Axial Muscles

• support the head and spinal column

• used in facial expression, chewing, and swallowing

• aid in breathing

• support and protect abdominal and pelvic organs

What are the functions of the axial muscles?

muscles of the head and neck

Muscles that are separated into several groups based on location and general actions; most attach to the skull or hyoid bone

muscles of facial expression

Muscles that attach to the subcutaneous layer (deep to skin) or skull bones; contraction moves skin and changes facial expression; most are innervated by cranial nerve VII

CN VII

The facial nerve

six

How many muscles move the eye?

muscles that move the eyes

medial rectus, lateral rectus, inferior rectus, superior rectus, inferior oblique, and superior oblique

common tendinous ring

The rectus muscles originate from this in the posterior orbit and attach to the anterior part of the sclera (outer part of the eyeball)

oblique muscles

These muscles originate within the orbit and attach to the posterolateral sclera of the eye

trochlea

The superior oblique passes through this pulley-like thingy

mastication

The process of chewing

CN V

The mastication muscles are innervated by which CN

temporalis

Elevates and retracts the mandible

Masseter

Elevates and protracts the mandible

lateral and medial pterygoid

Protract and move the mandible form side to side while chewing

intrinsic muscles

Muscles that curl, squeeze, and fold the tongue

extrinsic muscles

Muscles that attach from the head and neck to the tongue; end in the suffix -glossus (tongue)

pharynx (throat)

A tube extending from the oral and nasal cavities

CN X

Most of the muscles that form or attach to the pharynx and aid in swallowing are innervated by which CN?

superior, middle, and inferior pharyngeal constrictors

When food enters the pharynx, these three muscles contract sequentially to initiate swallowing and force the bolus inferiorly into the esophagus

suprahyoid muscles

Muscles superior to the hyoid that are associated with the floor of the mouth; elevate the hyoid during swallowing and speaking

Infrahyoid muscles

Muscles inferior to the hyoid; as swallowing ends, these muscles depress the hyoid bone and larynx

anterolateral neck muscles

Muscles that flex the head and/or neck

posterior neck muscles

Muscles that extend the head and/or neck

erector spinae

Muscles that maintain posture and help the body to stand erect

iliocostalis group

The erector spinae group that is most lateral; composed of cervical, thoracic, and lumbar parts

longissimus group

Erector spinae group that is composed of capitis, cervical, and thoracic parts

spinalis group

Erector spinae group that is the most medial; attack to the spinous processes of vertebrae; composed of cervical and thoracic parts

transversospinalis

Muscles that connect and stabilize the vertebrae; assisted by minor muscles interspinales, intertransversarii

quadrates lumborum

Muscle in the lumbar region

inhalation

During this, muscles contract to increase thoracic cavity dimensions, allowing lungs to fill with air

exhalation

During this, some muscles contract and others relax, causing the thoracic cavity to decrease in size and forcing air out of the lungs

diaphragm

What is the most important muscle for breathing? Contraction increases intra-abdominal pressure (important for urination, defecation, childbirth, and movement of venous blood)

external oblique

Superficial, lateral muscle; fibers directed inferomedially; aponeurosis forms the inguinal ligament

internal oblique

Deep to the external oblique; fibers directed superomedially

transverse abdominis

Deepest of the lateral muscles; fibers directed horizontally

rectus abdominis

Long, anterior muscle connecting the sternum to the pubic bone; divided into four muscle segments

pelvic diaphragm

The pelvic floor consists of three layers of muscles collectively known as?

• support pelvic organs

• control of defecation

• control of urination

• some reproductive processes

What are the functions of the pelvic diaphragm

ectoderm

This is located on the external surface of the embryo where the cells will eventually develop into the epidermis of the skin, derivatives of epidermis, including hair and nails, and the nervous system.