Surface Anatomy and Other
Landmarks
- Laryngeal prominence
(Adam's apple) in the midline formed by the thyroid cartilage at approximately
C4.
- Inferiorly the ring of the cricoid cartilage may be palpated at C6.
- The tips of the transverse processes of C1 are more prominent than those
of other cervical vertebrae and can be palpated in the parotid space.
- The hyoid bone: Its body is at the level of C3. It has lesser and
greater horns bilaterally.
- The thyroid cartilage lies at the levels of C4 and C5. The laryngeal
prominence is Adam's apple. The thyroid cartilage is composed of 2 lateral
laminae with superior and inferior horns. The inferior horns articulate with
the cricoid cartilage.
- The cricoid cartilage at C6. The upper end of the trachea is palpable
in the midline from the cricoid cartilage to the superior border of the manubrium.
- The thyrohyoid membrane is pierced by the internal laryngeal nerve
and vessels.
- The cricothyroid membrane may be used for a high tracheostomy.
*The preferred site of tracheostomy is at tracheal cartilages 2-4 (below cricoid
cartilage and isthmus of the thyroid gland).
Craniovertebral
Joints
- Atlanto-occipital joint: joint between atlas
(vertebra C1) and occipital bone; movements - flexion - extension of the neck
(nodding the head in "yes" movement).
- Atlanto-axial joint: joint between atlas (C1)
and axis (C2); movement: rotation of atlas on axis (shaking head in "no" movement)
- Ligaments of joint - stabilize joints and protect
medulla and spinal cord; some prevent excessive movement; some are extensions
of ligaments of spinal column
- Cruciate (cross) ligament - composed of
- Transverse ligament of atlas: transverse band
within vertebral canal which is attached to inner side of atlas; holds dens
of axis against inner aspect of anterior arch of atlas
- Superior and inferior bands: upper and lower
extensions from transverse ligament of atlas to occipital bone superiorly
and to body of the axis inferiorly.
Clinical note: Tear of cruciate ligament of
atlas can allow dens to be driven into spinal cord (resulting in quadriplegia)
or medulla (resulting in death).
- Alar ligament: extends laterally from dens
to occipital bone; prevents excessive rotation of head.
- Tectorial Membrane
: extension of posterior longitudinal ligament of spinal column -
extends from axis to occipital bone, posterior to cruciate ligament.
- Anterior atlanto-occipital membrane:= extension
of anterior longitudinal ligament - extends from atlas to occipital bone
