Brachial plexus

Question 1

What is brachial plexus?

Answer 1

A network of nerves innervating muscles of the shoulder, upper chest and arm

Anterior rami of C5 through T1

Question 2

Where does brachial plexus extend from?

Answer 2

Cervical neural foramina to axilla

Question 3

What is brachial plexus closely related to?

Answer 3

Scalene muscles

Subclavian artery

Question 4

Where does the brachial plexus begin?

Answer 4

Root of neck, passes through the axilla and runs through entire upper extremity

Question 5

What is the brachial plexus formed by?

Answer 5

Anterior rami of cervical spinal nerve C5, C6, C7 and C8 and first thoracic spinal nerve, T1

Question 6

What are the 5 parts that the brachial plexus is divided into?

Answer 6

1. Roots
2. Trunks
3. Division
4. Cord
5. Branches

Question 7

What does the roots refer?

Answer 7

Anterior rami of spinal nerves that comprise the brachial plexus

Question 8

What are the anterior rami of spinal nerves?

Answer 8

C5, C6, C7, C8 and T1

Question 9

Where does parties spinal nerves arise?

Answer 9

At each vertebral level

They leave the spinal cord via intervertebral foramina of vertebral column

Question 10

What does each spinal nerve divide into?

Answer 10

Anterior and posterior ramps

Question 11

What happens after the formation of the roots?

Answer 11

The nerves pass between anterior and medial scalene muscled to enter base of neck

Question 12

What happens at the base of the neck?

Answer 12

Roots of brachial plexus converge to form 3 trunks

Question 13

what are the 3 trunks?

Answer 13

1. Superior trunk: combination of C5 and C6 roots
2. Middle trunk: combination of C7
3. Inferior trunk: combination of C8 and T1 roots

Question 14

Where does the trunks traverse?

Answer 14

Laterally, crossing posterior triangle of neck

Question 15

What does each trunk divide into?

Answer 15

2 branches within posterior triangle of the neck

One division moves anteriorly and other posteriorly (anterior and posterior divisions)

3 anterior nerve fibre
3 posterior nerve fibre

Divisions leave posterior triangle and pass into axilla

They recombine into cord of brachial plexus

Question 16

What happens once the anterior and posterior divisions have entered the axilla?

Answer 16

They combine together to form 3 cords

Baked by their position relative to axillary artery

Question 17

What are the 3 cords?

Answer 17

1. Lateral cord
2. Posterior cord
3. Medial cord

Question 18

Lateral cord

Answer 18

1. Anterior division of superior trunk

2. Anterior division of middle trunk

Question 19

Posterior cord

Answer 19

1. Posterior division of superior trunk
2. Posterior division of middle trunk
3. Posterior division of inferior trunk to

Question 20

Medial cord

Answer 20

1. Anterior division of inferior trunk

Question 21

What do the cords give rise to?

Answer 21

Major branches of brachial plexus

Question 22

Where does the subclavian artery extend along?

Answer 22

Floor of interscalene triangle between anterior and middle scalene muscles

Question 23

What does the supraclavicular plexus include?

Answer 23

Roots and trunks

Question 24

Where is the retroclavicular plexus located?

Answer 24

Costoclavicular space, above subclavian artery and vein

Question 25

What does the subclavian artery form?

Answer 25

Floor of interscalene triangle

Question 26

What does the subclavian artery and vein take ?

Answer 26

Name of axillary artery and vein at lateral border of 1st rib

Question 27

What merges at dorsal root ganglion?

Answer 27

At each vertebral level Anterior-motor Posterior-sensory riots exiting from spinal cord within neural foramina

Question 28

What do both rami include?

Answer 28

A mixture of motor and sensory fibres

Question 29

What forms brachial plexus?

Answer 29

Anterior rami

Question 30

Why imaging?

Answer 30

Most brachial plexopathies present with vague and non-specific symptoms Purely/mostly motor symptoms are generally seen in young patients: usually preganglionic; stretch injury Mixed sensory and motor plexopathy - usually in older patients, usually post-ganglionic; tumours Clinical diagnosis: electrodiagnostic studies e.g. ENMG

Question 31

Brachial plexopathy

Answer 31

A form of peripheral neuropathy It occurs when there is damage to brachial plexus Direct injury to the verge; stretching injuries; pressure from Tumours in area or damage that results from radiation therapy

Question 32

What are specific symptoms of brachial plexopathy?

Answer 32

1. Brown-seguards syndrome 2. Ipsilateral phrenic nerve involvement 3. Ipsilateral scapular singing 4. Ipsilateral Horner’s syndrome

Question 33

Site of injury for brown-seguards syndrome

Answer 33

Spinal cord ipsilateral to avulsion

Question 34

Site of injury for ipsilateral phrenic nerve involvement

Answer 34

Supraclavicular brachial plexus involving roots, trunks or both

Question 35

What is site of injury for ipsilateral scapular winging

Answer 35

Proximal branches of C5 through C7

Question 36

What is site of injury for ipsilateral Horner’s syndrome?

Answer 36

Infraclavicular plexus

Question 37

What are medications for brachial plexus?

Answer 37

1. Mass involving the plexus (intrinsic/extrinsic) 2. Traumatic injury (preganglionic/postganglionic) 3. Entrapment syndromes (thoracic outlet syndromes: sites of compression) 4. Post-treatment evaluation (recurrent tumour vs radiation injury) 5. Others (diffuse/focal pathology)

Question 38

What is magnetic resonance (MR) neurography?

Answer 38

Group of techniques with the potential to allow optimal non-invasive evaluation of many abnormalities of brachial plexus 1. Structural 2. Microstructural

Question 39

What MRI is used to observe brachial plexus? I’m

Answer 39

1. Coronal STIR sequences - cover both sides 2. Sagittal STIR sequences on each side 3. Coronal T1w volumetric, isometric with and without gadolinium

Question 40

What is structural MR neurography?

Answer 40

Evaluation of longitudinal axis of peripheral nerve

Question 41

What are abnormal findings of brachial plexus?

Answer 41

1. Loss of fat planes around all or part of a plexus component 2. Diffuse or focal enlargement of a component 3. Presence of an eccentric or modular mass 4. Marked hyperintensity on STIR 5. Enhancement on T1-w images with fat suppression 6. Altered fasicular pattern