinaculum
- tendons of flexor dig sup/prof
- median nerve
- tendon of flexor pollicis longus
- flexor carpi radialis tendon
Structures that escape the flexor retinaculum.
- ulnar artery
- ulnar nerve
- palmar cutaneous branch median nerve
- palmaris longus
What are the attachments of the flexor retinaculum?
scaphoid
hook of hamate
trapezium
piseform
What are the branches of the brachial plexus from the roots?
C5
- Dorsal scapular nerve
C5, C6
Nerve to subclavius
C5, C6, C7
- Long thoracic nerve
What is the branch of the brachial plexus that exits from the trunks?
Suprascapular nerve exits from upper trunk in the posterior triangle of the neck(C5,C6)
What are the branches from the divisions of the brachial plexus?
there are NO branches associated with the divisions
What are our branches off the cords?
LATERAL (LML)
- lateral pectoral nerve
- Musculocutaneous nerve
- Lateral root of median nerve
MEDIAL (M4U)
- medial pectoral nerve
- medial cutaneous nerve of arm and forearm
- medial cord of median nerve
- ulnar nerve
POSTERIOR (ULTRA)
- upper and lower subscapular nerves
- thoracodorsal nerve
- radial nerve
- axillary nerve
What are the terminal branches of the brachial plexus?
POSTERIOR
- axillary
- radial
LATERAL
- musculocutaneous nerve
- median
MEDIAL
- ulnar
- median
What is the most common traction injury to the brachial plexus?
Erb’s palsy?
- C5, C6 injury
- arm is medially rotated, extended at elbow
- loss of sensation on lateral side of arm and forearm
What is Klumpke’s paralysis? How is it sustained?
- Damage to C8 T1
- birth inury with arm remaining above head during breech
- leads to claw hand with inability to extendfingers, ulnar sensory loss and potentially horner’s syndrome
How to test for radial nerve injury? High vs low?
- wrist drop
- interphalangeal joints will still be straightened by action of interossei and lumbricals
- sensory loss over 1st dorsal interosseous space
- HIGH INJURY: elbow extension (branch to triceps arises before nerve reaches humerus)
- LOW INJURY: extension of wrist
