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Chapter 3 Objective: Describe the functions of the musculoskeletal system. Introduction - The skeleton has 3 divisions 1. axial skeleton - bones that lie around the body’s center of gravity (skull, vertebrae, hyoid apparatus, ribs, sternum 2. appendicular skeleton - bones of the limbs 3. visceral skeleton - bones that form in soft organs (os penis, os cordis, os rostra) Bones have the following five functions: 1. form/structure - bones help define the shape and appearance of animals 2. protection - certain bones have critical roles in protection such as the skull and ribs 3. mineral storage - primary storage site for calcium and phosphorus 4. blood formation - marrow cavities of bones produce both red and white blood cells 5. leverage (mobility) - muscles work with bones to enable movement Objective: Detail the structure of bone. There are three types of bone cells: 1. Osteoblasts - cells that actively produce bone. They are destined to become... 2. Osteocytes - maintains bone matrix 3. Osteoclasts - cells that tear down bone so it can be rebuilt; active in formation of bone marrow cavities and spaces Types of bones: classified according to shape and structure 1. Long bones - longer than wide. Has central marrow cavity and distal and proximal epiphysis. (Femur) 2. Short bones - long as they are wide. (carpals and tarsals) 3. Flat bones - two plates of compact bone with spongy bone between. No marrow cavity. (pelvic bones, skull bones, ribs) 4. Irregular bones - odd shaped bones. (vertebrae) 5. Pneumatic bones - contain air spaces. (avian species) Anatomy of bones: Define the following terms. Articular Projections headcondyletrochleaNon-Articular Projections processtuberositytubercletrochanter- epicondylespinecrestDepressions cavitiesnotchfacetfoveafossaforamencanalParts of the Long Bone Diaphysis - the shaft of the bone (compact bone, central medullary canal, and spongy bone at the proximal and distal ends) epiphyses - proximal and distal ends of the bone (thin outer layer of compact bone with centers of spongy bone) metaphyses - regions in mature bone where diaphysis joins the epiphyses Objective - List two major sections of skeleton, name the corresponding bones, and outline species differentiation. Axial Skeletal System Cranium - combines numerous flat bones Temporal Frontal Nasal Parietal Occipital Zygomatic Arch Sphenoid Incisive Maxilla Mandible Nuchal crest Vertebral Column (feline) Cervical - 7 vertebrae (c1 = atlas, c2 = axis) Thoracic - 13 vertebrae Lumbar - 7 vertebrae Sacrum - 3 vertebrae; fused Coccygeal (Caudal) - variable depending on breed Ribs - head, neck, tubercle, shaft, costal cartilage Sternum - xiphiod cartilage, xiphoid process Appendicular Skeletal System Clavicle Collarbone; attaches to scapula in felines Not articulated with other bones in canines/may be missing. Large animals have only cartilage. Scapula Shoulder blade; large triangular bone Acromion process Humerus long bone extending from shoulder to elbow Head, greater and lesser tubercles, medial and lateral epicondyles, trochlea Ulna Caudal long bone of forelimb. Forms elbow joint by articulating with humerus. Fused with radius in equines. Trochlear notch, olecranon, lateral styloid process Radius Cranial long bone of forelimb. Head, radial tuberosity, medial styloid process Carpus Numerous irregularly shaped bones. Human wrist = animal knee. Metacarpals Articulate carpus with phalanges. Numbered from medial to lateral. Splint bones and cannon bone in equines. Phalanges (digits) Normally 3 phalanges in each digit. Digits numbered from medial to lateral. (roman numerals) Phalanges numbered from proximal to distal. (numbers) Canine = 5 digits Cloven hoof = two digits Equine = 1 digit with 3 phalanges Joint between cannon bone and first digit = fetlock Phalanx 1 = pastern bone Phalanx 2 = short pastern bone Phalanx 3 = coffin bone Pelvis Three pairs of fused bones Connects to the sacrum and coccygeal vertebrae Supports caudal half of body Attachment for hind limbs at hip joint Ilium - largest pair; flares to side Ischium - strongest and most caudal pair Pubis - most ventral pair Acetabulum Hip socket; articulates with end of femur Femur Proximal long bone of hind leg Longest bone in the body Head, neck, greater and lesser trochanter, medial and lateral condyle Patella Flat bone that glides over stifle joint Kneecap in humans Tibia Larger, more weight bearing bone of distal hind limb medial and lateral condyles, medial malleolus Fibula Long slender bone of lower hind limb Does not articulate at distal end in some species (horses) Head, shaft, lateral malleolus Tarsus Numerous irregularly shaped bones arranged in rows Human ankle Hock in animals Metatarsals Articulate tarsals with phalanges Phalanges (digits) Same as forelimb Objective - Name the joint types and the role in movement arthrology - study of joints Types of joints 1. fibrous - fixed joints that are brought together with dense connective tissue; skull 2. cartilage - bones that are connected directly with cartilage; growth plates 3. synovial - true joints; layer of bone covered with cartilage and enclosed in a capsule; elbow joint a. costochondral junction b. temporomandibular joint c. scapulohumeral joint d. humeroradioulnar joint e. carpal joint f. fetlock joint (equines)g. pastern joint (equines)h. coffin joint (equines)i. sacroiliac joint j. coxofemoral jointk. femorotibial jointl. tarsal jointm. tibiotarsal jointdesmology - study of ligaments a. nuchal ligamentb. cruciate ligamentsc. suspensory ligament- Myology - study of muscles allows movement in conjunction with bones over 600 muscles in the body help produce body heat form some internal organs (heart) Allied Muscular Structures tendons - strong, fibrous white bands that attach muscles to bones fascia - sheets of fibrous membrane that encloses muscles/separates groups ligaments - strong bands of fibrous tissue connecting bone to bone origin - fixed/less movable point of attachment to bone insertion - movable point of attachment to bone Muscle Composition myofibers - cells of muscle tissue sarcolemma - plasma membrane of a muscle cell sarcoplasm - cytoplasm of muscle cell Classification skeletal - voluntary muscles that are striated (striped); tongue, biceps smooth - involuntary muscles that are not striated; stomach, uterus cardiac - heart muscle; involuntary and striated Movement abduction - movement away adduction - movement towards flexion - makes angle smaller extension - makes angle larger MUSCLE GROUPS Facial orbicularis oculi - move the eyelids masseters - mastication; raise the mandible Neck, Back, and Thorax serratus - supports trunk pectoral - forms chest; adducts forelimb lattisimus dorsi - broadest back muscle; shoulder flexion intercostals - rib muscles diaphragm - separates chest/stomach cavity; allows lung expansion Forelimbs triceps brachii - extends forelimb; caudal humerus biceps brachii - forelimb flexion; cranial humerus Abdominal obliques - slanted muscles on abdominal side abdominis - floor of abdomen Hindlimbs gluteal - limb extension and adduction; pelvis quadriceps femoris - limb flexion and extension; cranial femur semimembranosus/semitendinosus - posterior hind limb; injections biceps femoris - posterior hind limb Miscellaneous arrector pili - muscles causing hair to stand on end cutaneous trunci - dermal muscle causing insect repelling skin twitches cremaster - part of spermatic cord; raises/lowers testicles in response to temp