Skeletal muscles - intro Flashcards
Muscle shapes
- muscles have many shapes, depending upon the size and actions of a specific muscle
- wide (latus), toothed (serratus), triangular (deltoid)
Muscle location
- skeletal muscles are attached to the bones
- each end of a muscle is attached to a different bone (contraction of the muscle causes bones to move their joints)
Muscle location
Origin and Insertion
-the specific anchoring ends of a muscle
Origin
- the beginning (proximal) attachment of a muscle
- this is the end that is attached to a site or bone that moves very little
- the bone may be fixed or immobile
Insertion
- this is the distal end of a muscle
- this end attaches to a bone with the most movement during contraction
Biceps brachii
Origin: scapula
Insertion: tuberosity of the radius
Action: flexion (bending) of the forearm
Single muscle actions
each muscle causes movement of a body part during contraction
Sternocleidomastoid
Origin: manubrium of sternum and medial clavicle
Insertion: mastoid proces and superior nuchal line
Action: one contraction alone: laterally flexes head and neck to same side and rotates head and neck to opposite side both contracting together
Innervation: spinal accessory (CN XI)
Pectoralis major
Origin: clavicle, sternum, superior six costal cartilages and abdominal aponeurosis
Insertion: lateral crest of intertubercular groove of the humerus
Action: flexes shoulder; adducts and medially rotates arm; extends shoulder from flexed position
Innervation: medial and lateral pectoral nerves
Muscle group actions
-groups with similar actions and groups with opposite actions
Groups with similar actions
- for most actions there are usually several muscles involoved
- one muscle has most of the responsibility for the action and is called the PRIME MOVER
- others muscles that aid the action are called SYNERGISTS
Bending (flexing) the forearm
Prime mover: biceps brachii
Synergists: brachialis and brachiordialis
Groups with opposite actions
- for each body movement there is an opposite action which returns the body to anatomical position
- muscles with opposite actions are called AGONISTS and ANTAGONISTS
Agonist muscle
a muscle that accomplishes a certain movement
-ie. biceps brachii
Antagonist muscle
- a muscle that works in opposition to another muscle
- ie. tricep
Types of actions
know all of the following…
Flexion
movement of a body part anterior to the coronal plane
Extension
movement of a body part posterior to the coronal plane
Abduction
movement away from the midline
Adduction
movement toward the midline
Rotation
the turning of a structure around its long axis, as in rotating the head or humerus
Pronation
rotation of forearm towards facedown
Supination
rotation of forearm faceup
Circumduction
combination of flexion, extension, abduction, and adduction
Elevation
moves structure superiorly
Depression
moves structure inferiorly
Protraction
gliding motion that moves a structure in an anterior direction
Retraction
moves the structure back to the anatomical position
Lateral excursion
moving the mandible to either the right or the left of the midline
Medial excursion
returns that mandible to that midline position
Opposition
movement of the thumb and little finger towards each other
Reposition
returns the thumb and little finger to the neutral position
Inversion
turns the ankle so that the plantar surface of the foot faces medially
Eversion
turns the ankle so that the plantar surface faces laterally
Head
Frontalis (1)-epicranius
raises scalp and eyebrows
Head
Occipitalis (1)-epicranius
draws scalp backwards
Head
Orbicularis oculi-(2)
closes eyelid
Head Orbicularis oris (9)
closes, compresses lips
Head
Buccinator (14)
compresses cheek, sucking
Head
Temporalis (22)
elavates and retracts mandible (chewing)
Origin: temporal fossa
Insertion: coroniod process, mandibular ramus
Head
Masseter (15)
elevates, protracts mandible (chewing)
Neck
Digastic (17,19)
elevates hyoid
Origin: mastoid process of temporal
Insertion: mandible near midline
Neck
Mylohyoid (16)
elevates hyoid
Neck
Sternohyoid (218)
depresses hyoid
Neck Sternocleidomastoid (21)
flexes, rotates head and neck
Torso Pectoralis Major (262)
flexes, adducts, and medially rotates arm
Origin: clavicle, strenum, superior six costal cartilages
Insertion: lateral crest of intertubercular groove of the humerus
Torso Serratus anterior (542)
abducts and rotates scapula
Torso
Diaphragm
depresses thorax floor
Torso External intercostals (255)
elevates ribs
Torso Internal intercostals (256)
depresses ribs
Torso
Trapezius (226)
extends head
Origin: occipital protuberance, nuchal ligament spinous processes of C7-T12
Insertion: clavicle, acromoin process and spine of scapula
Torso
Rhomboidius major
adducts and rotates scapula
Torso Latissimus dorsi (541)
adducts and medially rotates arm
