A&P 1: Muscles

Functional Joint

Functional Joint

Based on relative joint mobility (synarthrosis, amphiarthrosis, and diarthrosis)

Structural Joint

Based on the way bones are held together (cartilaginous, fibrous, and synovial)

Temporalis

Origin: Temporal fossa Insertion: Anterior mandibular ramus; Anterior coronoid process Actions: Elevates mandible

Sternocleidomastoid

Origin: Manubrium; Medial clavicle Insertion: Mastoid process; Superior nuchal line Actions: Flexes neck

Rectus Abdominis

Origin: Pubic crest; Pubic symphysis Insertion: Xiphoid process; Inferior ribs (5-7) Actions: Compresses abdomen

Iliopsoas

Origin: Iliacus (inner iliac surface); Psoas major/minor (T12-L5; Lateral/inferior sacrum) Insertion: Iliacus/Psoas major (Lesser trochanter, adjacent femoral shaft). Psoas minor (pectineal line; Iliopectineal eminence) Actions: flexes hip

Pectoralis Major

Origin: Medial half of anterior clavicle; Anterior costal cartilage Insertion: Greater tubercle of humerus; Lateral intertubercular groove Actions: Adducts in frontal plane

Latissimus Dorsi

Origin: Posterior crest of ilium; T7-S3 spinous processes; Ribs 10-12 Insertion: Medial intertubercular groove (humerus) Actions: Internally rotates arm

Deltoid

Origin: Anterior lateral 3rd of clavicle; Lateral acromion process; Inferior scapular spine Insertion: Deltoid tuberosity Actions: Abducts the arm

Biceps brachii

Origin: Coracoid process (short head); superior margin of glenoid fossa (long head) Insertion: Radial tuberosity; Bicipital aponeurosis Actions: Flexes elbow

Triceps brachii

Origin: Infraglenoid tubercle (long head); Lateral humeral surface (lateral head); posterior humeral surface (medial head) Insertion: Olecranon process (ulna) Actions: extends elbow

Extensor Digitorum

Origin: Lateral epicondyle (humerus) Insertion: tendons to dorsal bases of middle and distal phalanges, fingers 2-5 Actions: Weak elbow extension

Flexor Digitorum Superficalis

Origin: Medial epicondyle (humerus); Medial coronoid process (ulna); upper 2/3 of anterior radius Insertion: Tendons divide and attach to sides of middle phalanges of fingers 2-5 Actions: Flexes wrist

Gluteus Maximus

Origin: Posterior sacrum & coccyx; Posterior 1/4 iliac crest; Lumbar fascia Insertion: Lateral greater trochanter (femur); Iliotibial band of fascia lata Actions: Stabilizes trunk in hip extension

Rectus Femoris

Origin: Anterior inferior iliac spine; Superior/posterior margin of acetabulum Insertion: Superior aspect of patella; Patellar tendon to tibial tuberosity Actions: Extend knee

Biceps Femoris

Origin: Ischial tuberosity (long head); lower 1/2 linea aspera, lateral condylar ridge (short head) Insertion: Lateral condyle (tibia); head (fibula) Actions: Flex knee

Gastrocnemius

Origin: posterior surface of medial femoral condyle (medial head); posterior surface of lateral femoral condyle (lateral head) Insertion: Posterior calcaneus via Achilles’ tendon Actions: Plantar flex ankle

Tibialis Anterior

Origin: Upper 2/3 of lateral tibia Insertion: inner surface of medial cuneiform & 1st MT Actions: Dorsiflex ankle

Supraspinatus

Origin: Medial 2/3 supraspinous fossa (scapula) Insertion: Superior surface of greater tubercle (humerus) Actions: Stabilize GHJ

Infraspinatus

Origin: Medial aspect of infraspinous fossa (scapula) Insertion: Posterior surface of greater tubercle (humerus) Actions: Stabilize GHJ

Teres Minor

Origin: Posterior upper/middle aspects of lateral scapular border Insertion: Posterior surface of greater tubercle (humerus) Actions: Stabilize GHJ

Subscapularis

Origin: Subscapular fossa (scapula) Insertion: Lesser tubercle (humerus) Actions: Stabilize GHJ

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