Semispinalis Thoracis Muscle

Author: Scott A. Sheffield MS

Last update:

The semispinalis thoracis muscle is one of the intrinsic back muscles at the level of the thorax.

image descriptionSemispinalis Thoracis Muscle

Posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm, scapulae and the most superficial layer of the attached muscles. The labelled muscles are Trapezius, Deltoid and Latissimus Dorsi.
Posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm, scapulae and a deeper layer of the attached muscles. The labelled muscles are Sternocleidomastoid, Semispinalis Capitis, Splenius Capitis, Splenius Cervicis, External Intercostals, Longissimus Thoracis, Spinalis Thoracis and Iliocostalis Thoracis.
Posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm, scapulae and a deeper layer of the attached muscles. The labelled muscles are Semispinalis Capitis and Semispinalis Thoracis.
Posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm, scapulae and the deepest layer of the back and neck muscles. The labelled muscles are Semispinalis Cervicis and Semispinalis Thoracis.
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image descriptionAttachments of the Semispinalis Thoracis Muscle

Origin
a. Transverse processes of T6 – T10/12 vertebrae

Insertion
a. spinous processes of T1 – T4 and C6 – C7

Posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm, scapulae and the most superficial layer of the attached muscles. The labelled muscles are Trapezius, Deltoid and Latissimus Dorsi.
Posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm, scapulae and the deepest layer of the back and neck muscles. The labelled muscles are Semispinalis Cervicis and Semispinalis Thoracis.
Posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm and scapulae showing the origin of Semispinalis Cervicis at the transverse processes of T6 - T10/12 marked by a red circles and insertion at spinous processes of T1 - T4 and C6 - C7 marked by a blue line.
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Actions of the Semispinalis Thoracis Muscle:

a. Bilaterally image descriptionextends cervical (neck) and thoracic (back) vertebrae. 

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b. Unilaterally image descriptionlaterally flexes flexes cervical and thoracic vertebrae.

c. Unilaterally image descriptionrotates cervical and thoracic vertebrae to opposite side (= contralateral rotation).

Nerve to the Semispinalis Thoracis Muscle

a. Dorsal rami of upper thoracic spinal nerves.

An overview of the posterior muscles of the neck

A quiz image of the posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm, scapulae and the most superficial muscle layer. Muscles are labelled 1-3 and the answers are concealed.
A quiz image of the posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm, scapulae and the most superficial muscle layer. The muscles of the back and neck are labelled 1-3. The answers at the bottom are as follows 1. Trapezius 2. Deltoid 3. Latissimus Dorsi.
A quiz image of the posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm, scapulae and the deeper muscle layer. The muscles of the back and neck are labelled 1-4. The answers at the bottom are as follows 1. Supraspinatus 2. Infraspinatus 3. Teres Minor 4. Teres Major.
A quiz image of the posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm, scapulae and the deeper muscle layer. The muscles of the back and neck are labelled 1-4. The answers at the bottom are as follows 1. Levator Scapula 2. Rhomboids Minor 3. Rhomboids Major 4. Serratus Anterior.
A quiz image of the posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm, scapulae and the deeper muscle layer. The muscles of the back and neck are labelled 1-2. The answers at the bottom are as follows 1. Serratus Posterior Superior 2. Serratus Posterior Inferior.
A quiz image of the posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm, scapulae and the deeper muscle layer. The muscles of the back and neck are labelled 1-8. The answers at the bottom are as follows 1. Sternocleidomastoid 2. Semispinalis Capitis 3. Splenius Capitis 4. Splenius Cervicis 5. External Intercostals 6. Longissimus Thoracis 7. Spinalis Thoracis 8. Iliocostalis Thoracis
A quiz image of the posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm, scapulae and the deeper muscle layer. The muscles of the back and neck are labelled 1-6. The answers at the bottom are as follows 1. Semispinalis Capitis 2. Splenius Capitis 3. Splenius Cervicis 4. Longissimus Thoracis 5. Spinalis Thoracis 6. Iliocostalis Thoracis.
A quiz image of the posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm, scapulae and the deeper muscle layer. The muscles of the back and neck are labelled 1-5. The answers at the bottom are as follows 1. Semispinalis Capitis 2. Splenius Capitis 3. Splenius Cervicis 4. Longissimus Thoracis 5. Spinalis Thoracis.
A quiz image of a skeleton on a posterior view with the semispinalis capitis, splenius capitis, splenius cervicis and spinalis thoracis muscles labeled
A quiz image of the posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm, scapulae and the deeper muscle layer. The muscles of the back and neck are labelled 1-4. The answers at the bottom are as follows 1. Semispinalis Capitis 2. Splenius Capitis 3. Splenius Cervicis 4. Semispinalis Thoracis.
A quiz image of the posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm, scapulae and the deeper muscle layer. The muscles of the back and neck are labelled 1-2. The answers at the bottom are as follows 1. Semispinalis Capitis 2. Semispinalis Thoracis.
A quiz image of the posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm, scapulae and the deeper muscle layer. The muscles of the back and neck are labelled 1-2. The answers at the bottom are as follows 1. Semispinalis Cervicis 2. Semispinalis Thoracis.
A quiz image of the posterior view of the occipital region of the skull, cervical and thoracic regions of the spinal column, upper arm and scapulae showing the origin of Semispinalis Cervicis at the transverse processes of T6 - T10/12 marked by a red circles and insertion at spinous processes of T1 - T4 and C6 - C7 marked by a blue line.
Test yourself while observing the Semispinalis Thoracis Muscle.
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