Muscles Flashcards
Temporalis
O: Temporal fossa
I: Anterior portion of the mandibular ramus and coronoid process
A: Elevates mandible; also involved in retraction and lateral excursion
Sternocleidomastoid
O: Manubrium and medial portion of the clavicle
I: Mastoid process and superior nuchal line
A: One contracting alone: laterally flexes head and neck to the same side and rotates head/neck to the opposite side.
Both contracting together: flexes neck.
Rectus abdominis
O: Pubic crest and symphysis
I: Xiphoid process and inferior ribs (5–7)
A: Flexes lumbar spine; compresses abdomen; unilaterally flexes trunk ipsilaterally
Iliopsoas
O: Psoas major & Psoas minor: on intervertebral cartilages, along bodies and on lower borders of transverse processes of L1–5; body of T12, on sacrum lateral and inferior to L5–S1 articulation
I: Iliacus & psoas major: lesser trochanter of femur and shaft immediately inferior
I: Psoas minor: Pectineal line and iliopectineal eminence of ilium
A: Flexion of the hip.
External rotation of femur
Weak flexor of trunk
Pectoralis major
O: Medial half of anterior surface of clavicle, anterior surface of costal cartilages of ribs 1–6 and adjacent sternum
I: Greater tubercle of the humerus and intertubercular crest (lateral aspect of intertubercular groove)
A: Adducts in frontal plane, flexes in sagittal plane, horizontally adducts in transverse plane, and internally rotates arm
Latissimus dorsi
O: Posterior crest of ilium, spinous processes of T7– S3, ribs 10–12
I: Medial side of intertubercular groove of humerus
A: Adducts in frontal plane, extends in sagittal plane, horizontally abducts in transverse plane, and internally (medially) rotates arm
Deltoid
3 portions:
O: anterior lateral 1/3 of clavicle, lateral aspect of acromion process, and inferior edge scapular spine
I: Deltoid tuberosity of humerus (lateral) (anterior portion)
A: Adducts arm, assists in flexion, horizontal adduction, and internal rotation of glenohumeral joint (GHJ); (lateral portion) abduction of GHJ; (posterior portion) abduction, extension, horizontal abduction, and lateral rotation of GHJ
Biceps brachii
O: Long head: superior margin of glenoid fossa; Short head: coracoid process of scapula
I: Radial (bicipital) tuberosity of radius and bicipital aponeurosis
A: Flexes elbow, weakly flexes glenohumeral joint; supinates hand
Triceps brachii
O: Long head: Infraglenoid tubercle of scapula; Lateral head: lateral and posterior surfaces of the humerus; Medial Head: posterior humerus
I: Olecranon process of ulna
A: Extends elbow; adducts and extends glenohumeral joint
Extensor digitorum
O: Lateral epicondyle of humerus
I: 4 tendons to the dorsal surfaces of the base of middle and distal phalanges of fingers 2–5
A: Extends digits 2–5 at metacarpophalangeal (MCP) joints and wrist; weak extension of elbow
Flexor digitorum superficialis
O: Medial epicondyle of humerus; medial coronoid process of ulna; upper 2/3 of anterior border of radius
I: 4 tendons that divide and attach to the sides of medial phalanges of fingers 2–5
A: Flexes digits at MCP and PIP joints, flexes wrist; weak flexion of elbow
Gluteus maximus
O: Posterior 1/4 of iliac crest; posterior surface of sacrum and coccyx near ilium; and lumbar fascia
I: illiotibial band (tract) of fasci latae; Oblique ridge on greater trochanter;
Ridge on posterior femur surface inferior to trochanters (gluteal tuberosity);
A: Stabilizes trunk in hip extension; extension and external rotation of hip; lower fibers assist in hip adduction
Rectus femoris
O: Anterior surface of inferior iliac spine and superior & posterior margin of acetabulum
I: Superior aspect of patella and patellar tendon to the tibial tuberosity
A: Extension of the knee and flexion of the hip
Biceps femoris
O: Long head: ischial tuberosity; Short head: lower half of linea aspera and lateral condylar ridge of femur
I: Lateral condyle of tibia and head of fibula
A: Flexion of knee, extension of hip, external rotation of hip and knee
Gastrocnemius
O: Medial head: posterior surface of the medial femoral condyle; Lateral head: posterior surface of the lateral femoral condyle
I: Posterior surface of calcaneus via calcaneal (Achilles’) tendon
A: Plantar flexion of ankle; weak flexion of the knee
