Test 2 Material muscle know the origin, insertion, innervation, and action of a muscle

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Test 2 Material




Terms of the day:
Tachycardia – fast HR

Ligation- the act of binding

Lymphopenia – lymphocytic l., a reduction in the # of lymphocytes in the circulating blood

Dysrhythmia – defective rhythm

Dyscrasia - A morbid general state resulting from the presence of abnormal material in the blood, usually applied to diseases affecting blood cells or platelets.

Phlebotomy – venesection

Cardiomegaly – ht enlargement

Bradycardia – slow HR

Endarteretomy - Excision of diseased endothelial lining of an artery and also of occluding atheromatous deposits, so as to leave a smooth lining.

Sclerosis – Induration. In neuropathy, induration of nervous and other structures by a hyperplasia of the interstitial fibrous or glial connective tissue

Function of muscles

  1. movement

  2. heat production – shivering to raise body T

  3. posture and body support

Characteristics of Skeletal Muscle

  1. Irritability - muscles are sensitive to stimuli from nerve impulses

  2. Contractility - muscle contracts when it receives the required stimulus from motor neuron

  3. Extensibility – stretch beyond their normal resting state

  4. Elasticity – recoil to original length (even a roast has recoil –poke thumb into it elasticity)

Muscle Attachments – there are 2 ways:

  1. Tendons or sinews - a fibrous cord or band that connects a muscle to its boney attachment

  2. Aponeurosis - broad flat tendinous sheath, attaches muscle to bone

Connective Tissue Covering of Skeletal Muscle

  1. Endomysium - surrounds the individual muscle fibers ( = muscle cells )

  2. Perimysium- surrounds fasciculi ( bundles of muscle cells )

  3. Epimysium - surrounds entire muscle

  4. Fascia - covers muscle and attaches to skin

Muscle Groups

  1. Agonist - the primary mover of a joint ( agonist = flexed antagonist = relaxed )

  2. Antagonist - actions opposite of agonist (antagonist = flexed  agonist = relaxed )

  3. Synergist - muscles work together to accomplish a particular movement

  4. Flexors - flex a joint ( biceps brachii of olecranon joint )

  5. Extensors - extend a joint ( triceps brachii of olecranon joint )

Muscle Architecture and Fiber Arrangement – determines a muscle’s function

  1. Parallel - straplike, good endurance, not strong; ie. sartorius m., rectus abdominis m.

  2. Convergent - fan shaped, focuses force of contraction to a single point; gluteal mm.., deltoid

  3. Sphincter - close body openings; Orbicularis oris m. (“pucker” m)

  4. Pennate (“feather”) - fibers converge on a tendonous insertion, 3 types, uni, bi and multi pennate

Blood and Nerve Supply to a Skeletal Muscle

  1. GSE ( General Somatic Efferent ) - motor neuron into skeletal muscle

  2. GSA (General Somatic Afferent )- sensory neuron carries info from sk. Muscle ( pain, T, stretch ) Cell body in the dorsal root ganglion is associated with mechano-proprioreceptors

  3. Neuromuscular junction – or myoneural junction, where the nerve and the muscle synapse. Consists of the motor end plate ( where axon terminals contact sarcolemma ) and the cell membrane of a muscle fiber

  • Neurotransmitter – ACH ( stored in synaptic vescicles at axon terminals, released by nerve impulse into the neuromuscular cleft )

  • Receptors - nicotinic

  1. Motor Unit

  • Consists of a single motor neuron and all of the muscle fibers it innervates. 1 motor neuron may innervate as few as 2 or 3 muscle fibers ( fine control ) or as many as 200-300 muscle cells ( gross function )

  • Recruitment of motor units ( grocery bag story ) – How many muscle fibers are needed to perform a certain task?

5. Muscle Tone is a normal state of partial contraction, maintained by working out.

  • Spasm – too much muscle tone, irritation, knots, subluxation, charley horse.

  • Flaccid – not enough tone, from lack of use, subluxation?

  1. Origin of a muscle - the less movable of the two points of attachment of a muscle, that end which is attached to the more fixed part of the skeleton. The place where the muscle originates.

  2. Insertion of a muscle - the movable end, that end which moves in relation to the rest of the skeleton

Origin and insertion can flip flop sometimes, SCM example. Proximal and distal attachment is a better way. You have to be given a function in order to determine the origin and insertion. A muscle only does one thing, so origin and insertion cannot change.

Ask the origin of the muscle, give the function.

Naming of Muscles

  1. Shape - trapezius m. ( ok way to name )

  2. Location – pectoralis ( better way to name )

  3. Attachment - sternocleidomastoid m. ( best way to name )

  4. Size - maximus, minimus, etc.

  5. Direction of fibers – rectus (= straight), oblique, etc

  6. Muscle Action - flexor, extensor, etc.

  7. Relative position – profundus (=deep), superficialis, etc.

Many muscles combine 2 or more of these ways, like Flexor carpe brachialis longus

Muscles of the Axial Skeleton p. 241 - 253

Muscles of Facial Expression N 20

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