Muscular System pt. 3

origin

attachment point that remains fixed when muscle produces its main movement

• often the most proximal attachment, or closest to body midline

insertion

attachment point that moves when muscle produces its main movement

• often distal attachment, or farthest from body midline

which 3 muscles move head, neck, &/or back

• sternocleidomastoid

• splenius capitis

• erector spinae

which 4 muscles move the abdomen?

• rectus abdominis

• external oblique

• internal oblique

• transversus abdominis

sternocleidomastoid

anterior muscle of the neck; rotate and laterally flex head & flex head (if both R&L used)

• origin: sternum & clavicle

• insertion: mastoid process (temporal)

torticollis

when one side of the sternocleidomastoid is shorter than the other; leads to head rotation and laterally flexion

• in infants, caused by development tissue or trauma

• in adults, caused by muscle spasm

splenius capitis

deep muscle of the back; laterally flex & extend head (if both R&L used)

• origin: thoracic & cervical vertebrae

• insertion: occipital & temporal

which muscles are part of the erector spinae muscle group?

• longissimus

• iliocostalis

• spinalis

the deep muscles of the back, laterally flex & extend head/back, also helps maintain posture

linea alba

midline connective tissue band running from sternum to pubis

what are the 4 abdominal wall muscles?

• external oblique

• internal oblique

• transversus abdominis

• rectus abdominis (formers anterior wall of abdomen)

**action: laterally flex, flex & rotate abdomen

external oblique

most superficial layer of the lateral abdominal wall muscles

• origin: ribs

• insertion: linea alba & ilium

internal oblique

middle layer of the lateral abdominal wall muscles

• origin: ilium

• insertion: linea alba & lower ribs

transversus abdominis

deepest layer of the lateral abdominal wall muscles

• origin: ribs & ilium

• insertion: linea alba

rectus abdominus

forms the midline of the anterior wall of the abdomen

• origin: pubis

• insertion: ribs & xiphoid process (sternum)

hernia

when internal organs/tissues bulge through a weak spot in surrounding tissue

inguinal hernia

bulge through the abdominal wall in the inguinal region

diaphragm

main breathing muscle

• action: expands thoracic cavity

intercostals

• origin: ribs

• insertion: ribs

• action: pulls ribs up or down (changes thoracic volume ot pulling air into or pushing air out of lungs)

muscles of the posterior part of the shoulder

• trapezius

• latissimus dorsi

trapezius

superficial shoulder muscle on the back

• origin: occipital & vertebrae

• insertion: scapula & clavicle

• action: MANY movements

latissimus dorsi

superficial shoulder muscle on the back

• origin: vertebrae & ilium

• insertion: humerus

• action: adduct & extend shoulder

muscle of the anterior part of the shoulder

pectoralis major

pectoralis major

superficial shoulder muscle on the anterior trunk

• origin: sternum & clavicle

• insertion: greater tubercle (humerus)

• action: adduct & flex shoulder

muscle of the posterior, lateral, and anterior part of the shoulder (shoulder-covering muscle)

deltoid

rotator cuff muscles

• teres minor

• subscapularis

• supraspinatus

• infraspinatus

**action: stabilize shoulder joint, common insertion: humerus

rotator cuff injuries are typically caused by what?

• an acute injury-causing event

• repetitive stress

• age-related degeneration

what are the three anterior arm muscles?

• biceps brachii

• brachialis

• brachioradialis

**action: flex elbow

biceps brachii

main elbow flexor

• origin: scapula

• insertion: radius

brachioradialis

• origin: humerus (distal)

• insertion: radius

brachialis

• origin: humerus (mid)

• insertion: ulna

SLAP (superior labrum tear anterior-posterior)

repetitive stress injury caused by forces placed on biceps tendon when throwing

• common in “overhead” athletes

triceps brachii

posterior arm muscle

• origin: scapula & humerus

• insertion: olecranon process (ulna)

**action: extend elbow (& shoulder)

muscles that rotate the radius

supinator

• origin: humerus & ulna

• insertion: radius

• action: supinate

pronator teres

• origin: humerus & ulna

• insertion: radius

• action: pronate

muscles that flex/extend wrist

flexor & extensor carpi radialis

• origin: humerus

• insertion: base of metacarpals

flexor & extensor carpi ulnaris

• origin: humerus & ulna

• insertion: base of metacarpals

muscles that flex the fingers

flexor digitorum superficialis

• origin: humerus, radius & ulna

• insertion: middle phalanx of digits 2-5

flexor digitorum profundus

• origin: ulna

• insertion: distal phalanx of digits 2-5

muscle that extends the fingers

extensor digitorum

• origin: humerus

• insertion: distal phalanx of digits 2-5

carpal tunnel syndrome

flexor tendons and a nerve run through small “tunnel” formed from carpal bones

• repetitive movement of tendons can irritate the nerve leading to numbness/tingles/pain