Intro to muscular system, should complex and upper limb muscles

how do muscles attach to bones or other structures?

via tendons (made of dense regular CT)

what is the origin of muscles?

attachment point on bone/structure that is more stable, normally most proximal or medial attachment

what is muscle insertion?

attachment point to bone/structure that is more moveable, normally most distal or lateral attachment

what happens when muscles contract?

pull structures they are attached to closer together

what are functions of muscles?

muscles can only contract or relax; actions of one muscle are counteracted by those of another

what is an agonist?

the primary muscle performing a specific action

what is an antagonist?

the muscle(s) performing the opposite action

what is a synergist?

muscles that aid, adjust, and/or stabilize the action of the agonist

for elbow flexion with supinated forearms, what is the agonist, antagonist, and synergist?

agonist: biceps brachii

antagonist: triceps brachii

synergists: brachialis and brachioradialis (both flex elbow)

what are 5 types of muscles?

circular, convergent, fusiform, parallel, and pennate muscles

what are circular muscles?

muscle ribers arranged in a ring (sphincter)

what are convergent muscles?

muscle fibers have broad origin that converge to single insertion point

what is fusiform muscle?

expanded muscle belly that tapers at ends

what are parallel muscles?

fibers run parallel, creating strap-like muscles

what are pennate muscles?

fibers meet tendon at an angle

what is good about pennate muscles?

allows higher density of fibers per tendon

what are the different types of pennate muscles?

unipennate= fibers on one side of tendon

bipennate = fibers on both sides of tendon

multipennate = multiple bipennate “subtendons” that converge

example of circular muscle?

orbicularis oris

example of convergent muscle?

pectoralis major

example of fusiform muscle?

biceps brachii

example of parallel muscle?

sartorius

example of mulipennate?

deltoid

example of bipennate?

rectus femoris

example of unipennate?

extensor digitorum longus

How to infer muscle action?

based on origin and insertion and where the muscle crosses a joint

a muscle that crosses on the anterior side of a joint produces what function? example?

produces flexion

ex. pectoralis major

a muscle that crosses on the posterior side of a joint produces what action? ex?

produces extension

ex. latissimus dorsi

a muscle taht crosses on the lateral side of a joint produces what action? ex?

produces abduction

ex. deltoid middle fibers

a muscle that crosses on the medial side of a joint produces what action? ex.?

produces adduction

ex. teres major

what is fascia?

a connective tissue membrane that bundles structures together in the body

how are muscles often grouped together?

grouped together by being enveloped in fascial compartments

what’s helpful aobut facsial compartments?

helpful generalizing a muscle group’s common set of functions

ex. the anterior compartment of the arm contains 3 muscles: all of them flex either at the shoulder, the elbow, or both

where do axioappendicular muscles of the back originate and insert?

originate on axial skeleton and insert on either pectoral girdle or humerus

what are the axioappendicular back muscles?

trapezius (most superfical of back muscles)

latissimus dorsi

rhomboid major and rhomboid minor, both are deep to traps

levator scapulae (superior aspect of scapula and go to neck)

teres major

what are actions of trapezius?

elevates, depresses, and retracts scapula

actions of latissimus dorsi?

extends, adducts, and medially rotates arm at shoulder

actions of teres major?

extends, adducts, and medially rotates arm at shoulder but is more a synergist to lats

actions of rhomboids major and minor?

retracts scapula and rotates it downward

actions of levator scapulae?

elevates scapula and rotates it downward

what are the axioappendicular muscles of the “front”

pectoralis major and minor, and serratus anterior and maybe deltoid

action of pectoralis major?

flexes, adducts, and medially rotates arm at shoulder

actions pectoralis minor?

depresses scapula, holds scapula against rib cage

actions of serratus anterior?

protracts scapula and rotates it upward

deltoid actions?

abduction, flexion, extension, medial rotation and lateral rotaion of arm at shoulder

what are the posterior rotator cuff muscles?

supraspinatus, infraspinatus, and teres minor

what is origin, insertion, and action of supraspinatus?

origin: supraspinous fossa

insertion: greater tubercle of humerus

action: abduction of arm at shoulder

what is origin, insertion, and action of infraspinatus?

origin: infraspinous fossa

insertion: greater tubercle of humerus

action: lateral rotation of arm at shoulder

what is origin, insertion, and action of teres minor?

origin = lateral border of scapula

insertion = greater tubercle of humerus

action = lateral rotation of arm at shoulder

what is the anterior rotator cuff muscle?

subscapularis

origin, insertion, and action of subscapularis?

origin: subscapular fossa

insertion: lesser tubercle of humerus

action: medial rotation of arm at shoulder

what 4 muscles carry out shoulder abduction?

supraspinatus, deltoid, trapezius, and serratus anterior

what muscle initiates abduction?

supraspinatus (015º)

what muscle abducts from 15-180º?

deltoid

what muscles do upward roation of scapula past 90º abduction?

serratus anterior and trapezius

what muscles are in the anterior compartment of the arm?

coracobrachialis, biceps brachii, and brachialis

what is the origin, insertion, and action of coracobrachialis?

origin: coracoid process

insertion: shaft of humerus

action: flexion of arm at shoulder

what is origin, insertion, and action of biceps brachii?

origin: scapula (long head: supraglenoid tubercle, short head: coracoid process)

insertion: radial tuberosity

action: flexion of forearm at elbow and arm at shoulder. also supination of forearm

what is origin, insertion, and action of brachialis?

origin: shaft of humerus

insertion: ulnar tuberosity

action: flexion of arm at elbow

what muscles are in posterior compartment of arm?

triceps brachii and anconeus

origin, insertion, and action of triceps brachii?

origin: scapula and humerus

insertion: olecranon process

action: extension of forearm at elbow (all heads), extension of arm at shoulder (long head only)

function of anconeus?

weakly extends forearm at elbow

synergist to elbow extension

what are the three layers of the forearm and how many muscles in each?

superficial: 4 muscles

intermediate: 1 muscle

deep: 3 muscles

what are general actions of forearm?

flexion of wrist, digits and thumb. pronation of forearm

what are the muscles in the superficial and intermediate layer of forearm?

flexor digitorum superficalis, flexor carpi radialis, pronator teres, palmaris longus, and flexor carpi ulnaris

what does the flexor digitorum superficialis do?

flexes digits 2-5 at proximal interphalangeal joint (between proximal and middle phalanx)

• total of 4 tendons which insert on phalanges

what does the flexor carpi ulnaris do?

flexes wrist

what does palmaris longus do?

tenses skin of palm

what does the pronator teres do?

pronates forearm

• has most notable angle on forearm

what does the flexor carpi radialis do?

flexes wrist