Surface Anatomy & dermatomes

Question 1

Name the 3 parts of the sternum

Answer 1

Manubrium
Body
Xiphoid process

Question 2

What anatomical landmarks are found on the manubrium?

Answer 2

• The jugular notch forms its superior border.

Superolateral facet is for articulation with the clavicle Inferolateral facet is for articulation with the 1st rib via costal cartilage

The manubrosternal joint forms the inferior border. Second rib articulates at this level.
- Ribs can be counted from this level

Question 3

Why can’t we start from rib 1 when counting ribs?

Answer 3

The first rib is concealed by the clavicle. The first palpable rib is rib 2, which articulates with the sternum at the manubrosternal joint.

Question 4

Describe the body of the sternum

Answer 4

Made up of 4 fused segments
- Joints appear as ridges on the anterior surface
• Articular facets appear on lateral borders
- These articulate to costal cartilages of ribs 2-7

Question 5

Which rib articulates with the xiphoid process?

Answer 5

Rib 7

Question 6

What is meant by “true ribs”? And how many ribs are considered true ribs?

Answer 6

True ribs means ribs that articulate to the sternum directly. The firdt 7 ribs are true ribs.

Question 7

What is meant by “false ribs”? How many ribs are false ribs?

Answer 7

False ribs do not articulate directly to the sternum. Rather, they articulate via the costal cartilage of rib 7. (Ribs 8-10 are false ribs).

Question 8

What are floating ribs? And how many ribs are floating ribs?

Answer 8

Floating ribs do not articulate to the sternum at all. 2 ribs are floating ribs (ribs 11 and 12)

Question 9

What is a subcostal angle?

Answer 9

Medial margin formed by costal cartilage - Costal cartilages of Ribs 8-10
• Diaphragm attaches to it anteriorly

Question 10

Where is the breast located?

Answer 10

Between rib 2 and 6. It overlies the pectoralis major muscle.

Question 11

Where is the mammary gland located?

Answer 11

The mammary gland extends superolaterally along the lower margin of the pec major muscle.

Question 12

The _________________ connects the breast to the axilla

Answer 12

Axillary tail/process

Question 13

Describe the right border of the heart

Answer 13

3rd costal cartilage
- ± Finger’s width to right of the sternum
• To 6th costal cartilage

Question 14

Describe the left border of the heart

Answer 14

2nd intercostal space
- ± Finger’s width to left of the sternum
• To 5th intercostal space
- ± 9cm to left of the sternum - Midclavicular line
- Apex lies here

Question 15

Describe the superior and inferior borders of the heart

Answer 15

Superior border
• 3rd costal cartilage
To 2nd intercostal space Inferior border
• 6th costal cartilage
• To 5th intercostal space

Question 16

Describe the midaxillary line

Answer 16

Lateral vertical line along the coronal plane
- Beginning at the axilla and descends through abdomen
• Divides the body into anterior and posterior parts • Several structures found along this line

Question 17

Describe the scapular line

Answer 17

Posterior vertical line along the sagittal plane
Line crosses the inferior angle of the scapula Several structures found along this line

Question 18

Describe the Midclavicular line

Answer 18

Anterior vertical line along saggital plane
• Crosses costal margin at the 9th costal cartilage
• Extends from thorax to enter the thigh
- At the midpoint between ASIS and pubic tubercles - Referred to as the midinguinal line at this point

Question 19

Describe the surface anatomy of lung borders

Answer 19

Rib 6 along the midclavicular line
- Rib 8 along the midaxillary line
- T10 along vertebral column

Question 20

Describe the subcostal line

Answer 20

Superior horizontal line in the abdomen - Inferior to costal margins
• Lies at the inferior border of costal cartilage of Ribs 10
• Posteriorly, it passes through vertebral body of L3

Question 21

Describe the intertubercular line

Answer 21

Inferior horizontal line in the abdomen
• Connect the tubercles of the iliac crests
- Tubercles are located posterior to ASIS
• Posteriorly, it passes through L5 vertebral body
- Passes through its upper part

Question 22

List the 9 abdominal regions

Answer 22

Left and Right hypochondrium regions
Epigastric region
Left and right lumbar regions
Umbilical region
Left and right inguinal regions
Pubic region

Question 23

What is the transumbilical line?

Answer 23

Horizontal line along transverse plane
• Crosses the umbilicus
- At the level of L3/L4

Question 24

What is the median plane?

Answer 24

Vertical line dividing the body into left and right sides

Question 25

Name the 4 quadrants of the abdomen

Answer 25

R and L upper quadrants
R and L lower quadrants

Question 26

What are dermatomes?

Answer 26

Dermatomes are areas of skin supplied by - Single spinal cord level
- Single spinal nerve (Unilaterally)
• Formed from development of somites into the dermis
• Distribution overlap exists
- Most areas are supplied by a single spinal cord level

Question 27

What does C2-8 supply?

Answer 27

Head (except face and calp), neck and upper limbs

Question 28

What does the thoracic region supply?

Answer 28

Thoracic dermatomes (T1-T12)
the trunk
- T1 dermatome is mostly on the upper limbs
- T2 dermatome is the highest in the thorax

Question 29

What does the lumbar region supply?

Answer 29

Mostly supplies anterior surfaces of the thighs and legs and dorsum of the foot
- Also supply the medial and lateral surfaces of the thighs and legs
- Part of the plantar surface of the foot

Question 30

What does the sacral region supply?

Answer 30

Gluteal region
- Posterior surfaces of the thighs and legs
- S2-S4 dermatomes supply the perineum
- Plantar surface of the foot and part of the dorsum

Question 31

The coccygeal region supplies_____________.

Answer 31

Skinof the anus