Bones & Articulations of the Thorax

Function of the thoracic cage

protects heart, lungs, and some abdominal organs

What is the thoracic cage primarily composed of

osteocartilage

What structures form the thoracic cage

12 thoracic vertebrae + IVDs, 12 pairs of ribs, costal cartilage, sternum

What special features exist on thoracic vertebrae

facets for rib heads and tubercles; long SPs

What do facets of thoracic vertebral bodies articulate with

heads of ribs

Facets on thoracic transverse processes articulate with

tubercles of ribs

What is the structure of the thoracic spinous processes

long and inferiorly sloped

With the neck and trunk flexed, the first visible SP is

C7

What does the ALL attach to and what is its purpose

anterior vertebral bodies C1-sacrum; prevents hyperextension

What does the PLL attach to and what is its purpose

posterior vertebral bodies C2-sacrum; prevents hyperflexion

What does ligamentum flavum attach to and what is its purpose

connects adjacent laminae; preserves spinal curves and assists extension

What does the interspinous ligament attach to and what is its purpose

between SPs T1-L5; limits hyperflexion

What does the supraspinous ligament attach to and what is its purpose

tips to SPs C7 to sacrum; prevents hyperflexion

What does the nuchal ligament attach to and what is its purpose

continuation of supraspinous above C7; stabilizes cervical spine

What does the intertransverse ligament attach to and what is its purpose

between adjacent TVPs; limits lateral flexion

What are the three parts of the sternum

manubrium, body, xiphoid process

What bone lies subcutaneously at the thorax-neck junction

clavicle

What articulation forms the sternoclavicular joint

clavicle + manubrium

What type of bone is the sternum

flat bone

What do sternoclavicular ligaments attach to and what is their purpose

clavicle to manubrium; stabilize SC joint

What does the costoclavicular ligament attach to and what is its purpose

clavicle to 1st rib cartilage; limits clavicle elevation

What does the SC articular disc do

divides joint into compartments; improves stability

How do the ribs curve

anterior and inferior

Which ribs are true ribs

1-7

Which ribs are false ribs

8-10

Which ribs are floating ribs

11-12

What features does a typical rib have

head, neck, tubercle, shaft

How many facets are on a rib head

two

Where is the rib neck located

anterior to the corresponding TVP

What is the crest of the rib

superior border of neck

Where is the rib tubercle located

posterior surface at neck-shaft junction

What is the function of the rib tubercle

articulates with TVP; attachment for lateral costotransverse ligament

What does the costotransverse ligament attach to and what is its purpose

connects rib neck to TVP; stabilizes costotransverse joint

Where is the rib angle

point of greatest curvature change

What groove lies on the inferior rib border

costal groove

What does the costal groove protect

intercostal nerve and vessels

What rib is the broadest, most curved, and shortest

1st rib

Why is the 1st rib clinically important

many structures pass and attach to it

Where is the scalene tubercle

internal border of superior surface of 1st rib

What muscle attaches to scalene tubercle of the 1st rib

anterior scalene

What vein crosses the 1st rib anterior to scalene tubercle

subclavian vein

What nerve structure passes posterior to the 1st rib

inferior trunk of brachial plexus

What is the superior groove on the 1st rib for

subclavian vessels and brachial plexus

How long is the 2nd rib than the 1st

twice as long

What muscle attaches to the 2nd rib tuberosity

serratus anterior

What is costal cartilage made of

hyaline cartilage

What joint connects costal cartilage to sternum

vertebrosternal (sternocostal) joint

What do ribs 8-10 articulate with

cartilage of the rib above

Function of costal cartilages

adds elasticity and mobility

What is the infrasternal angle

angle where costal margins meet at xiphisternal joint

What does the superior costotransverse ligament attach to and what is its purpose

TVP above to rib neck; anchors rib to TVP

What does the lateral costotransverse ligament attach to and what is its purpose

TVP tip to rib; strengthens costotransverse joint

What do radiate sternocostal ligaments attach to and what is their purpose

bind costal cartilage to sternum, reinforce sternocostal joints

What does the intra articular sternocostal ligament attach to and what is its purpose

connects costal cartilage to sternum internally, stabilizes joint

What supports costochondral joints and what is its purpose

periosteum binding rib to cartilage, provides rigid stability

What do interchondral ligaments attach to and what is their purpose

bind adjacent costal cartilages (6-9), stabilizes interchondral joints

What are the joints of the ribs

costovertebral, costotransverse, sternocostal, costochondral, interchondral

What type are costovertebral joints

synovial plane

What articulates at costovertebral joints

rib head with superior and inferior vertebral facets + disc

What does the radiate ligament attach to and what is its purpose

attaches rib head to vertebral bodies and discs; stabilizes costovertebral joint

Which rib heads articulate ONLY with their own vertebra

ribs 1, 11, 12

What type are costotransverse joints

synovial plane

What articulates at costotransverse joints

rib tubercle with TVP of same number vertebra

Which ribs do NOT articulate with TVPs

ribs 11 and 12

What ligaments support costotransverse joints

superior, costotransverse, and lateral costotransverse ligaments

What type are costochondral joints

primary cartilaginous

What articulates at costochondral joints

rib end with costal cartilage

What movement occurs at costochondral joints

none

What type are interchondral joints (ribs 6-9)

synovial plane

What type is the joint between ribs 9-10

fibrous

What type is the 1st sternocostal joint

primary cartilaginous (synchondrosis)

What type are sternocostal joints 2-7

synovial plane

What ligaments support sternocostal joints

radiate sternocostal + intra-articular

What does the intra-articular ligament attach to and what is its purpose

connects rib head to IV disc; divides joint cavity and stabilizes rib head

What if often absent in sternocostal joints

articular cavities

What type is the sternoclavicular joint

saddle synovial

What forms the sternoclavicular joint

clavicle + manubrium + 1st costal cartilage

What divides the sternoclavicular joint

articular disc

What type is the manubriosternal joint

secondary cartilaginous (symphysis)

What type is the xiphisternal joint

primary cartilaginous (synchondrosis)

What happens to these joints in older adults

often fuse (synostosis)

Floating ribs are unattached

anteriorly

What are facet joints also called

zygapophyseal / apophyseal joints

What unites thoracic vertebral bodies

intervertebral discs

How is T1’s superior facet oriented

like cervical spine (up/back)

How are T2-T11 facets oriented

up/back/lateral; more upright inferiorly

What movement does thoracic facet orientation allow

slight rotation; limits flexion

What does the supraspinous ligament become above C7

nuchal ligament

What type are intervertebral joints

symphysis (secondary cartilaginous)

What ligaments support intervertebral joints

ALL and PLL

What movement occurs at intervertebral joints

slight rotation

What does the anterior longitudinal ligament do

prevent hyperextension

What does the posterior longitudinal ligament do

preserves spinal curves; assists extension

What do interspinous and supraspinous ligaments prevent

hyperflexion

What do intertransverse ligaments prevent

excess lateral flexion

What do iliolumbar ligaments prevent

anterior displacement of L5

Which lumbar ligaments have pain innervation

ALL and PLL

What is the annulus fibrosis

outer fibrocartilaginous disc layer

What is the nucleus pulposus

inner gelatinous disc core (85% water)

How are lumbar nerve roots named

for vertebra above