Bones of the trunk

Skeletal system

• Your bones manufacture blood cells.

• Our bones are held by our muscles

• The smallest bones are in our ears

Bones classified by shape: long, short, flat, irregular, round

Bone enclosed in periosteum, which is continuouswith tendons and ligamentsblood vessels in periosteum

Epiphysis- endsspongy bone contains red marrowcompact bone, articular cartilage

Diaphysis- middlecompact bonemedullary cavity- contains yellow marrow (fat)lined with endosteum (squamous epithelium)

Compact boneosteocytes within lacunaearranged in concentric circles called lamellae

This surround a central canal; complex is calledHaversian system

Canaliculi connect osteocytes to central canal andto each other

Prenatal developmentskeleton is mostly cartilaginous

Cartilage cells and then osteoblasts start todeposit minerals

Cartilaginous disk (epiphyseal disk) remainsin epiphysis

Cells eventually stop dividing

Bursae & Tendon Sheaths• Bursae: flat, fibrous sac

w/synovial membrane lining

• Tendon Sheaths: elongated bursae that wraps around tendons

• 3 Factors in Joint Stability:– Muscle Tone – Ligaments – Fit of Articular Surface

pg 219

Joint Shapes• Hinge: cylindrical end of 1 bone

fits into trough shape of other– angular movement-1 plane (eg)

elbow, ankle, interphalangal

• Plane: articular surface in flat plane– Short gliding movement– (eg) intertarsal, articular

processes of vertebrae

pg 224

Joint Shapes

• Condyloid: egg-shape articular surface + oval concavity– side-to-side, back+forth movement– (eg) metacarpophalangeal (knuckle)

• Pivot: round end fits into ring of bone + ligament– rotation on long axis– (eg) prox. radius/ulna, atlas/dens

pg 225

Thoracic cageribsthoracic vertebraesternumcostal cartilages

True ribs are directly attached to the sternum(first seven pairs)Three false ribs are joined to the 7th ribTwo pairs of floating ribs

Clavicles and scapulae

Help brace shouldersAttachment sites for muscles

Bones of upper limb

Humerus (upper arm)Radius; ulnaCarpals, metacarpals, phalanges

Bones of lower limb

FemurPatellaTibia, fibulaTarsals, metatarslas, phalanges

Radius and Ulna

• Radius on Top

• Ulna on Bottom

Carpals or (Wrist Bones)

Phalanges (Little Fingers)

Rib Cage

Sternum (Breastbone)

Characteristics - Ligaments• Ligaments hold the

vertebral column in an upright position– The broad Anterior

Longitudinal Ligament prevents hyperextension and is quite strong

– The cord like Posterior Longitudinal Ligament prevents hyperflexion and is relatively weak

Characteristics - Ligaments• Ligaments also

connect specific vertebra and support disc position– Supraspinos

ligament– Ligamentum

flavum– Interspinous

ligament

Intervertebral Discs• Intervertebral discs are cushion like pads

interposed between vertebra• The discs provide elasticity and

compressibility• Compression flattens discs• Discs are thickest in the cervical and lumbar

to provide flexibility

Characteristics - discs• Annulus fibrosus

surrounds the outer margin– Collagen fibers

• Nucleus pulposus is the semi fluid substance which shifts under body weight & pressure

• Herniation of discHerniation Herniation

of diskof disk

General structure of vertebrae• Common pattern– Body or centrum– Vertebral arch

• lamina• pedicle

– Vertebral foramen– Spinous process

• Muscles attach

– Transverse process• Muscles attach

General structure of vertebrae• Interlocking pattern– Superior and inferior

processes interlock– The inferior from

above and the superior from the vertebrae below form a movable joint

– The movement contributes to spinal rotation

Superior ArticularSuperior ArticularProcessProcess

General structure• Pedicles have

notches on their superior and inferior borders

• Lateral openings are called intervertebral foramen– Spinal nerves

from spinal cord exit through these foramina

Regional Characteristic: Cervical• Body is oval, but wide

side to side C3 - C7• Spinous process is

short and bifid (split) except in C7

• Vertebral foramen is triangular

• Transverse processes contain foramina for blood vessels leading to brain

Cervical Vertebrae C1

• Lateral masses articulates with the occipital condyles of the skull

Cervical Vertebrae C1

• Inferior articular surface articulates with C2 below

Body of the Body of the Vertebrae is Vertebrae is

missing missing

Cervical Vertebrae C2• The axis has the

odontoid process or dens is its unique feature

• The dens is the missing body of the atlas which fuses with the atlas during embryonic development

Regional Characteristic: Cervical • Spinous processes

project directly posteriorly

• Superior facets directed superoposteriorly

• Inferior facets directed inferoanteriorly

• Flexion/extension, lateral flexion and rotation

Regional Characteristic: Thoracic

• Body is larger than cervical; heart shaped

• Spinous process is long and sharp

• Vertebral foramen is circular

• Transverse processes project posteriorly and bear facets for ribs

Regional Characteristic: Lumbar

• Body is massive and kidney shaped

• Spinous processes are short and blunt

• Vertebral foramen is triangular

• Transverse processes are perpendicular to spinous process but has no special features

Regional Characteristic: Lumbar• Spinous process

projects posteriorly• Superior facets

directed medially• Inferior facets directed

laterally• Flexion/extension,

some lateral flexion, rotation prevented

Sacral• Ala are fused remnants

of transverse processes that articulate with hip bones to form the sacro iliac joints of the pelvis

• Sacral promontory – Center of gravity is 1 cm

posterior of this point

• Transverse line are sites of vertebral fusion

• Sacral foramina transmit blood vessels and nerves

SacralSacralpromontorypromontory

AlaAla

Sacral• On the posterior aspect

median sacral crest are fused spinous processes

• The vertebral canal continues inside the sacrum as the sacral canal

• Sacral hiatus is at the inferior end of the sacral canal

• Superior articular surface form a joint with the spinal column

Coccyx

• Coccyx articulates with sacrum

Sternum• Located on the anterior

midline of the thorax • Consists of three fused

bones; manubrium, body, and xiphoid process

• Manibrium articulates with clavicle & 2 ribs

• Body with ribs 2 - 7• Xiphoid attachment site

for abdominal muscle

Thorax to Vertebral Column

Ribs

Ribs• Ribs are bowed

flat bones• Long shaft• Tear drop shaped

with a costal groove on inner surface

• Head of rib has 2 facets to articulate with its vertebrae as well as the one above

Ribs• Tubercle of rib

articulates with transverse process

• Ligaments secure rib to transverse process

• Note how the transverse processes of thoracic vertebrae are angled posteriorly

Pelvis (Dancing Bone)

Femur (Largest Bone in the Body)

The Tibia and Fibula

Metatarsals

Phalanges

Calcaneous