muscle pt 2 Flashcards
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 than 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
MUSCLES OF THE NECK
Sternocleidomastoid (prayer muscle)
O: sternum and clavicle
I: mastoid process of temporal bone
A: pulls head to one side when only one contracts; flexes neck when both contract like you’re bowing your head in prayer
MUSCLES OF THE CHEST, SHOULDER, AND UPPER LIMB
Trapezius (named for trapezoid; has two parallel sides; on superior and posterior portion of back)
O: occipital bone and ligamentum nuchae
I: spine of scapula and lateral third of clavicle
A: four actions: 1) adducts scapula; 2) depresses scapula; 3) raises or elevates scapula; 4) extends the head
MUSCLES OF THE CHEST, SHOULDER, AND UPPER LIMB latissimus dorsi (on inferior and posterior back)
O: thoracolumbar fascia, all lumbar spines, lower thoracic spines
I: humerus
A: medial rotate, adduct, and depress humerus
MUSCLES OF THE CHEST, SHOULDER, AND UPPER LIMB Pectoralis major (chest muscle)
O: sternum, medial clavicle, 2-6 costal cartilages
I: humerus
A: medial rotate, adduct, and depress humerus
MUSCLES OF THE CHEST, SHOULDER, AND UPPER LIMB
Deltoid (gives definition to the shoulder; is both anterior and posterior)
O: lateral clavicle and spine of scapula
I: humerus
A: abducts humerus, assists the biceps and triceps
MUSCLES OF THE CHEST, SHOULDER, AND UPPER LIMB
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
MUSCLES OF THE CHEST, SHOULDER, AND UPPER LIMB
Rotator Cuffs pt 2
1) supraspinatus (above spine of posterior scapula)
2) infraspinatus (below spine of posterior scapula)
3) subscapularis (covers anterior scapula)
4) teres major (on small portion of posterior scapula)
O: scapula
I: proximal humerus
A: adduct and abduct humerus, medially and laterally rotate humerus
MUSCLES OF THE CHEST, SHOULDER, AND UPPER LIMB Biceps brachii (anterior arm muscle with two heads)
O: short head-coracoid process of scapula; long head-superior lip of glenoid cavity
I: radius
A: supinator (turns hand palm up) and flexes forearm
MUSCLES OF THE CHEST, SHOULDER, AND UPPER LIMB Triceps brachii (posterior arm muscle with three heads)
O: 1 head on scapula; 2 heads on proximal humerus
I: olecranon process of ulna
A: extends forearm, stabilizes the hinge joint of the elbow
MUSCLES OF THE CHEST, SHOULDER, AND UPPER LIMB
Forearm muscles in general
- Anterior forearm muscles are flexors of wrists and fingers
- Posterior forearm muscles are extensors of wrists and fingers
MUSCLES OF THE DEEP BACK, ABDOMINAL WALL, AND PELVIC OUTLET Rectus abdominis (also called the six pack)
O: 5th, 6th, and 7th costal cartilages; xiphoid process of sternum
I: pibic bone; pubic symphysis
A: supports and protects abdominal and pelvic viscera; flexes vertebral column; holds in your gut
The linea alba (white line of ________ ______ going down midline of rectus abdominis) and _________(belly button) are both landmarks of the rectus abdominis. The linea alba has no ____ ________ so incisions are commonly made here to lessen bleeding.
connective tissue; umbilicus; blood vessels
The _______ ________ has three muscles associated with it: ___________ _______(innermost layer with muscle fibers extending around the midline); ________ _______(middle layer with muscle fibers running up at an angle) and ________ __________ (outermost layer with muscle fibers running down at an angle)
rectus abdominis; transversus; abdominis internal oblique; external oblique
