📚 Question Bank

Correct Answer: B

The sternal angle is the distinct bony ridge where the manubrium meets the body of the sternum.

This is a vital clinical landmark because it marks the level of the 2nd costal cartilage, making it the starting point for counting ribs. It also aligns with the T4/T5 intervertebral disc posteriorly.

Correct Answer: C

A 'typical' rib (Ribs 3-9) has a generalized structure: a head with two articular facets, a neck, a tubercle, and a shaft with a costal groove.

Atypical ribs have unique features:

• Rib 1 is short, flat, and has only one facet on its head.
• Rib 2 is atypical due to its prominent tuberosity for the serratus anterior.
• Ribs 10, 11, and 12 typically have only a single facet on their heads.

Correct Answer: B

The costal groove is a distinct depression running along the inferior border of the inner surface of the rib shaft.

It provides a protective channel for the intercostal vein, artery, and nerve (VAN sequence from top to bottom). This is why a pleural tap (thoracentesis) is always performed just above the superior border of a rib, avoiding the groove below.

Correct Answer: C

This is a frequent exam trap!

The articulation between the 1st costal cartilage and the manubrium is a primary cartilaginous joint (synchondrosis), making it highly stable and immobile. Conversely, the sternocostal joints for ribs 2-7 are synovial plane joints, allowing slight gliding movements during respiration.

Correct Answer: B

The xiphisternal joint is the junction between the body of the sternum and the xiphoid process.

It lies at the level of the T9 vertebra. This landmark indicates the inferior limit of the central thoracic cavity and the anterior attachment point of the diaphragm.

Correct Answer: C

Ribs 11 and 12 are the floating ribs.

They are termed 'floating' because their anterior ends do not attach to the sternum or the costal margin. Instead, they end in the posterior abdominal musculature. They protect the kidneys posteriorly.

Correct Answer: B

The head of a typical rib (e.g., Rib 5) has two articular facets (demifacets) separated by a crest.

It articulates with the inferior demifacet of the vertebral body above it (T4) and the superior demifacet of the vertebral body of its own number (T5). The intervertebral disc lies between these two articulations.

Correct Answer: C

The tubercle of a typical rib has an articular and a non-articular part.

The articular part forms a synovial joint (the costotransverse joint) with the transverse process of the vertebra of the same number. For example, the tubercle of Rib 6 articulates with the transverse process of T6.

Correct Answer: B

Anatomically, the superior opening is called the thoracic inlet (or superior thoracic aperture). It is bounded by the T1 vertebra posteriorly, the 1st ribs laterally, and the manubrium anteriorly.

Clinical Note: Clinicians often confusingly refer to conditions compressing structures here as 'Thoracic Outlet Syndrome', despite it being the anatomical inlet.

Correct Answer: B

The 1st rib is short, broad, and flat. Its superior surface features the scalene tubercle, which serves as the insertion point for the scalenus anterior muscle.

This tubercle separates two shallow grooves: the anterior groove for the subclavian vein, and the posterior groove for the subclavian artery and lower trunk of the brachial plexus.

Correct Answer: C

During inspiration, the lower ribs (7-10) swing outward and upward, much like a handle being lifted on a bucket.

Because these ribs curve downward and outward from the spine, raising them pushes their lateral shafts further outward, significantly increasing the transverse (side-to-side) dimension of the thoracic cavity.

Correct Answer: B

The head of a typical rib articulates with two vertebral bodies, creating two separate synovial cavities.

These cavities are separated by the intra-articular ligament, which firmly anchors the crest of the rib head directly to the adjacent intervertebral disc. The radiate ligament surrounds the outside of the joint capsule.

Correct Answer: C

A cervical rib is an extra rib that develops from the costal element of the 7th cervical vertebra (C7).

It can be a fully formed bony rib or a fibrous band. Because it lies right at the thoracic inlet, it can compress the lower trunk of the brachial plexus (C8, T1) or the subclavian artery, causing Thoracic Outlet Syndrome.

Correct Answer: C

The joint between the manubrium and the sternal body is a symphysis (secondary cartilaginous joint), meaning the bone surfaces are covered in hyaline cartilage and connected by a pad of fibrocartilage.

This allows a slight hinging movement (the 'pump-handle' motion) during deep inspiration, pushing the sternum forward to increase the anteroposterior diameter of the chest.

Correct Answer: C

The 2nd rib is an atypical rib. It is much longer and thinner than the 1st rib but still lies relatively flat.

Its defining characteristic is a large, rough patch on its superior/outer surface—the tuberosity for the serratus anterior—which serves as the origin for a portion of that muscle.

Correct Answer: B

The 'pump-handle' mechanism involves the upper ribs (2-6) and the sternum.

Because these ribs slope downward from the spine to the sternum, elevating them pushes the sternum upward and forward (like a water pump handle). This action significantly increases the anteroposterior (AP) dimension of the chest.

Correct Answer: C

The superior costotransverse ligament is a strong band that extends from the upper border of the neck of a rib to the transverse process of the vertebra immediately above it.

This ligament suspends the rib and limits how far it can be depressed during forced expiration.

Correct Answer: C

Ribs 11 and 12 are the highly atypical 'floating ribs'.

They articulate only with their corresponding vertebral bodies (they have only one facet on their head). Because they do not articulate with transverse processes at all, they completely lack a neck and a tubercle.

Correct Answer: B

The costal margin is the lower border of the anterior thoracic wall.

It is formed by the medial borders of the 7th, 8th, 9th, and 10th costal cartilages. The right and left costal margins meet at the xiphisternal joint to form the subcostal angle.

Correct Answer: B

The heart lies immediately posterior to the sternum. Specifically, the right ventricle forms the majority of the anterior surface of the heart.

In severe blunt anterior chest trauma (like hitting a steering wheel), the sternum can be driven backward, directly bruising or even rupturing the right ventricle (myocardial contusion).

Correct Answer: B

Flail chest occurs when a segment of the rib cage breaks under stress and becomes detached from the rest of the chest wall (usually multiple ribs broken in two places).

This segment exhibits paradoxical movement: due to negative intrathoracic pressure, it gets sucked inward during inspiration, and due to positive pressure, it pushes outward during expiration. This severely compromises ventilation.

Correct Answer: C

Sternal puncture is a common method for obtaining bone marrow. The needle must be short and wide to avoid penetrating the posterior table of the bone.

If the needle goes too deep in the lower half of the sternal body, it will enter the middle mediastinum and strike the right atrium or right ventricle, leading to fatal cardiac tamponade. The aortic arch is higher up, behind the manubrium.

Correct Answer: B

The lower ribs protect the upper abdominal viscera. On the left side, ribs 9, 10, and 11 overlay the spleen.

A fracture of these ribs, particularly the 10th rib in the mid-axillary line, carries a high risk of splenic laceration, which can cause massive, life-threatening internal hemorrhage. (On the right side, these ribs protect the liver).

Correct Answer: B

To free the head of the rib from the vertebral bodies, the surgeon must deal with the joint of the head of the rib.

This requires cutting the radiate ligament (which surrounds the capsule anteriorly) and the deep intra-articular ligament (which tethers the crest of the head directly to the intervertebral disc). The costotransverse ligaments attach to the tubercle and neck, not the head.

Correct Answer: C

The costochondral joints are primary cartilaginous joints (synchondroses).

In these joints, the periosteum of the rib is continuous with the perichondrium of the cartilage, creating a bond so strong that under severe trauma, the bone will fracture or the cartilage will tear before the joint itself actually separates. No movement occurs at these joints.