practical 3

Sternocleidomastoid

Two-headed neck muscle running diagonally from the manubrium and medial clavicle to the mastoid process; laterally flexes the neck and rotates the head to the opposite side.

Trapezius

Large, superficial diamond-shaped muscle of the posterior neck and upper back that extends from the occiput down to the lower thoracic vertebrae; elevates, retracts, and depresses the shoulder blade.

Occipitofrontalis

Epicranial muscle with anterior and posterior bellies linked by a central sheet-like tendon; wrinkles the forehead, raises the eyebrows, and draws the scalp posteriorly.

Orbicularis oculi

Sphincter muscle arranged in concentric rings around each orbital margin; closes eyelids during winking, squinting, and sleeping.

Orbicularis oris

Complex circular sphincter muscle enclosing the mouth opening; compresses, purses, and protrudes the lips.

Zygomaticus major and minor

Pair of diagonal cheek muscles extending from the malar bone downward to the corner of the mouth; elevates the oral angle laterally to produce a smile.

Mentalis

Small V-shaped muscle pair located on the apex of the chin; elevates and wrinkles chin skin while pushing the lower lip outward.

Masseter

Thick, rectangular muscle of mastication covering the lateral mandibular ramus; elevates the jaw to close the mouth during chewing.

Temporalis

Fan-shaped muscle filling the temporal depression on the lateral skull that passes beneath the zygomatic arch to the coronoid process; elevates and retracts the mandible.

Suprahyoid muscles

Cervical muscle group located superior to the hyoid bone that elevates the hyoid and larynx to support swallowing and vocalization.

Infrahyoid muscles

Ribbon-like strap muscles positioned below the hyoid bone that depress the hyoid and thyroid cartilage following deglutition.

External intercostals

Superficial intercostal layer with fibers angled inferomedially ('hands in pockets'); raises the ribs to expand the chest cavity during inspiration.

Pectoralis major

Broad, fan-shaped chest muscle arising from the sternum and clavicle and inserting into the upper humerus; adducts, flexes, and medially rotates the arm.

Diaphragm

Dome-shaped musculotendinous internal divider between thoracic and abdominal compartments; flattens downward to drive negative-pressure breathing.

Rectus abdominis

Pair of vertical abdominal straps bound within an aponeurotic sheath and divided by horizontal tendinous intersections; flexes the trunk and compresses viscera.

External abdominal oblique

Outermost lateral abdominal wall muscle whose fibers run obliquely downward and inward; compresses the abdomen and rotates the trunk.

Internal abdominal oblique

Intermediate abdominal layer with fibers oriented upward and medially; flexes and rotates the vertebral column while compressing abdominal organs.

Transversus abdominis

Deepest abdominal wall muscle characterized by horizontally traveling fibers; constricts abdominal contents to stabilize core posture.

Rhomboids (major and minor)

Deep back muscles positioned between the medial scapular border and the upper thoracic spine; retract and downwardly rotate the shoulder blade.

Serratus anterior

Saw-toothed muscle slips lining the lateral rib cage originating on ribs 1-8; protracts the scapula forward around the thorax ('boxer muscle').

Pectoralis minor

Deep triangular anterior thoracic muscle originating from ribs 3-5 and attaching to the coracoid process; tilts the scapula anteriorly and downward.

Supraspinatus

Superior rotator cuff muscle occupying the fossa above the scapular spine, inserting onto the humeral greater tubercle; initiates arm abduction.

Infraspinatus

Rotator cuff muscle positioned in the broad fossa below the scapular spine, inserting on the greater tubercle; laterally rotates the arm.

Teres minor

Narrow cylindrical rotator cuff muscle positioned directly beneath the infraspinatus along the lateral border; externally rotates and stabilizes the shoulder joint.

Subscapularis

Anterior rotator cuff muscle filling the ventral concavity of the shoulder blade and inserting on the lesser tubercle; medially rotates the arm.

Brachialis

Deep anterior arm muscle underlying the superficial flexor, inserting on the ulnar coronoid process; chief flexor of the elbow.

Biceps brachii

Two-headed anterior arm muscle originating from the scapular coracoid process and supraglenoid tubercle, inserting onto the radial tuberosity; flexes and supinates forearm.

Brachioradialis

Superficial lateral forearm muscle spanning from the lateral supracondylar ridge to the radial styloid process; flexes elbow in mid-pronation.

Triceps brachii

Large three-headed posterior arm muscle inserting into the olecranon of the ulna; primary extensor of the forearm at the elbow.

Extensor digitorum

Superficial posterior forearm muscle that splits into four long tendons inserting into phalanges 2-5; extends the fingers and wrist.

Palmaris longus

Slender superficial forearm muscle bearing a long cord-like tendon that inserts directly into the palmar aponeurosis; tenses palmar fascia and weakly flexes wrist.

Flexor carpi ulnaris

Medial-most superficial forearm flexor inserting onto the pisiform and fifth metacarpal; flexes and ulnar adducts the wrist.

Iliacus

Fan-shaped muscle filling the internal basin of the ilium that joins the lumbar spine flexor to insert on the lesser trochanter; flexes the hip.

Psoas major

Long, cylindrical muscle arising from the lumbar vertebrae and descending under the inguinal ligament to the lesser trochanter; flexes hip and lumbar spine.

Gluteus maximus

Bulky superficial buttock muscle originating from the ilium and sacrum and inserting on the femur and iliotibial band; powerfully extends and laterally rotates the thigh.

Gluteus medius

Fan-shaped lateral hip muscle underlying the largest gluteal muscle and inserting on the greater trochanter; abducts the thigh and keeps the pelvis level when walking.

Gluteus minimus

Deepest and smallest of the buttock muscle group, sitting directly beneath the middle gluteal muscle; abducts and medially rotates the thigh.

Rectus femoris

Central superficial quadriceps muscle arising from the anterior inferior iliac spine and crossing two joints; extends the knee and flexes the hip.

Vastus lateralis

Largest component of the quadriceps group situated on the lateral aspect of the thigh; extends the knee joint.

Vastus medialis

Teardrop-shaped quadriceps muscle situated on the anteromedial distal thigh; extends knee and stabilizes patellar tracking.

Vastus intermedius

Deep quadriceps muscle lying directly underneath the central superficial flexor on the anterior femoral shaft; extends the knee.

Sartorius

Long, narrow strap muscle crossing diagonally from the anterior superior iliac spine to the medial proximal tibia; flexes, abducts, and laterally rotates the thigh.

Biceps femoris

Lateral hamstring muscle featuring long and short heads inserting on the fibular head and lateral tibial condyle; extends the thigh and flexes the knee.

Semitendinosus

Medial hamstring muscle with a long round distal tendon attaching to the medial proximal tibia; extends thigh and flexes knee.

Semimembranosus

Deep medial hamstring muscle marked by a broad membranous proximal attachment that inserts onto the posterior medial tibial condyle; extends thigh and flexes knee.

Tibialis anterior

Superficial muscle lying directly lateral to the anterior shin crest, inserting into the first metatarsal and cuneiform; dorsiflexes and inverts the foot.

Gastrocnemius

Two-bellied superficial posterior calf muscle spanning from the femoral condyles to the calcaneus via the Achilles tendon; plantarflexes the foot and flexes the knee.

Soleus

Broad, flat calf muscle situated deep to the gastrocnemius heads that inserts onto the calcaneus; primary plantarflexor used for standing posture and walking.

Flexor carpi radialis

A muscle located in the forearm that flexes and abducts the wrist. It originates from the medial epicondyle of the humerus and inserts on the bases of the second and third metacarpal bones.