2Chapter 11 Outline Muscles of the Head and Neck Muscles of the Vertebral ColumnMuscles of RespirationMuscles of the Abdominal WallMuscles of the Pelvic Floor
3Axial MusclesAxial 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.
4Five Groups of Axial Muscles Muscles of the head and neckMuscles of the vertebral columnMuscles of respirationMuscles of the abdominal wallMuscles of the pelvic floor
7Muscles 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.
11Muscles 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.
18Muscles 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
21Muscles 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.
22Extrinsic Tongue Muscles Genioglossus—protracts (sticks out) tongueStyloglossus—elevates and retracts tongueHyoglossus—depresses and retracts tonguePalatoglossus—elevates posterior part of tongue
26Muscles of the PharynxThe 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.
27Muscles of the PharynxThe 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.
30Muscles 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.
31Suprahyoid MusclesAll of these muscles elevate the hyoid bone during swallowing. They are as follows:DigastricGeniohyoidMylohyoidStylohyoid
36Muscles That Move the Head and Neck Anterolateral muscles—flex the head and/or neckPosterior muscles—extend head and/or neck
37Anterolateral 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.
39Posterior 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 capitisSplenius cervicusSemispinalis capitisLongissimus capitis
41Muscles 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 laterallyTransversospinalis—minor deep back muscles, deep to the erector spinae; connect and stabilize the vertebrae
42Erector SpinaeThe erector spinae muscles are organized into three groups:Iliocostalis—most lateral group comprised of cervical, thoracic, and lumbar partsLongissimus—comprised of capitis, cervical, and thoracic partsSpinalis—most medial group inserting onto the spinous process of vertebrae, comprised of cervical and thoracic parts
48Muscles of Respiration These muscles are involved in inhalation and exhalation:Serratus posterior superior—elevates ribs during inhalationSerratus posterior inferior—depresses ribs during exhalationExternal intercostals—elevates ribs during inhalationInternal intercostals—depresses ribs during forced exhalationTransverse thoracis —depresses ribs during exhalationDiaphragm—the major muscle of respiration
50DiaphragmInternal dome-shaped muscle that physically separates the thoracic and abdominopelvic cavitiesPossesses a central tendon onto which all of its fibers convergeContraction of diaphragm causes a depression of the muscle thus increasing the vertical dimensions of the thoracic cavity
53Muscles 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 inferomedialInternal oblique—middle of the three lateral muscles; directed at right angle to the external obliqueTransverse abdominis—deepest of three lateral muscles; directed horizontallyRectus abdominis—anterior muscle connecting the sternum to the pubic bone; divided into four muscle segments
58Muscles 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 organscontrol of defecationcontrol of urinationreproductive processes, such as erection and ejaculation
59Triangles 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 urethraAnal triangle—posterior triangle; contains the anus
60The Axial MusculatureMuscles of the Pelvic Floor- Perineum (Female)
61The Axial MusculatureMuscles of the Pelvic Floor- Perineum (Male)