Age / Sex : 29 / F

1) Obliquus capitis inferior muscle, Lt. 2) Intramuscular abscess

Discussion

Findings:

A focal fluid collection, suggesting an abscess between atlas and axis in Lt. parasagittal image and located in the structure running posteriorly and inferomedially from C1 to C2, obliquus capitis inferior muscle.

Diagnosis:

Intramuscular abscess in the obliquus capitis inferior muscle

Discussion:

Parasagittal T1-weighted image, cervical spine(Fig. 1)

 1, Hypoglossal canal

 2, Occipital condyle

 3, Lateral mass C1

 4, Vertebral artery

 5, Rectus capitis posterior major muscle

 6, Obliquus capitis inferior muscle

 7, Articular pillar C2

 8, C3 dorsal root ganglion

 9, Longus coli (cervicis) muscle

 10, Vertebral artery

 11, Apophyseal (facet) joint C3-4

 12, Multifidis muscle

 13, Semispinalis cervicis muscle

 14, Splenius capitis muscle

 15, Trapezius muscle

 16, Superior articular process

 17, Inferior articular process.

Obliquus capitis inferior muscle(Fig. 2)

Origin; spinous process of the axis

Insertion; lateral mass of atlas

Innervation; suboccipital nerve

Action; rotation of head and neck