The Skeletal System Overview Bones (206) Joints (many, but concerned with about 20) Cartilage (covers joints) Ligaments (connects bones) Functions: Support the Body Protection for organs Produce red blood cells Storage for nutrients Provide sites for muscle attachments (so move) Classifications Long bones - support Short bones - facilitate movement Flat Bones - provide protection - produce RBC's Irregular Bones - help make connections between typical bones Round bones - ??? (Over time, the shape of our bones has deformed due to the necessity or lack of nececessity) Long Bones larger in legs due to stress (more calcium laid down) Short Bones predominantly in hands in feet facilitate movement by elasticity shock absorbtion Flat Bones skull, pelvis, scapula Gross Structure Long bones in extremities proximal vs. distal medial vs lateral Anatomy of Long Bone Periosteum - encloses the bone - fibrous connective tissue - contains blood vessels Epiphysis - expanded portion at the end - made of spongy bone - compact bone at the end Diaphysis - between the epiphysis's - made of compact bone Medullary Cavity - cavity in center of the bone - contains the yellow marrow Articular Cartilage - connection between bones * Intro to Joints: Will cover in greater detail at end of bones * Classification of Joints Synarthrodial - immoviable (slight movements for shock absorbtion) Amphiarthrodial - slight mobility (intervertebral) cartiliage disk between bones Diarthrodial - limited mobility (several types) Structure of diarthrodial joints (use overhead) Joint cavity: houses the synovial fluid (lubricates) provides space for movement Hyaline cartilage: protects bones from abrasion absorbs shock between bones Synovial Membrane: encapsulates the joint Articular Capsule: surrounds the articulation (helps keep it together) Ligaments: connect the bones Tendons: attach muscle to the bone Joints of The Skeletal System (overheads, p. 108) Ball and Socket Condyloid (ellipsoidal) Gliding Hinge Pivot Saddle Growth and Development Skeleton begins as cartilage in prenatal development At fetal age 2 months: - osteoblasts begin to deposit calcium (ossification) - first begins in the center of the long bones - called primary ossification points - ossification extends along the shaft - at birth, shaft is fully ossified Postnatal bone growth occurs at secondary ossification points - called "epiphyseal plates" or "growth plates" * The epiphyseal plate has four layers 1) Zone of resting cells - serves as reservoir for future growth 2) Proliferative zone - cartilage cells increase in size 3) Hypertrophic zone - cartilage cells arrange themselves in vertical columns 4) Calcified cartilage zone - cartilage cells erode and bone is deposited by osteoblasts Ossification of short bones ossify from the center outward At birth, about 400 ossification centers exist After birth, another 400 more develop After puberty, growth plates ossify and bone stops - evidence that excessive stress can cause premature ossification Bone is constantly being broken down (osteoclasts) - rebuilt again by osteoblasts - else, we could not recover from a broken bone Fractures Simple - bone does not pierce the skin Compound - bone does pierce the skin Incomplete - bone broken, but not into two seperate parts Greenstick - incomplete break, usually occuring in children (young bones) Impacted - bone is wedged into bone, usually longitudally Comminuted - broken into several pieces Spiral - resulting from torsion (twisting) Surface Features of Bone (Show overhead) General Bone Considerations (206) - Axial System - 80 Skull - 29 Thorax - 25 Ribs - 24 (12 pairs) Sternum - 1 (Manubrium, Body, & Xyphoid Process Fused) Vertebra - 26 Cervical - 7 Thoracic - 12 Lumbar - 5 Sacrum - 1 (fused together - text counts as 1) Coccyx - 1 (text counts as 1) Appendicular System - 126 Upper Right and Left Extremities - 32 ea. Shoulder Girdle to Phalanges Lower Right and Left Extremities - 31 ea. Pelvic Girdle to Phalanges The Axial System Skull (29 bones) - two main parts: cranium (8) * connected together by sutures (mostly immovable) - frontal bone - parietal bones (2) - occipital bone - temporal bones (2) - sphenoid bone (extends to outside of cranium - bat) - ethmoid bone (found inside orbit - butterfly) ** (use overhead, Hole p. 192, 193) facial bones (13) - contain sinuses (air spaces lined with mucous membrane) (use overhead - Hole p.195) paranasal - empty into nose maxillary frontal sphenoidal ethmoidal mastoid - drain into moddle ear - the bones (use overhead p. 92) maxillae (2) palatine (2) zygomatic (2) lacrimal (2) nasal (2) vomer (1) inferior nasal conchae (2) - three lesser parts (8) mandible (1) middle ear bones (6) malleus (2) incus (2) stapes (2) hyoid bone (1) - critical features use overhead (p 190) Vertebral Column Vertebra - 26 Cervical - 7 Thoracic - 12 Lumbar - 5 Sacrum - 1 (fused from 5 Sacral) Coccyx - 1 (fused from 4 Coccygeal) Thoracic cage (25) Ribs (24) sternum (1) fused from 3 (body, manubrium, and xyphoid process) Appendicular System 32 in upper limbs, 31 in lower (ea) Upper Limb Shoulder girdle (2) Scapula Clavicle Limb (3) Humerous Radius Ulna Wrist (8) Carpals Hand Metacarpals (5) Phalanges (5) Lower Limb Pelvic girdle (1) coxal bone Limb (4) Femur Tibia Fibula Patella Ankle (7) Tarsals Talus Calcaneous Navicular Cuboid Cuneforms (3) - medial - lateral - intermedius Foot (10) Metatarsals (5) Phalanges (5) More on Joints (continued from beginning of Bones) Had classified joints previously as to mobility - synarthrodial - no mobility (skull) - amparthrodial - limited (vertebra) - diarthrodial - freely movable (carpals) Can also classify as to type of tissue that binds together fibrous joints cartilaginous joints synovial joints Fibrous joints - found between bones that are in close contact - bones fastened by a thin layer of fibrous connective tissue - no appreciable movement occurs at these joints Three types: Syndesmosis - bound by long fibers of connective tissue - forms an interosseous ligament - CT is flexible, so joint may permit some movement (amparthridic) - found at distal ends of tibia and fibula (tibiofibular articulation) Suture - occur only between flat bones of the skull (synarthrodic) - bones grow together and unite by CT - sutural ligament - infantile skull contains gaps between bones (fontanels) Gomphosis - occurs whey cone shaped bony process meets a bony socket - example is the peglike root of a tooth fastened to the mandible - fastened by the periodontal ligament (synarthrodial) Carrilaginous Joints - connected by Hyaline cartilage or Fibrocartilage Two types: Synchondrosis - bones are united by bands of hyaline cartilage - many are temporary structures that disappear due to growth - between epiphysis and diaphysis - converts to cartilage near age 25 - also is present between sternum and first rib (permanent) - the other rib connections are synovial joints Symphysis - is springy fibrocartilage connecting bones - each bones hyaline cartilage connects to the fibrocartilage - this type of joint has limited mobility - especially under compression - seen between the bones in the vertebra - also seen between coxal bones (symphesis pubis) - some mobility (amparthridic) Synovial Joints - makes up most of the joints of the skeletal system - are freely movable (diarthridic) - except for bony and tissue restrictions, muscular and tendon ROM General Structure of diarthrodial joints (use overhead) Hyaline cartilage: covers the ends of the bone called "articular cartilage" protects bones from abrasion - near frictionless diffuses compression by transmitting to other bones Subchondral Plate: bone where articular cartilage lies is typically cancellous bone (somewhat elastic) also helps absorb shock Ligaments: connects the bones provides primary support Joint capsule: holds joint together is secondary support has two distinct layers inner = SM, outer = AC Articular Capsule: outer layer of tissue surrounds the articulation (helps keep it together) dense, white, fibrous tissue very flexible to permit large ROM's Synovial Membrane: encapsulates the joint is only a few cells thick surrounds a closed sac (synovial cavity) secretes/absorbs a clear viscous fluid (synovial fluid) - consistency similar to egg-white - fills the gaps in the joint - lubricates - usually present in very small amounts - knee is about 0.5 ml or less may store adipose tissue may form movable fatty pads within the joint Synovial Joints: may be seperated into compartments by fibrocartilate disks are called menisci (meniscus) attaches to fibrous layer of the joint capsule projects inward into the joint ex: knee - menisci help distribute weight onto the articulations may contain closed, fluid filled sacs (bursae) synovial fluid surrounded by a syn membrane provide additional fusioning found between skin and bony prominences ex: patella, olecranon process Types of synovial joints Ball and Socket - allows for the largest ROM - moves in all planes - rotates as well ex: hip and shoulder Condyloid (ellipsoidal) - condyle of one bone fits into elliptical cavity of another - permits a variety of movements - rotation is not possible - ex: knee, metacarpals, phalanges Gliding - bones are narly flat or slightly curved - permits sliding back and forth - ex: wrist, ankle, processes of adjacent vertebrae Hinge - convex surface of one bone fits into concave of another - permits movement in only one plane - ex: elbow Pivot - cylindrical surface of bone rotates within ring of another - ring may be formed by both bone and fibrous tissue - movement limited to rotation - ex: neck (side to side) proximal ends of radius and ulna (head of radius rotates in notch, notch is from ulna and annular ligament) Saddle - formed by bones with both concave and convex regions - permits a variety of movements - ex: articulation between trapezium and first metacarpal Types of Joint movements: flexion extension hyperextension dorsiflexion plantarflexion abduction adduction rotation circumduction - end follows a circular path (finger) supination pronation eversion inversion protraction retraction elevation depression Examples of Joints The Shoulder Girdle Bones: Scapula Clavivle Articulations: Sternoclavicular sternum (manubrium) and clavicle provides most of the movement of the shoulder girdle weak because of no bony landmarks Acromioclavicular scapula (acromium process) and clavicle absorbes shock of shoulder impact weak because of no bony landmarks Coracoclavicular clavicle to sternum (coracoid process) supports the acromioclavicular (AC) joint may buffer rotator cuff tendons (rotation of humerous in throwing, striking) Shoulder Joint Bones: Scapula Humerous Articulation: Glenoid Fossa and Head of the Humerous Half of humerous is out of the socket, the bony arrangement is weak Ligaments: Coracohumeral: Stabilizes the humerous against upward and lateral displacement Glenohumeral Ligaments: (superior, middle, inferior) Stabilizes against forward displacement Elbow Bones: Humerous Radius Ulna Articulations: Ulna (Olecranon process) and Humerus (trochlea) Ligaments: Annular attaches radius to ulna Radial Collateral prevents adduction Ulnar Collateral prevents abduction Hip Bones: Pelvis Femur Articulation: Pelvis (Acetabulum) and Femur (Head) Deep socket, so fairly strong Angled slightly to anterior; providing support against posterior movement Ligaments: Anterior displacement: Iliofemoral (Y) Ilium (above acetabulum) to greater AND lesser trochanters Strongest ligament in the body Pubofemoral Pubic bone to lesser trochanter Posterior displacement Ischiofemoral Ischium to greater trochanter Additional Ligamentum teres Attaches inside socket, acetabulum to head of femur Knee Joint Bones: Femur Tibia Articulations: Femur (condyles) and Tibia (condyles) Meniscii (medial and lateral) between bones Ligaments: (many, know these) Medial Collateral Lateral Collateral Anterior Cruciate Posterior Cruciate Popliteal Patellar Quadriceps Motions: Flexion / Extension Gliding / Sliding (as knee flex's / extends) 90 degrees is where maximum sliding has occurred probably occurs as a cusion / absorbtion