General Myology (ECU Veterinary Medicine PDF)

First Year - First Semester 2023-2024  Myology :  The science which deals with the study of all types of muscles , tendon and accessory structures in the body. (N.B) Muscle tissue constitutes almost one-half of the total body weight.  Functions of the muscles: – Produces moveme...

First Year - First Semester 2023-2024  Myology :  The science which deals with the study of all types of muscles , tendon and accessory structures in the body. (N.B) Muscle tissue constitutes almost one-half of the total body weight.  Functions of the muscles: – Produces movements of the body parts and locomotion of individual. – Restrains movement. – Support the bone and other structure. – Responsible for heart beat and production of sound, peristaltic movement, vision, speech, etc. – Produces heat in hemothermic (warm blooded) animals (because skeletal muscle is in a state of tone and thus generates heat even when at rest). Types of Muscles Cardiac smooth/visceral skeletal/somatic striated, involuntary (without smooth not striated, involuntary striated, voluntary conscious) Only in the walls of heart, pulmonary the wall of hollow viscera movements of the finger or veins and cranial vena cava. intestines, blood vessels, gut and gross movements like the bladder wall. Also throat, skeletal muscle of the limbs, scrotum, skin and iris of the eye. meat (red flesh muscle), tongue, pharynx, beginning of the oeophageus. c contract quickly and powerfully but - Contract slowly and mildly, but cannot maintain contraction for a Contract quickly, powerfully and can remain contracted for a long long time, hence soon get fatigue, rhythmically, no fatigue or tired time, are not fatigued or tired tired Blood supply is abundant Blood supply is scanty Blood supply is abundant. Innervated by motor nerves from C.N.S autonomic nervous system central and autonomic (neurogenic) (Myogenic) nervous systems Multinucleate Uninucleate Mostly uninucleate  Classification of the muscular tissue (Classify according to) Function position Microscopic (morphology) appearance Voluntary In Voluntary Smooth Skeletal (visceral) cardiac Striated (Skeletal & cardiac) visceral  Each muscle has an origin and insertion.  The origin of a muscle may be defined as the attached end that is the most stationary (immovable) (less movable) (stable during movement)  The insertion of a muscle is the attached end where there is the most movement (movable toward origin)  The thickest part called belly ( venter ).  At contraction, the insertion is usually pulled toward origin origin belly insertion  Sometimes has an intermediate tendon dividing the muscle into two bellies, e.g. digastric muscle.  There may also be tendinous inscriptions or intersections, e.g. in the rectus abdominis muscle. Tendinous inscriptions Intermediate tendon Types of attachments: 1. Tendons (ribbon-like rounded)(short stout white fibrous tissue. 2. Aponeurosis: (Flat, expanded tendon)is sheet like white fibrous tissue. a. Muscle shapes: 1. Spindle shape M is (fusiform) 2. sheet like (flat) is planus 3. Two head is biceps brachii 4. three head is triceps brachii 5. Four head is quadriceps brachii 6. Two belly muscle is Digastrics 7. Ring- shaped muscle is Orbicularis or sphincter b. Muscles according to number of joints:  Uniarticular muscles: cross only one joint and act only this joint as supraspinatus, brachialis.  Biarticular muscles : cross two joints, so act on two joints as biceps brachii and Sartorius M.  polyarticular muscles: cross more than two joints. Ex. Flexor and extensors of digits. c. Muscles according to action:  Extensor & Flexor adductor & abductor  supinator & pronator Elevator & depressor  Rotator  sphincter & dilator  Muscles make pressure e.g: (Abdominal muscle) or squeezing d. Muscles according to orientation of the fibers: 1. Parallel (strape): muscles with parallel fiber extend a whole length of muscle from one end to other. Ex. Sartorius. 2. Fusiform (spindle shape): muscles with converge up on a tendon at both end of muscle. Ex. Biceps, pectinus. 3. pennate: muscles with short parallel fibers attached obliquely to a central axial tendon of muscle. a. Unipennate (like half feather) ex. genioglossus b. Bipennate ex. Gastrocnemius, common digital extensor(like complete feather) c. Multipennate ex. deltoid  Various arrangement of skeletal muscle fibers 1- parallel 2-Fusiform (pinnate) 3-Unipinnate 4-Bipinnate 5-Multipinnate Accessory structure associated with skeletal muscles: 1. Fascia Superficial fascia Deep fascia  dense, strong white fibrous  more or less fatty layer directly layer under superficial fascia. under the skin  it covers underlying muscles.  it acts a bad conductor of heat, keep a body Temp.  types: outer investing fascia,  It contain vessels, nerves, inner investing fascia and lymph glands. intermediate  2. Synovial bursa 3. Synovial shealth (vaginal sheath) synovial sac located between two structure Elongated form of bursa wrap around the that tend to rub against each other for short tendon. distance. Bursa contain only on enough fluid to reduce friction between parts. Inflammation: bursitis (increase in fluid Inflammation: synovitis or vaginitis lead to swollen) This bursa formed of single layer This sheath formed of two layers:- 1- inner synovial layer (surround the tendon) 2- superficial synovial layer (outside the tendon). The double fold of the membrane meet at the mesotendon. Ex. 1-Bicipital bursa. 2-Atlantic bursa. 3-Supraspinous bursa It gives adequate protection to the The protection for a long distance tendons structures moves only in a short distance. afforded by a synovial sheath. Synovial sheath and bursa Tendon They connect muscles to bones Fibrous bands of collagen in parallel bundles, connecting muscles to bone, in the form of cords or band Aponeuros when the fascia gives origin or is (flat insertion to the muscle, appear as a sheet of thick sheet associated with flat tendon):- muscles. Sesamoid minimize the friction, change the Bones direction and strengthen the force of the muscle. Ligament connect the bones to each other. Questions General arthrology First Year - First Semester 2023-2024  Joint or articulation is formed by union of two or more bones or cartilages by uniting medium (May be fibrous tissue or cartilage or others). Function of joint 1. facilitate the movement. 2. Flexibility and stability between bones. 3. bone growth.  Classification of the joint I- Functional: II- Structural: A) according to presence or A) according to the uniting absence of movement medium B) degree of mobility B) presence or absence of joint cavity  I: Functional Classification of the joints I. According to presence or absence of movement and degree of mobility:- 1- Synarthrosis (Fibrous): (Fixed / immovable Joints). 2- Amphiarthrosis (Fibrocartilagenous): (Tight / partly movable J.). 3- Diarthrosis (Synovial): (True/ movable Joints).  Fibrous joints Cartilagenous joints Synovial joints 1. Uniting medium is 1. Uniting medium is 1. uniting medium is fibrous tissue cartilage Synovia 2. No joint cavity 2. No joint cavity 2. Joint cavity present 3. are temporary (ossify 3. are temporary 3. perminent with age) 4. No or very limited 4. Movable 4. No movement movement 5. mostly in limbs 5. location in axial 5. axial skeleton skeleton  I- Functional Classification Synarthrosis Def: Group of joints that united by uniting medium that prevented its movement. *Characterized by: - No movement (fixed or immovable joints). - No joint capsule (cavity). -Are temporary as the uniting medium being ossified with age (synostosis). *Classification (accord. to uniting medium ): a) Syndesmosis (desmos = ligament = C.T.) b) Synchondrosis (chondros = cartilage) c) Synostosis ( os = bone) d) Synsarcosis ( sarx = meat = muscle ) e) Sutures (fibrous tissue)  II- Structural Classification (1. Fibrous joint) characterized by: - No movement (fixed or immovable joints). - No joint capsule (cavity). -Are temporary as the uniting medium being ossified with age ( synostosis ). * The chief types or examples: a) Sutures b) Syndesmosis c) Gomphosis  Structural classification of joints: Fibrous (Fixed) Cartilaginous Synovial (Freely (slightly movable) movable) Diarthrodial A. Sutures A. Primary Cartilaginous (synchondrosis) 1. plane They are the joints in the skull in which the Hyaline adjacent bony edges united by fibrous tissue (Sutural ligament). ( plane, squamous, serrate) B. Gomphosis B. Secondary Cartilaginous (symphysis) 2. Hinge Fibrocartilagenous C. Syndesmosis 3. pivot 4. Ellipsoid 5.saddle 6. Bicondylar 7. Ball and socket Fibrous Joint: Fixed joint or immovable joint (synarthrosis) where collagenous fibrous connective tissue unites 2 bones.  no joint cavity Ex. 1.Gomphosis: implantation of teeth in alveoli. 2. Syndesmosis: the bones are firmely united by fibrous tissue (interosseous ligament). with age, ossification to the fibrous tissue that called “synostosis” ex. The shaft of the splint bones or cannon bones, Radius, Ulna & Tibia &Fibula.  3. Sutures: United bones of the skull with fibrous tissue early in life then become ossify after maturity. Name Shape or margin Example Plane (Harmonic) Plane and smooth Inter-nasal bone palatine bones serrate Serrated(saw) Inter-frontal bone squamous The margins are beveled and Tempro-parietal bone bone scales overlap Foliate When the edges of one bones Vomero-palatine fits into a fissure or recess of Frontonasal in ruminant adjacent bone Cartilaginous Joint (Amphiarthrosis):  Bones are united by fibro-cartilage or hyaline cartilage or combination between two.  No joint cavity.  Limited or no movement. (compression or stretching)  Temporary. compare Fibro-cartilagionous (symphsis) hyaline cartilage joint (synchondrosis) United medium Fibrocartilage hyaline cartilage Ex. Pelvic symphysis, two bone of mandible in Union diaphysis, epiphysis in ruminant, sternebrae immature bone (Temporary) Movement Limited movement No movement  B. Symphysis (Fibrocartilagenous joint) Example: 1- Pelvic symphysis. 2- Intervertebral discs: Joints between the bodies of the vertebrae Vertebrae Fibrocartilaginous disc 3. Synovial joint (True joint)(diarthrosis):  present joint cavity  it is movable joint (motility)  Types: Simple joint Composite joint One formed by two articular surfaces One formed by several articular surfaces Essential (necessary) or constant structures Accessory or additional structures 1. Articular surface Ligaments 2. Articular cartilage Intra-articular plates of fibrocartilage 3. Articular capsule Marginal cartilage 4.Articular cavity  Structures of synovial joints A- constant B- inconstant (additional features) (essential structures) -Articular surfaces -Ligaments -Articular cartilage -Articular disc &menisci -Articular capsule -Joint cavity & synovia -Marginal cartilage The Structure of synovial joint:- 1- Articular surfaces:- - It is formed of dense compact bone and may have synovial fossae. - Covered by articular cartilage except synovial fossae. 2- Articular cartilages:- - It is hyaline in nature and non vascular. - Covering over the articular surfaces of the bones (has a blue tinge). - On the concave surface the peripheral part is the thickest, while on the convex surface the central parts is thickest. - Its function : diffuse pressure and friction. increase the curvature of bones. facilitate movements. 3- Articular capsule :- attached around the margin of the articular surface. - originated from the periosteum of bones. - consists of : *The fibrous layer (Capsular ligament): attached to margins of the articular surfaces. *The synovial layer: - It is a thin membrane richly supplied by network vessels and nerves, form folds and villi which projects into the cavity of the joint. - It lines the joint cavity except the articular cartilages. - It secretes and/or absorb synovia. Synovia (synovial fluid) It is fluid secreated and absorbed by the inner synovial layer of the joint. - It resemble the egg white but has a yellow ting and alkaline PH. - It present within synovial joint, around some tendons and within bursae. -Chemical composition: ( albumin, mucin, salts, fat droplets and degenerated cells from the synovial membrane as well as particles detached from the articular cartilages). Function of synovia: 1. Lubricate the articular surfaces and tendons. 2. Nutrition of cartilage. 3. Remove waste metabolites. 4. Enable wandering leukocyte to circulate in the joint cavity (immunity).  4- Ligaments:- They are strong bands of white fibrous tissue which bind the bones together. a) - Extracapsular ligaments (periarticular) (collateral ligaments). b) - Intracapsular ligaments ( intraarticular): inside the 2 layers of the joint capsule (Ex. Cruciate ligaments of the stifle joint). c) Interosseous ligaments: (Ex. Interosseous ligaments of the radius and ulna of the young horse). 5- Special structures :- a) Articular Discs and Menisci: it is plate of fibro cartilage located between articular cartilages. They divided the joint cavity completed as disc in TMG or partially in menisci of stifle joint. it help in variety of motion and decrease concussion. b) Marginal cartilage: it is ring of fibrocartilage which encircle the rim of articular Note: Marginal cartilage cavity. It enlarge the cavity and prevent the fracture of hip joint of Horse  Classification of synovial joint 1. According to no. of bones: 2. According to axis of movement 3. According to the shape / form of articular surfaces (anatomical): I. According to no. of bones: Anatomical classification of the joints: II. According to the shape of the articular surfaces. 1- Spheroidal (A ball and socket Joint): * Movement: free eg: Shoulder joint * Movement: free movement but some what limited * eg: Hip joint 3-Ellipsoid Joint: 3 skull eg: Atlanto-occipital Joint Atlas 4-Saddle Joint: Movement: Flextion and extension eg: Pastern Joint 5-Spiral (condylar) joint: 5 Femur Movement: flexion and extension Lateral Ex. Femorotibial (Stiffle)joint, TMG condyle of femur Lateral condyle of tibia Tibia 6- plane/Gliding : Flat articular surface allow simple sliding motion eg: carpus, tarsus III. According to axis of movement Biaxial joint Multiaxial joint Uniaxial joint 1. Hinge (Ginglymus) : Movement around movement around transverse axis many axes ex. Elbow joint allowing all types of movements 2. Pivot (trochoid) movement around longtiudinal axis Ex. Shoulder, hip joint ex. Atlanoaxial joint (rotation)  Biaxial joint 1. ellipsoidal j. : movement is (extension/flexion)& (adduction/abduction), ex. Atlano-occipital joint 2. Saddle joint: movement is (extension/flexion)& (adduction/abduction), the articular surface fit together ex. Inter-phalangeal joints 3. Condylar j.: convex articular condyles articulate with concave surface ex. TMG, stiffle. Movements of synovial joints: Gliding or sliding: flat surface glide over each other ex. Carpus, tarsus flexion: decrease the angle between two bones. extension: increase the angle between two bones. Hyperextension: if extension over 180 degrees. Ex. Fetlock joint. adduction: movement toward median plane Abduction: movement away median plane Rotation : movement of bone around long axis Circumduction: combination of movements (flexion, Abduction, extension, adduction) allowing the limb to outline a cone.