Arrangement of Fascicles

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Arrangement of Fascicles

• Remember a fascicle is several sheathed muscle
  fibers wrapped by a coarse fibrous membrane

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Arrangement of Fascicles

• Common fascicle patterns
• Circular
• When fascicles are arranged in concentric rings
  (sphincters)
• Convergent
• When the fascicles converge to a single insertion
• Triangular or fan-shaped
• Parallel
• The length of the muscle runs parallel to the
  long axis of the muscle
• Strap like

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Arrangement of Fascicles

• Common fascicle patterns
• Fusiform
• Modified parallel form
• Has a spindle-shaped muscle
• Has an expanded belly or gastor
• Pennate
• Short fascicles
• Attach obliquely to a central tendon
• Unipennate insert into one side of the tendon
• Bipennate inserts into opposite sides of the
  tendon
• Multipennate inserts into multiple places of
  the tendon

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Head and Neck Muscles

• Facial Muscles
• Frontalis covers the frontal bone from the
  cranial aponeurosis to the skin of the eyebrow
• Raises the eyebrows
• Occipitalis covers the posterior aspect of the
  skull
• Pulls the scalp
• Orbicularis Oculi fibers run in circles around
  the eyes
• Allows eye closing, squinting, blinking and
  winking

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Frontalis
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Frontalis
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Occipitalis
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Orbicularis Oculi
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Orbicularis Oculi
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Head and Neck Muscles

• Facial Muscles
• Orbicularis Oris the circular muscle of the
  lips
• Opens the mouth and protrudes the lips (kissing
  muscle)
• Buccinator fleshy, runs horizontally across the
  cheek
• Inserts into the orbicularis oris
• Flattens the cheek
• Doubles as a chewing muscle

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Orbicularis Oris
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Buccinator
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Head and Neck Muscles

• Facial Muscles
• Zygomaticus extends from the corner of the
  mouth to the cheek
• smiling muscle
• Raises the corners of the mouth

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Head and Neck Muscles

• Chewing Muscles
• Buccinator already mentioned
• Masseter covers the angle of the lower jaw
• Runs from the zygomatic process of the temporal
  bone to the mandible
• Closes the jaw
• Temporalis fan-shaped, overlying the temporal
  bone
• Inserts into the mandible and is a synergist to
  the masseter

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Masseter
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Temporalis
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Head and Neck Muscles

• Neck muscles
• Platysma single sheet-like muscle
• Covers the anterolateral neck
• Originates from the connective tissue of the
  chest muscle and inserts in the area around the
  mouth
• Pulls the corners of the mouth inferiorly
• Sternocleidomastoid paired muscle
• Two headed muscles, one on each side of the neck
• One head arises from the sternum, the other from
  the clavicle
• Head fuses before insertion into the mastoid
  process of the temporal bone
• Flex the neck

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Platysma
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Sternocleidomastoid
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Trunk Muscles

• Divided into Anterior and Posterior muscles
• Anterior
• Pectoralis Major large fan-shaped muscle
  covering the upper part of the chest
• Origin is in the sternum, should girdle, and
  first 6 ribs
• Insertion is on the proximal end of the humerus
• Flexes the arm

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Trunk Muscle

• Anterior Muscles
• Intercostal Muscles deep muscles of the ribs
• External intercostal muscles are used in
  breathing
• Raise the rib cage (air in)
• Internal intercostal muscles deeper than the
  external
• Used in breathing
• Lower the rib cage (air out)
• Muscles of the Abdominal Girdle reinforce the
  body trunk
• Consists of rectus abdominis, external and
  internal obliques, and transverse abdominis.
• Look like plywood
• Muscles run in different directions

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Intercostal Muscles
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Trunk Muscle

• Anterior
• Rectus oblique strap-like muscles
• Most superficial muscles of the abdomen
• Run from the pubis to the rib cage
• Flex the vertebral column
• Depress the abdomen during defecation and child
  birth
• External oblique paired superficial muscles
• Make up the lateral walls of the abdomen
• Fibers run downward and medially from the ribs to
  the illium
• Flex the vertebral column, and rotate the trunk

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Trunk Muscles

• Anterior
• Internal oblique paired muscles
• Deep to the external obliques
• Fibers run at right angles to those of the
  external obliques
• Rise out of the iliac crest and insert into the
  last 3 ribs
• Transversus abdominis deepest muscle of the
  abdomen
• Fibers run horizontally across the abdomen
• Arises from the lower ribs and iliac crest
• Inserts into the pubis

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Internal Oblique
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Trunk Muscles

• Posterior Muscles
• Trapezius
• Most superficial muscles of the posterior neck
  and upper trunk
• Together form a diamond shape
• Have a broad origin
• From the occipital bone of the skull to the end
  of the vertebral column
• Flare to insert into the scapular spine and
  clavicle

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Trunk Muscles

• Posterior Muscles
• Latissimus Dorsi
• Large flat muscle pair which covers the lower
  back
• Origin is in the lower spine and ilium
• Inserts into the proximal end of the humerus
• Extends and abducts the humerus

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Trunk Muscle

• Posterior Muscle
• Erector Spinae
• Back extension prime mover
• Deep muscles of the back
• Have 3 muscle columns
• Longissimus
• Iliocostalis
• Spinalis
• They span the entire length of the vertebral
  column
• They are back extensors and help bending at the
  waist

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Trunk Muscles

• Posterior Muscles
• Deltoid
• Fleshy triangular shaped
• Form the shoulder
• Origin is in the spine of the scapula to the
  clavicle
• Insertion is at the proximal end of the humerus
• Prime mover of arm abduction

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