Week 5

Question 1

Sensory regions supplied by the nerve roots of the brachial plexus

Answer 1

C5: lateral aspect of the shoulder
C6: thumb
C7: index finger
C8: little finger
T1: medial side of the elbow

Question 2

Claw Hand indicates

Answer 2

lower brachial plexus injury (C8-T1)

Question 3

The brachial plexus

Answer 3

is a major nerve network formed by the anterior branches of the C5-T1 spinal nerves. it supplies the upper limb and extends from the neck to the axilla (armpit) through the cervico-axillary canal. It’s essential for the motor and sensory innervation of the entire upper limb.

Question 3

Brachial plexus structure; R T D C T

Answer 3

Roots: The five roots (C5, C6, C7,C8,T1) they are located between the anterior and middle scalene muscles in the neck

Trunks: there are 3 trunks; superior, middle, and inferior.
-Superior trunk is formed by the union of C5 and C6 roots
-Middle trunk is a continuation of the C7 root
-Inferior trunk is formed by the union of C8 and T1 roots

Divisions: each trunk is then splits into 2 divisions (anterior and posterior), making a total of six divisions. these supply the flexor and extensor compartments of the arm

Cords: the divisions regroup into three cords named after their relation to the axillary artery.
-Lateral cord: formed from the anterior divisions of the superior and middle trunks
-Posterior cord formed from all three posterior divisions
-Medial cord formed from the anterior division of the inferior trunk

Terminal branches: these cords give rise to the major peripheral nerves of the upper limb, including the radial, axillary, musculocutaneous, median and ulnar nerves.

Question 4

Nerve branches and injuries are 2

Answer 4

superior plexus injury (C5-C6) and inferior plexus injury (C8-T1)

Question 5

Superior plexus injury (C5-C6)

Answer 5

Erb-Duchenne Palsy which results from an aexcessive increase in the angle between the neck and the shoulder e.g. a fall or birth injury. this stretches or ruptures the upper part of the brachial plexus.
Symptoms include waiter’s tip position where the arm hangs limply at the side with medial rotation and the palm facing backward.
Loss of movement impaired shoulder abduction, lateral rotation, supination and flexion at the elbow.

Question 6

Inferior plexus injury C8-T1

Answer 6

Klumpke’s paralysis caused by an upward pull of the arm (e.g. grabbing something during a fall or during birth). This affects the short muscles of the hand.
Symptoms: “claw hand” where the patient cannot extend their MCP joints or flex their IP joints in the finger
Muscle involvement: primarily affects the muscles innervated by the ulanr nerve leading to unopposed extension at the mcp joints and flexion at the IP joints of the fingers.

Question 7

Branches of the brachial plelxus and injuries are 5

Answer 7

-Musculocutaneous Nerve (C5-C7): it arises from the lateral cord and passes through the coracobrachialis muscle, and supplies the flexor muscles of the arm (biceps brachii, brahcialis, coracobrachialis)
Injury: rare but could result from trauma to the shoulder, leading to weakened elbow flexion and loss of sensation over the lateral forearm

• Axillary nerve (C5-C6): it arises from the posterior cord, winds around the surgical neck of the humerus nd supplies the deltid and teres minor muscles.
  Injury: often associated with fractures of the surgical neck of the humerus
  symptoms include loss of shoulder abduction beyond 15 degrees and numbness over the regimental badge area of the shoulder

-Radial nerve (C5-T1): runs in the radial groove of the humerus and supplies the triceps brachii, then divides into superficial (sensory) and deep (motor) branches in the forearm
Injury: mid-shaft fractures of the humerus can damage the radial nerve, leading to wrist drop (inability to extend the wrist and fingers) and another type of injury is crutch palsy compression fo the radial nerve in the axilla (from improper use of crutches or prolonged pressure) causing loss of extension at the elbow, wrist, and fingers

-Median nerve (C5-T1): runs down the arm without branching, enters the forarm through the cubital fossa, and passe s through the carpal tunnel to supply the hand.
Injuries can be above the elbow results in hand of bendiction when trying to make a fist (inability to flex index and middle fingers). Flexion of MCP joints is weak, thumb flexion and opposition are lost and forearm pronation is weak. another injury can be at the wrist carpal tunnel syndrome affects the lateral three-and-a-half fingers, causing numbness, tingling, weakness of thumb movements, and thenar muscle atrophy.

-Ulnar nerve (C8-T1): it passes behind the medial epicondyle of the humerus, then into the forearm and hand, supplying most of the intrinsic hand muscles.
Injuries at the wrist results in ulnar claw hand, with the ring and little fingers hyperextended at the MCP joints and flexed at the IP joints. There is also loss of finger abduction/adduction and atrophy of interosseous muscles. another injury site is at the elbow cubital tunnel syndrome results in less obvious clawing, as flexion at the IP joints is also impaired ( the ulnar paradox)

Question 8

Vascular supply of the upper limb

Answer 8

-Axillary Artery: extends from the outer border of the first rib to the lower border of teres major, where it continues as the brachial artery. The axillary artery is divided into three parts, with branches that supply the shoulder, thoracic wall, and upper arm.
First part of the branch is superior thoracic artery
Second part is the thoracoacromial and lateral thoracic arteries
Third part subscapular artery and anterior/posterior circumflex humeral arteries

-Brachial Artery continuation of the axillary artery into the arm. it bifurcates into the radial and ulnar arteries at the elbow (cubital fossa). it has 2 branches
first branch is profunda brachii artery (deep brachial) follows the radial nerve in the radial groove
second branch is radial and ulnar arteries that supply the forearm and hand

-Radial Artery travels down the lateral side of the forearm, winds around the wrists, and forms the deep palmar arch. The radial pulse can be palpated in the distal forearm and it plays a role in the blood supply to the hand

-Ulnar Artery: passes along the medial side of the forearm and enters the hand to form the superficial palmar arch. gives rises to the common interosseous artery, which further divides into the anterior and posterior interosseous arteries.

Question 9

Veins and lymphatic drainage

Answer 9

-Superficial veins
-Deep veins: run alongside the arteries, forming venae comitantes (paired veins)
-Lymphatic drainage: the upper limb is drained by superficial and deep lymphatic vessels, which primarily drain into axillary lymph nodes.

Question 10

superficial veins

Answer 10

-Cephalic vein: ascends along the lateral side of the arm and drains into the axillary vein
-Basilic vein ascends on the medial side and joins the deep veins to form the axillary vein
-Median Cubital Vein connects the cephalic and basilic veins at the elbow, commonly used for venipuncture