BIOLOGY 2401 ANATOMY

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BIOLOGY 2401ANATOMY PHYSIOLOGYPART ICHAPTER
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• THE MUSCULAR SYSTEM

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Skeletal Muscles Work Together

• Since muscles can only contract and shorten, to
  produce opposing motions it takes at least two
  different muscles.
• Muscle classifications
• Agonist muscle that causes an action
• Antagonist a muscle working in opposition to
  agonist
• Example the biceps brachii is the agonist when
  flexing the elbow to lift weights, but is the
  antagonist when the triceps brachii is extending
  the elbow to move a bowling ball back to prepare
  to bowl
• Synergists muscles that work together to cause a
  movement

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Information Revealed By the Names of Skeletal
Muscles

• The naming of muscles usually follows one of 7
  criteria
• Location of the muscle frontalis, temporalis
• Relative size of the muscle maximus, minimus
• Shape of the muscle deltoid, trapezius,
  rhomboid
• Direction of muscle fibers rectus, oblique,
  transversus
• Location of attachments sternocleidomastoid
• Number of origins biceps, triceps, quadriceps
• Action of the muscle adductor, flexor

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Arrangement of Fascicles

• The fascicles of muscles can be arranged in a
  variety of ways the most common are
• 1. Parallel - fascicles are parallel to the long
  axis of the muscle.
• Some of these are also classified as fusiform
  muscles.
• 2. Pennate - the fascicles are short and attach
  to a central tendon
• Can be unipennate, bipennate or multipennate
• 3. Convergent - muscle has a broad origin but the
  fascicles converge to one tendon.
• May be multipennate.
• 4. Circular - muscle has the fascicles arranged
  in concentric circles.

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Lever Systems

• Lever systems help move a load more efficiently
  or with greater speed.
• Quickly show lever types next

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Types of Lever Systems First Class
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Types of Lever Systems Second Class
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Types of Lever Systems Third Class
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Major Skeletal Muscles, Anterior ViewPrint on
full page for use as reference
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Major Skeletal Muscles, Posterior ViewPrint on
full page for use as reference
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For dissection labs

• Wear closed toed shoes
• Bring your own gloves

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Muscles of the Scalp and Face

• Epicranius consists of
• frontalis (or frontal belly of epicranius)
• occipitalis (or occipital belly of epicranius)
• These two muscles pull the scalp forward and
  backward
• Various muscles are involved in opening and
  closing the eyes and mouth, and smiling
• Ex orbicularis oculi, orbicularis oris,
  zygomaticus, etc.
• Usually insert in skin (rather than bone), and
  adjacent muscles often fuse
• There are multiple muscles involved in
  mastication (chewing)
• Prime movers temporalis and masseter
• Synergists buccinator and orbicularis oris

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Muscles of the Face
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Muscles of Mastication
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Muscles of the Neck Head Movements

• Sternocleidomastoid muscles flex the head/neck if
  they are both contracted or rotate the head if
  only one is contracted
• The trapezius muscle works with the deeper
  splenius muscles to extend and hyperextend the
  head/neck

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Muscles of the Deep Back Trunk Movements

• Erector spinae is the prime mover of back
  extension
• Erector spinae muscles consist of three columns
  on each side of the vertebrae
• (iliocostalis, longissimus, and spinalis)
• Lateral bending of the back is accomplished by
  unilateral contraction of these muscles

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Muscles of Respiration Inspiration

• Function of deep thoracic muscles is to promote
  movement for breathing
• External intercostals more superficial layer
  that lifts the rib cage and increases thoracic
  volume to allow inspiration
• Diaphragm most important muscle in inspiration

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Muscles of Respiration Expiration

• Internal intercostals deeper layer that aids in
  forced expiration

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Muscles of the Abdominal Wall

• The abdominal wall is composed of 4 paired
  muscles
• external obliques
• internal obliques
• rectus abdominis
• transversus abdominis
• Their fascicles run at right and oblique angles
  to one another, giving the abdominal wall added
  strength
• They are involved with lateral flexion rotation
  of the trunk
• They help promote urination, defecation,
  childbirth, vomiting, coughing, and screaming
  (and laughing)

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Muscles of the Abdominal Wall
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Muscles of the Abdominal Wall
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Muscles of Pelvic Floor and Perineum

• Pelvic diaphragm Funnel-shaped, supports the
  pelvic viscera. Pierced by anal canal, urethra ,
  in female, vagina.
• Perineum diamond-shaped area inferior to pelvic
  diaphragm. Anterior half of diamond is urogenital
  triangle posterior half is anal triangle

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Shoulder Muscles Found on Thorax

• Some of the muscles that control the shoulder
  (humerus or scapula) are found on the thorax
• Anterior Thorax
• pectoralis major,
• pectoralis minor, and
• serratus anterior
• Posterior Thorax
• latissimus dorsi,
• trapezius,
• levator scapulae, and
• rhomboids

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Shoulder Muscles on Thorax, Anterior View
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Shoulder Muscles on Thorax, Posterior View
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Muscles Inserting On and Moving the Humerus

• Flexion at shoulder (humerus moves anteriorly)
• Pectoralis major
• Anterior fibers of deltoid
• Abduction at shoulder (humerus moves laterally)
• Lateral fibers of deltoid
• Extention at shoulder (humerus moves posteriorly)
• Latissimus dorsi
• Posterior fibers of deltoid
• Stability and rotation at the shoulder (4 rotator
  cuff muscles)
• Supraspinatus
• Infraspinatus
• Teres minor
• Subscapularis

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Muscles Inserting on Humerus, Ant. View
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Muscles Inserting on Humerus, Posterior View
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Rotator Cuff, Anterior View)
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Muscles Moving the Antebrachium

• Elbow flexion
• Biceps brachii and
• Brachialis
• Elbow extension
• Triceps brachii

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Muscles Moving the Antebrachium
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Muscles Moving the Antebrachium Transverse
Section

• This transverse section shows the flexors in the
  anterior compartment and the extensors in the
  posterior compartment

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Movements at the Hip Joint

• Flexion of the Hip (femur moves anteriorly)
• Anterior compartment muscles
• Rectus femoris, tensor fascia latae and iliopsoas
• Extension of the hip (femur moves posteriorly)
• Posterior compartment muscles
• Gluteus maximus and
• 3 Hamstring muscles
• Biceps femoris, Semitendinosus, Semimebranosus
• Adduction of the hip (femur moves toward midline)
• Medial compartment muscles
• Adductors (5 of them)
• Abduction and Rotation of the Hip
• Gluteus medius, gluteus minimus, and sartorius

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Movements at the Knee Joint Some of the Same
Muscles (hip)

• Extension of the knee (tibia and fibula move
  anteriorly)
• The Quadriceps
• Rectus femoriship
• Vastus lateralis
• Vastus medialis
• Vastus intermedialis (deep to rectus femoris)
• Flexion of the knee (tibia and fibula move
  posteriorly)
• The Hamstrings
• Biceps femoriship
• Semitendinosuship
• Semimembranosuship
• Because the knee is backwards compared to the
  hip and most other joints, a muscle that flexes
  the hip would extend the knee.
• And a muscle that extends the hip, would flex the
  knee.

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Movements at the Hip Flexors, Adductors and
Rotators
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Movements at the Hip Extensors
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Movements at the Knee Extensors
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Movements at the Knee Flexors
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Muscles Moving the Hip and Knee Transverse
Section
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Movements at the Ankle

• Plantar Flexion (toes point downward)
• Posterior compartment muscles
• Gastocnemius
• Soleus
• Dorsiflexion (toes point upward)
• Anterior compartment muscles
• Tibialis anterior

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Movement at the Ankle Plantar Flexors
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Movement at the Ankle Dorsiflexors

• Muscles of the anterior compartment are the
  primary toe extensors and ankle dorsiflexors
• They include the tibialis anterior

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Practice Questions
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• A muscle that assists the muscle primarily
  responsible for a given action is a(n) 
• Antagonist 
• Synergist 
• Primary antagonist 
• Levator 
• Originator

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• A muscle that is inserted on the mandible is
  probably involved in 
• Frowning 
• Kissing 
• Wrinkling the forehead 
• Chewing 
• Blowing

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• Muscles ending in the suffix "-costal" would be
  associated with the 
• neck. 
• head. 
• groin. 
• abdomen. 
• ribs.

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• Muscles with fibers that run straight or parallel
  to the long axis of the body are called 
• Obliques 
• Rectus 
• Lateralis 
• Transversus 
• Medialis

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• The attachment site of the muscle tendon to the
  more movable bone is called the 
• Proximal end 
• Insertion 
• Distal end 
• Origin 
• Belly

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• The names of the muscles can indicate all of the
  following EXCEPT 
• The region of the body where the muscle is
  located 
• Action of the muscle 
• Fat content of the muscle 
• The direction of the muscle relative to the long
  axis of the body 
• Structural characteristics of the muscle

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• Muscles that act as sphincters to close openings
  are circular muscles.  True False

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• The deltoid muscle is named for its
  location.  True False

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Specific muscle questions
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• The muscle that extends the forearm while doing
  push-ups is the 
• Biceps 
• Pectoralis 
• Deltoid 
• Brachialis 
• Triceps

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• The muscular wall of the abdomen is composed of 
• glossal muscles. 
• oblique and rectus muscles. 
• spinal erector muscles. 
• pectoralis muscles. 
• muscles of mastication.

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• The major abductor muscle of the upper arm is
  the 
• subscapularis. 
• deltoid. 
• coracobrachialis. 
• teres major. 
• supraspinatus.

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• Which of the following muscles is NOT a muscle of
  the hamstring group? 
• Semimembranosus 
• Biceps femoris 
• Semitendinosus 
• Quadriceps femoris

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• The muscle that inserts on the acromion and
  scapular spine is the trapezius.  True False

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• The semimembranosus muscle belongs to the group
  known as the "hamstrings."  True False