Muscle Anatomy I - Lab 7

Vocabulary practice flashcards covering muscle anatomy fundamentals, actions, origins, insertions, and specific muscles of the head, neck, thorax, abdomen, and back from Lab 7.

Tendon

Dense fibrous connective tissue that attaches muscles to bones and to other muscles.

Aponeurosis

A broad, flat expanse of tendon.

Origin

The attachment point of a muscle that remains stationary during muscle contraction.

Insertion

The attachment point of a muscle that moves during muscle contraction.

Synergists

Groups of muscles working together to produce a common movement (for example, two flexors).

Antagonists

Groups or individual muscles that act in opposition to one another (for example, a flexor and an extensor).

Prime Mover

The single muscle in a group of synergists responsible for accomplishing the major desired action (such as the iliopsoas for hip flexion).

Flexion

A movement that brings two ventral surfaces closer together.

Extension

A movement that brings two primary ventral surfaces farther apart.

Dorsiflexion

The movement of bringing the toes upward toward the shin.

Plantar Flexion

Flexion of the foot downward, including the curling of the toes.

Abduction

Movement of a limb or body part away from the midline of the body.

Adduction

Movement of a limb or body part toward the midline of the body.

Circumduction

A circular movement in which the distal end of a bone traces a circle while the proximal end remains stationary.

Pronation

Rotation of the forearm that turns the palm to face posteriorly in the anatomical position.

Supination

Rotation of the forearm that turns the palm to face anteriorly in the anatomical position.

Inversion

The movement of turning the sole of the foot medially at the ankle.

Eversion

The movement of turning the sole of the foot laterally at the ankle.

Protraction

Moving the mandible or clavicle anteriorly along a plane parallel to the ground.

Retraction

Moving the mandible or clavicle posteriorly along a plane parallel to the ground.

Elevation

Movement of a body part in a superior direction.

Depression

Movement of a body part in an inferior direction.

Frontalis

The frontal belly of the epicranius covering the forehead and dome of the skull; originates on the epicranial aponeurosis, inserts into the skin of the eyebrows and root of the nose, and acts to raise the eyebrows and wrinkle forehead skin horizontally.

Occipitalis

The occipital belly of the epicranius overlying the posterior occiput; originates on the occipital and temporal bones, inserts into the epicranial aponeurosis, and acts to fix the aponeurosis, tighten the scalp, and pull the scalp posteriorly.

Orbicularis oris

A complex, multilayered sphincter muscle of the lips whose circular fibers encircle the mouth; closes, purses, and protrudes the lips (the kissing and whistling muscle).

Orbicularis oculi

A circular sphincter muscle surrounding the rim of the orbit; originates on the frontal and maxillary bones, inserts into the eyelid tissue, and produces closing of the eye, blinking, squinting, winking, and drawing the eyebrows inferiorly.

Zygomaticus

A pair of muscles extending diagonally from the cheekbone to the mouth corner; originates on the zygomatic bone, inserts into skin and muscle at the corner of the mouth, and acts to raise lateral corners of the mouth upward (the smiling muscle).

Buccinator

A thin, horizontal principal cheek muscle located deep to the masseter; compresses the cheek during chewing or whistling, holds food between the teeth, and draws the mouth corner laterally.

Platysma

An unpaired, sheet-like superficial neck muscle originating on the fascia of the chest; tenses the skin of the neck, assists in depressing the mandible, and pulls the lower lip down and back to produce a downward sag of the mouth.

Corrugator Supercilii

A small muscle associated with the orbicularis oculi; originates on the arch of the frontal bone above the nasal bone, inserts into the skin of the eyebrow, and acts to draw the eyebrows medially and inferiorly (furrowing the brows).

Levator palpebrae superioris

An extrinsic eye-region muscle located superior to the superior rectus that acts to elevate the upper eyelid.

Temporalis

A fan-shaped muscle of mastication originating on the temporal lines of the skull and inserting into the coronoid process of the mandible; elevates and retracts the mandible, closes the jaw, and produces incisor biting.

Masseter

A powerful mastication muscle covering the lateral mandibular ramus; originates on the zygomatic arch and inserts into the angle and ramus of the mandible to elevate the mandible, power molar chewing, and act as the prime mover of jaw closure.

Sternocleidomastoid

A two-headed anterior neck muscle originating on the sternal manubrium and medial clavicle and inserting into the mastoid process; flexes the head when contracted bilaterally and laterally rotates the head to the opposite side when contracted unilaterally; spasms cause torticollis (wryneck).

Scalenes

Lateral neck muscles deep to the platysma and SCM that originate on the transverse processes of cervical vertebrae and insert on the first two ribs; flex the neck bilaterally and laterally flex the neck unilaterally.

Pectoralis major

A large, fan-shaped upper limb muscle covering the superior chest; originates on the clavicle and sternum and inserts into the lateral edge of the bicipital groove of the humerus to adduct and medially rotate the arm.

Pectoralis minor

A flat, thin muscle obscured beneath the pectoralis major; originates on the anterior surfaces of ribs $3$ to $5$ and inserts onto the coracoid process of the scapula to draw the scapula forward and downward and assist in elevating ribs during inhalation.

Serratus anterior

The 'boxer\'s muscle' originating on the lateral side of ribs $1$ to $8$ and inserting along the vertebral border beneath the scapula; protracts, stabilizes, and fixes the scapula against the chest wall.

Diaphragm

A dome-shaped muscle forming the floor of the thoracic cavity; originates on the inferior internal rib cage and sternum and inserts into the central tendon, flattening upon contraction to act as the prime mover of inspiration.

External intercostals

$11$ pairs of muscles between the ribs whose fibers run obliquely down and forward; originate on the inferior border of the rib above and insert on the superior border of the rib below to elevate the rib cage during inspiration.

Internal intercostals

$11$ pairs of muscles running deep and perpendicular (down and posteriorly) to the external intercostals; draw ribs together and depress the rib cage to aid forced expiration.

Linea alba

A tendinous, fibrous midline seam that separates the left and right sides of the rectus abdominis muscle.

Rectus abdominis

A medial, segmented anterior abdominal muscle ('six-pack') enclosed in the rectus sheath; originates on the pubic crest and symphysis and inserts on the inferior rib cage to flex the trunk, maintain posture, and rotate the spine.

External oblique

The most superficial lateral abdominal muscle with fibers running downward and medially ('hands in pockets'); aids in trunk flexion bilaterally and drives lateral flexion and rotation unilaterally.

Internal oblique

The intermediate abdominal wall muscle with fibers running perpendicular to the external oblique; originates on the iliac crest and inserts into the rectus sheath to aid trunk flexion and same-side rotation.

Transversus abdominis

The deepest muscle layer of the abdominal wall; originates from the vertebrae and ilium and inserts into the posterior rectus sheath to compress abdominal contents.

Trapezius

A superficial diamond-shaped back muscle with three heads originating along the nuchal line and spinous processes of $\text{C7–T12}$; primarily acts to elevate, rotate, retract, and depress the scapula.

Latissimus dorsi

A broad, superficial back muscle originating on the iliac crest and thoracolumbar fascia and inserting into the bicipital groove of the humerus; acts as a prime arm mover for humeral extension, adduction, and medial rotation.

Levator scapulae

An intermediate neck and back muscle originating on the transverse processes of $\text{C1–C4}$ and inserting into the superior angle of the scapula; raises, rotates, and retracts the scapula, or pulls the head and neck laterally when the scapula is fixed.

Splenius capitis

An intermediate muscle located beneath the trapezius originating on cervical and thoracic vertebrae and inserting on the superior nuchal line and mastoid; acts to extend and rotate the head.

Rhomboid major

An intermediate back muscle originating on the spinous processes of $\text{T2–T5}$ and inserting into the lower $\frac{3}{4}$ of the medial border of the scapula to retract the scapula.

Rhomboid minor

A small intermediate back muscle originating on the spinous processes of $\text{C7–T1}$ and inserting into the upper $\frac{1}{4}$ of the medial border of the scapula to retract the scapula.

Semispinalis capitis

A deep back and neck muscle originating on cervical and thoracic vertebrae and inserting on occipital nuchal lines; functions in extending the head, extending the vertebral column, and maintaining neck posture.

Erector spinae group

A deep composite back muscle group made up of the iliocostalis, longissimus, and spinalis columns; originates on the sacrum and posterior iliac crest and inserts along the back, neck, and skull to extend the back and neck.