Muscles of the Back Flashcards
Name the categories of back muscles based on location and function.
Extrinsic (superficial and intermediate) and Intrinsic (deep).
What are the functions of the extrinsic back muscles?
The superficial extrinsic muscles act on the upper limbs, while the intermediate extrinsic muscles primarily assist in respiration.
List the superficial extrinsic muscles of the back and their primary action.
Trapezius, Latissimus Dorsi, Rhomboid Major, Rhomboid Minor, Levator Scapulae - they primarily aid in movement of the upper limbs.
Name the intermediate extrinsic back muscles.
Serratus Posterior Superior and Serratus Posterior Inferior, which assist in respiratory movements.
What are the three layers of intrinsic (deep) back muscles?
Superficial (Spinotransversalis), Intermediate (Erector Spinae), and Deep (Transversospinalis).
What are the muscles of the Spinotransversalis group?
Splenius Capitis and Splenius Cervicis, which extend and rotate the head and neck.
What muscles are in the Erector Spinae group, and what is their function?
Iliocostalis, Longissimus, Spinalis - they help with extension and lateral flexion of the vertebral column.
List the muscles in the Transversospinalis group.
Semispinalis, Multifidus, Rotatores - these stabilize and extend the spine and are involved in rotation.
What distinguishes intrinsic muscles from extrinsic muscles of the back?
Intrinsic muscles are involved in maintaining posture and movement of the vertebral column, whereas extrinsic muscles are involved in movement of the upper limbs or assist with respiration.
Which intrinsic muscles are primarily responsible for extension of the head and neck?
Splenius Capitis and Splenius Cervicis from the Spinotransversalis group.
Which group of muscles runs the entire length of the vertebral column?
The Erector Spinae group: Iliocostalis, Longissimus, Spinalis
How do the transversospinalis muscles contribute to spinal stability?
By connecting adjacent vertebrae and providing rotational stability, extending the spine, and postural support.
What action do the Serratus Posterior Superior and Inferior muscles facilitate?
Serratus Posterior Superior assists in inhalation, and Serratus Posterior Inferior aids in exhalation by controlling rib movement.
Which muscle group would you target to improve overall back stability and posture?
The Erector Spinae and Transversospinalis groups, as they are integral to maintaining posture and spinal alignment.
What are the two subgroups of the extrinsic back muscles?
Superficial (Posterior Axio-appendicular) and Intermediate.
List the superficial extrinsic muscles of the back.
Trapezius, Latissimus Dorsi, Rhomboid Major, Rhomboid Minor, Levator Scapulae.
What is the primary function of the superficial extrinsic muscles?
To facilitate movements of the upper limbs.
Which nerve innervates the Trapezius?
The spinal accessory nerve (Cranial Nerve XI).
Which muscle elevates the scapula and where is it located?
Levator Scapulae, which elevates the scapula, is located on the superior part of the medial border of the scapula.
List the intermediate extrinsic muscles of the back.
Serratus Posterior Superior and Serratus Posterior Inferior.
Describe the origin, insertion, and action of the Serratus Posterior Superior.
Origin: Ligamentum Nuchae & Spinous processes of C7-T3.
Insertion: 2nd to 5th ribs.
Action: Elevates ribs during inspiration.
Describe the origin, insertion, and action of the Serratus Posterior Inferior.
Origin: Spinous processes of T11-L2.
Insertion: 9th to 12th ribs.
Action: Depresses ribs during expiration.
What is the function of the intermediate extrinsic muscles in relation to respiration?
They assist in breathing by elevating and depressing the ribs.
Which rami innervate most of the extrinsic back muscles, and what is the exception?
Most are innervated by the anterior (ventral) rami of spinal nerves. The exception is the Trapezius, which is innervated by the spinal accessory nerve.
Where are the extrinsic muscles located in relation to the thoracolumbar fascia?
They lie superficial to the thoracolumbar fascia.
What is the superficial subgroup of intrinsic back muscles known as?
Spinotransversalis group.
Which muscles belong to the Spinotransversalis group?
Splenius Capitis and Splenius Cervicis.
What is the origin of Splenius Capitis?
Ligamentum Nuchae and Spinous processes of C7 to T4.
Where does the Splenius Capitis insert?
Temporal bone (mastoid process) and Occipital bone.
What actions does the Splenius Capitis perform on the head and neck?
Unilaterally: Ipsilateral rotation and lateral flexion of the head and neck.
Bilaterally: Extension of the head and neck.
What is the origin of Splenius Cervicis?
Spinous processes of T3 to T6.
Where does the Splenius Cervicis insert?
Transverse processes of C1 to C3
What actions does the Splenius Cervicis perform on the head and neck?
Unilaterally: Ipsilateral rotation and lateral flexion of the neck.
Bilaterally: Extension of the neck.
What is the primary action of the Spinotransversalis muscles when they contract bilaterally?
Extension of the head and neck.
How do the Spinotransversalis muscles assist in movement when contracted unilaterally?
Answer: They allow ipsilateral rotation and lateral flexion of the head and neck.
What is the intermediate subgroup of intrinsic back muscles called?
Answer: Erector Spinae group.
Which muscles make up the Erector Spinae group?
Spinalis, Longissimus, and Iliocostalis.
What is the common origin of the Erector Spinae muscles?
Iliac crest, sacrum, sacroiliac ligaments, and spinous processes of lumbar and sacral vertebrae.
What is the primary action of the Erector Spinae muscles when contracting unilaterally?
Lateral flexion of the vertebral column.
What is the primary action of the Erector Spinae muscles when contracting bilaterally?
Extension of the vertebral column.
Where is the Spinalis muscle located in the Erector Spinae group?
Closest to the spine (most medial of the Erector Spinae muscles).
Where is the Longissimus muscle located within the Erector Spinae group?
It lies intermediate between the Spinalis and Iliocostalis.
Where is the Iliocostalis muscle located within the Erector Spinae group?
It is the most lateral of the Erector Spinae muscles
What is the primary function of the Erector Spinae group in maintaining posture?
They help stabilize and extend the vertebral column, crucial for upright posture.
How do the Erector Spinae muscles contribute to side-to-side movement of the torso?
By laterally flexing the vertebral column when they contract unilaterally.
What is the deep subgroup of intrinsic back muscles called?
Transversospinalis group.
Which muscles make up the Transversospinalis group?
Semispinalis, Multifidus, and Rotatores.
What is the general origin and insertion pattern of the Transversospinalis muscles?
They originate from transverse processes and insert on spinous processes.
What is the common action of the Transversospinalis muscles when contracting unilaterally?
Contralateral rotation of the vertebral column.
What is the common action of the Transversospinalis muscles when contracting bilaterally?
Extension of the head and vertebral column.
Describe the location and vertebral span of the Semispinalis muscle.
Located primarily in the upper half of the back, it spans 4-6 vertebral segments.
What are the three parts of the Semispinalis muscle?
Semispinalis Capitis, Semispinalis Cervicis, and Semispinalis Thoracis.
Describe the location and vertebral span of the Multifidus muscle.
Extends from the sacrum to C2 and spans 2-4 vertebral segments.
What is the primary function of the Multifidus muscle?
It is a major stabilizer of the spine.
In which region are the Rotatores muscles most pronounced?
In the thoracic region.
What are the two types of Rotatores, and how many segments do they span?
Rotatores Brevis (spans 1 segment) and Rotatores Longus (spans 2 segments).
What is the main action of the Rotatores muscles?
Rotation of the vertebral column.
What is the orientation of the fibers in the Transversospinalis group?
Superomedial fiber orientation.
How do the Transversospinalis muscles contribute to vertebral stability?
They stabilize the vertebrae by connecting adjacent vertebrae, allowing for controlled rotation and extension.
