Lab 5: Muscle Anatomy and Physiology Flashcards
In the LT lab station, how did the EMG signal (trace) change when weight was added to the participants arm? Based on your data, when weight is added, what is occurring within the muscles to maintain joint position?
bigger graph spikes, tripes antagonises with bicep. Recruit more motor units to increase neural activity (as represented by graph). 1 textbook = small motor units, 3 textbooks = bigger motor units
muscle antagonist coactivation is a phenomenon where opposing muscle groups, such as biceps and triceps, contract simultaneously to stabilize a joint. When the bicep was contracting, what did you observe in the triceps tracing? what role do you think the triceps would play during elbow flexion?
triceps tracing would also slightly increase, because biceps and triceps work together during coactivation
pectoralis major
action: depress the scapula, or elevates the ribs, stabilizes by anteriorly tilting the scapula
origin: anterior surfaces of the 3rd to 5th ribs
insertion: coracoid process of scapula
serratus anterior
action: protraction of scapula, boxers muscle (flex elbow)
origin: from 1st to 8th or 9th ribs
insertion: entire anterior length of medial border of the scapula
levator scapula
action: elevates, retracts and rotates the scapula, as well as lateral flexion of the neck
origin: transverse processes of C1 to C4 vertebrae
insertion: superior angle of scapula
trapezius
action: retraction, internal rotation, elevation, depression
origin: external occipital protuberance, the medial third of the superior nuchal line, the nuchal ligament, and the spinous process of C7-T12
insertion: clavicle, acromion process and scapular spine
rhomboid major
action: scapular retraction, rotation
origin: spinous process of T1-T4 vertebrae
Insertion: medial border of scapula
rhomboid minor
action: scapular retraction, rotation
origin: spinous process of C6 to C8
insertion: medial border of scapula
shrug your shoulders. what muscles allow you to return to anatomical position?
trapezius muscles
Locate the prominent spine of the scapula posteriorly and follow the spine to its lateral end. What is this structure? Locate the junction between the structure and the clavicle by thrusting your arm anteriorly repeatedly until you can palpate it. What is this joint called?
The prominent structure at the lateral end of the spine of the scapula is the acromion, and the joint between the acromion and the clavicle is the acromioclavicular joint
Enables small gliding movements that are critical for full shoulder motion, especially during overhead activities.
Contributes to scapular rotation and positioning during arm movements.
deltoid
action: abduction (pull upwards), medial and lateral rotation, flexor and extensor of shoulder
origin: clavicle, acromion process and spine of scapula
insertion: deltoid tuberosity
latissimus dorsi
action: extension (pull arm backwards) , adduction (down to body), medial rotation
origin:spinous processes of T7 to L5, sacrum and iliac crest
insertion: medial crest of the intertubercular (bicipital) groove
pectoralis major
action: flexion (shoulder), extension (of arm when flexed), adduction, medial rotation (of arm)
origin: clavicle, sternum, superior six costal cartilages and abdominal aponeurosis
insertion: lateral crest of the intertubercular (bicipital) groove
Teres Major
action: extension (shoulder), adduction, medial rotation of arm
origin: lateral border of scapula
insertion: medial crest of intertubercular (bicipital) groove
Infraspinatus
action: lateral rotation (pull humorous towards back)
origin: infraspinous fossa of scapula
insertion: greater tubercle of humerus
subscapularis
action: holds head of humerus in place and medially rotates the arm
origin: subscapular fossa
insertion: anterior side of humerus
supraspinatus
action: abduction (pull up on humerus)
origin: supraspinous fossa
insertion: greater tubercle of humerus
teres minor
action: holds head of humerus in place and laterally rotates, adducts the arm
origin: scapula’s posterior surface, near the upper part of its lateral border.
insertion: greater tubercle of humerus
Locate the greater tubercle of the humerus on the superior surface of the shoulder. Place your hand on the superior and lateral portion of your shoulder, What muscle are you palpating? What is the origin and insertion of this muscle? What actions is it responsible for?
The supraspinatus is the most superior of the rotator cuff muscles
origin: supraspinous fossa
insertion: greater tubercle of humerus
action: abduction (pull up on humerus)
Palpate your biceps brachii. In order to feel this muscle contract, what action can you perform?
flexion and supination
Palpate your triceps brachii. In order to feel this muscle contract, what action can you perform?
extension (pull ulna into straightened position)
Identify the muscles comprising the quadriceps femoris group. What is the primary movement of these muscles?
rectus femoris (originates at hip and crosses knee and hip joint), vastus intermedius (center), vastus medialis (medial) , vastus lateralis (lateral)
action: extension at knee, flexion of hip
what is the longest muscle in the body? Generally where does the muscle originate and insert?
The sartorius muscle
origin: hip, crosses anterior surface of thigh
insertion: medial side of leg
identify the muscles compromising the hamstring group. What is the primary movement of these muscles?
semitendinosus (medial), biceps femoris (lateral and superficial) + lateral rotation of leg) , semimembranosus (deep)
action: flexion at knee, extension at hip
