Anatomy of the Thorax: Osteology and Muscles of the Thoracic Wall

spinous process of T1

In the normal standing position, the cranial scapular angle is next to what thoracic anatomy?

bodies of T4-5

In the normal standing position, the caudal scapular angle is next to what thoracic anatomy?

ventral end of first rib

In the normal standing position, the shoulder joint is next to what thoracic anatomy?

below ventral end of 5th intercostal space

In the normal standing position, the olecranon is next to what thoracic anatomy?

1.) form and protect the thoracic cavity

2.) serve as muscular attachments

Two functions of bones of the thorax

1.) thoracic vertebrae

2.) ribs

3.) sternum

Three types of bones of the thorax

central axis of the body that is made up of vertebrae containing the spinal cord

Vertebral column

50

Approximately how many vertebrae are present in the dog spine?

C7, T13, L7, S3, C20-23

Vertebral formula in the dog

1.) vertebral body

2.) vertebral arch

3.) vertebral foramen

4.) processes

Typical vertebrae consists of four structures:

main portion of the vertebra; thick bulky part of the vertebra

Vertebral body

ribs

costal fovea/demifacet

The vertebral body will articulate with the _______. What is this structure on the body called?

the dorsal part of the vertebra that arises from the body

Vertebral arch

1.) lamina

2.) pedicles

The vertebral arch consists of two structures:

left and right; form the roof (dorsal wall) of the vertebral column

lamina of vertebral arch

left and right; form the base (wall) of the vertebral foramen

pedicles of vertebral arch

surgery to remove the lamina of the vertebral arch; helps to decompress the spinal cord by enlarging the vertebral canal/foramen

Laminaectomy

hole in a single vertebra created by the vertebral body and vertebral arch

Vertebral foramen

canal formed by successive vertebral foramen; houses the spinal cord

Vertebral canal

formed between adjacent vertebrae within the column; space that allows spinal nerves to travel from the spinal cord to the periphery

Intervertebral foramen

processes

The vertebral arch has several bony _____________

1.) transverse

2.) spinous

3.) articular

Three processes of the vertebra:

process jutting out horizontally from the vertebral body

transverse process

process jutting out vertically from the vertebral arch

spinous process

small projections at the junction of the lamina and pedicle that contact adjacent bone

articular process

an intervertebral disc

Adjacent vertebral bodies are connected by...

fibrocartilaginous structure that is interposed in every intervertebral space, uniting the bodies of adjacent vertebrae

intervertebral disc

1.) anulus fibrosus

2.) nucelus pulposus

Two parts of intervertebral disc:

outer circumferential collagenous fibers of intervertebral disc

anulus fibrosus of intervertebral disc

inner gelatinous core of intervertebral disc

nucelus pulposus of intervertebral disc

rupture of the intervertebral disc; causes the nucelus pulposus to leak out

Herniated disc

C1 and C2

An intervertebral disc is found between every vertebrae except for...

vertebral body

1

vertebral arch

2

pedicle

2a

lamina

2b

vertebral foramen

3

spinous process

4a

transverse process

4b

articular process

4c

T11 vertebra

Anticlinal vertebra

radiographs; the spinous processes of T1-10 are angled caudally, but after T11, the anticlinal vertebra, the spinous processes are perpendicular to the body

The anticlinal vertebra can be used as a landmark in _________ of the thorax. Why?

yellow arrow

Where on this radiograph is the anticlinal vertebra?

bones in the chest that protect the heart and lungs

Ribs

13 pairs (26 total)

How many ribs are there in the dog?

1.) sternal ribs

2.) asternal ribs

Two types of ribs:

ribs that are directly attached to the sternebrae (ribs 1-9)

sternal ribs

ribs that are not directly attached to the sternebrae (ribs 10-13)

asternal ribs

the costal arch

Ribs 10-12 attach to the sternum via...

floating; it does not have a cartilaginous attachment to the sternum

Rib 13 is considered to be __________. Why?

1.) body

2.) costal cartilage

3.) intercostal space

4.) costochondral junction

Four parts of a rib:

dorsal bony part

body of rib

ventral cartilaginous part

costal cartilage of rib

space in between each of the ribs

intercostal space of ribs

junction between the body and costal cartilage of rib

costochondral junction

body of rib

1

costal cartilage of rib

2

costochondral junction

3

Sternum

located on the ventral floor of the abdomen

8

How many sternebrae are there?

1.) manubrium

2.) intersternebral cartilage

3.) xiphoid process

4.) xiphoid cartilage

Four structures of the sternum:

first sternebra

manubrium

cartilage that connects individual sternebra to each other

intersternebral cartilage

last sternebra

xiphoid process

cartilage process at the end of the xiphoid process

xiphoid cartilage

manubrium

1

intersternebral cartilage

2

xiphoid process

3

xiphoid cartilage

4

enshroud the thoracic cage and aid in respiration

Function of the thoracic wall muscles

1.) scalenus

2.) serratus ventralis

3.) serratus dorsalis cranialis

4.) serratus dorsalis caudalis

5.) external intercostal

6.) internal intercostal

7.) rectus thoracis

8.) transversus thoraci

Eight muscles of the thoracic wall

intercostal

All of the thoracic wall muscles are innervated by the _________ nerve

intercostal

All of the thoracic wall are supplied blood by the _________ artery

caudomedial

The intercostal nerve and arteries are located ____________ to each rib

caudal ventral

Muscles that aid in inspiration have fibers going in what direction?

1.) scalenus

2.) external intercostal muscle

3.) rectus thoracis

4.) serratus dorsalis cranialis

Four thoracic wall muscles involved in inspiration

cranial ventral

Muscles that aid in expiration have fibers going in what direction?

1.) internal intercostal

2.) transversus thoracis

3.) serratus dorsalis caudalis

Three thoracic wall muscles involved in expiration

supports the trunk

Serrtaus ventralis function

scalenus

1

serratus ventralis

2

serratus dorsalis cranialis/caudalis

3

external intercostal

5

rectus thoracis

7