Question

What is myasthenia gravis? Describe what part of the neuromuscular junction is impacted and how that is associated with the presentation of the patient. The drug neostigmine is used to both diagnose and treat MG. How does it work and what is its target? What is rigor mortis? What causes it? How long does it last?

Answer 1

What is myasthenia Gravis? Describe what part of neuromuscular junction is impacted and how that is associated with the presentation of the patient. The drug neostigmine is used to both diagnose and treat MG. How does it work and what is its target?

Ans. Myasthenia gravis (MG) is the most commonly encountered autoimmune disease of the neuromuscular junction. MG causes fluctuating weakness that worsens with activity and as the day progresses, and ocular weakness, causing ptosis and diplopia.

Patients with MG present with painless, specific muscle weakness, and not generalized fatigue. Myasthenic weakness typically affects the extraocular, bulbar, or proximal limb muscles. Droopy eyelids or double vision is the most common symptom at initial presentation of MG, with more than 75% of patients.

Neostigmine works by slowing the breakdown of acetylcholine when it is released from nerve endings. This means that there is more acetylcholine available to attach to the muscle receptors and this improves the strength of your muscles.

What is rigor mortis? What causes it? How long does it last?

Rigor mortis is when the muscles lock up post-mortem. It is the third stage of death. It occurs 4–6 hours after death.

The mechanism of rigor mortis is based on sustained contraction of the muscles of the body following death. This happens because inasmuch as ATP is required for contraction, it is equally needed for the muscles to relax. So, in the absence of ATP, there would be no relaxation of the contracted muscles.

The muscle stiffening usually starts from the facial muscles and ends with the diaphragm. The entire process lasts for 54 hours. Hence after 54 hours, the stiffness of the body (rigor mortis) should have disappeared.

Ans 31. The prime mover of inspiration is the (a) diaphragm, (b) internal intercostals, (c) external intercostals, (d) abdominal wall muscles

Ans 32. The muscles of the abdomen are made up of the muscles of the anterolateral abdominal wall and the muscles of the posterior abdominal wall. These muscles work together to protect the internal organs (viscera) by covering them completely. They also help to provide postural support, assist in forceful expiration and increase the intra-abdominal pressure.

The anterolateral abdominal wall consists of four layers- skin, superficial fascia (connective tissue), muscles and parietal peritoneum. The muscles of the anterolateral abdominal wall include flat and vertical muscles. The flat muscles are stacked on top of each other and have fibres that run in different directions, helping to strengthen the abdominal wall. There are two vertical muscles in the anterolateral abdominal wall, and these are situated near the midline of the body. The posterior abdominal wall is made up of the lumbar vertebrae, pelvic girdle, five posterior abdominal muscles and their associated fascia. Major nerves, vessels and organs are located on the inner surface of the posterior abdominal wall. The posterior abdominal wall is found medial to the lateral abdominal walls and is limited anteriorly by the posterior part of the parietal peritoneum.

The white line (Latin: linea alba) is a fibrous structure that runs down the midline of the abdomen in humans and other vertebrates. In humans linea alba runs from the xiphoid process to the pubic symphysis. The name means white line and the linea alba is indeed white, being composed mostly of collagen connective tissue.

33. Draw and describe the anterior triangle. What are its boundaries? Contents.

The anterior triangle is situated at the front of the neck. It is bounded:

• Superiorly – inferior border of the mandible (jawbone).
• Laterally – anterior border of the sternocleidomastoid.
• Medially – sagittal line down the midline of the neck.

The contents of the anterior triangle include muscles, nerves, arteries, veins and lymph nodes.

34. Draw and describe the posterior triangle. What are its boundaries? Contents.

Ans. The posterior triangle has the following boundaries:

Apex: Union of the sternocleidomastoid and the trapezius muscles at the superior nuchal line of the occipital bone

Anteriorly: Posterior border of the sternocleidomastoideus

Posteriorly: Anterior border of the trapezius

Inferiorly: Middle one third of the clavicle

Roof: Investing layer of the deep cervical fascia

Floor: (From superior to inferior)

1) M. semispinalis capitis

2) M. splenius capitis

3) M. levator scapulae

4) M. scalenus posterior

5) M. scalenus medius

Contents

A) Nerves and plexuses:

• Spinal accessory nerve (Cranial Nerve XI)
• Branches of cervical plexus
• Roots and trunks of brachial plexus
• Phrenic nerve (C3,4,5)

B) Vessels:

• Subclavian artery (Third part)
• Transverse cervical artery
• Suprascapular artery
• Terminal part of external jugular vein

C) Lymph nodes:

• Occipital
• Supraclavicular

D) Muscles:

• Inferior belly of omohyoid muscle
• Anterior Scalene
• Middle Scalene
• Posterior Scalene
• Levator Scapulae Muscle
• Splenius

35. Name the four muscles that form the rotator cuff of the shoulder. Use the acronym?

Ans. The acronym SITS is often used as the name for the collection of four muscles that make up the rotator cuff: supraspinatus, infraspinatus, teres minor, and subscapularis

36. Where is the femoral triangle located? Name the boundaries (SAIL). Name the contents (NAVY)

Ans. The femoral triangle (or Scarpa's triangle) is an anatomical region of the upper third of the thigh. It is a sub fascial space which appears as a triangular depression below the inguinal ligament when the thigh is flexed, abducted and laterally rotated.

The borders of the femoral triangle can be remembered using the word , SAIL expanded as

Lateral border: Sartorius (S)

Medial Border : Adductor Longus (A)

Base border: Inguinal Ligament (IL)

The contents of the Femoral triangle is abbreviated as NAVEL:

Femoral Nerve (N)

Femoral Artery (A)

Femoral Vein (V)

Femoral Canal (Empty space) (E)

Lymphatics (L)

37. Botulism is an acute neurologic disorder that causes potentially life-threatening neuroparalysis due to a neurotoxin produced by Clostridium botulinum. The toxin binds irreversibly to the presynaptic membranes of peripheral neuromuscular and autonomic nerve junctions.

Botulinum toxin, one of the most lethal biologic toxins, is produced by the bacteria Clostridium botulinum. It acts at the neuromuscular junction, where it binds to the presynaptic cholinergic terminal and inhibits the release of acetylcholine. This functional denervation causes weakness and atrophy