Brachial Plexus and Nerve Radial Nerve Essay

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Anatomy 232 - Study Notes

Week 1 – Anatomical Terminology

Studying Anatomy * Regional (e.g. thorax) * Systematic (e.g. pulmonary systems) * Functional (e.g. biomechanics of movement) * Clinical (relates to injury) * Surface anatomy (what structures you can feel under the skin) * Allows clear concise communication * Anatomical position > position of reference, standard around the world

Anatomical Terms

Anatomical Planes

Parasagittal cut into unequal left and right parts.

Muscle Contractions * Nervous stimulation causes muscle contraction = tension * Gravity pulls downward so no muscle required to produce movement inferiorly * Concentric – shortening of muscle to produce movement against resistance * Isometric – maintain muscle length to hold & may produce opposing movements at two joints * Eccentric – lengthening of muscle to control movement produced by gravity

Lever systems * Muscles pull bones acts as levers to move body segments * Lever systems include: * Fulcrum or axist – pivot point around which movement occurs * Load or resistance – to movement (usually the weight of body segment or stretch of muscle) * Effort – tension from muscles and effect of gravity/ momentum

* First class lever – fulcrum located between effort and load e.g. neck & head * Second class lever – load located between effort and fulcrum e.g. metatarsals & phalanges * Third class lever – effort located between fulcrum and load e.g. elbow

Mechanical Advantage * Mechanical advantage = effort located further from the fulcrum than the load * Always exists in 2nd class levers never in 3rd and sometimes in 1st

Contractions * Relationship between load and effort * Load = effort : no change in muscle length – isometric * Load < effort : muscle shortens – concentric * Load > effort : muscle lengthens – eccentric

Levers & Torque * Lever > object that can be made to rotate around an axis if force applied to it * Torque > turning effect on a lever produced by a force

Increasing Torque * Larger muscle size (create more tension) * Perpendicular line of pull (generates more torque) * Large moment arm (perpendicular distance from the muscles line of pull) * Long muscle fibres

Week 2 – Shoulder Joint

Shoulder complex * Pectoral girdle – scapula & clavicle > less stable more mobile * Glenohumeral joint – between scapula and humerus

Clavicle * Rotates 45 degrees around its long axis * Two ends medial and lateral * Superior and infereior surface * Two boarders anterior and posterior

Ligaments * Costoclavicular > rib & clavicle, triangular shape, stabilises sternoclavicular joint * Conoid > cone shaped * Trapezoid > rhomboid shape > prevents mechanical displacement of scapula on the clavicle

The Scapula


Joints of the shoulder complex * Sternoclavicular joint * Arcomioclavicular joint * Scapulothoracic joint * Glenohumeral joint

Sternoclavicular joint * Directs all shoulder movement * Elevation of clavicle 60 degrees * Rotation of clavicle anteriorly and posteriorly 25-30 degrees

Acromioclavicular joint * Supported by coracoclavicular ligament * Not much movement * Links scapula and clavicle together

Glenohumeral * Very shallow, ovoid > provides additional articular surface > important for suction cup effect * Has bony and ligamentous arch comprising acromion and coracocrominal ligament > prevents upward dislocation * Coracohumeral ligament prevents humeral head from falling out

Scacpulohumeral Rhythm * During shoulder elevation * Preserves length tension relationship between glenohumeral muscles * Glenohumeral joint paired with shoulder girdle to accomplish total range of movement in