Chapter 11 *Lecture Outline *See separate FlexArt PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Chapter 11 Outline 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 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: 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 Superior oblique (CN IV) depresses and turns eye laterally

Extrinsic Eye Muscles

Muscles of Mastication All are innervated by CN V3. Temporalis—elevates and retracts the mandible (pulls posteriorly) Masseter—elevates and retracts the mandible (pulls anteriorly) 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 Genioglossus—protracts (sticks out) tongue Styloglossus—elevates and retracts tongue Hyoglossus—depresses and retracts tongue Palatoglossus—elevates posterior part of tongue

Extrinsic Muscles of the Tongue Figure 11.6

Palatoglossus Styloglossus Genioglossus Hyoglossus 24

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: Digastric Geniohyoid Mylohyoid Stylohyoid

Suprahyoid Muscles Figure 11.8

Infrahyoid Muscles All of these muscles depress the hyoid bone during swallowing. They are as follows: Omohyoid Sternohyoid Sternothyroid Thyrohyoid

Infrahyoid Muscles Figure 11.8

Muscles of the Anterior Neck

Muscles That Move the Head and Neck Anterolateral muscles—flex the head and/or neck 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: 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. External oblique—most superficial lateral muscle; directed inferomedial Internal oblique—middle of the three lateral muscles; directed at right angle to the external oblique Transverse abdominis—deepest of three lateral muscles; directed horizontally 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: Urogenital triangle—anterior triangle; contains external genitalia and urethra 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 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Sacrum Sacroiliac articulation Ilium Coccyx Piriformis Coccygeus Ischial spine Obturator internus Anal canal Iliococcygeus Levator ani Vagina Pubococcygeus Urethra Obturator canal Urogenital diaphragm Pubic symphysis (a) Female, superior view Raphe Pubic symphysis Urogenital triangle Bulbospongiosus Pubic ramus External urethral sphincter Ischiocavernosus Superficial transverse Perineal muscle Urethra Deep transverse perineal muscle Perineal body Anus Anal triangle Levator ani External anal sphincter Gluteus maximus Superficial Deep (b) Male, inferior view Pubic symphysis Urethra Pubic ramus Urogenital triangle Vagina sphincter External urethral Bulbospongiosus Ischiocavernosus Urethra Vagina perineal muscle Superficial transverse Deep transverse perineal muscle Perineal body Levator ani Anus Figure 11.15 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