Human Anatomy Vol 1

THORAX

|- parietat

pleura

Fascia over

quadratus

lumborum

Costovertebral

angle/costo-

diaphragmatic

TECCSS

Quadratus

lumborum

Lateral arcuate

ligament

Costotransverse ligamenl

Levator costae

Longissimus

Lumbocostal

ligament

lliocostalis

Latissimus dorsi

Serratus posterior

inferior

External

(a) oblique

Figs 13.8a and b:

Middle layer of

thoracolumbar fascia

The right twelfth rib: (a) lnner surface, and (b) outer surface

(b)

I

b. The fascia covering the quadratus lumborum is

also attached to this part of the rib.

c. The internal intercostal muscle is inserted near the

upper border.

d. The costodiaphragmatic recess of the pleura is

related to the medial three-fourths of the costal

surface.

e. The diaphragm takes origin from the anterior end

of this surface.

3 The following are attached to the outer surface.

a. Attnchments on the medial half

i. Costotransverse ligament (Fig. 13.8b).

ii. Lumbocostal ligament

iii. Lowest levator costae

iv. Iliocostalis and longissimus parts of

sacrospinalis.

b. Attachments on the lateral half

i. Insertion of serratus posterior inferior

ii. Origin of latissimus dorsi

iii. Origin of external oblique muscle of abdomen.

4 The intercostal muscles are attached to the upper

border.

5 The structures attached to the lower border are:

a. Middle layer of thoracolumbar fascia.

b. Lateral arcuate ligament, at the lateral border of

the quadratus lumborum.

c. Lumbocostal ligament near the head, extending

to the transverse process of first lumbar vertebra.

The eleventh and twelfth ribs ossify from one

primary centre for the shaft and one secondary centre

for the head.

The costal cartilages represent the unossified anterior

parts of the ribs. They are made up of hyaline cartilage.

They contribute materially to the elasticity of the

thoracic wall.

The medial ends of the costal cartilages of the first

seven ribs are attached directly to the sternum. The

eighth, ninth and tenth cartilages articulate with one

another and form the costal margin. The cartilages of

the eleventh and twelfth ribs are small. Their ends are

free and lie in the muscles of the abdominal wall.

The directionof the costalcartilages isvariable. As the

first costal cartilage approaches the sternum, it descends

a little. The second cartilage is horizontal. The third

ascends slightly. The remaining costal cartilages are

angular. They continue the downward course of the rib

for some distance, and then turn upwards to reach either

the sternum or the next higher costal cartilage (see

Fig. 12.1).

Each cartilage has two surfaces, anterior and

posterior; two borders, superior and inferior; and two

ends, lateral and medial.

Attochmenls

AnferiorSu ce

L Anterior surface of the first costal cartilage articulates

with the clavicle and takes part in forming the

sternoclavicular joint. It gives attachment to:

a. The sternoclavicular articular disc (see Chapter 10).

b. The joint capsule.

c. The sternoclavicular ligament.

d. The subclavius muscle (Fig. 13.7).

2 The second to sixth costal cartilages give origin to

the pectoralis major (Fig. 13.9).

3 The remaining cartilages are covered by and give

partial attachment to some of the flat muscles of the

anterior abdominal wall. The intemal oblique muscle

is attached to the seventh, eighth and ninth cartilages;

and the rectus abdominis to the fifth, sixth and

seventh cartilages.

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