Musculoskeletal structures of the neck Flashcards
Describe the purpose of the cervical spine
The cervical spine is designed for mobility. Under normal circumstances this does not occur at the expense of stability. Head and neck movements are primarily concerned with the positioning of the eyes and thus the line of vision. The muscles of the upper cervical spine are highly innervated and thus ensure movements are made with a fine degree of precision.
Seven (7) cervical vertebrae form the cervical spine and support the head: C1 (atlas), C2 (axis) and C3-C7.
Describe the features of the cervical vertebrae
- short square shaped vertebral body for weight bearing, together with IV discs
note: concave superioir surface created by uncinate processes that form the uncovertebral clefts, with the reciprocal convex-shaped inferior surface of the vertebral body above - pedicles that attach vertebral body to vertebral arch
- laminae that extend from each pedicle, to form the vertebral arch
- large, triangular vertebral foramen, containing the spinal cord
- short bifid spinous process that projects posteriorly and is a site for muscle and ligament attachment
- a bifid transverse process, with anterior and posterior tubercles, that is a site for muscle and ligament attachments
- transverse foramen: for vertebral artery, veins and sympathetic nerves
- superior articular processes, articulating with inferior articular processes above to form zygapophysial or facet joint
- inferior articular processes, articulating with superior articular processes above to form zygapophysial or facet joint
Describe the atypical cervical verterbrae
- atlas, with no vertebral body
-
Anterior arch with anterior tubercle (there is no vertebral body)
The anterior arch of the atlas articulates with the dens of C2 and transverse ligamentto form the median atlanto-axial joint. This is a synovial pivot joint that provides the majority of cervical spine rotation and some flexion/extension. - Posterior arch with a posterior tubercle (instead of a spinous process
- Lateral masses that support the superior and inferior articular processes
- Kidney-shaped concave superior articular facets
_ The superior articular facets of C1 articulate with the kidney-shaped convex occipital condyles to form the atlanto-occipital joints. These synovial condyloid joints enable flexion/extension of the head on the neck, anda small amount of lateral flexion._ -
Inferior articular facets
The inferior articular facets of C1 articulate with the superior articular facets of C2 to form the lateral atlanto-axial joints which work together with the median atlanto-axial joint to provide cervical rotation and flexion/extension. - Longtransverse processfor muscle and ligament attachment with a transverse foramen for the vertebral artery
- Vertebral foramen that contains the spinal cord
-
Anterior arch with anterior tubercle (there is no vertebral body)
- axis
- Vertebral body with the dens that forms the median atlanto-axial joint ^[inferior articular surface of lateral mass for atlas, superior articular facet of axis, plane or gliding joints]
- Pedicles and laminae the surround the vertebral foramen containing the spinal cord
- Large bifid spinous process for muscle and ligament attachment
- Small transverse processes with a transverse foramen for the vertebral artery
- Superior articular processes and facets that form the lateral atlanto-axial joints with the inferior articular facets of the atlas
- Inferior articular processes and facets that form the first pair ofzygapophysial (facet) joints with the C3 superior articular facets
Describe the ligaments of the cervical spine
The joints of the cervical spine are supported by a number of ligaments.
Connects the anterior vertebral bodies and intervertebral discs up to the anterior tubercle of C1. The anterior atlanto-occipital membrane then connects the anterior tubercle of C1 to the occiput.
Posterior longitudinal ligament
Connects the posterior aspects of the vertebral bodies and intervertebral discs up to the C2 vertebral body. The tectorial membrane then connects C2 to the occiput.
Ligamentum flava
Composed of elastic tissue and connects the laminae of adjacent vertebrae up to the posterior arch of C1. The posterior atlanto-occipital membrane connects the posterior arch of C1 and the occiput.
Interspinous ligament
Connects adjacent spinous processes.
Ligamentum nuchae
Thisstrong broad ligament extending between theC7 spinous process and external occipital protuberance is an important site of muscle attachment. Inferiorlyis continuous with the supraspinous ligament at C7.
Supraspinatus ligament
The supraspinous ligament is a cord-like band that runs along and connects the tips of the spinous processes from vertebra C7 to the sacrum. It is continuous superiorly with the nuchal ligament of the cervical region. This ligament prevents separation of spinous processes during flexion and resists hyperflexion.
List and describe the ligaments of upper cervical spine
Transverse ligament
A strong thick horizontal band that passesbehind the dens of C2 as itattaches betweenthe lateral masses of C1. It is essential to maintaining the stability of the median atlanto-axial joint by preventing posterior displacement of the dens and anterior displacement of C1.
Superior and inferior longitudinal bands extend from the transverse ligament to the occipital bone (superiorly) and the body of C2 (inferiorly). The transverse ligament and longitudinal bands are collectively referred to as the cruciate ligament of the atlas.
Alar ligaments
Extend betweenthe sides of the dens andthe lateral margins of the foramen magnum. The alar ligaments prevent excessive rotation of the atlanto-axial joints.
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Describe the principles underlying neck muscles and action
Key concepts
- anterior neck muscles
- actions: flexion
- innervation: ventral rami
- lateral neck muscles
- actions: lateral flexion
- if diagonal fibres; action is rotation
- posterior neck muscles
- actions: extension
- innervation: dorsal rami
Exceptions:
- layers 1 and 2 of posterior neck muscles
- actions: extension and movements of shoulder girdle
- innervation: ventral rami
in cervical spine, muscles attaching to the skull move the head, whilst muscles that
attach to the cervical vertebrae will move the neck.
in cervical spine, muscles attaching to the skull move the head, whilst muscles that
attach to the cervical vertebrae will move the neck.
Describe the trapezius muscle
- Trapezius is located superficially
- Deep to skin and superficial fascia
- Medial Attachment: External occipital protuberance and superior nuchal lines; ligamentum nuchae; spinous processes C7-T12
- Lateral Attachment: Spine and acromion ofscapula; lateral one-third of clavicle
- Actions: Extension andlateral flexion of the head and neck
- Innervation: Spinal accessory (CN XI) nerve; C3-4 ventral rami
Describe the levator scapulae
Deep to the trapezius.
Innervated by CNXI and/or ventral rami
- Inferioir attachment: Medial border ofscapula
- Superior attachment: C1-4 transverse processes
- Actions: Extension andlateral flexionof the neck
- Innervation: Dorsal scapular nerve (C4,C5); C3-C4 ventral rami
The levator scapulaemuscle also acts upon the scapulato create m
Note:
Note:
The levator scapulaemuscle also acts upon the scapulato create movements of the shoulder girdle
Describe splenius capitis and cervicis
Splenius capitis
Posterior neck muscle
Therefor extensor
Innervated by dorsal rami
Deep to levator scapulae and rhomboid muscles.
Splenius capitis
- inferior attachment: Lower half ligamentum nuchae; C7-T4 spinous processes
- superior attachment: Mastoid process; lateral one-third superior nuchal line
- actions: Extension, lateral flexion and ipsilateralrotationof the head and neck
- innervation: dorsal rami
##### Splenius cervicis
- inferior attachment: T3-T6 spinous processes
- superior attachment: C1-C3 transverse processes
- actions: Extension, lateral flexion and ipsilateralrotationof the neck
- innervation: dorsal rami
Describe the cervicis
Posterior neck muscle
Therefore extensor
Innervated by dorsal rami
Describe the erector spinae
Posterior neck muscle
Therefore extensor
Innervated by dorsal rami
Describe the sternocleidomastoud
Lateral rotator.
Innervated by CNXI and/or ventral rami.
Superficial, deep to only skin, superficial fascia and fat.
- inferior attachment: Manubrium of sternum (sternal head); medial one-third of clavicle (clavicular head)
- superior attachment: Lateral half superior nuchal line (sternal head); mastoid process (clavicular head)
- actions: Flexion, lateral flexion and contralateral rotationof the head and neck. Also extension of the atlanto-occipital joints.
- innervation: Spinal accessory (CN XI) nerve; C2-C3/4 ventral rami
Describe the scalene
Lateral side of neck.
Deep to sternocleidomastoid muscle.
Made of three parts: anterior, middle, posterior.
Innervated by ventral rami.
Describe the anterior scalene
- superior attachment: C3-C6 transverse processes
- inferior attachment: rib 1 (Scalene tubercle)
- actions: Flexion, lateral flexion and contralateral rotation of the neck
- innervation: C4-C7 ventral rami
