10.18.11+-+Neck


 * Neck**

C1 is also called Atlas; it is flat, doesn't have a vertebral body, doesn't have a spinous process, and superiorly articulates with the occipital bone at the atlantooccipital joint. It does have the foramen transversarium. C2 is also called Axis; it's most unique structure is the dens. An extension superiorly of the vertebral body that is the axis that the head rotates around. It has a spinous process (normally bifid). Has the foramen transversarium. C3-C7 are a lot like thoracic vertebrae, but the transverse processes have the foramen transversarium. C7's spinous process is particularly long, called the vertebral prominence.
 * 1a. Describe the osteology of the 7 cervical vertebrae:**

The vertebral artery, the first superior branch of the subclavian artery runs anterior to the C7 foramen transversaria, but then runs through C6-C1 foramen transversaria before entering head.
 * 1b. Describe what structure passes through the foramen transversaria:**

C1 moves with the skull. C2 moves with the neck. Rotation occurs between them. The rotation of C1 (and the skull) around the dens of C2 allows for rotation of the head.
 * 1c. Describe the unique osteological features of the atlas and axis (C1 and C2 cervical vertebrae), and how these features contribute to head rotations:**

Anterior Longitudinal Ligament: Anterior side of vertebral body. Prevents hyperextension of spine. Posterior Longitudinal Ligament: Posterior side of vertebral body; once it reaches C1 and C2 called tectorial membrane. Prevents hyper flexion of spine. Ligamentum Flavum: Connect vertebral arches to eachother. Prevents hyperflexion of spine. Zygopophyseal Joint Capsule: Around zygopophyseal joints at superior and inferior articular facets. Interspinous Ligament: Loose connective tissue between spinous processes Supraspinous Ligament: Line of connective tissue running between spinous processes Nuchal Ligament: Unique to the neck. Connects external occipital crest to vertebral prominence. Fills the gap created by the lordosis of the cervical vertebrae. Prevents hyperflexion Cruciate Ligament: If facing anteriorly within the spinal column, the most superficial layer is the posterior longitudinal ligament, at this point known as the tectorial membrane. Deep to it lies the cruciate ligament. Deep to the cruciate ligament lies the posterior articular surface of the dens and its joint capsule. The cruciate ligament is shaped like a cross and is connected superiorly to the clivus of the occipital bone and inferiorly to the C2 vertebral body. Laterally it is connected to tubercles of the transverse process of C1. It protects the spinal cord during rotation. Alar Ligaments: Also called the check ligaments. Prevent over rotation of the neck. Attached proximally to the dens of C2 and distally to the medial surface of the foramen magnum of the occipital bone.
 * 2. Describe the ligaments of the cervical vertebrae, including ligaments that are shared with thoracic and lumbar vertebrae, and those that are unique to the cervical vertebrae:**


 * 3. Describe briefly the major function of the hyoid bone, including its roles in swallowing and breathing, and which muscles are considered "supra hyoid" and which muscles are considered "infra hyoid." Describe the points of attachment of each of these muscles:**

Through a series of connections, the movement of the hyoid bone seals or opens the respiratory passage. The supra and infra hyoid muscles are attached to to the ventral side of the hyoid bone and move it (generally) superiorly or inferiorly. The dorsal side of the hyoid bone is attached to the thyroid cartilage, which in turn is adjacent to the epiglottis. The epiglottis is a flap of cartilage (like a toilet seat) that when depressed closes the respiratory track. When the hyoid bone is raised, it also raises the thyroid cartilage. The thyroid cartilage raises the dorsal edge of the epiglottis while the ventral side remains stationary. This causes the respiratory track to close, allowing swallowing. The infra hyoid muscles lower the hyoid bone, lowering the thyroid cartilage, relieving the superior pressure on the dorsal edge of the epiglottis, allowing the dorsal edge to drop and the respiratory track to reopen.

Suprahyoid muscles: GMDS Geniohyoid: From geniotubercle on inner surface of medial mandible to body of hyoid bone Mylohyoid: From mylohyoid line of medial surface of mandible to body of hyoid bone Digastric: From digastric fossae on the anterior-inner surface of mandible to mastoid notch of temporal bone (groove medial to mastoid process); attached to body of hyoid via intermediate tendon loop Stylohoid: From styloid process of temporal bone to body of hyoid

Infrahyoid muscles: SOTS Sternohyoid: From manubrium of sternum to body of hyoid Omohyoid: From superior border of scapula to body of hyoid; angle created by fascial sling on sternal end of clavicle Thyrohyoid: From oblique line of thyroid cartilage to body of hyoid and greater horn of hyoid Sternothyroid: From manubrium of sternum to oblique line of thyroid cartilage

The stylohyoid ligament anchors the hyoid bone to the skull between the styloid process of the temporal bone and the lesser horn of the hyoid. The thyrohyoid membrane connects the thyroid membrane of the larynx to the hyoid. They limit movement of the hyoid bone by being inflexible and attaching the hyoid superiorly and inferiorly.
 * 4. Name the ligament that anchors the hyoid bone to the skull and the ligamentous sheet that attaches the hyoid bone to the larynx:**


 * 5. "Describe how the muscles of the superficial and pre vertebral compartments contribute to head and neck movements."**


 * I don't think this is what he meant. Only the platysma is in the superficial compartment, so I think he meant the investing layer.**

Compartments:

Superficial compartment of neck: Platysma Investing layer of deep compartment of the neck (red): Sternoclydomastoid, trapezoid Infrahyoid fascia (purple): Infrahyoid muscles (Sternohyoid, Omohyoid, Thyrohyoid, Sternothyroid) Prevertebral compartment of deep compartment of neck (orange): Anterior (anterior scalene, middle scalene, posterior scalene, longus colli, longus capitis) and Posterior (spinalis, longissimus, splenius, semispinalis, levator scapula) Pretracheal compartment of deep compartment of neck (blue): Thyroid and parathyroid glands, esophagus, larynx and trachea Buccopharyngeal (visceral) fascia (green): Borders retropharyngeal compartment (potential space for bacteria) with pre vertebral fascia. Carotid sheaths (brown): Internal jugular vein, common carotid artery, vagus nerve, sympathetic chain

Movements:

Flex Neck: Anterior group of pre vertebral muscles (scalenes and longus) Extend Neck: Posterior group of pre vertebral muscles (erector spine, deep cervical) Rotate Head Left: Right sternocleidomastoid Rotate Head RIght: Left sternocleidomastoid Tilt Head: Prevertebral muscles


 * 6. Describe the borders of the two major compartments of the neck -- the anterior triangle and the posterior triangle -- as well as the borders of the various sub-triangles making up these triangles. Describe the borders of the "root of the neck."**

Anterior Triangle: Mandible, Midline, Sternocleidomastoid Posterior Triangle: Trapezius, Clavicle, Sternocleidomastoid

Occipital Triangle (superior): Trapezius, Sternocleidomastoid, Inferior Omohyoid Belly Omoclavicular Triangle (inferior): Clavicle, Sternocleidomastoid, Inferior Omohyoid Belly

Submandibular Triangle (superior): Mandible, Posterior Digastric Belly, Anterior Digastric Belly Submental Triangle (anterior): Anterior Digastric Belly, Midline, Hyoid Carotid Triangle (posterior): Sternocleidomastoid, Posterior Digastric Belly, Superior Omohyoid Belly Muscular Triangle (inferior): Midline, Superior Omohyoid Belly, Sternocleidomastoid

Root of Neck (part of superior mediastinum): Superior thoracic inlet and superior edge of the great vessels and lungs. Brachiocephalic trunk, left subclavian a., R & L brachiocephalic vv., thymus, thyroid gland, parathyroid glands