Anatomy of Muscles Lecture 9 PDF

Muscles Anatomy unit  Objectives Define a muscle. Classify muscles according to their structure and functions. Differentiate the types of muscles, on the basis of structural peculiarities and functions. Understand terms related to muscles. Know how the mu...

Muscles Anatomy unit  Objectives Define a muscle. Classify muscles according to their structure and functions. Differentiate the types of muscles, on the basis of structural peculiarities and functions. Understand terms related to muscles. Know how the muscles are named. Muscles Definition: Are effectors which enable movement to be carried out Property: Muscle tissue has the capacity of becoming short in response to an appropriate stimulus. Terms related to Muscle:  Belly (Fleshy part, Contractile)  Tendon (C.T, Non-Contractile)  Aponeurosis (Flattened tendon) Muscles  Origin: is the point where the muscle is attached to immovable or less movable bone.  Insertion: is the point where the muscle attached to movable bone. The attachments (origin & insertion) may take the form of: 1. Tendon or Aponeurosis. 2. Combination of tendon and aponeurosis. 3. Attached directly to the periosteum.  Muscles SMOOTH MUSCLES CARDIAC MUSCLES SKELETAL MUSCLES Site Wall of viscera & blood vessels Wall of heart (myocardium) Attached to skeleton Contraction Involuntary Involuntary Voluntary Striations Absent Present Present Nerves supply Autonomic nerves Autonomic Somatic Muscle cell Spindle-shaped & Uni-nucleated Uni-nucleated Multinucleated Single central nucleus Single central nucleus Multiple peripheral nuclei  Shape of skeletal muscles Parallel Circular Pennate Triangular PARALLEL SKELETAL MUSCLES  Definition: the muscle fibers are parallel to each other.  Example: The sternocleidomastoid, rectus abdominis, and sartorius muscles  are examples.  It may be: 1. Quadrilateral. 2. Strap. 3. Strap with tendinous intersection. 4. Fusiform Strap- tendenous intersection PENNATE SKELETAL MUSCLES The muscle fibers runs obliquely and attached to the side of tendon It may be: 1. Unipennate ex. extensor digitorum longus 2. Bipennate ex. rectus femoris 3. Multipennate ex. deltoid TRIANGULAR SKELETAL MUSCLES The muscle fibers converge into a narrow tendon ex. Pectoralis major muscle CIRCULAR SKELETAL MUSCLES  The muscle fibers arranged in the form of a circle around the openings Ex. Orbicularis oris , Orbicularis occuli.  Action of skeletal muscles Fixator Prime movers Synergistic Paradox Antagonist Prime movers (agonist)  There are muscles responsible for a particular movement, e.g. the biceps muscle is the prime mover of flexion of the elbow joint. Antagonist There are muscles, which oppose the action of prime movers. During flexion of the elbow joint by the biceps muscle the triceps opposes the biceps and it is called an antagonist. Synergists Act to steady and to eliminate unwanted movements in proximal joints while distal joints are in action.  For example, the flexor and extensor muscles of the carpus contract to fix the wrist joint, and this allows the long flexor and the extensor muscles of the fingers to work efficiently.  Fixators It contracts to stabilize the origin of the prime mover so that it can act efficiently. For example, the muscles attaching the shoulder girdle to the trunk contract as fixators to allow the deltoid to act on the shoulder joint. Action of paradox: Muscles opposing the movement aided by gravity (against the force of gravity)(Biceps) Naming of Skeletal muscles: Direction of the muscle fibers: Orbicularis oris (close and protrude lips) Relative size of the muscle: Gluteus Maximus, Medius, Minimus Location of the muscle: Obturator Internus Number of the origin: Biceps, Triceps Shape of the muscle: Deltoid Action of the muscle: Pronator teres REFERENCE BOOK READING Clinical Anatomy by Regions, 10th edition, (LAWRENCE E. WINESKI). PAGES-63-67 https://next.amboss.com/us/ article/o500Og?q=power%20 muscle#vAXAl00 Definition: maximal effort a patient is able to exert from an individual muscle or group of muscles Assessment The patient is asked to flex and extend the extremities against resistance. Muscle power tests should be performed bilaterally for comparison. Muscle power grading 0: no contraction (complete paralysis) 1: flicker or trace of contraction 2: active movement, with gravity eliminated 3: active movement against gravity 4: active movement against gravity and moderate resistance 5: normal power (i.e., full range of motion against gravity and full resistance) Patterns of paresis distribution Quadriparesis: weakness in all four limbs Hemiparesis: weakness in half of the body Paraparesis: weakness affecting both lower extremities Monoparesis: paresis affecting a single limb