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Soft Tissue of the Back
Innervation
As a general rule, muscles associated with the back are innervated by the dorsal rami of the spinal nerves
They are innervated segmentally and near their origin
Only a couple of exceptions
Innervation
Innervation
The Exceptions
Serratus Posterior Superior• Lig. Nuchae and spinous processes of C7-T3
to 2nd to 5th ribs Serratus Posterior Inferior
• Spinous Proceses of T11-L2 to inferior borders of last 4 ribs
Elevate or depress ribs (accessory respiratory muscles)
Innervated by ventral rami
Serratus Post.
Major Groups of Back Muscles
Those that arise from the mid-line and run superiorly and laterally – The Splenius Muscles (Bandage)
Those that arise from near the mid-line or slightly laterally and run almost longitudinally with no marked inward or outward slant – called the Erector Spinae
Major Groups
The third group are those that arise laterally and run towards the mid-line as they travel up• Called the Transversospinalis group
Last – small muscles that run from one spinous process to another or one transverse process to another (interspinales and intertransvesus)
Splenius Muscles Splenius Capitis
• Lig. Nuchae and Spinous Process of C7-T4 to sup. Nuchal line and mastoid process
Splenius Cervicis• Spinous processes of T3-T6 to Transvers process of C2-C4
Both extend head and neck and can laterally flex (side bend) the head; Also support and can contribute to rotation of cervical spine and, thus, the head
Dorsal rami of spinal nerves nearest their respective origins
Splenius
Erector Spinae
Long Muscles with multiple, overlapping, origins Three sub groups; iliocostalis, longissimus,
spinalis Common “origin” of the entire group is a muscle
mass located on the posterior sacrum, iliac crest, and spinous process of lumbar vertebrae
Beyond that, specific muscles have various attachments
Erector Spinae
E. Spinae
E. Spinae
The three groups are broken down into sub -subgroups based upon where they are located
E.G., in the lumbar region called lumborum, in thoracic region called thoracis, in cervical region called cervicis and, if they reach anywhere on the skull, they are called capitis.
E.G., Iliocostalis lumborum
E. Spinae
Overlap or multiple attachments Despite the common “origin” of the group,
most muscles have various and multiple origins and insertions
These tend to overlap so that the group can traverse a large length of the back
Some components will attach as an insertion while new fibers will originate from the same region
E. Spinae
For example, the iliocostalis lumborum muscles will attach to the lower six ribs while the iliocostalis thoracis will originate from the lower six ribs and insert on the upper six ribs
Likewise the iliocostalis cervicis will originate from the upper six ribs and insert on the transverse process of C4 thru C6
All are innervated by the dorsal rami of the nerves nearest their origin – e.g., iliocostalis thoracis will be innervated by the lower thoracic nerves (T6-T12)
Longissimus
Generally, run from the transverse processes of one level of v. column up several levels to attach to another transverse process
The longissimus capitis originates on t. processes of T1-T4 and attach to the skull at the mastoid process, hence the name capitis
Is the only E.Spinae to attach to skull
Spinalis
E. Spinae nearest the mid-line, hence, the name spinalis
The spinalis group run from spines of one group of vetebrae to spines of v. several segments up
Most prominent in thoracic spine but also located in cervical and lumbar spine
General, Collective, Function of E. Spinae
To support spine (anti-gravity) To extend spine To laterally flex spine (side bend) To rotate the spine They work together
Transversospinalis Group
Arise laterally and run, more or less, to the mid-line
Semispinalis Capitis• Transverse Process C7-T6 to Occipital bone, near
mid-line, Extend head, rotate to same side
Semispinalis Cervicis• Transverse process T1-T6 to Spines of C2-C6, Extend
head (Cervical Spine) and side bend
Semispinalis
Semispinalis
Transversospinalis Group
Multifidi From the sacrum, and transverse
process of L., T. and lower C vertebrae to Spinous Process of Lumbar, thoracic and cervical vetebrae 2 or 3 levels up
Very large and obvious in lumbar region Support V. column. May contribute to
minor motions (lat. flex., rot., ext.)
Rotatores
Transverse processes of 2nd cervical to sacrum to lamina on vertebrae above origin (one segment)
Same function as multifidi
Interspinous and Intertransversus
Run between spinous processes or transverse processes
Blend with ligaments of same name Perform same function (Stability)
Small Muscles
Muscles mostly associated with the head
Sub-Occipital (Posterior) Triangle very small, support head on v. column, minor motions
Rectus Capitis Post. Major• Spinous process of C2 to Lateral aspect of nuchal line
• Dorsal ramus of suboccipital nerve
Rectus capitis Post. Minor• Post. Arch of atlas (C1) to med. aspect of inferior
nuchal line
• Dorsal ramus of suboccipital nerve
Sub-Occ. Triangle
Obliqus Capitis Superior• Transverse process Atlas to a point between
sup. and inf. Nuchal line
Obliqus Capitis Inferior• Spinous Process Axis to transverse process
atlas
Suboccipital Triangle
Anterior Muscles – all innervated by Ventral Rami
Sterno-Cleido-Mastoid Manubrium (S) and Medial ½ clavicle to
mastoid process Together – head flexion, unilaterally, side
bending (same side) rotation (opposite side)
CN XI and ventral rami of C2, C3
SCM
SCM - Anterior
Scaleni-AKA Pre-Vertebral
Scalaneus Anterior Ant tubercle of transverse process of C2-C6 Scalene tubercle of anterior surface of 1st rib Flex and rotate spine Reverse action = accessory respiratory muscle
by raising 1st rib. ventral rami C2-C6
Pre-Vertebrals
Scaleni
Scaleneus Medius from post. tubercle of transverse processes C2-C7 to sup. surface of 1st rib behind subclavian groove
Scaleneus Posterior from post. tubercles of transverse processes C4-C6 to lateral superior surface of 2nd rib
Flex, rotate elevate rib
Pre-Vertebral
Longus Coli
Bodies of C5-T3 to bodies of C2-C4 Bilaterally flexes cervical v., unilaterally
rotates rotate and side bend C2-C8 innervation
Longus Capitis
Ant. Tubercles of transverse processes of C3-C6
To inferior surface of basilar portion of occipital bone
Flex, c. v. and head rotate and flex c. v.
Anterior Small Muscles
Rectus Capitis Anterior• Ant. Surface of lateral mass of the atlas to inf. Surface
of occipital bone anterior to foramen magnum
• C1 – C2
Rectus Capitis Lateralis• Sup surface of transverse process of atlas to inferior
surface of jugular process, occipital bone
• C1-C2
Both support skull
Anterior Sub Occipital Muscles
Cervical Plexus
A small plexus originating from the ventral rami of C1-C4 with some contribution from C5
Mostly cutaneous type nerves One notable somatic motor nerve = the
Phrenic nerve to the diaphragm muscle The other motor nerves work with cranial
nerves to innervate hyoid type muscles
Cervical Plexus
Cervical Plexus
Cervical Plexus
Cervical Plexus
Phrenic Nerve in Thorax
Phrenic Nerve
Cervical Plexus
Suprahyoids
Infrahyoids
Comparison
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