set 2: muscles of trunk and arms. muscles of respiration breathing requires the use of muscles –...
TRANSCRIPT
Set 2: Muscles of trunk and arms
Muscles of Respiration• Breathing requires the use of muscles– diaphragm– external intercostal muscles– internal intercostal muscles
• Contraction of the first 2 produces Inspiration• Contraction of the last produces Forced Expiration• Normal Expiration requires little muscular activity– elastic recoil of tissues and gravity collapsing the chest– only inspiratory muscles active in braking action, so
exhalation is smooth
Muscles of Respiration -- Diaphragm
• Muscular dome between thoracic and abdominal cavities
• Muscle fascicles extend to a fibrous central tendon
• Contraction flattens it– increases the vertical dimension of the thorax drawing air into
the lungs– raises the abdominal pressure to help expel urine, feces and
facilitating childbirth
Central tendon
Muscles of Respiration -- Intercostals
• External intercostals– extend downward and anteriorly
from rib to rib– pull ribcage up & outward during
inspiration
• Internal intercostals– extend upward and anteriorly
from rib to rib– pull ribcage downward during
forced expiration
Muscles of the Abdomen• 4 Pairs of sheetlike muscles– external oblique– internal oblique– transverse abdominis– rectus abdominis
• Functions– support the viscera– stabilize the vertebral column– help in respiration, urination, defecation & childbirth
Rectus Abdominis & External Oblique• External
oblique– superficial– downward – anteriorly– inguinal
ligament
• Rectus abdominis– vertical,
straplike– tendinous
intersections– rectus sheath– linea alba
External oblique Rectus abdominis
Internal Oblique -Transverse Abdominis
• Internal oblique– anteriorly– upwards
• Transverse abdominis– horizontal fiber
orientation– deepest layer
Transverse abdominisInternal oblique
Superficial Muscles of the Back
Trapezius
Latissimus dorsi
SemispinalisSplenius
Levator scapulaeRhomboideusSupraspinatusInfraspinatusTeres major
Gluteus maximusGluteus medius
Anterior Scapular Muscle Group• Pectoralis Minor– ribs 3-5 to coracoid
process of scapula– protracts &
depresses scapula– lifts ribs during
forced expiration
• Serratus Anterior– ribs 1-9 to medial
border of scapula– abducts & rotates
or depresses scapula
– throwing muscle
Muscles Acting on the Scapula
Posterior Scapular Muscle Group
• 4 Muscles – superficial = Trapezius– deep = Rhomboids & Levator scapulae
• Trapezius– rotate scapula upward– retract scapula– depress scapula
• With Levator scapulae & Rhomboids elevates scapula
• With Serratus anterior depresses scapula
• Rhomboideus mm.– medial border of
scapula to C7-T1
Posterior Scapular Muscle Group
• Levator scapulae– from superior angle
of scapula to C1-C4
Muscles Acting on the Humerus• 9 Muscles cross the shoulder joint to the humerus– 2 axial muscles arise from axial skeleton– prime movers of humerus in flexion & extension– arise from sternum & clavicle OR T7-L5 & ilium
Pectoralis major Latissimus dorsi
• 7 scapular muscles arise from scapula
– Deltoid is prime mover• flexion, extension and
abduction of humerus
– Coracobrachialis assists in flexion
– Teres major assists in extension
– Remaining 4 form the rotator cuff muscles that reinforce the shoulder joint capsule
Muscles Acting on the Humerus
Posterior View of Chest in Cadaver
Rotator Cuff Muscles• Extending from
posterior scapula to humerus – supraspinatus– infraspinatus – teres Minor
• Extending from anterior scapula to humerus – subscapularis
All 4 help reinforce joint capsule.
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
Anterior View of Chest in Cadaver
Muscles Acting on the Elbow• Principal flexors – biceps brachii • inserts on radius
– brachialis • inserts on ulna
• Synergistic flexor– brachioradialis
• Prime extensor– triceps brachii• inserts onto ulna
CS Through Upper Limb & Forearm
Supination & Pronation of the Forearm
Supination• Supinator muscle• Palm facing anteriorly
Pronation• Pronator teres and Pronator
quadratus mm.• Palm faces posteriorly