Skeletal anatomy

Question 1

The sternal angle is a useful landmark for …..

Answer 1

1. Ribs are counted from this point (the 2nd rib)
2. Bifurcation of the trachea
3. Superior vena cava is formed here from the Lt. & Rt. brachiocephalic veins
4. Marks the beginning & end of the aortic arch

Question 2

The first bone to ossify in the fetal life is ……

Answer 2

the clavicle

* It is also the most commonly fractured bone

Question 3

Damage to the upper trunk of the branchial plexus causes ……., while for the lower trunk causes …..

Answer 3

• Inability to abduct, flex or rotate the arm

* damage to the ulnar N. (loss of sensation in medial arm, forearm & hand, as well as weakness)

Question 4

Innervation of the anterior abdominal muscles & skin is through …….

Answer 4

ventral rami of the lower 6 thoracic spinal nerves & ilioinguinal & iliohypogastric branches of the ventral rami of L1

Question 5

What is the innervation & action of abdominal muscles ??

Answer 5

1. EAO: T7 - T12 . Same for rectus muscles
2. IAO: T7 - T12 & iliohypogastric/ilioinguinal Nerves. Same for trasverse
   * EO & IO increase abdominal pressure, rotation & flexion
   * Transverse increases pressure only
   * Rectus muscles increase pressure & flexes the vertebral column
   * When flexing torso to the Right, the Rt. IAO with Lt. EAO contract