Bones And Joints Of Trunk

LEI Yueshan Department of Anatomy 雷岳山 Wuhan University School of Medicine

The bones of trunk

(In adult)

Including

The bones of trunk Vertebrae (24) Sacrum (1) Coccyx (1) Sternum (1) Ribs (24)

sternum

Ribs

Cervical vertebrae

Thoracic vertebrae

Vertebral Column Thoracic Cage Pelvis

Ⅰ.Vertebral Column Cervical vertebrae(C1-C7) Thoracic vertebrae(T1-T12 ) Lumbar vertebrae( L1-L5) Sacrum (1) Coccyx (1) -1-

Lumbar vertebrae

Sacrum Coccyx

1.General features of vertebrae ① vertebral body anterior, more massive part A typical spherical to oval supports body weight vertebra ② vertebral arch posterior to the vertebral body pedicles and laminae

vertebral foramen

A

viewed Superiorly

seven processes

body arch

vertebral foramen

spinal cord

vertebral body

vertebral canal housing B

-2-

C

viewed Laterally

viewed Laterally

Transverse process

vertebral notch

spinous process articular processes

vertebral body Pedicle

Viewed Laterally

vertebral body

Viewed superiorly

intervertebral foramen

vertebral arch ① pedicles

Intervertebral foramen

arch ---- body

pedicle the superior vertebral intervertebral notches foramina the inferior vertebral superior articular notches

② laminae ③ Seven processes ⅰ. spinous process

superior vertebral inferior notch

process

spinous process

Inferior articular process

projects dorsally from the fusion of the laminae on either side ⅱ. transverse processes project laterally from the junctions of the pedicles and laminae ⅲ. superior and inferior articular processes project cranially or caudally from the junctions of the pedicles and laminae -3-

vertebral body

2.Main characterstics of vertebrae in each regions

transverse transverse costal fovea costal facets

(1)Thoracic vertebrae Heart-shaped; medium; facets 1.Body for rib articulations ( the costal fovea) 2.Vertebral foramen

Small and round

3.Spinous process

Long ; slender; not split; tip points posterocaudally

4.Transverse processes

All but two(T11, T12 ) have facets for rib articulation (the

5.Articular facets of articular processes

Posteriorly or anteriorly;

-4-

Spinous process

Superior articular costal facet

fovea Vertebral body

transverse costal facets

superior demifacet for head of rib

transverse costal fovea ) Relatively coronary spinous process

inferior demifacet for head of rib

(2)Cervical vertebrae 1.Body Oval; small; curved faces 2.Vertebral foramen

Triangular ; large

3.Spinous process

Short; split (bifid ) other than C1,7; tip points posteriorly

4.Transverse Have transverse processes foramima 5.Articular facets Superoposteriorly of articular inferoanteriorly, processes

or

Relatively horizontal

-5-

Vertebral foramen Superior articular process Superior articular facet pedicle

Bifid tip of spinous process spinous process lamin a

transverse vertebral body foramen

(3)Lumbar vertebrae Kindey-shaped; thicker 1.Body and massive;

2.Vertebral foramen

Triangular and medium

3.Spinous process

Blunt; broad; tip points posteriorly

4.Transverse processes

long; no articular facets or transverse foramina

A Lateral view

5.Articular facets of Posteromedially or articular processes anterolaterally Relatively

sagittal plane

-6-

B Superior view

Table compares of each regions of vertebrae vertebrae Body

cervical

thoracic

lumbar

Oval; small Heart-shaped; medium; Kindey-shaped; facets for rib articulations thicker and massive (costal fovea )

Vertebral foramen Spinous process

Triangular ; large

Small; round

Short; bifid Long and slender; projects Blunt; broad; projects

posterocaudally

Transverse transverse All but two(T11, T12 ) have processes foramina facets for rib articulation

(transverse costal fovea)

Articular Relatively processes horizontal

-7-

Triangular; medium

posteriorly

long; no articular facets or transverse foramina

Relatively coronary Relatively sagittal

(4) Particular vertebrae 1) The atlas(C1) two lateral masses anterior arch posterior arch The following features:

transverse process

supererior articular facet

Fovea dentis (for dens of axis) on anterior arch

anterior arch

vertebral foramem posterior arch

Atlas, superior view

(1) No body or a spinous process transverse anterior (2) semicircular anterior arch tubercle foramem anterior ----fovea dentis arch transverse semicircular posterior arch process (3) oval superior articular facet vertebral foramem ------ articulating with the inferior occipital condyle articular posterior facet Posterior round inferior articular facet arch tubercle ------articulating with the axis -8Atlas, inferior view

dens

2) The axis(C2) Distinguishing feature: The dens ---projects superiorly Anterior articular surface

C2

C2 Right lateral view

posterior view

------Articulation with the fovea dentis

3) Vertebra prominens(C7) Spinous process: long and nonbifid a prominence under the skin -9-

Spinous process

C6

posterior view

C7

C7

The projecting anterior edge of the body of the 1st sacral vertebra

(5) The sacrum A. In adults consists of the five fused sacral vertebrae B. Anterior surface

The sacral promontory

smooth and concave ; four transverse lines ; anterior sacral foramina(4 pairs)

anterior sacral foramina Sacral hiatus

Sacral apex

Viewed posteriorly - 10 -

Sacral apex

Viewed laterally

transverse lines

Viewed anteriorly

C.Dorsal surface

rough and convex the median sacral crest the lateral sacral crest the intermediate sacral crest posterior sacral foramina (4 pairs)

sacral hiatus

sacral hiatus

sacral cornua

In the inferior end of the sacral canal, resulted from the absence of the laminae and spinous processes of S4 and S5 vertebrae. leads into the sacral canal

sacral cornua

Sacral tuberosity

posterior sacral foramina

Intermediate Project inferiorly on each side sacral crest Sacral of the sacral hiatus, representing hiatus the inferior articular processes of

S5 vertebra - 11 -

Lateral sacral crest Median sacral crest

Sacral cornua

Coccyx

Viewed posteriorly

D.Lateral surfaces The auricular surface ----articulating with ilium Auricular surface

The sacral tuberosity

Sacral tuberosity

---- for the ligament attachment

lateral sacral crest

(6)The coccyx no pedicles, laminae, or spinous processes in adulthood

median sacral crest

Sacral hiatus

sacral cornua

coccyx

Viewed posteriorly - 12 -

sacral curve

Viewed laterally

Ⅱ. Sternum Broad and triangular Manubrium

The jugular notch The clavicular notch The 1st costal notch

An obtuse angle of the The sternal junction of manubrium with angle body, slightly convex forward. Forms a useful landmark A series of articular facets (costal Body notches ) on the lateral margins articulating with costal cartilages from rib pairs 2-7 Xiphoid - 13 -

Ⅲ Rib The costal bone The costal cartilage True ribs Attaching directly to the sternum (1-7) False ribs Costal arch (8-10) Floating ribs (11,12) (8-12) a head a neck

Structure

Tubercle:

projecting dorsally

a costal groove, a body costal angle - 14 -

superior demifacet for head of rib

transverse costal facets

Scalene tubercle Head

tubercle

The first rib head spinous process

neck

inferior demifacet for head of rib

The 12th rib

Highlights of this chapter Important Concepts sacral promontory sternal angle intervertebral foramen

Important Contents Main characterstics of vertebrae in each regions The features of the sternum and the ribs

- 15 -

LEI Yueshan Department of Anatomy 雷岳山 Wuhan University School of Medicine

The bones of trunk (sample)

What to observe in the practice 1.When you pick up a typical vertebra, you first identify which region it is according to the particular features: costal fovea, transverse costal fovea; bifid, transverse foramen. 2.Then you must find the the following structures: vertebral body, pedicles, laminae, vertebral foramen, spinous process, Superior, inferior articular processes, transverse processes, superior vertebral notches, the inferior vertebral notches, intervertebral foramina 1) The atlas(C1): anterior arch, posterior arch, superior facet, inferior articular facet 2) The axis(C2): dens 3) Vertebra prominens(C7): Spinous process 4) The sacrum: transverse lines, anterior or posterior sacral foramina, sacral promontory, the median or lateral sacral crest, sacral cornua, sacral hiatus, auricular surface, sacral tuberosity 3.Sternum: manubrium,

body, Xiphoid, jugular notch, clavicular notch, sternal angle, costal notch 4.Rib: head, neck, body, tubercle, costal groove

1.General features of vertebrae ① vertebral body ② vertebral arch

vertebral foramen

pedicle superior superior articular inferior processes

vertebral notch

① pedicles

the superior vertebral notches intervertebral the inferior foramina vertebral notches

spinous process

inferior articular processes

② laminae

Seven processes spinous process superior articular processes inferior articular processes transverse processes - 16 -

vertebral body

function Muscle attachment

parts spinous process articular processes

Restriction of movement Protection of spinal cord

transverse process

Support of body weight

vertebral body

A

2.Main characteristics of vertebrae in each regions transverse costal facets

Superior articular facet

superior demifacet for head of rib

spinous process - 17 -

inferior demifacet for head of rib

(1)Thoracic vertebrae

Bifid tip of spinous process

Vertebral foramen

Spinous process Lamina

Superior articular facet Pedicle

Transverse foramen Vertebral body

(2)Cervical vertebrae

(3) The atlas(C1) supererior articular facet

anterior arch

vertebral foramem

anterior tubercle

transverse foramem

transverse process

articular facet (for dens of axis) on anterior arch

Atlas, superior view

(4)The axis(C2)

Atlas, inferior view

(5) Vertebra prominens(C7)

dens

- 18 -

inferior articular posterior facet arch Posterior tubercle

C2

Spinous process

C7

(6)Lumbar vertebrae

Viewed laterally

- 19 -

Viewed superiorly

(7) The sacrum and coccyx The sacral promontory

Sacral tuberosity

Transverse lines

Anterior sacral foramena

lateral sacral crest

Posterior sacral foramena Sacral hiatus coccyx

- 20 -

Viewed anteriorly

Viewed posteriorly

median sacral crest

Sacral cornua

(7) The sacrum

auricular surface

Viewed laterally - 21 -

The Sternum

The sternum The rib

- 22 -

Viewed anteriorly

LEI Yueshan Department of Anatomy 雷岳山 Wuhan University School of Medicine

Joints of bones of trunk

Ⅰ.Joints of vertebral column Joints of vertebral bodies and the arches Intervertebral disc 1.Joints of vertebral bodies Anterior longitudinal lig. Posterior longitudinal lig. ① Intervertebral disc anulus fibrosus ---Outer fibrous part a shock absorber nucleus pulposus ---Gelatinous central mass Intervertebral disc

nucleus pulposus anulus fibrosus -1-

Viewed superiorly

Viewed anteriorly

Prolapsed disc Rupture

anulus fibrosus Area of protrusion

nucleus pulposus

Because of trauma or degenerative changes , the relatively thin posterior part of the anulus fibrosus may rupture, allowing the nucleus pulposus to protrude posterolaterally into the vertebral canal. The escaped disc can compress the adjacent spinal nerve roots and cause pain of leg and/or lower part of back. -2-

② Anterior longitudinal lig. The sacrum Anterior surfaces

The foramen magnum

Vertebral bodies Intervertebral discs

Prevent hyperextension Maintain stability ③ Posterior longitudinal lig. C2 (axis) the sacrum Posterior Vertebral bodies surfaces Intervertebral discs Prevent -3-

Hyperflexion Posterior protrusion of the intervertebral discs

Posterior longitudinal lig.

Anterior longitudinal lig.

Viewed lateriorly

2 ． Joints of vertebral arches The zygapophysial joints Accessory ligaments (1) The zygapophysial joints The superior articular process The inferior articular process Plane synovial joints Only slightly gliding Zygapophysial joints

Viewed anteriorly

-4-

(2) Accessory ligaments 1) Ligamenta flava Laminae ------ laminae Prevent hyperflexion and injury of discs

2) Interspinous ligaments:

Intervertebral disc Anterior longitudinal ligament

Ligamentum nuchae Ligamenta flava

Spinous process -------spinous process

3) Supraspinous ligament : ------A strong fibrous cord Interconnects the tips of the spinous processes

C7 ----- the sacrum 4) Ligamentum nuchae: -------A large elastic lig.

Interspinous lig. Supraspinous lig.

C7 ---- the external occipital crest Maintain the head in an upright position -5-

3. Joints of the atlas with the axis 1) Median atlantoaxial joint ----a pivot joint

The fovea dentis of atlas The dens Transverse ligament of atlas 2) Lateral atlantoaxial joints(2) The inferior articular facets of Cl The superior articular facets of C2 Movement: the head to turn from side to side (as when shaking the head to indicate “no”) The skull and atlas rotate as a unit on the axis. -6-

Anterior arch dens Transverse lig. atlas axis Median atlantoaxial joint Occipital bone

Apical lig. of dens Alar lig.

C1

Lateral atlantoaxial C2 joint Lateral atlantoaxial joints

4.Joints of the vertebral column with the cranium The atlantooccipital joints Condyloid, cooperated joints Occipital condyles Superior articular surfaces of the atlas Movement: nodding

Atlantooccipital joints Occipital Apical lig. of dens bone Alar lig.

C1

C2

Viewed posteriorly -7-

5.Vertebral column as a whole and its Movements (1) Vertebral column as a whole

① Viewed anteriorly: The width of the vertebral bodies C2 S2

S2 Co

small large

large small

progressively larger to bear the progressively greater body weight

-8-

② Viewed posteriorly: The spinous processes cervical The cervical region: region long, horizontal and bifid The thoracic region: In the upper part: slant downward and overlapping In the middle part: long and almost vertical In the lower part stumpy , nearly Lumbar region horizontal a groove of vertebral column

-9-

C2

bifid C7

③ Viewed laterally

Cervical curve

Four physiological curves (In the sagittal plane)

Thoracic To provide a flexible support (shockcurve absorbing resilience) for the body Cervical curve Convex forward, Secondary curves Lumbar curve Hold up its head(3-4 months) Thoracic curve Sacral Concave forward, Primary curves curve Lumbar curve Convex forward, Secondary curves Lumbar curve Cervical curve Begins to walk and assumes the Primary curve upright posture (12 months) Sacral curve Concave forward, Primary curves - 10-

newborn

3~4months

12 months

The forming of curves in the infant

(2) Movements of the vertebral column The following movements of the vertebral column are possible: ①Anterior flexion (bending forward)

The extent and variety of the movements

③Lateral flexion (bending to the side )

influenced by The elasticity, thickness of the intervertebral discs

④Rotation or twisting

Surfaces muscles and ligaments

②Extension (bending backward)

The shape and direction of articulation

Extension

②

flexion

①

③ Lateral bending - 11 -

④

Movements of the vertebral column

Rotation

(3) Functions of the vertebral column (1)Protects the spinal cord and spinal nerves. (2)Supports the weight of the body. (3)Provides a partly rigid and flexible axis for the body and a pivot for the head. (4)Help maintain an upright body position, as in sitting or standing.

- 12 -

Ⅱ.Joints of the thoracic cage The costovertebral joints The sternocostal joints The interchondral joints

costal transverse costal fovea fovea

1.The costovertebral joints ribs vertebrae （ 1 ） Joints of costal head The heads of ribs The costal fovea on the bodies of the thoracic vertebrae （ 2 ） Costotransverse joints The tubercle of the ribs The transverse costal fovea on the transverse processes - 13 -

Joints of costal head Costotransverse joints

2.The sternocostal joints costal cartilages (2—7) costal notches of the sternum The 1st rib The manubrium of the sternum

synchondrosis

3. The interchondral joints The costal arch formed by the costal cartilages of 7th, 8th, 9th and 10th ribs to articulate one by one with small interchondral joints. - 14 -

Infrasternal angle

4. Thoracic cage as a whole An osseous—cartilaginous cage; conical in shaped 12 thoracic vertebrae 12 pairs of ribs with their costal cartilages the sternum their connections thoracic vertebrae sternum ribs costal cartilages

- 15 -

The superior aperture of thorax The inferior aperture of thorax The 1st thoracic vertebra

The 1st pair of ribs and their costal cartilages

The superior border of manubrium The sternal angle

Xiphoid process The costal arches T12 - 16 -

The free border of 12th and 11th ribs laterally

5. Functions of thoracic cage Three functions (1) It protects structures in the thoracic cavity the heart, lungs, thymus, and the others (2) It protects some upper abdominal organs such as the liver (3) It serves as an attachment point for muscles involved with 1) respiration 2) the position of the vertebral column 3) movements of the pectoral girdle and upper limbs - 17 -

Highlights of this chapter Important Concepts Intervertebral disc costal arch

Important Contents 1.Joints of vertebral bodies 2.Joints of vertebral arches 3.Vertebral column as a whole and its movements

- 18 -

Lei Yueshan Department of Anatomy 雷岳山 Wuhan University School of Medicine

Joins of bones of trunk (sample)

What to observe in the practice 1.Joints of vertebral bodies: Intervertebral disc; nucleus pulposus, anulus fibrosus; Anterior longitudinal lig. Posterior longitudinal lig. 2 ． Joints of vertebral arches: The zygapophysial joints; Ligamenta flava; Interspinous lig.; Supraspinous lig.; Ligamentum nuchae

3. Vertebral column as a whole: ① Viewed anteriorly: The vertebral bodies ② Viewed posteriorly: The shape and direction of the spinous processes ③ Viewed laterally Four physiological curves 4.The costovertebral joints

1 ） Joints of cotal head 2 ） Costotransverse joints

5.The sternocostal joints 6. The interchondral joints; the costal arch 7.The structure of thorax

Ⅰ.Joins of vertebral column 1.Joints of vertebral bodies

Intervertebral disc Anterior longitudinal ligament Posterior longitudinal ligament nucleus pulposus anulus fibrosus

Posterior longitudinal ligament nucleus pulposus - 17 -

anulus fibrosus

Anterior longitudinal ligament

2 ． Joints of vertebral arches (1) The zygapophysial joints (2) Accessory ligaments 1) Ligamenta flava 2) Interspinous ligaments 3) Supraspinous ligament 4) Ligamentum nuchae

Ligamentum nuchae

Ligamenta flavum Zygapophysial joint intervertebral disc

Interspinous lig.

Anterior longitudinal lig.

- 18-

Viewed anteriorly

Supraspinous lig.

5.Vertebral column as a whole Bifid C2 S2

Long, overlap

Cervical

Thoracic

small large

stumpy , horizontal

Lumbar

Sacral curve

① Anterior view ② Posterior view The vertebral bodies The spinous processes - 19 -

③ Lateral view physiological curves

Ⅱ.Joints of the thoracic cage 1.The costovertebral joints （ 1 ） Joints of cotal head （ 2 ） Costotransverse joints

Costotransverse joints

Joints of costal head - 20 -

2. The sternocostal joints 3. The interchondral joints

Sternocostal costal cartilages joints costal notches Interchondral joints

- 21 -

4.Thoracic cage The superior or inferior aperture of thorax The 1st thoracic vertebra

The 1st pair of ribs and their costal cartilages

The superior border of manubrium The sternal angle

Xiphoid process The costal arches T12 - 22 -

The free border of 12th and 11th ribs laterally