The soft tissues attached to the occipital bone in the plane of the collar between the upper and lower collar lines and the upper and lower collar are called the soft tissues of the occipital region. In addition to localized pain and discomfort in the occipital region, soft tissue damage in this region can also cause neck pain and discomfort, headache, migraine, forehead pain and discomfort, and also vertigo symptoms. The headache, migraine and vertigo symptoms are relatively more frequent.
The trapezius muscle, which is attached to the inner third of the superior collar line, is also attached to the external occipital ridge, the collar ligament, all the spinous processes of the seventh cervical vertebra to the twelfth thoracic vertebra and the supraspinous ligament; the upper fibers are downward, the lower fibers are upward, and the middle fibers are horizontal, then converge outward to the shoulder. The superior muscle fibers end at the posterior margin of the lateral 1/3 of the clavicle; the middle muscle fibers end at the medial margin of the scapular crest and the superior lip of the scapular gonad; the inferior fibers form a sliding tendon membrane on the smooth triangular plane of the medial end of the scapular gonad and attach to the nodes of the lateral end of the scapular gonad. This muscle is thinner and forms a triangular tendon membrane attached to the vertebral spine from the 6th cervical vertebra to the 3rd thoracic vertebra. Below the 3rd thoracic vertebra is attached by shorter tendinous fibers.
The average thickness of the muscle located at the suprascapular angle was (3.78±1.53) mm, the rhomboid muscle and the deep facet fascia were found to be thickened and whitened, and the fascia became smooth and easy to separate, the average area of the thickened fascia was 4 cmX2cm. 12.5% of the bursa was present, with an average area of 2 cmX2cm. 78.12% of the paraspinal nerves were located within the thickened fascia. The paraneoplastic nerve was located in the posterior border of the sternocleidomastoid muscle in 87.5% of the cases, and in 12.5% of the cases, the paraneoplastic nerve was located in the posterior border of the sternocleidomastoid muscle, and the point of penetration was located above the Erbs point (1.03±1.0) cm. The distance between the entry point of the paramedian nerve and the clavicle was (4.4±2.3) cm. After entering the muscle, the paramedian nerve was divided into two branches, of which the descending branch traveled inward and downward, crossing the dorsal side of the scapular raphe and curving downward, and the nearest distance from the superior scapular angle was (2.0±0.6) cm.
The outer 1/2 of the superior occipital collar line is attached to the sternocleidomastoid muscle, and its muscle bundles are mainly located in the inner 1/3 of this muscle, only a few muscle bundles are attached to the skull. The ratio of sternocleidomastoid fast fibers II to slow fibers I is 2:1. This composition suggests that the sternocleidomastoid muscle is suitable for intermittent loading rather than prolonged continuous contraction. Innervation: The motor fibers of the sternocleidomastoid muscle (including some trapezius muscles) have a close connection to the brainstem for their primary function. The cervical segment of the 11th pair of cerebral nerves travels through the sternocleidomastoid muscle. The motor fibers of the cervical segment of the paramedian nerve originate from the anterior roots (motor fibers) in the C1-5 vertebral canal and then ascend through the foramen magnum into the skull to join the intracranial segment of the paramedian nerve. Finally, together with the vagus nerve, it exits the skull closely through the jugular foramen. The intracranial segment of the paramedian nerve emits motor nerve fibers to several laryngeal muscles and motor fibers to the sternocleidomastoid muscle. The paramedian nerve branches through the sternocleidomastoid muscle to innervate the superior trapezius muscle and also branches to the sternal and clavicular heads of the sternocleidomastoid muscle. In a significant number of patients, the motor fibers of the intracranial segment of the vagus nerve cross the paramedian nerve at the jugular foramen and are distributed to the sternocleidomastoid muscle.
The lateral part of the superior occipital collar line: the splenius capitis originates from the spinous process and the collar ligament of the upper thoracic vertebrae and the 7th cervical vertebrae, on the deep surface of the superior sternocleidomastoid muscle, and ends at the lower part of the mastoid process and the lateral part of the superior collar line; it is innervated by the lateral branch of the posterior branch of the 2nd-5th cervical nerve.
The longest muscle is attached to the mastoid, which belongs to the intermediate column of the sacrospinous muscle. It starts from the back of the sacrum and the posterior part of the iliac crest, and the fibers attach upward to the dorsal side of the transverse process and upward to the temporalis mastoid respectively.
The middle layer is the multifidi, with short and slightly oblique fibers spanning 2-4 vertebrae, and the deep layer is the rotatores, with the shortest fibers spanning only one vertebrae. Contraction of the transverse spinous muscle on both sides allows the trunk to extend posteriorly, and unilateral contraction allows the trunk to flex laterally to the same side and turn to the opposite side. The transverse spinous process is innervated by all posterior branches of the spinal nerve. The superior obliquus capitis superior starts from the transverse process of the atlantoaxial vertebrae, and ends at the bony surface of the collar plane above the inferior occipital collar line, with one side contracting to turn the head to the opposite side and lateral flexion to the same side, and both sides contracting to tilt the head back.
Inferior collar line: attached to the posterior rectus muscle (the lateral part is large, the medial part is small). The vertebrooccipital muscle group is located below the occipital bone, the posterior side of the atlanto- and cardinal vertebrae, and the deep side of the cephalic semispinal muscles (multifidus, rotator spinae), acting on the atlanto-occipital and atlanto-axial joints, including the posterior large and small rectus muscles and the head and inferior oblique muscles 4 muscles. The rectus capitis posterior major is triangular in shape, starting from the spinous process of the cardinal vertebrae and ending at the lateral part of the inferior collar line. The posterior rectus capitis minor is also triangular in shape, smaller and medial, starting from the posterior atlantoaxial tuberosity and ending at the medial part of the inferior collar line. Both are innervated by the posterior branch of the inferior occipital nerve, and the two muscles have the same effect, with one side contracting to turn the head to the opposite side and both muscles contracting to tilt the head back.
The obliquus capitis inferior originates from the spinous process of the pivot vertebrae, which is oblique and superior, and ends at the transverse process of the atlantoaxial vertebrae. Contraction of one side causes the head to turn ipsilateral and flex, and contraction of both sides causes the head to tilt back.
The collateral ligament is composed of elastic fibers and begins at the spinous processes of all cervical vertebrae and ends at the external occipital ridge and the external occipital crest. It is triangular in shape, with the bottom up and the tip down, attached to the posterior nodes of the cervical vertebrae and the tips of the cervical 2-7 spinous processes, with free and hypertrophic edges, and flanked by several muscles such as the cephalic grip, cervical grip, and rhomboid muscles, whose main function is to control excessive forward flexion of the neck. The cervical 2 spinous process and the cervical 7 spinous process of the collateral ligament are the concentrated area of the bilateral oblique muscle pulling stress to both sides from the occipital ridge and the occipital ridge, which is a good site for chronic injury. The common sites of damage to the collateral ligament are at the attachment point of the inferior cervical vertebrae, at the attachment point of the lower edge of the occipital ridge, or at the attachment point of the oblique muscle on both sides of the collateral ligament.
The superficial structure of the collateral ligament: In gross anatomical specimens, the composition of the superficial part of the collateral ligament is relatively clear, but the relationship between it and the muscle level is difficult to reveal perfectly. At the upper end of the collateral ligament there are very few fibers. Progressively downward, the fibers of the collateral ligament are difficult to distinguish from the surrounding connective tissue because of their slenderness. From the level of C2 to 5, a superficial layer consisting of the tendon fibers of the rhomboid and cephalicus or cephalic semispinalis muscles on both sides running horizontally and continuing with each other is visible. At C6 to 7, tighter horizontal fibers were seen consisting of tendinous fibers from both oblique muscles interconnected across the midline, showing the appearance of bundles of continuous horizontally oriented travel. Below C2, the superficial layer of the collateral ligament was found to be composed of musculotendinous fibers from the rhomboid, cephalic, small (large) rhomboid, and superior posterior serratus muscles on both sides, which were horizontally continuous with each other in their midline, especially in C6-7.
(ii) Structure of the dorsal and ventral parts of the collateral ligament: In gross anatomical specimens, the fiber patterns of the dorsal and ventral parts of the collateral ligament are difficult to be dissected and identified, whereas in bioplasticized thin-section specimens, they are more clearly separated.
(iii) Occipital to C1 (upper part of the collateral ligament): In the bioplastic specimens, the dorsal part of the collateral ligament, as well as the superficial part of the collateral ligament described above, did not show longitudinally distributed connective tissue fibers, and horizontally oriented fibers could be seen, and it was difficult to confirm whether they belonged to the tendon membrane of the uppermost part of the trapezius muscle or part of the deep cervical fascia, except for a slight increase in the thickness of the collateral ligament. The ventral part of the collateral ligament in this region was occupied by the loose connective tissue between the cephalic semispinalis and the inferior rectus cephalicus on both sides, and the midline structure was indistinguishable here.
④Part C2~5 (middle of the collateral ligament): the dorsal and ventral parts of the collateral ligament at the levels of C2, C3, C4, and C5 gradually became obvious when observed on bioplasty specimens. The dorsal part of the collateral ligament is a dense connective tissue triangle consisting of tendinous connective tissue fibers from the rhomboid and cephalic muscles on both sides or from the rhomboid, cephalic and cephalic semispinal muscles that cross and continue horizontally. Most of the fibers of the ventral part of the collateral ligament originate from the fibers of the dorsal part of the collateral ligament crossing at the midline, while a small portion is the tendinous fibers of the muscle ipsilateral to the fork of the spinous process, which fuse with the fibers of the midline and attach ventrally to the fork of the spinous process and the central part of the fork.
⑤ Part C6~7 (lower part of the collateral ligament): It can be observed on the bioplastic thin section that at the level of C6~7, the ventral and dorsal parts of the collateral ligament are closely fused together as a dense connective tissue body composed of tendon fibers from the muscles of the oblique, cephalicus, rhomboid and superior posterior serratus on both sides. Most of the tendinous fibers cross each other and cross the midline before attaching to the tip of the C6-7 spinous process.
The collateral ligament is structurally a double layer of dense elastic fibrous plates separated by a layer of reticular tissue, with the posterior free edge of the two layers united. The free edge of the two laminae are united and extend beyond the occipital ridge to the C7 spinous process. From here, the elastic fibrous plate attaches to the medial aspect of the lateral occipital ridge, the posterior C1 node, and the medial aspect of the cervical bifurcation, acting as a bilateral compartment for attachment of the cervical muscles. There is also the collateral ligament consisting of a dorsal (cords) and a ventral (lamina) portion. The dorsal part extends from the lateral aspect of the external occipital ridge to the C7 spinous process. The ventral portion extends anteriorly from the dorsal portion up to the posterior tuberosity of the atlas, the spinous process of the remaining spine and continues to the interspinous ligament. However, due to the constraints of ancient anatomical methods of study, the fine anatomy of the collateral ligament and its relationship to the surrounding muscles are summarized from observations of gross anatomy. From the present observations, it was found that the structural composition of the ventral and dorsal parts of the collateral ligament, i.e., the lamellar and coracoid parts, is different in various parts of the entire cervical spine; moreover, the collateral ligament is different from the supraspinous ligament, i.e., it is not a homologous ligament.
Previous literature described the collateral ligament as being composed of longitudinally aligned connective tissue fibers, whereas modern ultramicroanatomy has revealed that the vast majority of the fibers of the collateral ligament are transversely aligned tendinotendinous tissue fibers; previous literature described the collateral ligament as being homologous to the supraspinous ligament and a continuation of the supraspinous ligament, but today’s anatomy confirms that the collateral ligament is either directly attached to the spinous process or continues to be attached to the spinous process. The clearest evidence of these findings is that the ventral and dorsal portions of the collateral ligament, at the level of the C6-7 spinous process, are composed of the tendinous fibers of the oblique, cephalic, lesser rhomboid, and superior posterior serratus muscles as a single unit. The collateral ligament is locally composed of connective tissue fibers of different musculotendinous membranes and the way in which the fibers travel and the way in which they are clearly attached to the C6-7 spinous process is different from what has been described in the past. The entire connective tissue fiber structure of the collateral ligament is characterized by different composition and fiber alignment at different cervical vertebral levels. In the upper cervical region the extraoccipital bulge to C1 and most of the space in the posterior midline is occupied by sparse connective tissue. At the superficial level is a horizontally oriented layer of dense connective tissue connecting to the midline and traveling with the deep cervical fascia, accompanied by very few longitudinal fibers, and it is difficult to see the attachment to the occipital bone, which is only from the deep cervical fascia or a very few oblique tendon membrane fibers, and is not tightly attached. This is different from the previous description of “tight attachment of the collateral ligament to the occipital bone”. In gross anatomical specimens, the rhomboid muscle migrates to the superior end of the collateral ligament, occasionally with a very small number of longitudinal fibers.
In the middle cervical region, C2-5, the distinction between the superficial, ventral and dorsal parts of the collateral ligament is clearly visible. The superficial layer originates from the tendinous fibers of muscles such as the rhomboid and cephalicus muscles on both sides, and they migrate horizontally toward the midline and continue each other; in its deeper dorsal part, the tendinous fibers of muscles such as the rhomboid and cephalicus or cephalicus semispinalis muscles on both sides cross in the midline and form a dense connective tissue triangle, corresponding to the previously described cords of the collateral ligament; this part, near the inferior end of the collateral ligament, is accompanied by a gradual increase in tendinous fibers and becomes This part is relatively thick near the inferior end of the collateral ligament, accompanied by a gradual increase in tenosynovial fibers; while the tenosynovial fibers in the dorsal part cross and migrate ventrally, continuing to the interspinous ligaments of C2-5 and attaching to the spinous processes of C2-5, forming the ventral part of the collateral ligament, or equivalent to the previously described membranous part. The superficial, ventral and dorsal parts of the collateral ligament are basically a single unit composed of musculotendinous fibers.
In the lower cervical region C6-7, the superficial, ventral and dorsal parts of the collateral ligament are no longer clearly separated, but consist of a dense connective tissue body composed of musculotendinous fibers from the rhomboid, rhomboid, superior posterior serratus or and cephalicus muscles on both sides. These fibers travel superficially at the horizontal level and continue on both sides. The vast majority of fibers in the dorsal and ventral portions cross in the midline and then attach tightly to the spinous processes of C6-7, with very few being directly attached to the spinous processes. No distinct longitudinal fibers were identified in the collateral ligament, a finding that again differs from previous descriptions of the collateral ligament as belonging to the supraspinous ligaments of both the thoracic and lumbar spine. The occasional appearance of short longitudinal fibers in the gross specimen may have given the impression that the collateral ligament is a longitudinal ligament. However, closer inspection reveals that some of the longitudinal fibers on the superficial level are more precisely from the oblique muscles rather than the adjacent spinous process. The connective tissue fibers in the collateral ligament either originate from the adjacent musculotendinous membrane, in the case of the uppermost superficial portion of the collateral ligament, or from a stratification of the deep cervical fascia.
Innervation of the occipital region: the parieto-occipital region is innervated by the greater occipital nerve or the lesser occipital nerve, which is a posterior branch of the C2-3 spinal nerve; the periauricular region is also innervated by the greater occipital nerve, which is a posterior branch of the C2-3 spinal nerve.
The greater occipital nerve is the medial branch of the posterior branch of the C2 spinal nerve. the posterior branch of the C2 spinal nerve is located between the posterior arch of the atlantoaxial vertebrae and the cardinal plate, and the inferior aspect of the inferior cephalic oblique muscle is penetrated, and it is divided into a smaller lateral branch and a larger medial branch, respectively, outside the traffic of the posterior branches of the 1st and 3rd cervical nerves. The lateral branch innervates the longest cephalic muscle, the pinch muscle, and the cephalic semispinal muscle. The medial branch is the greater occipital nerve. The occipital nerve runs diagonally upward, successively through the cephalic semispinalis and oblique tendon membrane, accompanied by the vertebral arteries and veins and their branches, and is distributed above the superior collar line to the skin of the top of the skull.
The third occipital nerve is the cutaneous branch of the posterior branch of the third cervical nerve, which is distributed in the skin near the collar and the external occipital ridge.
The posterior branch of the 1st cervical nerve, the inferior occipital nerve, crosses between the posterior arch of the atlantoaxial spine and the vertebral artery into the inferior occipital triangle, and branches to innervate the posterior rectus major, posterior rectus minor, superior oblique and inferior oblique muscles of the head.
Clinical symptoms and mechanism of soft tissue damage in the occipital region: In case of soft tissue damage in the occipital region, in addition to symptoms such as pain, soreness, swelling and pulling sensation in the local occipital region, headache and migraine may also occur. The receptors in the occipital region and the deep soft tissue of the upper S cervical segment are connected to the cerebellum, vestibular nerve nucleus, red nucleus, thalamus and other centers related to vertigo, and the receptors distributed in the soft tissue of this region are stimulated by the aseptic inflammation of the soft tissue damage, and then are transmitted to the center through the fibers of the posterior branch of the cervical spinal nerve to cause excitation in the cerebellum and subcortical centers such as the vestibular nerve nucleus. At the same time, the occipital nerve also has anastomotic branchlets that communicate with the occipital nerve and the auricular nerve, so when the soft tissue in the occipital cervical region is damaged, the nerve can also be stimulated to cause pain and tinnitus in the ear and other signs of dysfunction. Soft tissue damage in the occipital area can also cause eye symptoms such as orbital pain and dry eyes.