MUSCLES OF TORSO

A Visual Guide

Muscles of the Torso

4. Posterior Torso Muscles

3. Anterior Torso Muscles

2. Why Study Torso Muscles?

1. Muscles of the Torso

ÍNDICE

Why Study Torso Muscles?

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Anterior Torso Muscles

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• Superficial layer: trapezius, latissimus dorsi, levator scapulae, rhomboid major and minor muscles

• Intermediate layer: serratus posterior superior and inferior muscles

Posterior Torso Muscles

posterior torso muscles

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The erector spinae group forms the majority of the muscle mass of the back and it is the primary extensor of the vertebral column. It controls flexion, lateral flexion, and rotation of the vertebral column, and maintains the lumbar curve. The erector spinae comprises the iliocostalis (laterally placed) group, the longissimus (intermediately placed) group, and the spinalis (medially placed) group.

Erector spinae

Deep Torso Muscles

The deep torso muscles are essential for breathing and providing core stability. The diaphragm is the main muscle used for breathing.

Deep Torso Muscles

The superficial muscles of the back are located beneath the skin and superficial fascia of the back and extend between the vertebral column and bones of the pectoral girdle and arm. Their principal function is to support and move the upper limb through movement of the scapula and humerus.

The iliocostalis group includes the iliocostalis cervicis, associated with the cervical region; the iliocostalis thoracis, associated with the thoracic region; and the iliocostalis lumborum, associated with the lumbar region. The three muscles of the longissimus group are the longissimus capitis, associated with the head region; the longissimus cervicis, associated with the cervical region; and the longissimus thoracis, associated with the thoracic region. The third group, the spinalis group, comprises the spinalis capitis (head region), the spinalis cervicis (cervical region), and the spinalis thoracis (thoracic region).

Functions of the latissimus dorsi muscle include: Adduction: This means it pulls the arm towards the body. Extension: It extends the arm backward, as when reaching behind. Internal rotation: It rotates the arm inward, as when turning a doorknob. Hyperextension: It can also extend the back, especially when reaching overhead.Additional functions:Stability: It helps stabilize the shoulder joint.Breathing: It can assist in breathing by pulling the rib cage downward.

The levator scapulae muscle is a small, elongated muscle located on the side of the neck. Its primary function is to elevate the scapula (shoulder blade). This action is essential for various upper body movements, such as raising the shoulder, shrugging, and turning the head to the side.In addition to elevating the scapula, the levator scapulae muscle also contributes to:Neck flexion: It can help to flex the neck, bringing the chin closer to the chest.Scapular rotation: It can rotate the scapula upward.Overall, the levator scapulae muscle is a crucial component of the shoulder girdle, playing a vital role in upper body movement and stability.

Functions of the serratus posterior superior muscle include:

• Elevation of the ribs: This muscle helps to elevate the upper ribs during inspiration (breathing in).

• Rotation of the scapula: It can contribute to the upward rotation of the scapula, which is important for shoulder movements like reaching overhead.

Functions of the serratus posterior inferior muscle include:

• Depression of the ribs: This muscle helps to depress the lower ribs during expiration (breathing out).

• Rotation of the scapula: It can contribute to the downward rotation of the scapula, which is important for certain shoulder movements.

Functions of the rhomboid major muscle include:

• Retraction of the scapula: This means it pulls the shoulder blade backward, towards the spine.

• Elevation of the scapula: It can also help to elevate the shoulder blade.

• Rotation of the scapula: It can contribute to the downward rotation of the scapula.

The rhomboid minor muscle is a smaller, more superficial muscle located above the rhomboid major muscle. It shares many of the same functions as the rhomboid major, including:

• Retraction of the scapula: It pulls the shoulder blade backward.

• Elevation of the scapula: It helps to raise the shoulder blade.

• Rotation of the scapula: It contributes to the downward rotation of the scapula.

The transversospinales muscles run from the transverse processes to the spinous processes of the vertebrae. Similar to the erector spinae muscles, the semispinalis muscles in this group are named for the areas of the body with which they are associated. The semispinalis muscles include the semispinalis capitis, the semispinalis cervicis, and the semispinalis thoracis. The multifidus muscle of the lumbar region helps extend and laterally flex the vertebral column.

Functions of the latissimus dorsi muscle include:

• Adduction: This means it pulls the arm towards the body.

• Extension: It extends the arm backward, as when reaching behind.

• Internal rotation: It rotates the arm inward, as when turning a doorknob.

• Hyperextension: It can also extend the back, especially when reaching overhead.

• Stability: It helps stabilize the shoulder joint.

• Breathing: It can assist in breathing by pulling the rib cage downward.

Functions of the pectoralis major muscle include:

• Adduction: This means it pulls the arm towards the body. Internal rotation: It rotates the arm inward, as when turning a doorknob.

• Flexion: It flexes the arm at the shoulder joint, bringing the arm forward and up.

• Horizontal adduction: It moves the arm horizontally across the chest.

• Stability: It helps stabilize the shoulder joint.

• Breathing: It can assist in breathing by pulling the rib cage upward.

Functions of the serratus anterior muscle include:

• Protraction of the scapula: This means it pulls the shoulder blade forward and away from the spine.

• Upward rotation of the scapula: It helps to rotate the scapula upward, which is essential for shoulder movements like reaching overhead.

• Lateral rotation of the scapula: It can also contribute to the lateral rotation of the scapula.

• Stability: It helps stabilize the scapula and shoulder joint.

• Breathing: It can assist in breathing by pulling the rib cage upward.

Functions of the external oblique muscle include:

• Lateral flexion of the trunk: This means it bends the trunk to the side.

• Rotation of the trunk: It can rotate the trunk to the opposite side.

• Compression of the abdomen: It helps to compress the abdominal organs, which is important for functions like breathing, coughing, and childbirth.

• Stability of the pelvis: It helps to stabilize the pelvis and lower back.

Functions of the linea alba include:

• Structural support: It provides structural support for the abdominal wall, helping to maintain its shape and integrity.

• Attachment point: It serves as an attachment point for the rectus abdominis muscle, one of the primary muscles of the abdomen.

• Protection: It helps to protect the abdominal organs from injury.

Functions of the rectus abdominis include:

• Flexion of the trunk: This means it bends the trunk forward, as when doing a sit-up.
• Pelvic tilt: It can help to tilt the pelvis anteriorly, which is important for maintaining good posture and back health.
• Compression of the abdomen: It helps to compress the abdominal organs, which is important for functions like breathing, coughing, and childbirth.
• Stability of the core: It is a key muscle for core stability, which is essential for balance, coordination, and overall body strength.

Functions of the tendinous intersection include:

• Structural support: It provides structural support for the abdominal wall, helping to maintain its shape and integrity.

• Attachment point: It serves as an attachment point for the rectus abdominis muscle, one of the primary muscles of the abdomen.

• Protection: It helps to protect the abdominal organs from injury.

Functions of the rectus sheath include:

• Protection: It protects the rectus abdominis muscle and the underlying structures from injury.

• Support: It provides support for the rectus abdominis muscle, helping to maintain its position and function.

• Attachment point: It serves as an attachment point for the rectus abdominis muscle and for other abdominal muscles.

• Structural integrity: It contributes to the overall structural integrity of the abdominal wall.

The rectus sheath is an important anatomical structure that plays a vital role in the function of the abdominal muscles and the protection of the abdominal organs.

Functions of the transversus abdominis include:

• Compression of the abdomen: It helps to compress the abdominal organs, which is important for functions like breathing, coughing, and childbirth.

• Stability of the core: It is a key muscle for core stability, which is essential for balance, coordination, and overall body strength.

• Posture maintenance: It helps to maintain good posture by supporting the lumbar spine.

• Protection of internal organs: It helps to protect the abdominal organs from injury.

The transversus abdominis it is a powerful muscle that plays a vital role in overall health and well-being.

The external oblique muscle is a large, flat muscle located on the sides of the abdomen. It is one of the three layers of abdominal muscles.Functions of the external oblique muscle include:

• Lateral flexion of the trunk: This means it bends the trunk to the side.

• Rotation of the trunk: It can rotate the trunk to the opposite side.

• Compression of the abdomen: It helps to compress the abdominal organs, which is important for functions like breathing, coughing, and childbirth.

• Stability of the pelvis: It helps to stabilize the pelvis and lower back.

Functions of the aponeurosis of the internal oblique include:

• Structural support: It provides structural support for the abdominal wall, helping to maintain its shape and integrity.

• Attachment point: It serves as an attachment point for the internal oblique muscle and for other abdominal muscles.

• Protection: It helps to protect the abdominal organs from injury.

• Compression of the abdomen: It contributes to the compression of the abdominal organs, which is important for functions like breathing, coughing, and childbirth.

The aponeurosis of the internal oblique is an important anatomical structure that plays a vital role in the function of the abdominal wall.

Functions of the internal oblique muscle include:

• Lateral flexion of the trunk: This means it bends the trunk to the side.

• Rotation of the trunk: It can rotate the trunk to the opposite side.

• Compression of the abdomen: It helps to compress the abdominal organs, which is important for functions like breathing, coughing, and childbirth.

• Stability of the core: It is a key muscle for core stability, which is essential for balance, coordination, and overall body strength.

• Support of the abdominal wall: It helps to support the abdominal wall, providing structural integrity and protection for the abdominal organs.

Functions of the quadratus lumborum muscle include:

• Lateral flexion of the trunk: This means it bends the trunk to the side. Extension of the lumbar spine: It helps to extend the lumbar spine, straightening the back.

• Stability of the lumbar spine: It is a key muscle for stabilizing the lumbar spine, which is important for maintaining good posture and preventing back pain.

• Elevation of the pelvis: It can help to elevate the pelvis, which is important for walking and running.

The quadratus lumborum muscle is a powerful muscle that plays a vital role in core strength, stability, and posture. It is often targeted in exercises that aim to strengthen the lower back and core muscles.

Functions of the iliacus muscle include:

• Hip flexion: It is the primary muscle responsible for flexing the hip joint, which is the movement that brings the thigh towards the chest. This is essential for activities like walking, running, and climbing.

• Pelvic stability: It helps to stabilize the pelvis, particularly during weight-bearing activities.

• Posture maintenance: It contributes to maintaining good posture by supporting the lumbar spine.

The iliacus muscle is a powerful muscle that plays a vital role in lower body movement and stability. It is often targeted in exercises that aim to strengthen the hip flexors, such as hip flexor stretches and lunges.

Functions of the psoas muscle include:

• Hip flexion: It is the primary muscle responsible for flexing the hip joint, which is the movement that brings the thigh towards the chest. This is essential for activities like walking, running, and climbing.

• Pelvic stability: It helps to stabilize the pelvis, particularly during weight-bearing activities.

• Posture maintenance: It contributes to maintaining good posture by supporting the lumbar spine.

The psoas muscle is a powerful muscle that plays a vital role in lower body movement and stability. It is often targeted in exercises that aim to strengthen the hip flexors, such as hip flexor stretches and lunges.

Functions of the diaphragm include:

• Inspiration (breathing in): When the diaphragm contracts, it flattens downward, creating more space in the chest cavity. This allows the lungs to expand and fill with air.

• Expiration (breathing out): When the diaphragm relaxes, it returns to its dome shape, reducing the space in the chest cavity. This forces the lungs to expel air.

• Abdominal pressure: The diaphragm also plays a role in increasing abdominal pressure during activities such as coughing, sneezing, and childbirth.

The primary function of the left psoas major is to flex the hip joint. This means it brings the thigh towards the chest. This movement is essential for activities such as walking, running, climbing, and sitting up.

Functions of the left quadratus lumborum include:

• Lateral flexion of the trunk: This means it bends the trunk to the left side.

• Extension of the lumbar spine: It helps to extend the lumbar spine, straightening the back.

• Stability of the lumbar spine: It is a key muscle for stabilizing the lumbar spine, which is important for maintaining good posture and preventing back pain.

• Elevation of the pelvis: It can help to elevate the pelvis, which is important for walking and running.

Functions of the pericardium include:

• Protection: The pericardium protects the heart from injury and infection.

• Anchoring: It anchors the heart in place within the chest cavity.

• Lubrication: The pericardial fluid, which is contained between the two layers of the pericardium, acts as a lubricant, reducing friction between the heart and surrounding tissues.

• Pressure regulation: The pericardium helps to regulate the pressure within the heart and prevents it from expanding too much.

Functions of the right dome of the diaphragm include:

• Inspiration: When the diaphragm contracts, it flattens downward, creating more space in the chest cavity. This allows the lungs to expand and fill with air. The right dome of the diaphragm plays a particularly important role in inspiration, especially when the body is lying down on the right side.

• Abdominal pressure: The right dome of the diaphragm can also contribute to increasing abdominal pressure during activities such as coughing, sneezing, and childbirth.

• Liver support: Due to its close proximity to the liver, the right dome of the diaphragm may also play a role in supporting the liver and maintaining its position in the abdominal cavity.