Muscles I Flashcards
Human motion
-generated by forces acting on levers about axes (joints)
-anatomically, these forces are muscular contractions
Muscle function:
To cause movement, both ends of each muscle must be attached to bone:
-origin or proximal attachment - the attachment closer to the centre of the body
-insertion or distal attachment - the attachment is away from the centre of the body
Agonists
Prime movers
Antagonist
Opposing muscles
Stabilizers:
-ex. When arm internally rotates, the muscle is attached to the humerus & scapula & it will try to move both bones… unless scapula is stabilized
Muscle function & mobility is influenced by:
-muscular strength
-muscular flexibility
-tendons
-coordination (motor)
Muscles that move the head & neck:
-muscles posterior, anterior, lateral to the neck (cervical region)
Muscles that move the head & neck: functions
-maintain a neural head position
-permit a wide range of movement
Muscles that move the head & neck: sternocleidomastoid attachments:
(Sternum/ clavicle/ mastoid process) - bump behind ear
-sternum & clavicle to origin
-base of skull (mastoid process) insertion
Sternocleidomastoid function:
-flexes neck to chest - when all sides contract
-rotates neck & head toward opposite shoulder - when one side contracts
Muscles that move the head & neck: erector spine attachments:
Skull
-superior: skull (back)
-inferior: sacrum & ilium (posterior)
Erector spine functions:
Ability to maintain erect position
-upper portion extends the neck
-lower portion extends trunk
Muscles that move the trunk:
-rectus abdominis, obliques, transverse abdominis
Function:
-flexion, extension (mild)
-lateral flexion
-rotation
-expel contents through colon
Anterior muscles that move the trunk: rectus abdominis (L,R) attachments:
-sternum & adjacent ribs to pubic bone
Rectus abdominis functions:
-trunk flexion
-pelvis stabilization
Anterior muscles that move the trunk: abdominal external oblique (L,R) attachments
-lateral ribs downward to
-anterior crest of ilium, pubis, linea alba
Abdominal external oblique (L,R) function:
-trunk flexion & rotation
-pelvis stabilization
Anterior muscles that move the trunk: abdominals internal obliques (2) attachments:
-linea alba downward to
-lateral crest of pubis & ilium
Abdominals internal obliques (2) functions:
-trunk flexion
-pelvis stabilization
Anterior muscles that move the trunk: abdominals trans versus abdominis (L,R) attachments:
-linea alba to
-lower ribs, crest of ilium & to spine
Abdominals trans versus abdominis (L,R) functions:
-compresses abdomen
-spine & trunk stabilization
Posterior muscles that move the trunk: erector spinae attachments:
Runs length of the spine
-iliac crest
-all vertebrae to skull
Erector spinae functions:
-trunk extension, anti gravity muscles
-very important in back injury prevention
Posterior muscles that move the trunk: erector spinae:
Lateral flexion of the trunk (to the right):
-right abdominals (not tranversus)
-right erector spinae
Muscles that move the humerus: deltoid
Anterior deltoid
Middle deltoid
Posterior deltoid
Muscles that move the humerus: anterior deltoid attachment
Proximal attachment: origin
-lateral clavicle
Distal attachment: insertion
-deltoid tubercle of humerus
Anterior deltoid function
-shoulder (humerus) flexion
-internal (medial) rotation
Muscles that move the humerus: middle deltoid attachment
Proximal: origin
-lateral clavicle, acromion process
Distal: insertion
-deltoid tubercle of humerus
Middle deltoid function
-shoulder (humerus) abduction
Muscles that move the humerus: posterior deltoid attachment
Proximal: origin
-lateral spine of the scapula
Distal: insertion
-shoulder (humerus) extension
-external (lateral) rotation
Muscles that move the humerus: pectoralis major attachment
Proximal: origin
-sternum & clavicle
Distal: insertion
-lip of bicipital groove of humerus
Pectoralis major function:
-horizontal adduction of humerus
-bringing arm down from overhead (in extension or adduction)
-internal (medial) rotation of humerus
Muscles that move the humerus: Latissimus dorsi attachment
Proximal: originate
-bottom 6 thoracic vertebrae
-all lumbar vertebrae, sacrum
Distal: insertion
-pass under arm to the lip of bicipital groove
Latissimus dorsi function:
-horizontal adduction of humerus
-bringing arm down from overhead (in extension or adduction)
-internal (medial) rotation of humerus
Muscles that move the humerus: supraspinatus attachments
Proximal: origin
-supraspinous fossa of scapula
Distal: insertion
-superior (top of) humerus
Supraspinatus function:
-abducts humerus
Muscles that move the humerus: Infraspinatus attachment
Proximal: origin
-infraspinous fossa of scapula
Distal: insertion
-posterior (proximal) humerus
Infraspinatus functions:
-abducts humerus
-lateral rotation of humerus
Muscles that move the humerus: Subscapularis attachments
Proximal: origin
-subscapular fossa of scapula
Distal: insertion
-anterior proximal humerus
Subscapularis function
-abducts humerus
-medial rotation of humerus
Rotator cuff: SIS
Subscapularis
Infraspinatus
Supraspinatus
Muscles that move the scapula: trapezius
Proximal: origin
-base of skull to T12 vertebrae
Distal: insertion
-spine of scapula
Trapezius function:
-scapular stabilization (scapular)
-upper: shoulder elevation (neck extension)
-middle: shoulder retraction (scapular adduction)
-lower: shoulder depression
Muscles that move the scapula: Serratus anterior attachment
Proximal:
-anterior medial border scapula
Distal:
-anterior ribs 1-8
Serratus anterior function
-scapular stabilization
-shoulder protraction
Muscles that stabilize the scapula:
-the muscles that move the scapula (trapezius) will also be very important stabilizers or fixations of the scapula when other muscles attempt to move the humerus
-improper conditioning of the prime movers without any conditioning the stabilizers is cause for many injuries
