PBL 1

Question 1

What is the central sulcus?

Answer 1

groove separating the parietal and frontal lobes

Question 2

What is the lateral sulcus?

Answer 2

groove separating the frontal and parietal lobes from the temporal lobe

Question 3

what area of the hand does the median nerve supply?

Answer 3

3 1/2 fingers and hand on palmar aspect

3 1/2 fingers only on dorsal aspect

Question 4

what area of the hand does the ulnar nerve supply?

Answer 4

1 1/2 fingers and hand on palmar AND dorsal aspect (pinkie side)

Question 5

what area of the hand does the radial nerve supply?

Answer 5

dorsal surface of the lateral three and a half digits (hand part not fingers)

Question 6

know the dermatome areas of the arm (C5 - T1/2)

Answer 6

C5 - upper outer arm
C6 - Thumb and outer forearm
C7 - Middle finger
C8 - Little finger
T1 - Inner forearm
T2 - Upper inner arm

Question 7

what effect does superior extension of a Pancoast tumour have on nerves of the brachial plexus?

Answer 7

Can lead to nerve compression which causes weakness in the hand and causes muscle atrophy, particularly in the interosseous muscles

Question 8

what is the main difference between a peripheral and brachial plexus nerve lesion?

Answer 8

Peripheral nerve lesion only affects one nerve whereas brachial plexus affects lots of nerves (so lots of the arm)

Question 9

what are symptoms of a peripheral nerve lesion and what causes it?

Answer 9

severe, continuous pain with a burning sensation, tingling/total loss of sensation in the part of the body affected by the damaged nerve.

Causes: Cut/tear of nerve tissue, severe bruising, nerve stretching

Question 10

what are symptoms of a brachial plexus lesion and what causes it?

Answer 10

lack of muscle control in the arm, hand, or wrist, and lack of feeling or sensation in the arm or hand

Causes: nerve compression or stretch due to birth-related palsies, trauma and peripheral tumours.

Question 11

what is horner’s syndrome and what is it characterised by?

Answer 11

Rare disorder which results from disruption of the sympathetic nerves supplying the face usually due to a lesion or tumour.

Characterised by:
 constricted pupil (miosis)
 drooping of upper eyelid (ptosis)
 absence of facial sweating on one side (unilateral anhidrosis)
 sinking of eyeball into socket (apparent enophthalmos but not actually)

Question 12

Why does miosis occur (constriction of pupil)?

Answer 12

Miosis occurs because of the loss of sympathetic drive to the iris dilator muscle through long ciliary nerve. Results in unopposed (parasympathetic) constriction of the pupil.

Question 13

Why does Ptosis and sinking of eyeball into socket occur?

Answer 13

because of loss of sympathetic supply to the eye. The superior tarsal muscle has smooth muscle fibres that help to elevate the upper eye lid when they eye’s open. Loss of this nerve supply lead to ptosis and causes narrowing of the area between the eyelids which creates the illusion of enophthalmos. Recession of the eye into its socket does not ACTUALLY occur. (just appears like that)

Question 14

Why does unilateral anhidrosis occur?

Answer 14

because of the disruption of the sympathetic nerve supply to the sweat glands.

Question 15

What does the sympathetic pathway to the eye involve?

Answer 15

Consists of a 3-neuron pathway which begins in the CNS

Question 16

Describe the first-order neuronal fibres in the sympathetic pathway to the eye

Answer 16

First-order neuronal fibres: arise from the posterolateral hypothalamus, descend through the brainstem and terminate in the spinal cord at the ciliospinal centre (C8 - T2).

Question 17

Describe the second-order neuronal fibres in the sympathetic pathway to the eye

Answer 17

Second-order neuronal fibres (pre-ganglionic):
o Exit through T1 root, travel close to the lung apex through the para-vertebral sympathetic chain and the stellate ganglion
o Terminate in the superior cervical ganglion.
(Tumours involving upper lobe of the lung and thoracic outlet can interrupt this pathway because of their proximity to these structures)

Question 18

Describe the third-order neuronal fibres in the sympathetic pathway to the eye

Answer 18

Third-order sympathetic fibres (post-ganglionic):
o Exit the superior cervical ganglion to form a plexus surrounding the internal carotid artery.
o Plexus then ascends into the cavernous sinus, runs a short course on the 6th cranial nerve and then follows the ophthalmic division of the trigeminal nerve to the orbit.

Supplies the iris dilator muscles through long ciliary nerve and the smooth muscle fibres of upper and lower lid (superior and inefrior tarsal). Vasomotor and sweat gland fibres to the face follow a different course after leaving the ganglion.

Question 19

Why may a patient with a tumour (e.g. Pancoast tumour) present with upper limb swelling and discolouration?

Answer 19

As the tumour grows, it partially or completely compresses the vein and loss of sympathetic innervation also leads to loss of vascular tone. Oedema results as a failure of venous drainage and discolouration may also occur as the blood stays stagnant and begins to coagulate.

Question 20

what is a Pancoast tumour and where is it located?

Answer 20

A tumour of the pulmonary apex which can lead to neurological problems. It is situated at the top end of either the right or left lung.

Question 21

what type of tumour are Pancoast tumours? what is the most common type?

Answer 21

Most Pancoast tumours are non-small cell carcinomas and the most common type is adenocarcinoma

Question 22

what is found in each of the compartments of the thoracic outlet? (including its rough borders)

Answer 22

o Anterior: from the sternum to the anterior scalene muscle, contains subclavian vein and internal jugular vein

o Middle: from anterior to posterior scalene muscle, contains subclavian artery

o Posterior: beyond the middle, contains branches of the brachial plexus, sympathetic chain and stellate ganglion.

Question 23

Describe the effects of compression of structures within the thoracic outlet

Answer 23

compression of stellate ganglion –> Ptosis, anhidrosis and miosis
compression of the brachial plexus –> Weakness of hand and muscle atrophy of interosseous muscles
occlusion of the subclavian vein –> Discolouration and swelling of arm

Question 24

Describe the diagnosis of Pancoast tumour and mention why it is difficult

Answer 24

Diagnosis is difficult due to absence of typical lung cancer symptoms.
• Chest X-ray
• MRI – most accurate, contrast can be used to display the extent of the damage.
• CT scan
• Angiogram: to look at the involvement of the subclavian artery/vein
• Biopsy
• PET scans identify the metastasis of cancer

Question 25

Describe the management of Pancoast tumour

Answer 25

Removal of cancer:
o Chemotherapy
o Radiation therapy - both to reduce size of tumour
o Surgery – removal of entire lung, nearby tissues, major artery

Symptom management:
o Pain relief medication
o Steroids to reduce nerve pressure