Gross Anatomy of the Muscular System
Lab
Week of February 18, 2008
Marieb & Mitchell: Exercise 15
Martini: Chapter 11
• muscle– fascicles
• fibers
• fibers of a single fascicle always parallel
• fascicles of a muscle can be arranged in various ways
Organization of Skeletal Muscle Fibers
Muscles are classified by how the fascicles are organized
1. Parallel (e.g., biceps brachii muscle)• most common arrangement
2. Convergent (e.g.,pectoralis muscle)• fascicles fan or triangle shaped, converge to attach
Muscles are classified by how the fascicles are organized
3. Pennate (unipennate, bipennate and multipennate)• fasicles form angle toward tendon
4. Circular (e.g.,orbicularis oris)• sphincter, contracts to reduce diameter of opening
Origins and Insertions
• The ends of skeletal muscles are always attached to other structures– fixed end is called ORIGIN
• usually attached to bone or cartilage
– movable end is called INSERTION• usually proximal to insertion
How are muscles named?
1. location in the body • e.g., temporalis muscle
2. Origin and Insertion• first part = origin, 2nd part = insertion
3. Fascicle Organization• e.g., Rectus means “straight”• e.g., transverse means “across”• e.g., oblique means “oblique angle”
How are muscles named?
4. Relative Position• e.g., superficialis, internus, lateralis, etc…
5. Structural Characteristics (shape and size)• e.g., deltoid, rhomboid, major, longus, etc…
6. Action• e.g., abductor, extensor, rotator, etc…
Muscular Actions
• Agonists (prime mover)– responsible for a particular movement
• Antagonist– against movement of agonist
• Synergists– aid agonists, stabilize an action
• Fixators– specialized synergists– immobilize the origin of agonist so all tension is
exerted at the insertion point
Muscles of the Head and Neck
• Epicranius – frontalis
• action: raises eyebrows, wrinkles forehead
Muscles of the Head and Neck
• Epicranius– occipitalis
• action: tenses and pulls scalp posteriorly
Muscles of the Head and Neck
• Orbicularis Oculi– action: closes eye, squinting
Muscles of the Head and Neck
• Orbicularis oris– action: constricts mouth (whistle, kissing)
Muscles of the Head and Neck
• Zygomaticus– action: the elevates corners of mouth and
upper lip• smiling muscle • antagonist to depressor
anguli oris
Muscles of the Head and Neck
• Levator Labii Superioris– action: raises upper lip, opens lips
Muscles of the Head and Neck
• Depressor Labii Inferioris– action: depresses lower lip
Muscles of the Head and Neck
• Depressor Anguli Oris– action: draws corners of mouth down
• frowning muslce• antagonist to
zygomaticus
Muscles of the Head and Neck
• Depressor Anguli Oris– action: draws corners of mouth down
• frowning muslce• antagonist to
zygomaticus
Muscles of the Head and Neck
• Masseter– origin: zygomatic arch– insertion: mandibular ramus– action:
• elevates mandible• closes jaw
Muscles of the Head and Neck
• Temporalis– action:
• elevates mandible• closes jaw
Muscles of the Head and Neck
• Sternocleidomastoid– origin: clavicle or manubrium– insertion: mastoid process– action:
• together: flex neck• 1 side: bends head
towards shoulder and
turns face to opposite
side
Muscles of the Head and Neck
• Scalenes– origin: cervical vertebrae – insertion: Ribs 1-2– action: elevates ribs,
flexes neck
Muscles of the Head and Neck
• Splenius Capitis– action: extend and hyperextend head
Muscles of the Trunk and Back
• Erector Spinae– iliocostalis– spinalis– longissimus
• together: extends vertebral column
• along: lateral flexion
Muscles of the Trunk and Back
• External Intercostals– origin: rib above – insertion: rib below– action: elevates ribs
• inspiration
Muscles of the Trunk and Back
• Internal Intercostals– origin: rib below – insertion: rib above– action: depresses ribs
• breath out
Muscles of the Trunk and Back
• Diaphragm– origin: xiphoid process,
cartilage of ribs 4-10, lumbar
vertebrae– action: expands thoracic
cavity, compresses abdominopelvic cavity
Muscles of the Trunk and Back
• Transverse Abdominus– insertion: linea alba– action: compresses
abdominopelvic cavity
Muscles of the Trunk and Back
• Internal Oblique– insertion: linea alba– action: compresses
abdomen, depresses ribs, flexes or bends spine
Muscles of the Trunk and Back
• External Oblique– insertion: linea alba– action: compresses
abdomen, depresses ribs, flexes or bends spine
Muscles of the Trunk and Back
• Rectus Abdominus– origin: pubic symphesis– insertion: xyphoid
process– action: depresses ribs,
compresses abdomen, flexes vertebral column
Muscles of the Trunk and Back
• Trapezius– origin: midline of neck
and back– insertion: clavicles and
scapular spines– action: elevation,
depression, rotation, adduction of scapula, extension of head
Muscles of the Trunk and Back
• Rhomboid Major– origin: T2-T5 spinous
processes– insertion: vertebral
border of scapula– action: adduction of
scapula
Muscles of the Trunk and Back
• Rhomboid Minor– origin: C7 and T1
spinous process– insertion: vertebral
border of scapula– action: adduction of
scapula
Muscles of the Trunk and Back
• Levator Scapulae– origin: C1-4 transverse
process– insertion: vertebral
border of scapula– action: elevates scapula
Muscles of the Trunk and Back
• Pectoralis Minor– origin: anterior surface of
ribs 3-5– insertion: coracoid
process of scapula– action: depresses and
contracts scapular end of clavicle (in complement with subclavius muscle)
Muscles of the Trunk and Back
• Serratus Anterior– origin: ribs– insertion: scapula– action: abducts scapula,
swings shoulder anteriorly
Gross Anatomy of the Muscular System
Lab
Week of February 25, 2008
Marieb & Mitchell: Exercise 15
Martini: Chapter 11
MUSCLES OF THE UPPER EXTREMITIES
Pectoralis Major
• Origin– Cartilages of ribs 2-6, body of sternum,
inferior medial clavicle• Insertion
– Humerus (greater tubercle and lip of intertubercular groove)
• Action– Flex, adduct, medially rotate shoulder joint
Latissimus Dorsi
• Origin– T6-12, lumbar, sacrum, ileum
• Insertion– Humerus (floor of intertubercular groove)
• Action– Adduction, extension, medial rotation at the
shoulder joint
Coracobrachialis
• Origin– Coracoid process of scapula
• Insertion– Humerus (shaft)
• Action– Adduct, flex at shoulder joint
Supraspinatus
• Origin– Supraspinous fossa of scapula
• Insertion– Humerus (greater tubercle)
• Action– Abduction at shoulder joint, stabilizes joint
• Rotator cuff group
Infraspinatus
• Origin– Infraspinous fossa of scapula
• Insertion– Humerus (greater tubercle)
• Action– Lateral rotation at shoulder joint
• Rotator cuff group
Teres Minor
• Origin– Lateral border of scapula
• Insertion– Humerus (greater tubercle)
• Action– Lateral rotation at shoulder joint, stabilizes
• Rotator cuff group
Subscapularis
• Origin– Subscapular fossa of scapula
• Insertion– Humerus (lesser tubercle)
• Action– Medial rotation at shoulder joint
• Rotator Cuff Group
Teres Major
• Origin– Inferior angle of scapula
• Insertion– Humerus (lip of intertubercular groove)
• Action– Extension, adduction, medial rotation at
shoulder joint
Deltoid
• Origin– Clavicle, scapula (spine and acromion)
• Insertion– Deltoid tuberosity of humerus
• Action– Altogether Abduction at shoulder joint– Anterior flexion, medial rotation at shoulder– Posterior extension, lateral rotation at
shoulder
Biceps Brachii
• Origins– Long head
• Supraglenoid tubercle of scapula
– Short head• Coracoid process of scapula
• Insertion– Tuberosity of radius
• Action– Flex at elbow AND shoulder joint, supination
Brachialis
• Origin– Humerus
• Insertion– Ulna
• Action– Flexes forearm (elbow joint)
Triceps Brachii• Origin
– Long: Infraglenoid tubercle of scapula
– Lateral: humerus
– Medial: humerus
• Insertion– Olecranon of Ulna (for all 3)
• Action– Long: extension elbow joint, extension and adduction
at shoulder joint– Lateral and Medial: extension at elbow joint
Brachioradialis
• Origin– Distal humerus
• Insertion– radius
• Action– Flexion at elbow joint
Pronator Teres
• Action– Pronation (forearm)
Flexor Carpi Ulnaris
• Action– Flex, adduct wrist
Flexor Carpi Radialis
• Action– Flex, abduct wrist
Flexor Digitorum Superficialis
• Action– Flexion at proximal interphalangeal– Flexion at metacarpophalangeal– Flexion at wrist
Extensor Carpi Radialis Longus
• Action– Extend, abduct wrist
Extensor Carpi Radialis Brevis
• Action– Extend, abduct wrist
Extensor Carpi Ulnaris
• Action– Extend, adduct wrist
Extensor Digitorum
• Action– Extension at finger joints and wrist joints
Adam Packet 1:muscles of the head, neck, chest and back
• Using the Adam software, identify the muscles in the packet (pgs 8-16).
• Answer questions 1-15 on a SEPARATE piece of notebook paper and turn it in by NEXT LAB PERIOD.
• NOTE:– You will find the answers in Exercise 15 of Marieb and
Chapter 11 of Martini.