Human Anatomy: Muscular System Practice

Vocabulary practice cards for muscle anatomy including origins, insertions, innervations, and functional actions of thoracic, abdominal, and spinal muscles.

Serrato posterosuperior (Serratus posterior superior)

A muscle originating from the nuchal ligament and spinous processes of $C7$ to $T3$, inserting into the superior borders of ribs $2$ to $4$. It is innervated by intercostal nerves $2$ to $5$ and functions in proprioception and as an accessory inspiratory muscle.

Serrato posteroinferior (Serratus posterior inferior)

A muscle originating from the spinous processes of vertebrae $T11$ to $L2$, inserting into the inferior borders of ribs $8$ to $12$ near their angles. It is innervated by intercostal nerves $9$ to $11$ and the subcostal nerve, serving as an accessory expiratory muscle.

Elevadores de las costillas (Levatores costarum)

Muscles originating from the transverse processes of $T7$ to $T11$ and inserting between the tubercle and the angle of the underlying ribs. They are innervated by the posterior rami of nerves $C8$ to $T11$ and act to elevate the ribs.

Intercostales externos (External intercostals)

Muscles that originate from the inferior border of a rib and insert into the superior border of the rib below. They are innervated by the intercostal nerve and elevate the ribs during forced inspiration.

Intercostales internos (Internal intercostals)

Muscles originating from the inferior border of a rib and inserting into the superior border of the rib below. Their interosseous portion depresses the ribs, while the interchondral portion elevates them during forced inspiration.

Subcostales

Muscles located on the internal surface of the lower ribs near their angles, inserting into the superior borders of the $2nd$ or $3rd$ underlying ribs. They are innervated by the intercostal nerve and likely act like the internal intercostals.

Transverso del tórax (Transversus thoracis)

A muscle originating from the posterior surface of the lower sternum and inserting into the internal surface of costal cartilages $2$ to $6$. It is innervated by the intercostal nerve and slightly depresses the ribs.

Pectoral mayor porción clavicular (Pectoralis major, clavicular head)

Originates from the sternal half of the clavicle and inserts into the intertubercular groove of the humerus. Innervated by nerves $C5-C6$, it performs flexion of the arm at the shoulder and adduction of the humerus.

Pectoral menor (Pectoralis minor)

Originates from ribs $3$ to $5$ and inserts into the coracoid process of the scapula. Innervated by the medial pectoral nerve ($C8-T1$), it mediates depression, downward rotation, and abduction of the scapula, and elevation of the ribs.

Subclavio (Subclavius)

Originates at the junction of the $1st$ rib and its cartilage, inserting into the subclavius groove of the clavicle. It is innervated by the nerve to subclavius ($C5-C6$) and depresses the clavicle downward and forward.

Diafragma (Diaphragm)

A primary muscle of respiration originating from the xiphoid process, cartilages of ribs $7$ to $12$, and lumbar vertebrae $L1-L3$. It is innervated by the phrenic nerve ($C3-C5$) and expands the thoracic cavity while compressing the abdominal cavity.

Serrato anterior (Serratus anterior)

Originates from ribs $1$ to $9$ and inserts into the medial border of the scapula. Innervated by the long thoracic nerve ($C5-C7$), it performs depression, abduction, and upward rotation of the scapula and elevates ribs if the scapula is fixed.

Obturador externo (Obturator externus)

Originates from the external surface of the obturator membrane and adjacent bones, inserting into the trochanteric fossa of the femur. It is innervated by the posterior branch of the obturator nerve ($L3-L4$) and laterally rotates the thigh.

Grácil (Gracilis)

Originates from the body of the pubis and inserts into the medial surface of the proximal tibia. It is innervated by the obturator nerve ($L2-L3$) and acts in hip adduction and knee flexion.

Piriforme (Piriformis)

Originates from the pelvic surface of the sacrum and inserts on the superior border of the greater trochanter of the femur. It is innervated by the nerve to piriformis ($S1-S2$) and performs lateral rotation and abduction of the thigh.

Pectíneo (Pectineus)

Originates from the superior ramus of the pubis and inserts into the pectineal line of the femur. It is innervated by the femoral and obturator nerves ($L2-L3$) and performs hip adduction and flexion.

Psoas mayor

Originates from the transverse processes of $L1-L5$, vertebral bodies of $T12-L5$, and adjacent discs. It inserts into the lesser trochanter of the femur and is innervated by anterior branches of lumbar nerves $L1, L2$; it flexes the thigh and trunk.

Glúteo mayor (Gluteus maximus)

Originates from the posterior ilium, sacrum, coccyx, and sacrotuberous ligament. It inserts into the iliotibial tract and gluteal tuberosity of the femur and is innervated by the inferior gluteal nerve ($L5-S2$) to extend, laterally rotate, and abduct the thigh.

Escaleno anterior (Anterior scalene)

Originates from the anterior tubercles of the transverse processes of $C3$ to $C6$ and inserts into the scalene tubercle of the $1st$ rib. It is innervated by the cervical plexus ($C4-C6$) and elevates the $1st$ rib, performs lateral neck flexion, and ipsilateral head rotation.

Esternocleidomastoideo (Sternocleidomastoid)

Originates from the manubrium and medial third of the clavicle, inserting into the mastoid process and superior nuchal line. It is innervated by the accessory nerve and cervical spinal nerves ($C2-C3$), performing neck flexion, lateral flexion, and contralateral head rotation.

Platisma (Platysma)

A superficial muscle originating from the fascia of the pectoral and deltoid muscles, inserting into the mandible and subcutaneous tissue of the lower face. It is innervated by the facial nerve (cervical branch) and depresses the corners of the mouth.

Semiespinoso torácico (Semispinalis thoracis)

Originates from the transverse processes of $T6$ to $T12$ and inserts into the spinous processes of $C6$ to $T4$. It is innervated by the dorsal rami of spinal nerves and functions to extend the vertebral column and perform contralateral rotation.

Cuadrado lumbar (Quadratus lumborum)

Originates from the iliolumbar ligament aponeurosis and iliac crest, inserting into the inferior border of the last rib and spinous processes of $L4-L1$. Innervated by spinal nerves $T12$ and $L1-L2$, it deprimes the $12th$ rib and provides lateral flexion and lumbar stabilization.

Dorsal ancho (Latissimus dorsi)

Originates from spinous processes of $T7-L5$, the sacral crest, iliac crest, and the last $3$ to $4$ ribs. It inserts into the intertubercular groove of the humerus and is innervated by the thoracodorsal nerve ($C6-C8$), acting in extension, adduction, and internal rotation of the arm.

Recto del abdomen (Rectus abdominis)

Originates from the pubic crest and symphysis, inserting into the cartilages of ribs $5, 6, 7$ and the xiphoid process. It is innervated by spinal nerves $T7-T12$ and functions to flex the vertebral column and compress abdominal viscera.

Transverso del abdomen (Transversus abdominis)

Originates from the inguinal ligament, iliac crest, costal cartilages of the lower six ribs, and lumbodorsal fascia. It inserts into the linea alba and pubis, acting to compress abdominal viscera and tense the abdominal wall.

Oblicuo interno del abdomen (Internal oblique)

Originates from the inguinal ligament, iliac crest, and lumbodorsal fascia, inserting into the pubis, lower ribs, and linea alba. It executes bilateral compression of viscera and unilateral lateral flexion and ipsilateral rotation of the spine.

Oblicuo externo del abdomen (External oblique)

Originates from the external surfaces and lower borders of the eight inferior ribs ($5$ to $12$), inserting into the iliac crest, pubis, and linea alba. It performs bilateral trunk flexion and unilateral ipsilateral flexion and contralateral rotation.

Multífidos (Multifidus)

Muscles originating from the sacrum, EIPS, and processes of $L$, $T$, and $C4-C7$, inserting into the spinous processes of all vertebrae above their origin. They stabilize vertebrae and perform rotation of the thoracic column and neck extension.

Trapecio (Trapezius)

A muscle with superior, middle, and inferior fibers originating from the occipital bone, nuchal ligament, and spinous processes of $C7-T12$. It is innervated by the accessory nerve ($XI$) and cervical plexus ($C3-C4$), moving the scapula in elevation, adduction, or depression.