The suboccipital muscles are a group of four muscles situated underneath the occipital bone. All the muscles in this group are innervated by the suboccipital nerve. They are located within the suboccipital compartment of the neck; deep to the sternocleidomastoid, trapezius, splenius and semispinalis muscles. They collectively act to extend and rotate the head.

Rectus Capitis Posterior Major

-The rectus capitis posterior major is the larger of the rectus capitis muscles.

-The Rectus capitis posterior major is located laterally to the rectus capitis posterior minor.

• The Rectus capitis posterior major originates from the spinous process of the C2 vertebrae (axis), and inserts into the lateral part of the inferior nuchal line of the occipital bone.

Rectus Capitis Posterior Minor

The rectus capitis posterior minor is the most medial of the suboccipital muscles.

The rectus capitis posterior minor rns from the posterior tubercle of the C1 vertebra to the medial part of the inferior nuchal line of the occipital bone.

Obliquus Capitis Inferior(OCI)

-Obliquus capitis inferior is the most inferiorly positioned of the suboccipital muscles. It is the only capitis muscle that has no attachment to the cranium.

•Obliquus Capitis Inferior(OCI) Originates from the spinous process of the C2 vertebra, and attaches into the transverse process of C1.

Obliquus Capitis Superior

The obliquus capitis superior is located laterally in the suboccipital compartment.

• Obliquus Capitis Superior(OCS) originates from the transverse process of C1 and attaches into the occipital bone (between the superior and inferior nuchal line)

Suboccipital Triangle

The suboccipital triangle is an area bordered by three of the suboccipital muscles:

1. Superomedial: Rectus capitus posterior major

2. Superolateral: Obliquus capitus superior

3. Inferior: Obliquus capitus inferior

• Floor: Posterior atlanto-occiptal membrane and posterior arch of the C1 vertebrae (atlas)

• Roof: Semispinalis capitus

The contents that the suboccipital triangle have is the vertebral artery, suboccipital venous plexus and suboccipital nerve

CERVICAL BONES

The cervical spine is the most superior portion of the vertebral column, lying between the cranium and the thoracic vertebrae.

It consists of seven distinct vertebrae, two of which are given unique names:

• The first cervical vertebrae (C1) is known as the atlas.

• The second cervical vertebrae (C2) is known as the axis.

Characteristics of cervical vertebra

The cervical vertebrae have three features :

1. Triangular vertebral foramen.

2. Bifid spinous process – this is where the spinous process splits into two distally.

3. Transverse foramina – holes in the transverse processes. They give passage to the vertebral artery, vein and sympathetic nerves.

C1 & C2 vertebra

Atlas

-The atlas (C1) differs from the other cervical vertebrae in that it has no vertebral body and no spinous process.

-The atlas has an articular facet anteriorly, which articulates with the dens of the axis.

-The atlas also has lateral masses on either side of the vertebral arch, which provide an attachment for the transverse ligament of the atlas.

The posterior arch has a groove for the vertebral artery and C1 spinal nerve.

Axis

-The axis (C2) is easily identifiable due to its dens (odontoid process) which extends superiorly from the anterior portion of the vertebra.

-The dens articulates with the articular facet of the atlas, in doing so creating the medial atlanto-axial joint. This allows for rotation of the head independently.

WHAT IS Present throughout Vertebral Column?

There are two different joints present throughout the vertebral column:

• Between vertebral bodies – adjacent vertebral bodies are joined by intervertebral discs, made of fibrocartilage. This is a type of cartilaginous joint, known as a symphysis.

• Between vertebral arches – formed by the articulation of superior and inferior articular processes from adjacent vertebrae. It is a synovial type joint.

Whats Unique to Cervical Spine?

The atlanto-axial and atlanto-occipital joints are unique to the cervical spine.

The atlanto-axial joints are formed by the articulation between the atlas and the axis:

• There are two lateral atlanto-axial joints which are formed by the articulation between the inferior facets of the lateral masses of C1 and the superior facets of C2. These are plane type synovial joints.

• The medial atlanto-axial joint is formed by the articulation of the dens of C2 with the articular facet of C1. This is a pivot type synovial joint.

The atlanto-occipital joints consist of an articulation between the spine and the cranium. They occur between the superior facets of the lateral masses of the atlas and the occipital condyles at the base of the cranium. These are condyloid type synovial joints, and permit flexion at the head i.e. nodding.

ATLANTO-OCCIPITAL AND ATLANTO-AXIAL JOINTS

• Synovial joints, no IV discs

• Atlanto-occipital joints- permit flexion and extension-nodding movement (YES), synovial condyloid.

• Atlanto-axial joint- 3 articulations, 2 lateral atlanto-axial joints (plane), 1 median atlanto axial joint==(pivot)==, pivot movement turning from side to side(NO).

LIGAMENTS

• Joints are supported by numerous ligaments;

1.Anterior Longitudinal ligament(ALL)

Attached superiorly to the base of the skull and runs the length of vertebral column to insert inferiorly to the anterior surface of the sacrum.

2.Posterior Longitudinal Ligament (PLL)

Posterior surface the vertebral body. Like the (ALL) attached along the length of the vertebral column to IV discs and vertebral bodies.

Upper part of the PLL that connects C2 to the base of the skull is called the tectorial membrane.

SUPRASPINOUS LIGAMENT AND LIGAMENTUM NUCHAE

• Supraspinous ligament: connects and passes along the tips of spinous processes of C7-sacrum.

• From vertebra C7 to skull the ligament becomes distinct- Ligamentum nuchae

Anatomical Relationships

The transverse foramina of the cervical vertebrae provide a passageway through which the vertebral artery, vein and a plexus of sympathetic nerves can pass.

There are two vertebrae where this is not the case:

• C7 – the vertebral artery runs around the vertebra, instead of passing through through the transverse foramen. The vertebral vein and associated nerves are still present in the foramen.

• Atlas – the vertebral artery runs along the groove for the vertebral artery instead of through the transverse foramen.

The spinal nerves extend from above their respective cervical vertebrae, through the intervertebral foramen created by the joints at the articular processes.

The C7 vertebra has a set of spinal nerves extending from above (C7) and below (C8) the vertebra. Therefore there are eight spinal nerves associated with seven cervical vertebra(I know right,confusion!)