The Axial Muscles: Muscles of the Trunk

This final section is concerned with the muscles that control movements and posture within the trunk, the cervical, the thoracic, and the lumbar regions of the body.

There is an obvious pattern to the order of these muscles that makes learning them easy.

The muscles that are located anterior to the spinal cord (vertebral canal) are collectively known as the “____ muscles” and there are three groups: the _____, the ____, and the _____ muscle groups (see cross sections in ID notecards).

The muscles located posterior to the spinal cord are the “____ muscles.”

The Axial Muscles: Neck Muscles

Neck muscles, like the remaining trunk muscles (thoracic and abdominal) can be divided into three groups:

1. Prevertebral muscles (immediately after vertebrae):
The longus coli and longus capitis muscles (coli = neck; capitis = head) ___ the cervical vertebrae and head. They lie on the anterior surface of the cervical and upper thoracic ____ but are not easily seen in any lab model since they are covered by the esophagus, trachea, and the ventral muscles.

The Axial Muscles: Neck Muscles

2. Ventral muscles:
Lying anterior (ventral) to the ORGANS of the neck are the strap muscles, also called ______ muscles. They move or stabilize the ____ and larynx during swallowing movements.

3. Lateral muscles:
The anterior, middle, and posterior scalene muscles extend to the first __ __ and stabilize the thoracic cage during forced _____. They also laterally flex the ___ when working unilaterally.

The Axial Muscles: Thorax Muscles

Thorax muscles also can be divided into three groups:

1. Prevertebral muscles:
The ___ ___ muscles (previous page) begin in the thorax. But since the vertebrae are relatively ____ in the thorax, most of its vertebrae do NOT have prevertebral muscles.

The Axial Muscles: Thorax Muscles

2. Ventral muscles:
Ventral muscles are also missing from the thorax in most humans. A small percentage of humans do have muscles running vertically over the sternum (____ muscles), do you?

3. Lateral muscles:
The muscles of this layer are the so-called _____ muscles.

From deep to superficial, these are the ______ thoracis muscles, ____ intercostals, and the _____ intercostals.

Even more superficial are the serratus muscles. Serratus posterior muscles assist in _____ the ____.

The Axial Muscles: Abdominal Muscles

1. Prevertebral muscles:
The psoas major lies along the ventral surface of the ____ vertebrae. It extends past the hip to the femur, where it moves the __ joint.

2. Ventral muscles:
The rectus abdominis is a large ventral muscle that ____ the vertebral ____ (as when doing sit-ups).

3. Lateral muscles:
The fibers of the lateral muscles of the abdomen run in the same direction of comparable muscles in the
thorax.

From deep to superficial, the muscles include the ____ abdominis, the ____ oblique, and the _____ oblique. Muscles of these layers help twist your lower trunk and compress its contents to build ______ _______ (as when sneezing, coughing, defecating, etc.).

The Axial Muscles: Back Muscles

The epaxial muscles are nestled close to the spinal column. These back muscles extend from the sacrum to the head, and are comprised by two groups.

A deep transversospinalis group that lies just ____ to the spinous processes of vertebrae. These muscles span __ vertebrae and mostly ____ the spine and maintain _____.

The more superficial erector spinae group consists of muscles spanning ____ vertebrae and are major ____ of the spinal column.

Lower Limb Muscles: Reminder!!!

As a reminder from the appendicular skeleton lab, this page depicts the motions of the lower limb joints.

1. Hip motions:

2. Knee motions:

3. Talocrural (ankle) motions:

4. Metatarsophalangeal joints:

5. Interphalangeal joints:

Lower Limb Muscles: The Hip Muscles

Flexion and Extension

Extension of the femur is accomplished by the ____ _____. It originates from the iliac crest and sacrum and it’s distal tendon attaches to the posterior femur. Some of its tendon forms the _____ (IT) tract.

The IT tract or band is a tough region of the deep fascia encasing the leg, the tensor fascia lata, that extends to the lateral surface of the proximal tibia.

Flexion of the femur occurs through a two-part muscle, the _____. The iliacus portion originates from the iliac fossa and crest, while the psoas major originates from the anterior surfaces of _____ vertebral bodies. Together, they pass under the ___ ______ and insert on the _____ trochanter.

Another flexor is the ___ ____ ____, which is responsible for swinging the leg forward when walking. It originates from the iliac crest and inserts on the __ ____.

Lower Limb Muscles: The Hip Muscles

Rotation

The lateral hip rotators include several muscles. Those dedicated to the task are attached deep on the posterior pelvis and sacrum. Collectively, they can be called the ___ ___ _____. These muscles insert on the _____ trochanter.

Medial rotation is accomplished by the tensor fascia lata (above) and part of the gluteus medius (next page).

Lower Limb Muscles: The Hip Muscles

Abduction

The primary abductor of the femur is the gluteus ____, which lies deep to the larger g. maximus. It originates from the lateral surface of the ilium and inserts on the _____ trochanter. Aside from abduction, this muscle stabilizes your hips when the contralateral leg is ___ bearing weight.

Lower Limb Muscles: The Hip Muscles

Adduction

The adductors are located on the medial surface of the femur. The _____ is the shortest of these muscles and can be seen just medial and deep to the large femoral nerve, artery, and vein on the lab models.

Recall from the your study of pelvis osteology that the pectineus muscle has its origin at the pectineal ____.

A group of three adductor muscles originate on the ___ ____ of the pubis.
They include the adductor ___, ____, & ____ muscles. These muscles along with the pectineus insert on the posterior and medial femur.

The longest adductor is the _____. While sharing an origin with the other adductors on the inferior ramus, it travels further to the medial surface of the ____ for its insertion. As can be seen from their attachments, the adductors pull the leg ____.

Lower Limb Muscles: Knee Muscles

The flexors and extensors of the tibia are among the _____ muscles in the body.

The quadriceps on the anterior surface of the femur are the main _____, and the flexors on the posterior surface are known as the _____.

Lower Limb Muscles: Knee Muscles

Flexors of the Knee: The Posterior Compartment of the Thigh

The “hamstring” muscles ____ the knee. They all originate from the ischial _____. Their insertions are on the medial surface of the tibia (________ & ________), or the lateral surface of the fibular head (___ ______).

The biceps are so-called due to their two “heads.” The long head originates with the other ______, while the ____ head originates from the posterior femur. Thus, it can be said that their are 4 hamstring muscles.

Lastly, a small muscle spans the popliteal region, from the tibia __ to the femur. This short rotator that unlocks the knee is the _____ muscle. It has a minor role in _____. It’s origin and insertion (posterior tibia & posterior lateral femur) are unusual in that the insertion is proximal and origin distal.

Can you explain why some anatomists would consider the proximal attachment to be the insertion?

Lower Limb Muscles: Knee Muscles

Extensors of the Knee: the Anterior Compartment of the Thigh

The ______ (4 heads) on the anterior surface of the femur are responsible for extension of the knee. The vastus lateralis, vastus medialis, vastus intermedius, and the rectus femoris combine to form a common ____, the quadriceps _____ (known as the ____ tendon below the patella).

This tendon inserts on the ____ _____. The 3 vastus muscles originate from the anterior femur, while the rectus femoris attaches to the ___.

A fifth extensor is the ____, a thin muscle that spans from the anterior superior iliac spine to the tibial tuberosity.

Lower Limb Muscles: Ankle and Foot Muscles

____ compartments separate the muscles of the lower leg. The ____ compartment contains the dorsiflexors of the foot and extensors of the toes.

The ____ compartment contains the plantarflexors of the foot, the flexors of the toes, and the inverter of the foot.

The ____ compartment contains muscles that evert the foot.

Lower Limb Muscles: Ankle and Foot Muscles

Plantarflexors of the Ankle: The Posterior Compartment

The ______ is the large powerful muscle that gives your calf definition. It attaches from the femur down to the calcaneus. Its large distal tendon is the calcaneal (_____) tendon.

Deep to the gastrocnemius is the _____ muscle. Its origin is the fibular head and its insertion the same as the gastrocnemius (the ____). Compared to the gastrocnemius, this muscle is flatter and physiologically adapted to endurance activity.

Running between these two muscles is the _____. It originates on the femur and joins the calcaneal tendon to insert on the ____. Its insignificant muscle body is only about 2 inches in length, but its long tendon is useful in _______ surgery of torn or ruptured tendons.

Lower Limb Muscles: Ankle and Foot Muscles

Plantarflexors of the Ankle: The Posterior Compartment

Deep to the gastrocnemius, soleus and plantaris are the flexor digitorum longus, tibialis posterior, and flexor hallucis longus. These muscles originate on the posterior _____ membrane (and parts of the tibia or fibula).

Although all of these muscles have a very minor role in plantarflexion, the primary action of the flexor digitorum longus and flexor hallucis longus are ____ of the 2nd-5th toes and flexion of the hallux, respectively.

Notice the position of these muscles on the posterior surface of the leg. The flexor of the big toe (your most medial toe) is on the lateral side, and the flexor of the remaining digits is found on the medial side of the lower leg. Obviously, the tendons of these muscles must _____ to attach to their respective distal phalanges.

As for the tibialis posterior, it is the primary ____ of the foot. It’s tendons attach to the tarsals and metatarsals on the plantar surface of the foot.

Lower Limb Muscles: Ankle and Foot Muscles

Dorsiflexors of the Ankle: The Anterior Compartment

The anterior compartment of the lower leg contain the ____ of the toes and the _____ of the ankle. These three muscles originate on the anterior surface of the _____ membrane and the adjacent bones.

There are two extensors that mirror the function of the flexor muscles in the posterior lower leg. The extensor digitorum longus and extensor hallucis longus attach to the phalanges to ____ the toes and hallux, respectively.

The third muscle is the tibialis ____. The tibialis anterior attaches near the tendon for the tibialis posterior on the tarsals. Its primary function is to _____ the foot.

Lower Limb Muscles: Ankle and Foot Muscles

Dorsiflexors of the Ankle: The Anterior Compartment

Everters of the Ankle: The Lateral Compartment

A small group of muscles, the fibularis ____ and ____ evert the foot. They attach from the fibula to the tarsals.