Anatomy
What structure are the brachial plexus cords named for their position relative to?
Axillary artery
- Thickening of capillary walls in endoneurium
- Demyelination
- Myelin replaced with fibrosis
Where are the trunks of the brachial plexus located?
What forms the cervical, brachial and lumbosacral plexuses?
Anterior rami
What is Meralgia Paraesthetica?
Pain or abnormal sensation of the lateral thigh caused by entrapment of the lateral cutaneous nerve of the thigh under the inguinal ligament
Where would you expect the first signs of UMN pattern weakness to develop in the lower limbs?
Proximally in the lower limb, hip flexion is 1st to be weak
Where would you test the distribution of the cutaneous distribution of the deep fibular nerve?
web space between the first and second toes
Patient presents complaining of numbness in the lateral aspect of their forearm, inability to bend their elbow and difficulty lifting their arms up in front on their body. What structure has likely been damaged to cause this pattern of symptoms?
Musculocutaneous nerve
For 100 points each name four signs you would expect to see in a Klumpke's Palsy
- impaired sensation in C8 and T1 dermatomes
- impairment in C8 and T1 myotomes
- Horner's Syndrome (sympathetic fibres from T1)
- weak triceps reflex
- Claw hand (loss of flexor function of the wrist and the lumbricals --> wrist and the MCP are extended and the DIP and PIP are flexed. Since the median nerve is more severely affected, the first two digits have a greater degree of MCP extension and DIP/PIP flexion compared to the third and fourth digits)
Patient presents with new onset difficulty climbing stairs and a tingling sensation that started about a week ago in their toes and has now spread to up to the level of their knee.
While taking a history patient reports they had a bad stomach bug a few weeks ago that they did not seek medical assistance for as it passed on its own.
What condition does this patient likely have? Explain the pathological process causing this condition
Guillan Barre Syndrome
Immune system inappropriately attacks and destroys myelin leading to demyelination which slows the conduction of nerve impulses
For 100 points each name four signs of an Erb's Palsy
- impaired biceps reflex
- impaired sensation in C5 + C6 dermatomes
- impaired function in C5 + C6 myotomes
- paralysis of hemidiaphragm
- waiters tip position (loss of the lateral rotators of the shoulder, arm flexors, and hand extensor muscles --> arm hanging by the side and rotated medially, forearm extended and pronated and wrist flexed)
A patient presents with loss of motor function and sensation in their lower limbs. On examination hyperreflexia in the patella reflex and achilles reflex, a positive babinski sign and hyporeflexia in the triceps reflex is observed. At what level would you expect this patients spinal cord lesion?
C7
Patient presents with blurred vision, changes in facial expression and difficulty speaking that get worse as the day goes on. On examination ptosis is observed. Initially strength on shoulder abduction and adduction is equal bilaterally but, after the patient moves their left arm up and down 20 times strength is notably less on this side. What condition does this patient likely have and what is the pathological process causing this condition?
Myasthenia Gravis
Type 2 hypersensitivity reaction - B cells produce autoantibodies that bind to nicotinic acetylcholine receptors on muscle cells leaving them unable to bind acetylcholine and initiate muscle contraction. Autoantibodies also activate complement pathway leading to inflammation which causes destruction muscle cell and reduces the number of acetylcholine receptors on the muscle cell surface.
What is the likely cause of this patients symptoms?