Lateral Pharyngeal Region

In order to view the prevertebral region, which we will do next, the pharynx and related structures should be cleaned well so that they can be preserved when the pharynx and skull are reflected forward.
 
 
With the sternomastoid reflected, clean and structures in the carotid sheath:
  • internal jugular vein
  • common carotid artery
  • vagus nerve with its superior laryngeal branch


When the fingers are gently slid behind the carotid sheath structures (arrows), the internal jugular vein can be reflected freed from the lateral pharyngeal structures.

If traced far enough cephalad, you will reach the base of the skull and the jugular foramen.

When the jugular vein is reflected, you can get a good view of the common carotid and its branches.
 
  1. common carotid artery
  2. external carotid artery
  3. internal carotid artery
  4. superior thyroid artery
  5. internal laryngeal artery
  6. lingual artery
  7. facial artery
stylohoid muscle (8)
posterior belly of digastric (9)
Reflection of the carotid artery and its branches reveal:
 
  1. stylopharyngeus muscle
  2. glossopharyngeal nerve
  3. styloglossus muscle
  4. upper vagus
  5. superior laryngeal branch of vagus
  6. internal laryngeal
  7. external laryngeal
  8. inferior pharyngeal constrictor
  9. middle pharyngeal constrictor
  10. esophagus
Walls of the pharynx and related structures:
 
  • superior pharyngeal constrictor (spc)
  • middle pharyngeal pharyngeal constrictor (mpc)
  • inferior pharyngeal constrictor (ipc)
  • bodies of cervical vertebrae (bcv)
  • arrows point to the retropharyngeal space.
The retropharyngeal space is held loosely to the front of the vertebrae and the anterior longitudinal ligament by loose connective tissue and fingers can easily be placed in this space to separate the pharynx from the vertebrae.

It is time in your studies that you start looking at another dimension of the body, cross section. Learning to identify structures on a cross section will give you a third dimension in the anatomy of a region. This is particularly important if you would like to study radiographs, cat scans, or MRI's of the human body. At this particular time, you are unable to see the pharynx in its entirety and how the structures around it are related to each other. The cross section image below is made at about the C6 level of the vertebral column. Many of the back muscles have already been identified by now and have not been labeled. The labels in the image are related to the neck structures you have studied.
 

In looking at a cross section and in preparation for viewing MRI's, always keep in mind that you are looking up the body (as if you were standing at the foot of a patient's bed and examining him/her from the foot up).
Your right side is the patients left side (this is very important to practice. Start with an obvious structure and work around it:
 
  • sternomastoid (sm)
  • external jugular vein (ej)
  • Internal jugular vein (ij)
  • common carotid artery (cca)
  • vagus (v)
  • thyroid cartilage (light blue)
  • laryngeal pharynx (lp)
  • inferior pharyngeal constrictor (ipc)
  • retropharyngeal space
  • sympathetic chain (sc)
  • body of C6
  • deep cervical lymph nodes (dcln)
This is a cross section taken through the 3rd cervical vertebra (15). Most of the labeled structures have been identified already:
  1. orbicularis oris
  2. mandible
  3. buccinator muscle
  4. depressor anguli oris
  5. medial pterygoid muscle
  6. masseter
  7. mandibular canal
  8. parotid gland
  9. sternomastoid
  10. posterior belly of digastric muscle
  11. internal jugular vein
  12. internal carotid artery
  13. superior pharyngeal constrictor
  14. trapezius muscle
Cross section through the Atlas and occipital condyles:
  1. orbicularis oris muscle
  2. maxilla
  3. levator anguli oris muscle
  4. buccal fat pad
  5. buccinator muscle
  6. zygomaticus major muscle
  7. masseter muscle
  8. ramus of mandible
  9. parotid gland
  10. mastoid process
  11. atlas
  12. occipital condyle
  13. vagus nerve
  14. internal jugular vein
  15. internal carotid artery
  16. medial pterygoid muscle
  17. lateral pterygoid muscle

Prevertebral Region

In order to view the prevertebral region, the skull and cervical viscera must be reflected forward. The dotted line is the plane of separation.
  • pharynx (ph)
  • longus colli (lc)
  • scalene anterior (sa)
  • scalene medius (sm)

Prevertebral Region

The background for the prevertebral region is the cervical vertebral column. The viscera of the neck (pharynx-exophagus and larynx-trachea) lie just anterior to:
  • bodies of cervical vertebrae
  • anterior longitudinal ligament (all)
The next layer forward is made up of muscles that act to move the vertebrae, forward and laterally flexing the neck:
  1. rectus lateralis
  2. rectus anterior
  3. longus capitis
  4. longus cervicis
  5. scalene medius
  6. scalene anterior
  7. scalene posterior
  8. anterior longitudinal ligament
Also at the muscular layer are the nerves that make up the cervical plexus (1-4) and the roots of the phrenic nerve and the brachial plexus:
  1. anterior ramus of C1
  2. C2
  3. C3
  4. C4
  5. C5
  6. C6
  7. C7
  8. C8
  9. T1
Remember from the upper limb that C5 and C6 merge to form the upper trunk of the brachial, C7 forms the middle trunk and C8 and T1 form the lower trunk.

C3-C5 form the phrenic nerve

The cervical part of the sympathetic chain is found running along the prevertebral region and consist of the:
  • superior cervical ganglion (1)
  • middle cervical ganglion (2)
  • inferior cervical ganglion (3)
  • 1st thoracic ganglion (4)
Notice that the cupola of the lung extends up into the root of the neck (5).
At the root of the neck (already covered in another lesson), we can see the large arteries emerging from the thorax:
  1. common carotid
  2. subclavian
  3. vertebral
  4. internal mammary
  5. thyrocervical trunk
  6. suprascapular
  7. transverse cervical
  8. ascending cervical
The terminal branch of the thyrocervical trunk is the inferior thyroid artery (not labeled)
Finally, the remaining items at the root of the neck are:
  1. brachiocephalic vein
  2. vertebral vein
  3. internal jugular vein
  4. external jugular vein
  5. thoracic duct
  6. right lymphatic duct
Posterior Cervical Triangle   Pharynx & Larynx


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