Anatomical Basis of Dentistry
-
Upload
rabkacicie -
Category
Documents
-
view
8 -
download
1
description
Transcript of Anatomical Basis of Dentistry
Anatomical Basis of Dentistry: Intro to Musculoskeletal system
Chapter 1.3, 1.4. 1.5
-O-
Cartilage
• Supporting connective tissue
• Consists of cells (chondroblast chondrocytes) contained within a ground substance of a rigid gel
• No neurovascular element within nutrients diffuse through ground substance
• Fetal skeleton is mostly cartilage, replaced by bone subsequently
• Growth: internal growth (from inside) & appositional growth (from surface)
Cartilage: types
• Hyaline (hyalos = glass). Gross: bluish white, translucent. Found in fetal skeleton, articular cartilage, costal cartilage, respiratory cartilages, auditory cartilages
• Elastic cartilage. Gross: yellowish because of the elastin fibers. Found in the external ear and in the epiglottis
• Fibrocartilage: more collagen fibers. It is found in tendon insertions and the intervertebral discs
Bone
• Living tissue
• Consisting of cells (osteoblasts osteocytes) within an organic framework (matrix)
• Bone matrix is calcified (unlike cartilages)
• Calcification prevents diffusion of nutrients direct vascular supply is needed
• Growth: internal growth not possible only appositional through periosteum
Bone: functions
• Support: rigid framework of the body
• Movement: act as levers for muscles
• Protection: the brain and thoracic viscera are protected
• Hemopoiesis: within the marrow space of bone
• Storage: for calcium and phosphorus
Bone classification
By Region:
• Axial: skull-vertebrae-costae-sternum
• Appendicular: bones of the upper and lower limbs
By shape:
• Long bones: • hollow tubes/shafts/diaphysis capped at both ends by epiphysis
• Cross section: (1) outer compact layer, (2) inner cancellous/spongy layer of trabeculated bone, (3) marrow space containing blood-forming tissue or fats
• Blood supply: (1) nutrient arteries, (2) periosteal arteries, (3) epiphyseal arteries
By shape (continued):
• Short bones: cuboidal not tubular carpal bones, tarsal bones
• Flat bones: thin and flat, sandwich of 2 layers of compact bone and a cancellous layer (diploe) in between skull, scapula
• Irregular bones: bones that fit none of the previous description maxilla, lacrimal, etc
• Sesamoid bones: grow within a tendon patella (largest sesamoid)
Bone: surface features
• The surface of individual bones is marked by features that reflect• Attachment of muscles and ligaments raised areas
• Passage of nerves and vessels openings, depressions
• Articulation with other bones joint surface, either raised or depressed
• Elevations: condyle, epicondyle, process, plate, tubercle, tuberosity, trochanter, malleus, crest, linea, spine
• Depressions: fossa, sulcus, notch/incisura
• Spaces: foramen, canal, fissure
Joints
• Articulation or union between two or more bones
• By the degree of movement:• Synarthroidal: NO movement
• Amphiarthroidal: SOME movement
• Diarthroidal: FREE movement
• By the joint tissue: fibrous connective tissue, cartilage, combo connective + cartilage, combo cartilage + joint cavity
Fibrous joints
• 3 types: Suture, Syndesmosis, gomphosis
• Sutures: • only between bones of the skull. Fetal amphiarthrodial adult synarthodial
• Squamous, serrated, denticulate
• Syndesmosis: amphiarthrodial, united by fibrous interosseous membrane
• Gomphosis: peg-and-socket articulation between the roots of the teeth and the alveolar processes, united by the fibrous periodontal ligament. Normally NO mobility.
cartilaginous joints
Primary cartilaginous joints (synchondroses)
• Develop between 2 bones od endochondral origin
• Solid plate of hyaline cartilage between apposing surfaces
• E.g. sphenooccipital synchondrosis
Secondary cartilaginous joints (symphysis)
• Amphiarthordial
• Apposing bony surfaces are covered with cartilage but separated by fibrous/fibrocartilage
• E.g. Intervertebral discs, symphysis pubis, symphysis menti
Synovial joints
• Freely movable (diarhtrodial)
Characteristic:
• Articular cartilage: hyaline, fibrocartilage. No blood vessels
• Joint cavity: between the articular surfaces, contains thin synovial fluid
• Capsular ligament: surrounds the joint,
• synovial membrane: lining the internal surface of the capsule, but not the articular cartilage
• Disc: not always present, if present it divides the joint cavity to compartments in Temporomandibular joint
Synovial joints: Axes
• Multiaxial joints: 3 planes• Ball-and-socket joint
• Saddle/ellipsoid joint
• Biaxial joints: 2 planes (no rotation)• Condyloid joint
• Uniaxial joints: 1 plane• Plane joint
• Hinge joint (ginglymus)
• Pivot joint
Skeletal Muscles
• Skeletal attached to bones, span joints, move one bone in relation to another
• Mostly under voluntary control
• Striated from the histological sections
Skeletal muscles: nomenclature
• Indicating the shape: (e.g. deltoid, trapezius)
• Indicating the number of origins (e.g. triceps, biceps)
• Indicating the location (e.g. temporalis, brachialis)
• Indicating the number of bellies (e.g. digastricus)
• Indicating the function: (e.g. levator veli palatini, tensor tympani)
• Indicating the origin and insertion (e.g. thyrohyoid)
Skeletal muscles: parts
Fleshy portion/Venter
• Contains muscle fibers
• Muscle fibers/cells-fasiculus-muscles-group of muscles/compartment
• Endomysium-perimysium-epimysium-intermuscular septa
Tendinous portion: attaching part of the muscle
• Cylindrical tendons
• Linear tendon
• Aponeurosis
• Common tendon
Skeletal muscles: origin and insertion
• Origin: proximal end of a muscle
• Insertion: the distal end of a muscle
• In movements, the insertion moves toward the stationary origin as the muscle contracts
• Technically, origins and insertions can be interchanged
Skeletal muscles: architecture
• The arrangement of the muscle fiber bundles/fasciculi
• Parallel and converging fibers (no interruption of the fasciculi from origin to insertion for the range of movement): • rectangular muscles, triangular muscles, fusiform muscles
• Pennate muscles (central tendon with obliquely arranged muscle bundles for power): • unipennate, bipennate, multipennate
• Sphincter muscles (circular muscles encircle openings, where contraction closes the opening)
Skeletal muscles: Actions
• Types of contraction: • Isotonic (same tone) produce actual movement• Isometric (same length) no movement
• Action of muscle groups• Prime movers: Muscles that are controlled by pyramidal system and are used
to initiate a particular movement• Antagonist: muscles that produce movement in the opposite direction of the
prime movers. • Synergists: muscles that are controlled by extrapyramidal system to refine the
movement of the prime movers• Fixators: indirectly involved in the movement by stabilizing the body.