Anatomy & Physiology (LAB 5) - Muscles PT.1: Muscles of Head, Neck & Trunk

Frontalis (frontal belly)

raises the eyebrows; innervated by facial nerve (cranial nerve VII)

Occipitalis (occipital Belly)

fixes aponeurosis & pulls scalp posteriorly; innervated by facial nerve

Corrugator supercilii***

pulls eyebrows medially & inferiorly; innervated by facial nerve

Orbicularis oculi

closes eye for blinking & squinting; innervated by facial nerve

Zygomaticus major & minor

responsible for smiling; innervated by facial nerve

Risorius

pulls corner of lip laterally; innervated by facial nerve

Levator labii superioris

opens lips; innervated by facial nerve

Depressor labii inferioris

pulls lower lip inferiorly; innervated by facial nerve

Depressor anguli oris

pulls corner of mouth down & laterally; innervated by facial nerve

Orbicularis oris

closes lips; innervated by facial nerve

Platysma

tenses skin of neck; innervated by facial nerve

epicranial aponeurosis

connects the frontal and occipital region of our head; innervated by facial nerve

Sternocleidomastoid

flexes and laterally rotates the head; innervated by cranial nerve XII

Scalenes***

elevates first two ribs (superior, middle, inferior); innervated by cervical spinal nerves

Mentalis

wrinkles chin; innervated by facial nerve

Buccinator***

compresses cheek; innervated by facial nerve

Masseter

primary mover of jaw closure; innervated by trigeminal nerve

Temporalis

closes jaw; innervated by trigeminal nerve

Pterygoid (lateral)

provides side-to-side grinding movements; innervated by trigeminal nerve

Pterygoid (medial)

acts w/ lateral pterygoid to protract mandible & promote side-to-side grinding movement; innervated by trigeminal nerve

facial nerves

Muscles of Facial Expression Innervated by

Trigeminal Nerves

Muscles of Mastication innervated by

Suprahyoid

above the hyoid bone

Infrahyoid

below the hyoid bone

Trapezius

stabilizes, elevates, retracts, & rotates scapula; innervated by cranial nerve XI

Latissimus dorsi

prime mover of arm extension; innervated by thoracodorsal nerve

Levator scapulae***

elevates & adducts scapula; innervated by cranial spinal nerves & dorsal scapular nerves

Rhomboid major & minor***

stabilize scapula; innervated by dorsal scapular nerves

Teres major

extends, medially rotates, & adducts arm; innervated by lower subscapular nerve

Splenius capitis & cervicis***

extend/hyperextend head; innervated by cervical spinal nerves

Semispinalis: capitis, cervicis & thoracis***

extends vertebral column; capitis is top, cervicis middle, and thoracis bottom; innervated by spinal nerves

Quadratus Lumborum

laterally flexes vertebral column; innervated by upper lumbar spinal nerves

Erector spinae/Paraspinal

group of 3 muscles:
- Iliocostalis
- Longissimus
- Spinalis

Iliocostalis

extends vertebral column & laterally flexes vertebral column; innervated by spinal nerves

Longissimus

extends vertebral column & extends & rotates head; innervated by spinal nerves

Spinalis

extends vertebral column; innervated by spinal nerves

Deltoid

prime mover of arm abduction when all its fibers contract simultaneously; innervated by axillary nerve

Supraspinatus***

initiates abduction of arm; innervated by suprascapular nerve

Infraspinatus***

rotates arm laterally; innervated by suprascapular nerve

Subscapularis***

rotates arm medially; innervated by subscapular nerves

Teres minor***

same actions as infraspinatus muscle; innervated by axillary nerve

Pectoralis major

adducts & medially rotates arm; innervated by lateral & medial pectoral nerves

Pectoralis minor***

w/ ribs fixed, pulls scapula forward & downward; innervated by lateral & medial pectoral nerves

Serratus anterior***

rotates scapula so it moves laterally & upward; innervated by long thoracic nerve

Rectus abdominus

flex & rotate lumbar region of vertebral column; innervated by intercostal nerves

External oblique

flex vertebral column & compress abdominal wall. trunk rotation & lateral flexion; innervated by intercostal nerves

Internal oblique***

same action as its external counterpart; innervated by intercostal nerves

Transversus abdominus***

compresses abdominal contents; innervated by intercostal nerves

Linea Alba

midline tendinous seam joining the abdominal muscles

Aponeurosis of external obliques

the white part most inferior part of the abdomen

Intercostal Nerves

Abdominal Muscles are innervated by

Diaphragm***

prime mover of inspiration & flattens on contraction; innervated by phrenic nerve

Phrenic Nerve

The diaphragm is innervated by the

External intercostals

pull rubs toward one another to elevate rib cage & responsible for inspiration; innervated by intercostal nerves

Internal intercostals

pull ribs together and depress rib cage; innervated by intercostal nerves

Intercostal nerves

Intercoastals innervated by the

Levator Ani

supports & maintains position of pelvic organs; innervated by inferior rectal nerve

Coccygeus

supports pelvic organs; innervated by S4 & S5

Ischiocavernosus

retards venous drainage & maintains erection of penis/clitoris; innervated by pudendal nerve

Bulbospongiosus

empties male urethra; innervated by pudendal nerve

Pudendal nerve

Pelvic Floor & Perinium innervated by

Flexion

bending movement along sagittal plane that decreases angle of joint

Hyperextension

opposite of flexion; involves increasing the angle btw bones in the sagittal plane

Extension

Straightening of a joint

Dorsiflexion

"toes up"; raising foot upwards

Plantarflexion

"toes down"; pointing foot downwards

Rotation

Turning a bone around its own long axis

Pronation

rotating the forearms from a "palms forward" to a "palms backward" position

Supination

rotating the forearms from a "palms backward" to a "palms forward" position

Circumduction

moving a limb so that the distal end of that limb draws a circle (think "circumference" of a circle)

Abduction

movement of a limb away from a midline of the body within coronal plane (think reaching out arms to abduct someone)

Adduction

movement of a limb toward the body (think adding to your body)

Inversion

Turning side of foot medially (standing on lateral side of foot)

Eversion

Turning sole of foot laterally (standing on medial side of foot)

Protraction

movement of a body part in an anterior direction

Retraction

movement of a body part in an posterior direction

Elevation

movement of a body part superiorly

Depression

movement of a body part inferiorly

Opposition

touching the thumb to the tips of other fingers on same hand (pinching/grasping)

Agonist

the muscle that provides most of the force for a particular action (aka prime mover)

Antagonist

a muscle that opposes/does the opposite of the agonist

Synergist

muscles that work to accomplish the same action (assists/helps the prime mover)

Fixator

muscle that helps stabilize/immobilize a bone; important for posture

origin

attached to immovable bone

insertion

attached to moveable bone