Muscle Notes Part 2 Flashcards
Masseter
Origin: Zygomatic
Insertion:Ramus and angle of mandible
Action:Closes jaw
What two muscles are necessary to close the jaw?
Temporalis and masseter
How many pounds of pressure per square inch can the human jaw exert?
About 200 pounds of pressure per square inch
Think of Mike Tyson when he bit off another boxer’s ear
Can other animal’s jaws exert more pounds of pressure per square inch that a human jaw?
A Rottweiler can exert about 330 pounds of pressure per square inch
A snapping turtle can exert even more pressure than a Rottweiler
Sternocleidomastoid (prayer muscle)
Origin:Sternum and clavicle
Insertion:Mastoid process of temporal bone
Action:Pulls head to one side when only one contracts; flexes neck when both contract like you bowing your head to pray
Trapezius (named for trapezoid; has two parallel sides; on superior and posterior portion of back)
Origin: Occipital bone and ligamentum nuchae
Insertion:Spine of scapula and lateral third of clavicle
Action:Four actions 1 adducts scapula 2 depresses scapula 3 raises or elevates scapula 4 extends the head
Latissimus Dorsi (on inferior and posterior back)
Origin: Thoracolumbar fascia, all lumbar spines, lower thoracic spines
Insertion: Humeris
Action: Medial rotate, adduct, and depress humerus
Pectoralis major (chest muscle)
Origin:Sternum, medial clavicle, 2-6 costal cartilages
Insertion: Humerus
Action: Adduct and medial rotate the humerus
Deltoid (gives definition to the shoulder; is both anterior and posterior )
Origin:Lateral clavicle and spine of scapula
Insertion:Humerus
Action:Abducts humerus, assists the biceps and triceps
Rotator Cuffs
Four muscles associated with the scapula and having the same O, I, and A
Form a protective “cuff” around the ball and socket joint of the shoulder
Supraspinatus
(above spine of posterior scapula)
Infraspinatus
(below spine of posterior scapula)
Subscapularis
(covers anterior scapula)
Teres Minor
(on small portion of posterior scapula)
Rotator Cuffs
Origin:Scapula
Insertion:Proximal humerus
Action:Adduct and abduct humerus, mediallu, and laterally rotate humerus
Biceps Brachii (anterior arm muscle with two heads)
Origin: Short head -coracoid process of scapula; long head-superior lip of glenoid cavity
Insertion:Radius
Action:Supinator (turns hand palm up) and flexes forearm
Triceps Brachii (posterior arm muscle with three heads)
Origin: 1 head on scapula; 2 heads on proximal humerus
Insertion: Olecranon process of ulna
Action: Extends forearm, stabilizes the hinge joint of the elbow
Forearm muscles in general
Anterior forearm muscles are flexors of wrists and fingers
Posterior forearm muscles are extensors of wrists and fingers
Rectus abdominis (also called the six pack)
Origin: 5th, 6th, and 7th costal cartilages; xiphoid process of sternum
Insertion: Pubic bone; pubic symphysis
Action: Supports and protects abdominal and pelvic viscera; flexes vertebral column;hold in your gut)
The ____ ____ (white line of connective tissue going down midline of rectus abdominis) and umbilicus (belly button) are both landmarks of the rectus abdominis. The linea alba has no blood vessels so incisions are commonly made her to lessen bleeding
linea alba
The ____ _____has three muscles associated with it: transversus abdominis (innermost layer with muscle fibers extending around the midline); internal oblique (middle layer with muscle fibers running up at an angle) and external oblique (outermost layer with fibers running down at an angle )
rectus abdominis
External Oblique
Origin: Lower 8 ribs
Insertion: Linea alba
Action:Support and protect abdominal and pelvic viscera; flex vertebral column; aid in breathing, vomintting, defecating, childbirth, laughing, coughing, sneezing
