Skeletal System Notes PDF

SKELETAL SYSTEM INTRODUCTION/DIVISIOS OF THE SKELETAL SYSTEM Adult human skeleton consists of 206 named bones, most of which are paired. At birth, human skeleton is at least 270, most of it are cartilage and are unfused. Bones of adult skeleton are g...

SKELETAL SYSTEM INTRODUCTION/DIVISIOS OF THE SKELETAL SYSTEM Adult human skeleton consists of 206 named bones, most of which are paired. At birth, human skeleton is at least 270, most of it are cartilage and are unfused. Bones of adult skeleton are grouped into 2 principal divisions: o AXIAL – along the longitudinal axis/vertical line that runs through the body’s center of gravity from the head to space of both feet. APPENDICULAR SKELETON o APPENDICULAR – consists of Pectoral girdle bones of the upper and lower o Clavicle – 2 limbs + bones forming the girdles o Scapula – 2 that connect the limbs to the Upper limbs axial skeleton o Humerus – 2 ▪ **Functionally, auditory o Ulna – 2 ossicles in the middle ear o Radius – 2 are not part of either axial o Carpals – 16 or appendicular skeleton o Metacarpals – 10 but are grouped with axial o Phalanges – 28 skeleton for convenience. Pelvic girdle AXIAL SKELETON o Hip/pelvic/Coxal bone – 1 Skull Lower limbs o Cranium – 8 o Femur – 2 o Face – 14 o Patella – 1 Hyoid bone – 1 o Fibula – 2 Auditory ossicles – 6 o Tibia – 2 Vertebral column – 26 o Tarsals – 14 o Metatarsals – 10 Thorax o Phalanges – 28 o Sternum – 1 o Ribs – 24  SUTURAL BONES – classified by location rather than shape. Are small bones located in sutures (joints) between certain cranial bones. TYPES OF BONES LONG BONES – greater length than widths, has shaft or epiphysis (end), slightly curved for strength. o Femur, tibia, fibula, humerus, AXIAL SKELETON ulna, radius, phalanges SHORT BONES – somewhat cube- SKULL shaped and are nearly equal in length The bony framework of the head that and width contains 22 bones (excluding bones of o Carpals, tarsals middles ears) and rests on the superior FLAT BONES – generally thin and end of the vertebral column. composed of 2 nearly parallel plates of 2 categories: compact bone. For protection and o CRANIAL BONE (8) – forms the extensive muscle attachment. cranial cavity that encloses and o Cranial bones, sternum, ribs, protects the brain scapula ▪ Frontal bon, 2 parietal IRREGULAR BONES – have complex bone, 2 temporal bone, shapes and cannot be grouped into any occipital bone, sphenoid category and ethmoid bone o Vertebrae, hip bones, certain o FACIAL BONES (14) – 2 nasal facial bones, calcaneus bones, 2 maxillae, 2 zygomatic SESAMOID BONES – develop in certain bone, 2 lacrimal bones, the tendon where there is considerable mandible, 2 palatine bones, 2 friction, tension, and physical stress inferior nasal conchae, and the such as palms and soles vomer o Patella CRANIAL BONES medial to the orbit, anterior to sphenoid and posterior to nasal bones. FRONTAL BONE Nasal septum – divides nasal cavity Forms the forehead, the roofs of the into R and L orbits, and most of the anterior parts of Cribriform plate – anterior floor and the cranial floor. forms roof of nasal cavity Soon after birth, L and R sides of frontal bone are united by the metopic suture, which usually disappears between the ages of 6 and 8 PARIETAL BONE Form the greater portion of the sides and roof of the cranial cavity The inner surface of the parietal bones contains many protrusions depressions that accommodate the blood vessels supplying the dura mater, the superficial connective tissue (meninx) covering the brain. OCCIPITAL BONE Posterior part and most of the base of the cranium TEMPORAL BONE Form the inferior lateral aspects of the cranium and part of the cranial floor Temporomandibular joint – mandibular fossa + articular tubercle articulates (forms a joint) with mandible **Mastoiditis – a painful inflammation caused by middle ear infection that was left untreated that spread into the mastoid air cells. SPHENOID BONE FACIAL BONES Wedge-shaped lies at the middle part of the skull. NASAL BONE Keystone of the cranial floor – Paired, small flattened rectangular articulates with all other cranial bones shaped bone that forms the bridge of the nose ETHMOID BONE Protect the upper entry to nasal cavity Delicate bone with spongy-like appearance, anterior to the cranial floor, LACRIMAL BONE SUTURES Paired, thin, smallest bone of the face, posterior and lateral to the nasal bone Is an immovable join that holds most Lacrimal fossa – vertical tunnel that skull bones together houses the lacrimal sac (gathers tears 4 prominent sutures: and passes to nasal cavity) 1. Coronal suture - frontal bone + parietal bone PALATINE BONE o Bregma – junction of coronal and 2 L-shaped bone forms posterior portion sagittal suture of hard palate `` 2. Sagittal suture – 2 parietal bones (fontanels, soft spots) INFERIOR NASAL CONCHA 3. Lambdoid suture – 2 parietal + Inferior to middle nasal concha, not part occipital of ethmoid bone o Lambda – junction of sagittal and occipital suture VOMER 4. 2 squamous sutures – 2 parietal + Triangular bone on floor of nasal cavity. temporal Forms the inferior portion of bony nasal septum MAXILLAE Upper bone jaw, part of cranium Hard palate – bony roof of the mouth, separates nasal cavity from the oral cavity Infraorbital foramen – passage for infraorbital blood vessels and nerve, maxillary division of trigeminal nerve ZYGOMATIC BONE FONTANELS Cheekbones, temporal process projects posteriorly and articulates with Fontanels – incompletely developed zygomatic process that forms cranial bones. Seres as a spacers for zygomatic arch growth of neighboring skull bones and provide some flexibility to the fetal skull, MANDIBLE allowing skull to change shape as it Lower jawbone, largest and strongest passes the birth canal facial bone Form and location of 6 fontanels: Temporomandibular joint – condylar process articulates with mandibular 1. Unpaired anterior fontanel – largest fossa and articular tubercle of temporal roughly a diamond shape, located at bone. midline along 2 parietal bone and frontal bone. Closes 18-24 months after birth -4TH  2. Unpaired posterior fontanel – smaller than anterior fontanel, located midline between 2 parietal bone and occipital bone. Closes about 2 months after birth -1ST 3. Paired anterolateral fontanels/sphenoid fontanels – small and irregular, located among frontal, parietal, temporal and sphenoid bones. Closes 3 months after birth – 2ND 4. Paired posterolateral fontanels/mastoid fontanel – irregular shape, located laterally among temporal, parietal, and occipital bone, Begins to close 1-2 months after birth, closure generally not complete until 12 AUDITORY OSSICLES months – 3RD Malleus, incus, and stapes – are three small bones in the middle ear that transmit air vibrations from the outer ear into the inner ear, so they can be processed as sound. They are named after their resemblance to a hammer, anvil, and stirrup, respectively. Malleus – outermost Incus – middle Stapes – innermost HYOID BONE Single, U-shaped bone, it does not articulate with any other bone Supports tongue, provides attachment for muscle of neck and pharynx Located anterior to the neck between mandible and larynx ** hyoid bone, cartilages of larynx and trachea are often fractured in strangulation VERTEBRAL COLUMN Thoracic and sacrum – concave/cupping in Aka spine, back bone, spinal column, Curves increases strength of spine and makes 2/5 of your height, composed of helps maintain balance in upright series of bones called vertebrae position, absorbs shocks during Consists of bone and connective tissue walking/running and help protect that surrounds and protects the spinal vertebrae from fracture cord that is consist of nervous and Single curve in fetus – single anterior connective tissue concave curve About 71 cm/28 inches in average adult o 3rd month after birth – infant male and about 61 cm/24 inches in begins to hold head -anterior average adult female convex cervical curve develops Strong flexible rods that can move o When child sits up =, stands, or APLRot walk – anteriorly convex lumbar Contains 26 vertebrae: curve develops 1. 7 cervical vertebra o Thoracic and sacral curves – 2. 12 thoracic vertebrae primary curves, they retain the 3. 5 lumbar vertebrae original embryonic curvature 4. 1 sacrum (consist of 5 fused sacral o Cervical and lumbar curves – vertebrae secondary curves, they form 5. 1 coccyx (consist of 4 fused later, several month after birth coccygeal vertebrae) All curves are fully developed by age 10. However, secondary curves may be progressively lost in old age (increase kyphosis/osteoporosis) NORMAL CURVES OF VERTEBRAL COLUMN Normally there are 4 curves in adult, seen in lateral view Cervical and lumbar – convex/ bulging out forward THORAX 11th and 12th rib, aka floating ribs – does not attached to the sternum Refers to the entire chest region Thoracic cage – sternum, ribs and their VERTEBRAL REGIONS costal cartilages and bodies of the thoracic vertebrae CERVICAL VERTEBRAE Atlas/C1 – top of the cervical vertebrae, STERNUM/Breastbone inferior to the base of the skull. Has no A flat, narrow at the center of anterior body and spinous process, allows chest, 15cm/6 inches in length motion ‘yes’ Has 3 parts: (typically fused by age 25) Axis/C2 – has dens/odontoid process 1. Manubrium – uppermost which allows the atlas to rotate, allows 2. Body – largest and middle part motion ‘no’ 3. Xiphoid process – smallest and Vertebra prominence/C7 – has the inferior part, consists of hyaline longest and largest non-bifid spinous cartilage during infancy and childhood process on the cervical vertebra and does not completely ossify until age 40 LUMBAR VERTEBRAE Largest and strongest unfused THORACIC BONE bones RIBS SACRUM 12 pairs Triangular bone formed by union of 5 Rib 1-7 aka true/vertebrosternal ribs, sacral bon have direct attachment to the sternum by hyaline cartilage – costal cartilage COCCYX Rib 8-12 aka false/vertebrochondral Triangular in shaped, formed by ribs, because their costal cartilage is union of 4 coccygeal bone either attached indirectly to the sternum or not attached at all. Cartilages of 8th, 9th, 10th pairs or rib attach to one another and then to the cartilage of 7th rib  UPPER EXTREMITY Has 30 bones in 3 location: (1 side only, 60 for both sides) 1. Humerus in arm (1), + scapula = glenohumeral joint 2. Radius and ulna on forearm 3. Carpals (8), metacarpals (5) and phalanges (14) on wrist and hand APPENDICULAR SKELETON PECTORAL/SHOULDER GIRDLE Attaches the bones of upper limbs to the axial skeleton Pectoral girdle does not articulate with axial skeleton, it is hold by group of large muscle o Clavicle + sternum = sternoclavicular joint ▪ S-shaped bone, medial half is convex anteriorly, lateral half is concave anteriorly HUMERUS ▪ Most frequent fractured bone in the body ▪ Clavicular mid region – weakest point/midpoint/junctio n ULNA Located on the medial aspect, is longer than radius “pak u” – Pinky on the Ulnar side Olecranon – elbow Trochlear notch – forms elbow with olecranon and coronoid fossa (part of humerus)  On the medial side, trochlea + coronoid o Triquetrum – three cornered process (ant), olecranon (post) o Pisiform – pea shaped Distal row: o Trapezium – 4-sided figure with no 2 sides parallel o Trapezoid – 4-sided figure with 2 sides parallel o Capitate – head shaped o Hamate – hooked RADIUS Smaller bone of the forearm, located on the lateral side Proximal radioulnar joint – radial notch + head of radius Distal radioulnar joint – head of ulna + ulnar notch Allows forearm pronation and supination METACARPALS, PHALANGES/PHALANX/DIGIT Metacarpals – longest bone on hand Proximal phalanges Middle phalanges Distal phalanges Thum – pollex, has 2 phalanges CARPALS Aka wrist, proximal region of hand Intercarpal joint – articulation between carpals Proximal row: o Scaphoid – boat like o Lunate – moon shaped PELVIC GIRDLE LOWER EXTREMITIES Consists of 2 hip bone/Coxal Has 40 bones in 4 locations: bone/pelvic bone aka os coxa 1. Femur in the thigh Sacroiliac joint – posteriorly 2. Patella Pubic symphysis – anteriorly, 3. Tibia and fibula on lower leg fibrocartilage disc 4. 7 tarsals on ankle 3 parts 5. 5 metatarsal and 14 phalanges on 1. Ilium – superiorly, largest foot 2. Ischium – posteroinferior 3. Pubis – anteroinferior FALSE AND TRUE PELVIS False (greater pelvis) – portion of the FEMUR bony pelvis superior to the pelvic brim Aka thigh bone, longest, heaviest and True (lesser) pelvis – bony pelvis strongest bone in the body inferior to the pelvic brim PATELLA TARSAL Aka kneecap, a small, triangular bone Proximal region of the foot – 7 bones located anterior to the knee joint 1. Talus (talus + calcaneus = heel) Base – broad proximal end, which 2. Calcaneus – largest and strongest develops in the tendon of the 3. Navicular – little boat quadriceps femoris muscle 4. 3 cuneiform – wedge-shaped Apex – pointed distal part (medial, intermediate, lateral) 2 articular facets – on the posterior 5. Cuboid – cube-shaped surface for medial and lateral condyles of femur TIBIA Aka shin bone, larger, medial, weight bearing bone of the leg ** tibia mean flute – it is used to make musical instrument on ancient times Helps stabilize the knee joint FIBULA ARCHES OF THE FOOT Parallel and lateral to the tibia, but small Longitudinal arch “fibula is Lateral” Transverse arch Helps stabilize the ankle joint Lateral malleolus – distal lateral aspect  ARTICULAR SYSTEM/JOINTS CARTILAGINOUS JOINTS Characterized by solid hyaline cartilage JOINTS or fibrous cartilage Aka articulation or arthrosis – points of Movements range from immovable to contact between 2 bones, bone and slightly movable cartilage or bone and teeth 2 subtypes: synchondroses and Arthrology – study of joints symphyses Kinesiology – study of motion o Synchondroses - a cartilaginous 3 classifications: joint in which the connecting 1. Fibrous joint material is a solid piece of 2. Cartilaginous joint cartilage that allows little or no 3. Synovial joint movement (1st rib and manubrium of sternum) FIBROUS JOINTS ▪ Epiphyseal cartilage - Characterized by dense irregular hyaline cartilage growth connective tissue (collagen fibers) centers during Movements varies from immovable to endochondral bone slightly movable formation, not joints 2 sub types: sutures and syndesmoses associated with o Sutures – thin layer of dense movements (epiphyseal irregular connective tissue, plate) occurs only on the skull o Symphyses - a cartilaginous joint in o Syndesmosis – has greater which the ends of the articulating articulating surface and more bones are covered with hyaline dense connective tissue than in a cartilage, but a broad, flat disc of suture fibrous cartilage connects the bones ▪ Interosseous ligament (pubic symphysis) (AnTiFi) and interosseous membrane (radioulna)– permits limited movement SYNOVIAL JOINTS Characterized by presence of a space between the articulating bones called articular cavity. Movements range from slightly movable to slightly moveable Bones are covered with hyaline cartilage, but a broad, flat disc of fibrous cartilage connects the bones (pubic symphysis)  Articular cartilage – a hyaline cartilage 3. PIVOT/trochoid joint that reduces friction between bones in rounded or pointed surface of one bone joint during movement and helps articulates with a ring formed partly by absorbs shock another bone and partly by a ligament. Articular capsule – encloses the Uniaxial. articular cavity Example: atlanto-axial joint “no”, Synovial fluid - reducing friction by radioulnar joint lubricating the joint, absorbing shocks 4. ELLIPSOID/condylar joint the convex oval-shaped projection of one bone fits into the oval-shaped depression of another bone. Biaxial Example: radiocarpal, MCP TYPES OF SYNOVIAL JOINTS 5. SADDLE/sellar joint the articular surface of one bone is 1. PLANE/arthrodial joint saddle-shaped, and the articular are flat or slightly curved. Biaxial, surface of the other bone fits into the triaxial/multiaxial “saddle” as a sitting rider would sit. primarily permit back-and forth and Biaxial plus limited circumduction side-to-side movements between the Example: CMC, sternoclavicular joint flat surfaces of bones, but they may also 6. BALL AND SOCKET/spheroidal joint rotate against one another consists of the ball-like surface of one Example: intercarpal joint, sternocostal bone fitting into a cuplike depression of joints another bone. Triaxial 2. HINGE Example: glenohumeral joint, hip joint convex surface of one bone fits into the concave surface of another bone convex surface of one bone fits into the concave surface of another bone Example: elbow, ankle TEMPOROMANDIBULAR JOINT combined hinge and plane joint formed by the condylar process of the mandible and the mandibular fossa and articular tubercle of the temporal bone. only freely movable joint between skull bones (with the exception of the ear ossicles) Movements: depression/jaw opening, elevation/jaw closing, protraction, retraction and lateral displacement