Section 3 Flashcards
What is frontalis?
- the muscle that covers the frontal bone and lifts the eyebrows, causing the forehead to wrinkle
What is orbicularis oculi?
- a muscle surrounding the eye that forcefully closes the eye when contracted
-it originates on the frontal and maxillary bones
What is zygomaticus?
- a muscle that extends from the zygomatic arch to the corners of the mouth
- it draws the angle of the mouth superiorly and posteriorly, causing one to smile :)
What is orbicularis oris?
- a muscle that surrounds the mouth and enables the puckering of lips
- it originates on the maxillary bones or mandible bones
- sometimes referred as a kissing muscle
What are the temporalis and masseter muscle used in?
Mastication (chewing)
What is the temporalis?
- a fan-shaped muscle
- extends from the temporal fossa of the parietal bone to the coronoid process of the mandible
- elevates and pulls the mandible posteriorly (retract)
What is the masseter?
- a powerful muscle
- extends from the zygomatic arch to the angle of the mandible (lower jaw)
- its action is to elevate and protract (move forward) the jaw
Which muscle flexes the neck, and rotates the head to the opposite side
The sternocleidomastoid muscle flexes the neck with bilateral contraction, and rotates the head to the opposite side with unilateral contraction.
Where is the sternocleidomastoid muscle attached?
“Sterno” and “cleido” mean that the inferior attachment of the muscle is at the sternum and the clavicle
“Mastoid” means that the superior attachment of the muscle is on the mastoid process of the temporal bone
Therefore the sternocleidomastoid has one attachment at the sternum and clavicle and another attachment at the mastoid process
What does the sternocleidomastoid muscle do?
It flexes the neck with bilateral contraction, and rotates the head to the opposite site with unilateral contraction.
(It is an anterior muscle that moves the head)
What two main posterior muscles move the head?
Semispinalis capitis and splenius capitis
Where is the semispinalis capitis?
- “capitis” means head: referring to the fact that this muscle inserts to the occipital bone
- “spinalis” means half of the spine
Therefore the semispinalis capitis attaches at the occipital bone and lies on each side of the spine
What does the semispinalis capitis do?
Extends the neck with bilateral contraction, and turns the face slightly to the opposite side with unilateral contraction
(its a posterior muscle that moves the head)
Where is the splenius capitis?
- “capitis” means head referring to the insertion of the muscle on the occipital bone
- “splenius” means bandage, suggesting that the muscle looks like a bandage
Therefore the splenius capitis attaches at the occipital bone and is shaped like a bandage.
What does the splenius capitis do?
Extends the neck with bilateral contraction, and causes flexion and lateral rotation of the neck with unilateral contraction.
(its a posterior muscle that moves the head)
What are the external and internal intercostal muscles of the thorax?
External intercostals are the most superficial, and their fibers run anteriorly and inferiorly between the ribs. They aid in inspiration.
Internal intercostals lie deep to the externals, and their fibers run posteriorly and inferiorly. They aid in expiration.
What do the intercostal muscles of the thorax do?
They aid in the process of breathing
What are erector spinae muscles?
A group of muscles that help keep the spine erect.
They run down both side of the spinal column.
What do the abdominal wall muscles do?
They facilitate movement of the trunk, and aid in breathing
What are the four types of abdominal muscles?
- External oblique
- Internal oblique
- Transversus abdominis
- Rectus abdominis
Where is the external oblique and how do its fibers run?
- the most superficial of the anterolateral abdominal wall musculature
- its fibers run anteriorly and inferiorly
What are the functions of the external oblique?
- bilateral: flexes the vertebral column and compresses the abdominal wall. used in forced expiration
- unilateral: lateral flexion and rotation of the vertebral column
Where is the internal oblique and how do its fibers run?
- lies deep to the external oblique
- its fibers run anteriorly and superiorly
What are the functions of the internal oblique?
- bilateral: flexes the vertebral column and compresses the abdominal wall
- unilateral: lateral flexion and rotation of the vertebral column
How does the transversus abdominis run (position)?
- runs horizontally, deep to the internal oblique
What are the functions of the transversus abdominis?
- bilateral: flexes the vertebral column and compresses the abdominal wall. used in forced expiration
- unilateral: lateral flexion of the vertebral column
Where does the rectus abdominis lie?
- it lies on either side of the linea alba and is separated by tendinous intersections
(linea alba = a line of connective tissue down the middle of the abdomen for muscle attachment)
What is linea alba?
linea alba = a line of connective tissue down the middle of the abdomen for muscle attachment
Compare bilateral and unilateral contraction.
Bilateral contraction is referring to the bilateral, paired muscles working simultaneously. So, for example, bilateral contraction of the left and right sternocleidomastoid work together to flex the neck.
Unilateral would then just be one.
