Skeletal Muscles Spring 2019

Week 3 Homework Due* Quiz 2 Skeletal Muscles Actions Naming Assignments and Homework Figure 10.15 Week 3 Homework Due Quiz 2 Skeletal Muscles Actions Naming Assignments and Homework Figure 10.15 Origin - the less movable of the two points. Tend to be the more proximal attachment. Insertion - the more movable of the two points. Tend to be the more distal attachment. Remember: Muscles do not always insert on bone. Connective tissue E. g. – Tendons or aponeurosis Muscle Attachment Functional groups Agonist –produces the primary force for a specific joint movement. Example: biceps brachii muscle is the agonist that produces elbow flexion. Antagonist – produces the opposite joint movement of the agonist. Example: triceps brachii muscle is the antagonist for the biceps brachii muscle Synergist – assists another muscle to accomplish a movement. Example: brachialis is a synergist, it aids biceps brachii in producing elbow flexion. Study Tip: Because agonists and antagonist have opposite movements, they are generally located on opposite sides of the joints on which they act. Muscle actions and Joint Movements Remember: All joint motions are described based on their deviation from anatomical position. Movements in the Sagittal plane Flexion – movement that decreases the angle of a joint. The biceps brachii is not “flexed” it is contracted “Flexors” (e.g. Flexor Digitorum). Ex- bending the elbow or the knee. Ball and socket joints- raising upper or lower appendages. Extension – movement that increases the angle of a joint. “Extensors” (e.g. forearm extensors). Ex- extending/straightening the elbow or the knee. Ball and socket joints- lowering upper or lower appendages Flexion Muscle actions and Joint Movements Remember: All joint motions are described based on their deviation from anatomical position. Movements in the Frontal plane Abduction – the movement of a body part away from the midline. Muscles that cause abduction are often referred to as abductors. Example: raising the upper limbs laterally Adduction - the movement of a body part toward the midline of the body. Muscles that cause adduction are often referred to as adductors. Example: lowering the upper limbs to the sides Abduction Adduction Muscle actions and Joint Movements Remember: All joint motions are described based on their deviation from anatomical position. Movements in the Frontal plane Elevation – movement that raises a body part vertically. “Levators” Ex- Levator Scapulae Depression – movement that lowers a body part vertically. “Depressors” Ex- Platysma pulls the mandible down, opening the mouth. Muscle actions and Joint Movements . Movements in the Transverse plane Pronation – rotary movement which results in an appendage facing downward. “Pronators” Ex- rotating the palms so that they face downward. Supination – rotary movement which results in an appendage facing upward. “Supinators” Ex- rotating the palms so that they face upwards. Study Tip: remember that we pour when we pronate and we supinate when we hold a bowl of soup Muscle actions and Joint Movements Special Movements and Muscle Types Dorsiflexion – movement that decreases the angle between the dorsal surface of the foot and the shin. Example: taking one's foot off the gas pedal. Plantarflexion – movement that increases the angle between the dorsal surface of the foot and the shin.. Rotation – circular movement that combining flexion, extension, adduction, and abduction. Example: the windmill motion a baseball pitcher makes when throwing. Tensors – muscle whose function is to render a part firm and tense How to interpret Bone names Location What do the words mean? What is the muscle telling me? Bicep = 2 heads Sternocleidomastoid = Sternum, clavicle, mastoid process Function What joint(s) does the muscle cross and on what side? Bicep femoris – knee and posterior side What happens if the muscle is shortened? Flexion of knee Muscles Names Location Shape Size Fiber Orientation Number of Origins Attachment Location Action Relative position Miscellaneous Figure 10.15 Naming – Location Brachi (=arm). Forearm and hand often feature Latin words relating to these regions. Radi (=radius) Ulnar (=ulna) Carpi (=wrist) Palma (=palm) Digitorum (=fingers) Ex- Extensor Carpi Ulnaris Thigh- femoris (=femur) or gluteus (=buttocks). Leg and foot often feature Latin words relating to these regions. Tibialis (=tibia) fibularis or perone (=fibula) planta (=sole of the foot) digitorum (=toes) Ex- Rectus femoris Naming – Shape Deltoid = ? (delta) Trapezius = trapezoid. Naming – Relative size Maximus (=largest), medius (=middle), minimus (=smallest), Longus (=long), and brevis (=short) Major (=larger) and minor (=smaller). For every “longus” muscle there will be a “brevis” Example: zygomaticus major and zygomaticus minor indicate their rough location in the body and their relative size Usually named in reference to imaginary line. Rectus (=straight) Transversus (=across) Oblique (=slanted) Example: rectus abdominus is a muscle with straight fibers located in the abdomen Figure 10.15 Naming – Orientation of Fibers Naming – Number of Origins Bi- (=two), tri- (=three), or quadri- (=four) are often used to denote the number of origins (ceps = heads). Example: the biceps brachii has two origins, while triceps brachii has three. Further examples: Quadriceps. Naming – Location of Attachments Some muscles are named according to their origin and insertion. When this is the case, the origin(s) is/are named first. Example: the sternocleidomastoid muscle of the neck has origins on the sternum (sterno) and clavicle (cleido) and an insertion on the mastoid process of the temporal bone (mastoid). Many of the muscles of the head and neck are named for their origins and insertions. Naming – Action Actions feature prominently in the names of muscles that cross joints Example Flexor carpi radialis causes flexion of the wrist on the lateral side of the forearm. Pronator teres pronates the forearm. Adductor magnus and adductor longus in the thigh adduct the hip joint. Naming – Relative Position Some muscles are named for how close they are to the body surface or to a structure. Latin roots and words such as sub- (=beneath), supra- (=above), infra- (=below), superficialis (=superficial), and profundus (=deep) are often used to denote a muscle’s position. Common terms like internal (=deep) and external (=superficial) are also used. Example: the subscapularis muscle is “beneath” to the scapula (it sits in the subscapular fossa). The supraspinatus muscle is located above the scapular spine. Quiz 3 requires all information on this list except the innervation (will be on exam 1). Important reminders Be aware of multiple terminologies; e.g. the fibularis longus is also know as the peroneus longus. Blank limb key on Blackboard. This key has all the limb muscles that you have to know for the lab exam. Your TA can check to make sure you have correctly identified each muscle. Learn muscle names. Muscles can be difficult for first time students. Try to break the muscle name down into its root words. This will usually reveal a great deal of information about the muscle. Know your orientation. Make sure you can figure out whether the limb is a left or a right. Missing muscle. The coracobrachialis is located in the arm but is not shown in the lab manual. You still need to know it. Muscle actions table on Blackboard. You need to know the origin, insertion, and action of the muscles on this table.