Naming Skeletal Muscles Named according to a number of criteria:•Direction of muscle fibers relative to longitudinal axis of the muscle

– Rectus: Fibers oriented straight with respect to longitudinal axis– Oblique: Fibers run at an angle to the longitudinal axis– Orbicularis: Fibers run in a circular path

•Relative size– Major for bigger and minor for smaller;– Maximus for biggest, intermedius for middle and minimus for smallest – Longus for longest and brevis for shortest.

•Location– Pectoralis major is found in the chest region– Rectus femoris is found near the femur

•Location of the origin and insertion– Brachioradialis attaches to the humerus (origin) and the radius (insertion)

•Number of origins– Biceps means two heads– Triceps means three heads

•Shape– Deltoid means triangular in shape.– Trapezius is shaped like a trapezium or kite

•Action – Flexor and extensor– Adductor and abductor

Skeletal Muscles Of Facial Expression

Skeletal Muscles Of Facial Expression• Frontalis: Lies over forehead; wrinkles forehead

and raises eyebrows• Orbicularis oculi: Encircle eye; close eyes, squint,

blink and wink• Zygomaticus: From cheek to corner of mouth;

raises corners of mouth for smiling• Orbicularis oris: Present in lips; closes mouth and

protrudes lips• Mentalis: In mental region; wrinkles chin,

protrudes lower lip• Buccinator: Thin muscles, attach to orbicularis

oris; compress cheek as in whistling and sucking

Skeletal Muscles Of Mastication

• Masseter: Powerful muscle covering lateral aspect of mandibular ramus; elevates mandible during chewing

• Temporalis: Covers parts of temporal, frontal and parietal bones; works with masseter to elevate mandible during chewing

• Digastric: Two bellies united by an intermediate tendon, forming V shape under the chin; open mouth and depress mandible

Muscles That Act The Head And Neck

• Sternocleidomastoid:Extends from

manubrium of sternum and clavicle to mastoid process of temporal; flexes and rotates the head laterally

Muscles Of Respiration

External intercostals: Lie between ribs; fibers run downwards and anteriorly; pull ribs towards one another to lift rib cageInternal intercostals: Lie between ribs; fibers run deep and at right angles to external intercostals (i.e. run downward and posteriorly); depress rib cageDiaphragm

Muscles Of Respiration• Diaphragm: Broad muscle, pierced by aorta, inferior vena cava and

oesophagus; forms floor of thoracic cavity; fibers converge from margins of thoracic cage towards central tendon; prime muscle for inspiration

Muscles Of Abdominal Wall

• Rectus abdominis: Medial superficial muscle pair extending from pubis to rib cage; segmented by 3 tendinous intersections; used in sit ups and curls

• External oblique: Largest and most superficial of 3 lateral muscles; fibers run downward and medially; flex vertebral column and compress abdominal cavity

• Internal oblique: Most fibers run upward and medially

• Transverse abdominis: Deepest layer, fibers run horizontally; compress abdominal contents

• Linea Alba: Tendinous raphe (seam) between right and left rectus abdominus

Muscles Of Anterior Thorax

• Pectoralis major: Large fan-shaped muscle covering superior part of chest; major muscle for flexion, rotation and adduction of arm

• Serratus anterior: Fan-shaped muscle, inferior to pectoral muscles on lateral rib cage; deep to scapula; origins have saw-tooth appearance; rotates scapula to inferior angle laterally and upwards

Trapezius Of Posterior Thorax

• Kite-shaped flat muscle• Upper fibers run inferiorly

to scapula• Middle fibers run

horizontally to scapula• Lower fibers run superiorly

to scapula• Major muscle for stabilizing,

raising, retracting and rotating scapula

Muscles Of Posterior Thorax

• Trapezius: Most superficial muscle of posterior thorax; stabilizes, raises, retracts and rotates scapula

• Levator scapulae: Located at back and side of neck, deep to trapezius; elevates or adducts scapula

• Rhomboids: Deep to trapezius, inferior to levator scapulae; the minor muscle is more superficial; stabilize scapula

Muscles Of The Arm

• Pectoralis major: Prime mover of arm flexion

• Latissimus dorsi: Prime mover of arm extension

• Deltoid: Thick, rounded shoulder mass, common site of intramuscular injection; prime mover of arm abduction

• Biceps brachii: Two-headed fusiform muscle; stabilizes shoulder joint; flexes elbow joint and supinates forearm

• Brachialis: Strong muscle, immediately deep to biceps brachii on humerus; major forearm flexer

• Brachioradialis: Superficial muscle of lateral forearm, extends from distal humerus to distal forearm; forearm flexer

• Triceps brachii: Large fleshy muscle of posterior compartment of arm, has 3 heads (long and lateral heads lie superficial to medial head); powerful forearm extensor

Latissimus dorsi

• Broad, flat triangular muscle of lower back; covered by trapezius superiorly

• Powerful mover of arm extension, adducts arm and medially rotates arm at shoulder

Rotator Cuff Muscles

• Group of 4 muscles and their tendons in the shoulder

• Muscles form a cuff around shoulder joint and attach at upper portion of arm

– Supraspinatus: Deep to trapezius, superior to scacpular spine; stabilizes shoulder joint, prevents downward dislocation of humerus

– Infraspinatus: Partially covered by deltoid and trapezius, inferior to scapular spine; rotates humerus laterally

– Teres minor : small elongated muscle, inferior to infraspinatus muscle; rotates humerus laterally

– Subscapularis: Forms part of posterior wall of axilla, tendon passes in front of shoulder joint; chief medial rotator of humerus

Muscles Of The Thigh, Leg, Foot And Ankle

Muscles Of The Thigh, Leg, Foot And Ankle

Muscles Of The Thigh, Leg, Foot And Ankle