Myology PDF 2016

PRINICIPLES OF MYOLOGY Def: science deals with muscles Skeletal muscles are the active part of locomotor system Smooth muscles move the viscera Cardiac muscle produces heart contraction Prof. Ahmed Saber Vet. Anat. 1. 2016 The main characters of muscles are: Irritability or Excitab...

PRINICIPLES OF MYOLOGY Def: science deals with muscles Skeletal muscles are the active part of locomotor system Smooth muscles move the viscera Cardiac muscle produces heart contraction Prof. Ahmed Saber Vet. Anat. 1. 2016 The main characters of muscles are: Irritability or Excitability - responsive to chemical, electrical, or mechanical stimuli Contractility - ability of muscle to contract (shorten) Extensibility - ability to be passively stretched Elasticity - ability to return to its original length Prof. Ahmed Saber Vet. Anat. 1. 2016  Types of muscles 1- smooth muscles: Structures: long spindle shaped, uni-nucleate, and non-striated (smooth) Locations: wall of visceral organ The control: involuntary autonomic control or endocrine control (myo-epithelial cells) function: Involuntary contractions that move materials through the organs Prof. Ahmed Saber Vet. Anat. 1. 2016 2- Cardiac muscles Structures: cylindrical, mostly uninucleate striated, and Branching and joins forming myocardium network (syncytium). The fibers are connected end-to-end at sites called intercalated disks. Prof. Ahmed Saber Vet. Anat. 1. 2016  Locations: wall of heart The control: involuntary function: Involuntary autonomic control and special local conducting system cause contractions of heart Prof. Ahmed Saber Vet. Anat. 1. 2016 3- Skeletal muscles They forming about 40-45 % of body weight The muscle cell = muscle fiber = myofiber structures: – Elongated, multinucleated, with long and transverse striation. – Each muscle is divided into bundles or fascicles – Each fascicles is composed of numerous muscle fiber (cells) Locations: in all body & forming active part of locomotor system Prof. Ahmed Saber Vet. Anat. 1. 2016 Skeletal muscles (cont.) The control: voluntary control function: voluntary somatic movement of the body Maintain body position Stabilizing the joint Heat production Guarded body entrances and orifices Prof. Ahmed Saber Vet. Anat. 1. 2016  Architecture of skeletal muscle Each single muscle is consists of numerous bundles (fascicles) Each fascicles is consists of numerous muscle fibers The muscle fiber is the structural unite of muscle Fiber Fascicle Epimysium Muscle Tendon bone Prof. Ahmed Saber Vet. Anat. 1. 2016  Architecture of skeletal muscle Epimysium: CT layer ensheated the entire Muscle fascicle muscle Blood vessels Perimysium: CT layer ensheated each muscle Epimysium bundle (fascicle) Endomysium: CT layer ensheated each muscle Muscle fiber & Perimysium endomysium fiber Epimysium, perimysium and endomysium extend at the muscle end forming tendon or aponeurosis They protect the cells and provide passage for vessels and nerves Prof. Ahmed Saber Vet. Anat. 1. 2016 Architecture of skeletal muscle Muscle fiber Perimysium Fascicle Endomysium Epimysium Prof. Ahmed Saber Vet. Anat. 1. 2016 Microscopic structures Myofiber Myofibril Myofilaments Actin Myosin Prof. Ahmed Saber Vet. Anat. 1. 2016 Gross anatomy of skeletal muscle 1- anatomical parts: A- origin: usually the proximal attachment of muscle Less movable part Somtime more that one head (biceps) B- insertion: Usually distal attachment More movable C- belly: The main balk of muscle between origin and insertion Prof. Ahmed Saber Vet. Anat. 1. 2016 Gross anatomy of skeletal muscle 2- skeletal muscle attachment a) Bone b) Cartilage c) Deep fascia (indirectly to bone) d) Skin and superficial fascia e) Intermediate tendon f) No attachment (no origin & no insertion, as orbicularis oris) Prof. Ahmed Saber Vet. Anat. 1. 2016 Gross anatomy of skeletal muscle 3- arrangements of skeletal muscle fibers Based on the angle between fiber and the line of pull A- Parallel fibers: 1.Strap (sartorius) Strap 2.Quadrates (quadratus femoris) B- Fusiform (biceps brachi (bundles nearly Fusiform paralel) Prof. Ahmed Saber Vet. Anat. 1. 2016 C- oblique fibers (pennation) Unipennate The fibers attached to tendon at oblique angle (feather like) 1- unipennate: on one side of tendon Bipennate ex extensor digitorun longus M 2- bipennate : on both sides of tendon, ex rectus femoris M 3- multipennate: muscle fibers attached to several fibrous bands Multipennate within the muscle, the bands join forming one tendon, ex deltoid M 4- Centripennate: one central tendon Prof. Ahmed Saber Vet. Anat. 1. 2016 C- circular fibers 1- circular: no attachment, around orifices, ex orbicularis oris (around mouth) Circular 2- convergent: broad origin and pointed insertion, ex pectoralis major Convergent Prof. Ahmed Saber Vet. Anat. 1. 2016  Functional types of muscles 1. Prime mover (Agonist muscles) – muscles most involved – cause joint motion through a specified plane of motion when contracting 2. Antagonist muscles – located on opposite side of joint – have the opposite action to agonist Prof. Ahmed Saber Vet. Anat. 1. 2016 3. Synergist – assist in action of agonists – not necessarily prime movers for the action 4. Fixators (stabilozers) – Fix the joint Prof. Ahmed Saber Vet. Anat. 1. 2016  Blood and nerve supply Vessels and nerves pass through the connective tissue sheaths Belly is more vascular One neuron supply variable number of muscle fibers Motor unites = neuron+ muscle fiber innervated by this neuron Prof. Ahmed Saber Vet. Anat. 1. 2016 Prof. Ahmed Saber Vet. Anat. 1. 2016  Accessory structures of skeletal muscle 1. Sesamoid bone – In course of some tendon – as superficial and deep flexor tendons – Protect the tendon – Decrease friction – Redirect the pull angle of the tendon Prof. Ahmed Saber Vet. Anat. 1. 2016 2. Fascia Body wall is sheath of CT found all Internal fascia over the body Divided into Internal fascia (endothoracic, Body abdominaland pelvic) cavity External fascia ( superficial and deep fascia) skin Deep fascia Superficial fascia Prof. Ahmed Saber Vet. Anat. 1. 2016 3. Synovial sac Is sac filled with synovia Located between two structures to decrease the friction between these structures 1. Subtendinous Synovial 2. Subcutaneous Tendon sac 3. subligamentous Bone Prof. Ahmed Saber Vet. Anat. 1. 2016 4. Tendon synovial sheath elongated sac under the tendon The edges of the sac become reflected around the tendon Consists of – Outer fibrous layer – Double inner synovial – Parietal and visceral layer in between small cavity filled with synovia At edges meeting, the mesotendon present Prof. Ahmed Saber Vet. Anat. 1. 2016 4. Tendon synovial sheath Mesotendon Outer fibrous Parietal synovial layer tendon Synovial fluid Visceral synovial layer Prof. Ahmed Saber Vet. Anat. 1. 2016 Prof. Ahmed Saber Vet. Anat. 1. 2016 5. Retinaculum Transverse band of deep fascia around carpal and tarsal joints It fix the tendon and ligaments in its position As, flexor and extensor retinaculum of carpus Prof. Ahmed Saber Vet. Anat. 1. 2016