Muscles of the Human Body: Thorax, Back, Limbs, Abdomen, Head, and Neck

Comprehensive flashcards covering the origin, insertion, and action of key human muscles across the thorax, back, upper limb, abdomen, lower limb, head, and neck based on the lecture summary tables.

Grande pettorale

A thoracoappendicular muscle with three origins: the clavicular part (medial half of the anterior margin of the clavicle), the sternocostal part (anterior surface of the sternum and 2nd to 6th costal cartilages), and the abdominal part (upper anterior lamina of the rectus sheath). It inserts onto the crest of the greater tubercle of the humerus. Action: adducts and internally rotates the humerus, elevates the trunk if fixed on the humerus, and acts as an accessory inspiratory muscle.

Piccolo pettorale

A thoracoappendicular muscle originating from ribs II, III, and IV and inserting onto the coracoid process of the scapula. Action: lowers the scapula when fixed on the thorax; elevates the ribs (inspiratory muscle) when the scapula is fixed.

Succlavio

An extrinsic thoracic muscle originating from the superior surface of rib I and its costal cartilage, inserting into the subclavian groove on the inferior surface of the clavicle. Action: depresses the clavicle.

Dentato anteriore

A thoracoappendicular muscle originating from the lateral surface of the first 10 ribs and inserting into the medial border of the scapula. Action: shifts the scapula forward and outward, and elevates the ribs (inspiratory muscle).

Diaframma

An extrinsic thoracic muscle with sternal (posterior xiphoid process), costal (inner surface of the lower 6 ribs), and lumbar origins (right medial crus [L2-L4], left medial crus [L2-L3], intermediate crura [L3 body], and lateral crura [L2 costiform processes]). It inserts into the central tendon (centro tendineo). Upon contraction, it lowers and elevates the last 6 ribs, widening the thoracic cavity and causing inspiration.

Muscoli elevatori delle coste

Intrinsic thoracic muscles originating from the transverse processes of C7-T11. They insert onto the superior border and external surface of the rib below (brevis), or may skip a rib in the lower thorax to reach the next one down (longus). Action: elevate the ribs (inspiratory muscles).

Muscoli intercostali

Intrinsic thoracic muscles organized in three layers: external intercostals (origin: inferior border of ribs; insertion: superior border of the rib below; inspiratory), internal intercostals (origin: medial lip of costal groove; insertion: superior border of rib and costal cartilage below; expiratory), and innermost intercostals (origin: inferior border of ribs internally; insertion: superior border of the rib below; expiratory).

Trasverso del torace

An intrinsic thoracic muscle originating from the posterior surface of the body and xiphoid process of the sternum and inserting onto the internal surface and inferior border of costal cartilages II through VI. Action: depresses the costal cartilages (expiratory).

Trapezio

A spinoappendicular muscle divided into three parts: descending (origin: superior nuchal line, external occipital protuberance, nuchal ligament; insertion: lateral third of the posterior border of the clavicle), transverse (origin: spinous processes and interspinous ligaments C7-T3; insertion: medial border of acromion and posterior scapular spine), and ascending (origin: spinous processes and interspinous ligaments T3-T12; insertion: medial scapular border at spine origin). Action: moves, elevates, or depresses scapula; tilts head or elevates trunk.

Grande dorsale

A spinoappendicular muscle originating via the posterior layer of the thoracolumbar fascia at spinous processes of the lower 6-7 thoracic vertebrae, lumbar vertebrae, median sacral crest, and external lip of the posterior iliac crest; inserts into the crest of the lesser tubercle of the humerus. Action: brings humerus backward with internal rotation; lifts trunk and ribs when fixed on humerus.

Dentato posteriore superiore

A spinocostal muscle originating from the spinous processes of C6-T2 and inserting onto the external surface of ribs II to V lateral to the costal angle. Action: elevates the ribs (inspiration).

Dentato posteriore inferiore

A spinocostal muscle originating from the posterior layer of the thoracolumbar fascia at spinous processes T11-L3 and inserting onto the external surface of the last four ribs. Action: depresses the ribs (expiratory).

Muscolo erettore della colonna

A major spinodorsal muscle complex comprising the iliocostalis, longissimus, and spinalis columns. Action: extends the vertebral column to maintain an erect posture; slips inserting into the head bilaterally extend the head, or unilaterally extend and tilt the head toward the ipsilateral side.

Muscoli trasversospinali

Deep spinodorsal muscles including semispinalis (thoracis, cervicis, capitis), multifidus, and rotatores. Action: extend the vertebral column and rotate it to the contralateral side; fibers inserting onto the occipital bone extend the head and rotate it contralaterally.

Deltoide

A shoulder muscle composed of three parts: clavicular (origin: lateral third of anterior clavicle), acromial (origin: apex and lateral margin of acromion), and spinous (origin: posterior margin of scapular spine). All insert into the deltoid tuberosity of the humerus. Action: abducts humerus (whole muscle); flexes/internally rotates (clavicular); extends/externally rotates (spinous); elevates trunk when fixed on humerus.

Sottoscapolare

A shoulder muscle originating from the subscapular fossa of the scapula and inserting into the lesser tubercle of the humerus. Action: adducts, internally rotates the humerus, and stabilizes the glenohumeral joint.

Sopraspinato

A shoulder muscle originating from the medial 2/3 of the supraspinous fossa of the scapula and inserting into the superior facet of the greater tubercle of the humerus. Action: abducts and externally rotates the humerus, and stabilizes the shoulder joint.

Bicipite brachiale

A biarticular anterior arm muscle with a long head (origin: supraglenoid tubercle of scapula) and a short head (origin: apex of coracoid process), inserting into the radial tuberosity. Action: stabilizes humerus head in the glenoid cavity, assists arm flexion, adduction, and abduction; flexes the forearm on the arm and acts as a supinator when the forearm is pronated.

Tricipite brachiale

A posterior arm muscle consisting of a long head (origin: infraglenoid tubercle of scapula), lateral head (origin: posterior humerus above radial groove), and medial head (origin: posterior humerus below radial groove), all inserting into the olecranon of the ulna. Action: adducts and extends the humerus at the shoulder; extends the forearm at the elbow.

Brachioradiale

A lateral forearm muscle originating from the lateral supracondylar ridge and lateral epicondyle of the humerus and inserting into the styloid process of the radius. Action: flexes the forearm on the arm and maintains the forearm in an intermediate position between pronation and supination.

Muscoli lombricali (mano)

Hand muscles originating from the lateral borders of the four flexor digitorum profundus tendons (the 3rd and 4th also arise from adjacent medial borders), inserting onto the dorsal extensor expansion of digits 2 through 5. Action: flex the proximal phalanges and extend the middle and distal phalanges of the medial four digits.

Retto anteriore dell'addome

An anterior abdominal muscle originating with three heads from the external surface of costal cartilages V, VI, VII and the xiphoid process, inserting into the superior pubic ramus between the pubic tubercle and pubic symphysis. Action: depresses the ribs (expiratory), flexes the thorax on the pelvis (or vice versa), and increases intra-abdominal pressure.

Obliquo esterno dell'addome

An anterolateral abdominal muscle originating from the outer surfaces of the lower 8 ribs and inserting into the iliac crest and an aponeurosis forming the inguinal ligament and superficial inguinal ring crura. Action: depresses ribs (expiratory); unilaterally tilts lumbar spine and rotates thorax contralaterally; bilaterally flexes lumbar spine and increases intra-abdominal pressure.

Quadrato dei lombi

A posterior abdominal muscle composed of a posterior bundle (origin: inner lip of iliac crest and iliolumbar ligament; insertion: costiform processes of L1-L4 and lower border of rib XII) and an anterior bundle (origin: costiform processes of L2-L4; insertion: rib XII). Action: depresses rib XII and laterally tilts the lumbar spine and pelvis.

Grande psoas

An internal hip muscle originating from fibrous arches spanning the lateral surfaces of bodies T12-L4 and intervening intervertebral discs, inserting into the lesser trochanter of the femur. Action: flexes, adducts, and externally rotates the thigh when fixed on the spine; flexes and ipsilaterally bends the trunk when fixed on the femur.

Grande gluteo

A superficial gluteal muscle originating from the iliac crest, posterior gluteal line, thoracolumbar fascia, gluteus medius fascia, sacrotuberous ligament, and lateral surfaces of the sacrum and coccyx; inserts into the gluteal tuberosity of the femur and iliotibial tract. Action: extends and externally rotates the thigh; extends the pelvis when fixed on the femur.

Piriforme

A deep external hip muscle originating from the pelvic surface of the sacrum lateral to the II, III, and IV anterior sacral foramina and the margin of the greater sciatic notch; inserts into the superior end of the medial surface of the greater trochanter. Action: externally rotates and abducts the femur, and stabilizes the hip joint.

Sartorio

An anterior thigh muscle originating from the anterior superior iliac spine (spina iliaca anteriore superiore) and inserting into the upper medial surface of the tibia. Action: flexes the leg on the thigh and thigh on the pelvis; abducts and externally rotates the thigh (crossing legs).

Quadricipite femorale

An anterior thigh muscle comprising the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius, inserting onto the patella and via the patellar ligament into the tibia. Action: extends the leg at the knee, flexes the thigh on the pelvis (via rectus femoris), and maintains upright posture and ambulation.

Tibiale anteriore

An anterior leg muscle originating from the lateral surface of the tibia, interosseous membrane, and crural fascia; inserts into the medial surface of the 1st cuneiform and base of the 1st metatarsal. Action: dorsiflexes and supinates (inverts) the foot; brings the leg closer to the dorsum of the foot when weight-bearing.

Muscolo tricipite della sura

A superficial posterior leg muscle complex consisting of the gastrocnemius (medial and lateral heads from the femoral epicondyles/condyles) and soleus, inserting into the calcaneal tuberosity via the Achilles tendon. Action: produces plantarflexion and supination; flexes the leg on the thigh; extends the leg on the foot when weight-bearing.

Popliteo

A deep posterior leg muscle originating from the lateral epicondyle of the femur and posterior capsule of the knee, inserting into the posterior surface of the tibia above the soleal line. Action: flexes the leg on the thigh and internally rotates the leg.

Muscolo massetere

A masticatory muscle composed of a superficial part (anterior portion of the lower margin of the zygomatic arch) and deep part (posterior portion of the lower margin of the zygomatic arch), inserting into the masseteric tuberosity on the lateral surface of the mandibular ramus. Action: elevates the mandible.

Muscolo pterigoideo laterale

A masticatory muscle with a superior head (infratemporal surface of the greater wing of the sphenoid) and an inferior head (lateral surface of the lateral pterygoid plate), inserting into the pterygoid fovea of the condylar neck and the TMJ capsule/articular disc. Action: protrudes the mandible bilaterally; moves the mandible forward toward the opposite side unilaterally.

Sternocleidomastoideo

A lateral neck muscle originating via a sternal head (manubrium of sternum) and clavicular head (medial quarter of clavicle), inserting into the mastoid process and anterior superior nuchal line. Action: unilaterally flexes the head ipsilaterally and rotates it contralaterally; bilaterally extends the head; elevates the thorax (accessory inspiratory) when fixed on the head.

Digastrico

A suprahyoid neck muscle consisting of an anterior belly (origin: digastric fossa of the mandible; insertion: intermediate tendon) and a posterior belly (origin: intermediate tendon; insertion: mastoid notch of the temporal bone). Action: anterior belly depresses the mandible; posterior belly extends the head.

Muscoli scaleni (anteriore, medio, posteriore)

Lateral neck muscles originating from cervical transverse processes (anterior: C3-C6 anterior tubercles; middle: C2-C7; posterior: lower 3-4 cervical posterior tubercles). Anterior and middle insert onto the 1st rib; posterior inserts onto the 2nd rib. Action: elevate ribs 1 and 2 during inspiration; tilt the cervical spine ipsilaterally when fixed on the ribs.