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Chapter 11
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Chapter 11 Outline
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•
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Muscles of the Head and Neck
Muscles of the Vertebral Column
Muscles of Respiration
Muscles of the Abdominal Wall
Muscles of the Pelvic Floor
Axial Muscles
• Axial muscles have both their origins and
insertions on parts of the axial skeleton.
• Axial muscles support the head and spinal
column.
• Axial muscles are used in facial
expression, chewing, and swallowing.
• Axial muscles aid in breathing and support
and protection of the abdominal and pelvic
organs.
Five Groups of Axial Muscles
1.
2.
3.
4.
5.
Muscles of the head and neck
Muscles of the vertebral column
Muscles of respiration
Muscles of the abdominal wall
Muscles of the pelvic floor
Figure 11.1
Figure 11.1
Muscles of Facial Expression
• These muscles have their origin in the
superficial fascia or on the skull. They
insert into the superficial fascia of the skin.
• When they contract they contort the skin
thereby causing changes in facial
expression.
• Most of these muscles are innervated by
cranial nerve VII (CN VII), the facial nerve.
Muscles of Facial Expression
Figure 11.2
Figure 11.3
Muscles of Facial Expression
• Buccinator—compresses the cheek
against the teeth when we eat to keep
food from getting into the vestibule. It is
also the muscle of suckling. It is used to
compress air in the oral cavity to play a
wind instrument.
Muscles of Facial Expression
Figure 11.2
Muscles of Facial Expression
Muscles of Facial Expression—
continued
Extrinsic Eye Muscles
• Six muscles move the eye
• Originate from a common tendinous ring in the
posterior orbit and attach onto the anterior sclera
(outer surface) of the eye
Figure 11.4
Extrinsic Eye Muscles
The six extrinsic eye muscles, innervation,
and movement of the eye are:
1.
2.
3.
4.
5.
Medial rectus (CN III) pulls eye medially
Lateral rectus (CN VI) pulls eye laterally
Inferior rectus (CN III) pulls eye inferiorly
Superior rectus (CN III) pulls eye superiorly
Inferior oblique (CN III) elevates and turns
eye laterally
6. Superior oblique (CN IV) depresses and
turns eye laterally
Extrinsic Eye Muscles
Muscles of Mastication
All are innervated by CN V3.
1. Temporalis—elevates and retracts the
mandible (pulls posteriorly)
2. Masseter—elevates and retracts the mandible
(pulls anteriorly)
3. Lateral and medial pterygoids—protract and
move the mandible from side to side while
chewing
Muscles of Mastication
Figure 11.5
Muscles of Mastication
Muscles That Move the Tongue
• The tongue is comprised of intrinsic
muscles that curl, squeeze, and fold the
tongue.
• The extrinsic muscles attach to the
tongue and cause the tongue to perform
other movements such as protraction,
retraction, depression, and elevation.
Extrinsic Tongue Muscles
1. Genioglossus—protracts (sticks out)
tongue
2. Styloglossus—elevates and retracts
tongue
3. Hyoglossus—depresses and retracts
tongue
4. Palatoglossus—elevates posterior part
of tongue
Extrinsic Muscles of the Tongue
Figure 11.6
Palatoglossus
Styloglossus
Genioglossus
–Hyoglossus
Extrinsic Muscles of the Tongue
Muscles of the Pharynx
• The pharynx, commonly called the
“throat” is a funnel-shaped tube that lies
posterior to and extends inferiorly from the
oral and nasal cavities.
• Several muscles help form this muscular
tube or attach to it and aid in swallowing.
• Most of these muscles are innervated by
CN X.
Muscles of the Pharynx
•
•
The primary pharyngeal muscles are the
superior, middle, and inferior
constrictor muscles.
When a bolus of food enters the pharynx,
these three muscles contract
sequentially to initiate swallowing.
Muscles of the Pharynx
Figure 11.7
Muscles of the Pharynx
Muscles of the Anterior Neck
•
Muscles of the anterior neck are divided
into the suprahyoid and infrahyoid
muscles.
─ Suprahyoid muscles are superior to
the hyoid bone.
─ Infrahyoid muscles are inferior to the
hyoid bone.
Suprahyoid Muscles
All of these muscles elevate the hyoid bone
during swallowing. They are as follows:
1. Digastric
2. Geniohyoid
3. Mylohyoid
4. Stylohyoid
Suprahyoid Muscles
Figure 11.8
Infrahyoid Muscles
All of these muscles depress the hyoid bone
during swallowing. They are as follows:
1. Omohyoid
2. Sternohyoid
3. Sternothyroid
4. Thyrohyoid
Infrahyoid Muscles
Figure 11.8
Muscles of the Anterior Neck
Muscles That Move
the Head and Neck
1. Anterolateral muscles—flex the head
and/or neck
2. Posterior muscles—extend head and/or
neck
Anterolateral Neck Muscles
• Sternocleidomastoid muscles are the
major muscles of this compartment.
• Upon bilateral contraction, they cause
flexion of neck.
• Upon unilateral contraction, they cause
lateral flexion and rotation of head to the
opposite side.
Sternocleidomastoid Muscle
Figure 11.9
Posterior Neck Muscles
Posterior muscles extend the head and/or neck
when they contract bilaterally. When they contract
unilaterally they turn the head and neck to the
same side. The major muscles in this compartment
are:
• Splenius capitis
• Splenius cervicus
• Semispinalis capitis
• Longissimus capitis
Posterior Neck Muscles
Figure 11.10
Muscles of the Vertebral Column
There are two major groupings of muscles that are
responsible for movement of the vertebral
column:
• Erector spinae—maintain posture, help to
stand erect; bilateral contraction extends the
spinal column and unilateral contraction flexes
the column laterally
• Transversospinalis—minor deep back
muscles, deep to the erector spinae; connect
and stabilize the vertebrae
Erector Spinae
The erector spinae muscles are organized into
three groups:
•
•
•
Iliocostalis—most lateral group comprised of
cervical, thoracic, and lumbar parts
Longissimus—comprised of capitis, cervical,
and thoracic parts
Spinalis—most medial group inserting onto
the spinous process of vertebrae, comprised of
cervical and thoracic parts
Erector Spinae Muscles
Figure 11.11
Transversospinalis Muscles
Figure 11.12
Quadratus Lumborum
• A muscle that also moves the vertebral
column
• Bilateral contraction causes extension of
spinal column
• Unilateral contraction laterally flexes
vertebral column
Muscles of the Vertebral Column
Muscles of the Vertebral Column—
continued
Muscles of Respiration
These muscles are involved in inhalation and exhalation:
1.
2.
3.
4.
5.
6.
Serratus posterior superior—elevates ribs during
inhalation
Serratus posterior inferior—depresses ribs during
exhalation
External intercostals—elevates ribs during inhalation
Internal intercostals—depresses ribs during forced
exhalation
Transverse thoracis —depresses ribs during
exhalation
Diaphragm—the major muscle of respiration
Muscles of Respiration
Figure 11.13
Diaphragm
• Internal dome-shaped muscle that
physically separates the thoracic and
abdominopelvic cavities
• Possesses a central tendon onto which all
of its fibers converge
• Contraction of diaphragm causes a
depression of the muscle thus increasing
the vertical dimensions of the thoracic
cavity
Diaphragm
Figure 11.13
Muscles of Respiration
Muscles of the Abdominal Wall
Four anterolateral muscles collectively compress and hold
the abdominal organs in place. They also flex the
vertebral column.
1. External oblique—most superficial lateral muscle;
directed inferomedial
2. Internal oblique—middle of the three lateral muscles;
directed at right angle to the external oblique
3. Transverse abdominis—deepest of three lateral
muscles; directed horizontally
4. Rectus abdominis—anterior muscle connecting the
sternum to the pubic bone; divided into four muscle
segments
Muscles of the Abdominal Wall
Figure 11.14
Muscles of the Abdominal Wall
Figure 11.14
Muscles of the Abdominal Wall
Muscle Actions on the
Axial Skeleton
Muscles of the Pelvic Floor
This structure consists of three layers of muscles
known as the pelvic diaphragm. These muscles
participate in the following functions:
• support of the pelvic organs
• control of defecation
• control of urination
• reproductive processes, such as erection and
ejaculation
Triangles of the Pelvic Floor
•
•
The diamond-shaped region between the
lower extremities is called the perineum.
If you draw a line between the two
ischeal tuberosities, you have divided
that diamond-shaped area into two
triangles:
1. Urogenital triangle—anterior triangle;
contains external genitalia and urethra
2. Anal triangle—posterior triangle; contains
the anus
The Axial Musculature
Muscles of the Pelvic Floor- Perineum (Female)
The Axial Musculature
Muscles of the Pelvic Floor- Perineum (Male)
Triangles of the Pelvic Floor
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Sacrum
Sacroiliac articulation
Ilium
Piriformis
Coccyx
Coccygeus
Ischial spine
Obturator internus
Anal canal
Iliococcygeus
Pubococcygeus
Vagina
Levator
ani
Obturator canal
Urethra
Urogenital diaphragm
Pubic symphysis
(a) Female, superior view
Pubic symphysis
Raphe
Pubic ramus
External urethral
sphincter
Bulbospongiosus
Urogenital
triangle
Ischiocavernosus
Urethra
Deep transverse
perineal muscle
Superficial transverse
Perineal muscle
Perineal body
Anus
External anal
sphincter
Levator ani
Anal
triangle
Gluteus maximus
Superficial
Deep
(b) Male, inferior view
Pubic symphysis
Pubic ramus
External urethral
sphincter
Urethra
Vagina
Urogenital
triangle
Bulbospongiosus
Urethra
Vagina
Deep transverse
perineal muscle
Ischiocavernosus
Superficial transverse
perineal muscle
Perineal body
Figure 11.15
Anus
Levator ani
Anal
triangle
External anal
sphincter
Gluteus maximus
Superficial
Deep
(c) Female, inferior view
Muscles of the Pelvic
Floor Triangles
Muscles of the Pelvic
Floor Triangles—continued