Skeletal System

Fidya, drg, M.Si

Part of Skeletal System

• Skeleton • Cartilages• Ligaments• Joint

Consist of :• Birth skeletal 270• Adult skeletal 207/206

Why different?

Function of Skeletal

• Support• Storage of minerals• Blood cell production• Protection• Body movement

FUNCTIONS OF THE SKELETON

• Supports the body.– The bones of the lower limbs

support the entire body when we are standing, and the pelvic girdle supports the the abdominal cavity

• Protects soft body part– The bones of the skull protect the

brain; The rib cage protects the heart and lungs.

• Produces blood cells– All bones in the fetus have red

bone marrow that produces blood cells. In the adult, only certain bones produce blood cells.

• Stores minerals and fat– All bones have a matrix that contains calcium

phosphate, a source of calcium ions and phosphate ions in the blood. Fat is stored in yellow bone marrow

• Along with the muscles, permits flexible body movement– While articulations ( joints ) occur between all

the bones, we associate body movement in particular with the bones of the limbs

Skeletal System

Divide into 2 division:• Axial skeleton• Appendicular skeleton

Skeletal System

Axial Skeleton

• Skull• Hyoid Bone• Auditory ossicle• Vertebral Column• Rib cage

Appendicular skeleton

• Pectoral gridle• Upper extremitas• Pelvic gridle• Lower extremitas

SkullConsist of:

Cranial bone (8)• frontal (1)• parietal (2)• occipital (1)• temporal (2)• sphenoid (1)• ethmoid (1)

Facial bone (14)• maxilla (2)• palatine (2)• zygomatic (2)• lacrimal (2)• nasal (2)• vomer (1)• inferior nasal concha (2)• mandible (1)

Mandible

• Forms the lower jaw

• Largest, strongest bone of the face

• It has a body and two upwardly projecting sections called rami

• Houses lower dentition

Hyoid Bones

• The hyoid bone above the larynx below the

mandible

• Supports the tongue • Assists in swallowing

Os Hyoid

• Unique part of the skeleton not attach directly to any other bone.

• Located: the neck region, below the mandible. Suspended from the styloid process of the temporal bone by the stylohyoid muscles and ligaments.

• Has a body, two lesser cornua extending anteriorly, and two greater cornua, which project posteriorly to the stylohyoid ligaments.

• Supports the tongue and provides attachment for some of its muscles.

• It may be palpated by placing a thumb and a finger on either side of the upper neck under the lateral portions of the mandible and firmly squeezing medially.

In case: Fracture Hyoid

• This bone is carefully examined in an autopsy when strangulation is suspected, because it is frequently fractured during strangulation.

• However, this is not necessarily the case in children and adolescents, where the hyoid bone is still flexible as ossification is yet to be completed

Auditory ossicle

• Three small paired bones, called auditory ossicles

• Located within the middle-ear cavities in the petrous part of the temporal bones.

• From outer to inner, the malleus (“hammer”), incus (“anvil”), and stapes (“stirrup”).

• Their movements transmit sound impulses through the middle-ear

Vertebral Column

• Composed of 33 individual vertebrae, some of which are fused.• Consist of 7 cervical, 12 thoracic, 5 lumbar, 4 to 5 fused sacral,

and 3 or 5 fused coccygeal• Adult vertebral column composed of a total of 26 movable parts. • Vertebrae are separated by fibrocartilaginous intervertebral discs.• Secured to each other by interlocking processes and binding

ligaments.• Between the vertebrae are openings called intervertebral foramina

that allow passage of spinal nerves.

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 ArticularProcess

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 Vertebrae is

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

Sacralpromontory

Ala

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

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

Rib Cage

• The cone-shaped, flexible rib cage, consists of the thoracic vertebrae,

• 12 paired ribs, costal cartilages, and the sternum.

• Encloses and protects the thoracic viscera • Directly involved in the mechanics of

breathing.

Pectoral Gridle

• Two scapulae and two clavicles• having only an anterior attachment to the axial

skeleton sternoclavicular joint at the sternum. • Lacking a posterior attachment to the axial skeleton, the

pectoral girdle has a wide range of movement.• Function:

- To provide attachment areas for the numerous muscles that move the shoulder and elbow joints.

Claviculae

• Lies almost horizontally on each side of the neck, extending from the sternum to the acromion of the scapula

Scapulae

Upper Extremitas

• Brachium : - Humerus• Antebrachium: - Radius

- Ulna• Manus: - Carpus

- Metacarpus

- Phalanges

The humerus

is the longest and largest bone of the upper limb. It extends from the scapula to the elbow joint and has a body and two ends

The bones of forearmThe radiusThe radius is the lateral bone of the two in the forearm. It has a shaft and two ends.

The proximal endA head, neck and tuberosity;head is disc-shaped and its upper surface is a shallow cup—articular fovea for articulation with the capitulum of the humerus. Its articular circumference articulates with radial notch of the ulna.

Shaft of radius: interosseous border

Distal endUlnar notch, styloid process, carpal articular surface

The bones of hand

• Three parts: the carpal bones, the metacarpal bones and phalanges

• The carpal bones• There are eight short bones, arranged in

two rows of four• Proximal row from lateral to medial

include:• Distal row from lateral to medial include:

Pelvic Gridle

• Formed by two ossa coxae. together with sacrum and coccyx pelvis

• United anteriorly at the symphysis pubis• Attached posteriorly to the sacrum of the vertebral

column. • Function:

- support the weight of the body from the vertebral column (with assosiated ligament)

- supports and protects the lower viscera, (urinary bladder, reproductive organs, developing fetus)

Lower Extermitas

• The lower limb which is similar to the upper, is connected to the trunk by a girdle, the pelvix girdle, the free lower limb is divided into three segements, the thigh, the leg and the foot.

• Femoralis• Genu • Crus : - Tibia

- Fibula• Pes

Femoralis

Genu

Crus

Pes

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