M3s3 Axial Muscles

Question 1

Muscles of facial expression

Answer 1

• refer to good notes for images
  -muscles of facial expression insert into the skin
  -contraction of these muscles produce various facial expression by moving the skin
  -know 4 muscles
  Frontails - muscle that covers the frontal bone and lifts the eyebrows, causing forehead to wrinkle
  Orbicularis oculi - muscle surrounding the eye that forcefully closes the eye when contracted. Originates on the frontal and maxillary bones
  Orbicularis oris - surrounds mouth and enables the puckering of lips. Originates on maxillary bones or mandible and sometimes referred to as kissing muscle
  Zygomaticus - extends from the zygomatic arch to corners of mouth. Draws the angle of the mouth superiorly and posteriorly, causing one to smile

Question 2

Muscles of mastication (chewing)

Answer 2

-refer to goodnotes for image
-2 muscles
Temporalis - fan shaped muscle that extends from temporal fossa of the parietal bone to coronoid process of the mandible. Temporalis muscle elevates and pulls the mandible posteriorly (retract)

Masseter - powerful muscles that extends from zygomatic arch to the angle of the mandible (lower jaw). It’s action to elevate and protract (move forward) the jaw

Question 3

Muscles that move head

Answer 3

-refer to goodnotes for diagram
-three muscles involved in moving the head, grouped into anterior and posterior

Anterior: sternocleidomastoid muscle
-flexes the neck with bilateral contraction and rotates the head to the opposite site with unilateral contraction
-name of muscle indicates where attached. Sterno and Cleo mean inferior attachment of muscle at sternum and clavicle. Mastoid means superior attachments of muscle is on mastoid process of temporal bone. In other terms, one attachment at sternum and clavicle and another at mastoid process

Posterior: 2 main ones which move head
1. Semisphonalis capitis - extends the neck with bilateral contraction and turns face slightly to opposite side with unilateral contraction
2. Splenius capitis - extends the neck with bilateral contraction, causes flexion and lateral rotation of the neck with unilateral contraction

Question 4

Muscles of thorax

Answer 4

-intercostal muscles of the thorax aid in process of breathing
-focus on 2 typed on intercostal muscles
External:
-most superficial and their fibres run anteriorly and inferior lay between ribs
-aid in inspiration
Internal:
-lie deep to the externals and their fibres run posteriorly and inferiorly
-aid in expiration
* refer to goodnotes

Question 5

Muscles of back

Answer 5

*refer to goodnotes
-the erector spinae muscles are a group of muscles that help keep the spine erect
-run down both sides of the spinal column

Question 6

Muscles of abdominal wall

Answer 6

*refer to goodnotes please
-abdominal wall muscles facilitate movement of trunk and aid in breathing
- 4 types

External Oblique -
-most superficial
-its fibres run anteriorly and inferiorly
Functions:
-bilateral: flexes the vertebral column and compresses the abdominal wall. Used in forced expiration
Unilateral: lateral flexion and rotation of the vertebral column

Internal oblique -
-lies deep to the external oblique
-fibres run anteriorly and superiorly
Functions:
-bilateral: flexes the vertebral column and compresses the abdominal wall
Unilateral: lateral flexion and rotation of the vertebral column

Tran versus abdominis -
-runs horizontally
-deep to internal oblique
Functions:
-bilateral (both sides): flexes the vertebral column and compresses the abdominal wall. Used in forced expiration
-Unilateral (one side): lateral flexion of the vertebral column

Rectus abdominis -
-lies on either side of the lines alba (line of connective tissue down the middle of the abdomen for muscle attachment) and separated by tending us intersections
Functions:
Flexion of truck
Forced expiration