Anatomy of the Muscular System: Introduction &
Muscles of the Head, Neck, and Trunk
Notice: To optimize your learning in this course, we advise that you complete the labs and modules
as indicated in the BIOD 151 Lab Schedule.
The muscular system and the skeletal system work together to provide movement for the human
body. Muscle tissue is found in three distinct types in the body; skeletal, smooth, and cardiac.
Skeletal muscles must have a blood and nervous supply to provide movement. Skeletal muscles are
under conscious control, meaning that a person can consciously decide to use these muscles to
complete an action. Communication within the body to coordinate movement starts in the brain with
a message that is sent through the spinal cord and eventually attaches to a muscle. Peripheral
nerves carry the signal from the central nervous system (brain and spinal cord) to a specific
muscle destination to provide movement. Messages from the central nervous system to a muscle
are called a motor actions. Nerves also carry information from the external environment to the
central nervous system, called sensation or sensory input. (see Figure 5.1 and Figure 5.2) Spinal
nerves combine to form complex networks of peripheral nerves throughout the body.
Figure 5.1 Posterior view of the nervous system. The brain and spinal cord (central nervous
,system) connect to the peripheral nervous system. Examples of peripheral nerves are spinal nerves
(cervical, thoracic, and lumbar), the upper trunk of the brachial plexus, and the radial nerve.
Figure 5.2 Peripheral nerves carry the communication from the central nervous system (brain and
spinal cord) to the muscle. Peripheral nerves also carry information from the environment to the
central nervous system.
Tendons are connective tissues that connect skeletal muscle to bone at each end (see Figure 5.3).
Tendons are flexible, can bend at the joints, and help cushion against sudden
movement. Ligaments are connective tissue that connects bone to bone, helping to stabilize joints
where bones meet.
,Figure 5.3 Skeletal muscles attach to bones via tendons at points called the origin and insertion.
The origin is the fixed point while the insertion is the place that is moved during a muscle
contraction.
All skeletal muscles have an origin, insertion, and action. The origin is the bony site of attachment
which is stationary during the movement. The insertion of a muscle is the bony site of attachment
that is moved by the muscle contraction. (see Figure 5.3)
The origin and insertion can be reversed in different types of movement. For this module, the
standard origin and insertion points are referenced from anatomical position.
The action of the muscle is what effect is produced by the muscle’s contraction. For example, the
triceps is the primary extensor of the forearm. The innervation is the peripheral nerve that supplies
a muscle with the message from the brain. For example, the innervation of the biceps brachii is the
musculocutaneous nerve. (see Figure 5.4)
, Figure 5.4 Anterior view of the musculocutaneous nerve (blue) innervates the biceps brachii muscle.
Muscles are generally studied in groups. The following muscle list is an overview of some of the
major muscles in the body. Study the location of the muscle in the body. In addition, if listed, study
the origin, insertion, innervation and action of these muscles.
Muscles of Facial Expression: (See Figure 5.5)
The muscles in this grouping help to facilitate all the actions within the face. All the varied facial
expressions are enabled by these muscles. CN is an abbreviation for cranial nerve. There are
twelve pairs of cranial nerves that originate on the ventral surface of the brain, controlling muscles
and functions of several organs and glands.
Orbicularis oculi
Action: eye closure
Innervation: Facial nerve (CN VII)
Orbicularis oris
Action: mouth closure: closes lips, protrudes lips forward, presses lips against teeth
Muscles of the Head, Neck, and Trunk
Notice: To optimize your learning in this course, we advise that you complete the labs and modules
as indicated in the BIOD 151 Lab Schedule.
The muscular system and the skeletal system work together to provide movement for the human
body. Muscle tissue is found in three distinct types in the body; skeletal, smooth, and cardiac.
Skeletal muscles must have a blood and nervous supply to provide movement. Skeletal muscles are
under conscious control, meaning that a person can consciously decide to use these muscles to
complete an action. Communication within the body to coordinate movement starts in the brain with
a message that is sent through the spinal cord and eventually attaches to a muscle. Peripheral
nerves carry the signal from the central nervous system (brain and spinal cord) to a specific
muscle destination to provide movement. Messages from the central nervous system to a muscle
are called a motor actions. Nerves also carry information from the external environment to the
central nervous system, called sensation or sensory input. (see Figure 5.1 and Figure 5.2) Spinal
nerves combine to form complex networks of peripheral nerves throughout the body.
Figure 5.1 Posterior view of the nervous system. The brain and spinal cord (central nervous
,system) connect to the peripheral nervous system. Examples of peripheral nerves are spinal nerves
(cervical, thoracic, and lumbar), the upper trunk of the brachial plexus, and the radial nerve.
Figure 5.2 Peripheral nerves carry the communication from the central nervous system (brain and
spinal cord) to the muscle. Peripheral nerves also carry information from the environment to the
central nervous system.
Tendons are connective tissues that connect skeletal muscle to bone at each end (see Figure 5.3).
Tendons are flexible, can bend at the joints, and help cushion against sudden
movement. Ligaments are connective tissue that connects bone to bone, helping to stabilize joints
where bones meet.
,Figure 5.3 Skeletal muscles attach to bones via tendons at points called the origin and insertion.
The origin is the fixed point while the insertion is the place that is moved during a muscle
contraction.
All skeletal muscles have an origin, insertion, and action. The origin is the bony site of attachment
which is stationary during the movement. The insertion of a muscle is the bony site of attachment
that is moved by the muscle contraction. (see Figure 5.3)
The origin and insertion can be reversed in different types of movement. For this module, the
standard origin and insertion points are referenced from anatomical position.
The action of the muscle is what effect is produced by the muscle’s contraction. For example, the
triceps is the primary extensor of the forearm. The innervation is the peripheral nerve that supplies
a muscle with the message from the brain. For example, the innervation of the biceps brachii is the
musculocutaneous nerve. (see Figure 5.4)
, Figure 5.4 Anterior view of the musculocutaneous nerve (blue) innervates the biceps brachii muscle.
Muscles are generally studied in groups. The following muscle list is an overview of some of the
major muscles in the body. Study the location of the muscle in the body. In addition, if listed, study
the origin, insertion, innervation and action of these muscles.
Muscles of Facial Expression: (See Figure 5.5)
The muscles in this grouping help to facilitate all the actions within the face. All the varied facial
expressions are enabled by these muscles. CN is an abbreviation for cranial nerve. There are
twelve pairs of cranial nerves that originate on the ventral surface of the brain, controlling muscles
and functions of several organs and glands.
Orbicularis oculi
Action: eye closure
Innervation: Facial nerve (CN VII)
Orbicularis oris
Action: mouth closure: closes lips, protrudes lips forward, presses lips against teeth
