The Axilla And The Brachial Plexus

Question 1

What are the trunks of the brachial plexus and which roots attach to which?

Answer 1

Superior, middle and inferior
C5 and C6 to superior
C7 to middle
C8 and T1 to inferior trunk

Question 2

What are the divisions of the brachial plexus and which trunks attach?

Answer 2

Anterior and posterior divisions.

Each trunk has an anterior and posterior division

Question 3

What are the cords of the brachial plexus? Which divisions connect to each cord?

Answer 3

Lateral, posterior and medial

The anterior divisions from the superior and middle trunk attach to lateral cord
The posterior divisions from the superior, middle and inferior trunks connect to posterior cord
The anterior divisions from the inferior trunk connects to the medial cord.

Question 4

What are the branches of the brachial plexus?

Answer 4

Muscular cutaneous 
Axillary
Median
Radial
Ulnar

Question 5

What are the roots of each of the branches of the brachial plexus?

Answer 5

Musculacutaneous- c5,c6, c7
Axillary- c5,c6
Median- c5-T1
Radial- c5-T1
Ulnar- c8-T1

Question 6

What is contained within the Axilla?

Answer 6

Axillary artery
Axillary vein
Brachial plexus
The tendons of the muscles attaching to the scapula such as biceps brachi and corocobrachialis
Axillary lymph nodes

Question 7

What are the borders of the Axilla?

Answer 7

The apex
The lateral wall
The medial wall
The anterior wall
The posterior wall

Question 8

What lies by the apex of the Axilla?

Answer 8

Lateral border of the first rib, the superior border of the scapula and posterior clavicle

Question 9

What lies by the lateral wall of the Axilla?

Answer 9

The intertubular groove of the humerus

Question 10

What lies by the medial border of the Axilla?

Answer 10

The serratus anterior and the thoracic wall including the costal muscles

Question 11

What lies by the anterior border of the Axilla?

Answer 11

Two layers formed by pec major and pec minor and the subclavius muscles

Question 12

What lies by the posterior border of the Axilla?

Answer 12

The subscapularis (large triangular muscle)’ the teres major and the latissiumus dorsi

Question 13

Gives an example of a upper brachial plexus injury, which roots are damaged and the effects of this:

Answer 13

Erbs palsy
Damage to c5 and c6 from an excessive increase in angle between the neck and shoulder
Weakens muscles responsible for lots of things and waiters tip deformity.

Question 14

Give an example of a lower brachial plexus injury, and the effects of it:

Answer 14

Klumpkes palsy, occurs from excessive adduction of the arm affecting nerves derived from T1. Mainly ulnar and median nerves.
Paralyses the small muscles of the hand.

Question 15

What are the 3 main muscles of the pectoral region that act on the upper limb?

Answer 15

Pec major
Pec minor
Serratus anterior

Question 16

Describe pec major, where does it attach? What movement does it cause? Which nerves is it innervated by?

Answer 16

• most superficial muscle in chest wall
• large and fan shaped
• 2 heads, one arising from the clavicle and one from the sternum and ribs
• attached to the intratrabecular groove of the humerus
• acts to adduct the shoulder and medially rotate the humerus at the shoulder
• Innervated by pectoral nerves, medial and lateral, which are small branches of the brachial plexus.

Question 17

Describe pec minor, where does it originate, where does it attach to, what movement and which nerve?

Answer 17

Smaller and posterior to pec major
Originates from 3-5th rib intercostal cartilage
Attaches to corocoid process of the scapular
Acts to depress the shoulders
Innervated by the pectoral nerve

Question 18

Describe serratus anterior, where does it originate, where does it attach to, what movement does it cause. Which nerve innervates it?

Answer 18

It’s a more lateral muscle
Originates from 2nd-8th rib and attaches to the medial border of the scapula
Acts to rotate the scapula and holds it against the rib cage
Innervates by the long thoracic nerve

Question 19

What symptoms can be noticed from someone with a long thoracic nerve injury?

Answer 19

Leads to paralysis of serratus anterior

Scapula protrudes particularly when the patient is asked to push against the wall.

Question 20

What does the Muscularcutaneous nerve innervate?

Answer 20

• Innervates the brachialis which is a muscle which flexes the elbow joint
• biceps brachi and corocobrachialis which adduct the humerus

Question 21

What does the Axillary nerve innervate?

Answer 21

• The deltoid, the teres major and long head of biceps brachi.
• Sensory supply to the regimental badge area
• Divisions of this nerve wrap around the head of the humerus

Question 22

What does the median nerve innervate?

Answer 22

• Innervates most of the flexor muscles in the forearm, also the thenar muscles and lateral 2 lumbricles.
• supply to th palm, and the anterior side of the lateral 3 and half fingers.

Question 23

What does the radial nerve innervate?

Answer 23

Innervates the triceps and extensor muscles in the posterior forearm.
Sensory supply to the posterior arm and forearm as well as posteria lateral aspect of the hand

Question 24

What does the ulnar nerve innervate?

Answer 24

The hand muscles except the ones Innervated by the median nerve, the flexi carpi ulnaris
The anterior and posterior surfaces of the medial one and half fingers.

Question 25

What are the roots of the brachial plexus?

Answer 25

C5-C8 and T1