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Arrangement of Fascicles

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1 Arrangement of Fascicles
Remember: a fascicle is several sheathed muscle fibers wrapped by a coarse fibrous membrane

2 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

3 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

4 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

5 Frontalis

6 Frontalis

7 Occipitalis

8 Orbicularis Oculi

9 Orbicularis Oculi

10 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

11 Orbicularis Oris

12 Buccinator

13 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



16 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

17 Masseter

18 Temporalis

19 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

20 Platysma

21 Sternocleidomastoid


23 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



26 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

27 Intercostal Muscles


29 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


31 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

32 Internal Oblique


34 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


36 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


38 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


40 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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