Organization of the Neck Hankin Describe the cervical fascia and compartments



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© 2009 Mark Tuttle

Organization of the Neck - Hankin

  1. Describe the cervical fascia and compartments.

    1. Investing layer

      1. Surround the entire neck

      2. Just deep to platysma m. anteriorly

      3. Invests:

        1. Trapezius m.

        2. Sternocleidomastoid m.

        3. Parotid gland

        4. Submandibular gland

    2. Pretrachial layer

      1. Muscular

        1. Invests Infrahyoid mm.

      2. Visceral

        1. Invests Trachea, including the buccopharyngeal membrane on the posterior aspect of the trachea

        2. The Buccopharyngeal membrane invests the constrictor muscles of the pharynx

        3. Thyroid

        4. Parathyroid

        5. Trachea

        6. Pharynx

        7. Esophagus

    3. Prevertebral layer

      1. Deep to the investing layer

      2. Contains all the associated muscles of the vertebral column

    4. Carotid sheath

      1. Closely invests:

        1. Common carotid aa.

        2. Internal carotid a.

        3. Jugular v.

        4. Carotid sinus & body

        5. Sympathetic fibers

        6. Vagus n.

        7. Deep cervical lnn.

  2. Describe the cervical regions/triangles.

    1. What are their boundaries and contents?

      1. Lateral Cervical Region (Posterior Cervical Triangle)

        1. Boundaries

          1. Anterior: SCM

          2. Posterior: Trapezius

          3. Inferior: Clavicle

          4. Roof: Investing fascia

        2. Deep to this you can see:

          1. Splenius capitus

          2. Lavator scapulae

          3. Middle/anterior scalene mm.

        3. Contains

          1. Muscles

            1. Muscular floor

            2. Splenius capitis

            3. Levator scapulae

            4. Middle scalene

            5. Posterior scalene

            6. Omohyoid (inferior belly)

          2. Arteries

            1. Transverse cervical a.

            2. Suprascapular a.

            3. Subclavian a. (3rd part)

            4. Occipital a. (part)

          3. Veins

            1. Subclavian v.

              1. External jugular v.

                1. Transverse cervical v.

                2. Suprascapular v.

                3. Anterior jugular v.

          4. Nerves

            1. Accessory n. (CN XI)

            2. Roots of brachial plexus

            3. Suprascapular n.

            4. Phrenic n. (C3-5)

            5. Cervical plexus (C1-4) – cutaneous branches (C2-4) (Come out at Herb’s Point)

              1. Lesser occipital n. (C2)

              2. Great auricular n. (C2-3)

              3. Transverse cervical n. (C2-3)

              4. Supraclavicular nn. (C3-4)

        4. Divided into

          1. Occipital triangle (above omohyoid m. inferior belly)

          2. Omoclavicular (Subclavian) triangle (below the omohyoid m. inferior belly)

      2. Anterior Cervical Region/Anterior Cervical Triangle

        1. Boundaries

          1. Anterior: Anterior midline of neck

          2. Posterior: SCM

          3. Superior: Mandible

        2. Subdivisions

          1. Submental triangle (unpaired)

            1. Anterior belly of digastric mm.

            2. Hyoid bone (in middle/inferior)

          2. Submandibular (digastric) triangle

            1. Anterior belly of digastric mm.

            2. Posterior belly of digastrics mm.

          3. Carotid

            1. Omohyoid m.

            2. Posterior belly of digastrics m.

            3. SCM

          4. Muscular

            1. Omohyoid m.

            2. SCM

            3. Midline of neck

        3. Subdivisions floor/contents

          1. Submental triangle

            1. Floor

              1. Mylohyoid mm.

            2. Contents

              1. Submental lnn.

              2. Small vv. (tributaries of anterior jugular v.)

          2. Submandibular (digastrics) triangles

            1. Floor

              1. Mylohyoid m.

              2. Hyoglossus m.

              3. Middle pharyngeal constrictor m.

            2. Submandibular gland

            3. Submandibular lnn.

            4. Mylohyoid m.

            5. Hypoglossal n. (CN XII)

            6. Parts of facial artery & vein

          3. Carotid triangle

            1. Floor

              1. Inferior pharyngeal constrictor m.

            2. Contents

              1. Common carotid a.

              2. Internal carotid a.

              3. External carotid a.

              4. Carotid body & sinus

              5. Internal jugular v.

              6. Deep cervical lnn.

              7. Vagus n. (CN X)

              8. Hypoglossal n. (CN XII)

              9. Accessory n. (CN XI)

              10. Branches of cervical plexus

              11. Larynx

              12. Pharynx

              13. Thyroid & PT glands

          4. Muscular triangles

            1. Infrahyoid mm.

            2. Thyroid & PT glands

  3. What structures are found at the “key vertebral levels” in the neck?

C3

Hygoid bone

C4

Carotid bifurcation

C4-5

Thyroid cartilage

C5-6

Cricoid Cartilage (C6)

Inferior limit of pharynx and larynx

Superior limit of trachea and esophagus

Indentation between cricoids cartilage and 1st tracheal ring



C6-T1

Thyroid gland


Muscles of the Neck

  1. Describe the neck muscles.

    1. You should know their innervation, attachments, and primary actions

      1. OK

Endocrine 1: Hypophysis and Pineal - Chiaia

  1. Describe the histology of the pituitary gland; include the infundibular stalk, the four main parts, and its embryology.

    1. Anterior Lobe (From oral ectoderm/Adenohyphosis/Ratke’s Pouch)

      1. Pars Distalis

        1. Most anterior portion (75% of entire pituitary)

        2. Dense cords of secretory epithelial cells

        3. Supported by reticular fibers

        4. Contains sinusoidal capillaries which are lined by fenestrated endothelial cells w/diaphragms

      2. Pars Tuberalis

        1. Wraps around the infundibular stalk to hold the two lobes together during development before they fuse

        2. Arranged in short longitudinally oriented cords

        3. Portal system corses through here on way to pars distalis

        4. Mostly chromophils here (mostly gonadotrophs)

      3. Pars Intermedia

        1. In between the pars distalis and posterior lobe (pars nervosa)

        2. Basophilic cells in lower mammals

        3. In humans, chromophobic cells surrounding aggregates of colloid filled follicles called Ratke’s Cysts (maybe some basophils too)

        4. Marked by an indentation called Rathke’s Cleft

    2. Posterior Lobe (From neural ectoderm/Neurohyphosis)

      1. Pars Nervosa

        1. The posterior lobe

        2. Does not contain secretory epithelial cells

        3. Highly branched non secretory, glial-like cells called pituicytes whose processes end in close association to capillaries

          1. Thought to serve a nutritive function like glial cells in CNS

        4. **Axon terminals w/Granules are diagnostic

        5. **Vesicle bound hormones cause dilations of the axon terminals called Herring Bodies

      2. Infundibulum

        1. The stalk part of the posterior lobe

  2. Identify chromophils and chromophobes of the pars distalis. Indicate which pituitary hormones are made by each, what are the functions of each hormone and what is the target organ, tissue or cell of each.

    1. Chromophils (50%)

      1. Acidophils (α cells, 40%)

        1. Large, densely staining cells

        2. Cytoplasm packed with small specific acidophilic staining granules

        3. Types (Distinguished only immunocytochemically):

          1. Somatotrophs

            1. Spherical to ovoid

            2. Centrally located nucleus

            3. Secretions:

              1. Growth Hormone (chondrocyte growth ↑)

                1. Somatomedins (cartilage, mitosis ↑)

              2. Somatotrophin

          2. Mammotrophs

            1. Concentrated in the posterolateral portion of Pars distalis

            2. Secretions:

              1. Prolactin (milk secretion, progesterone ↑, infertility in males)

        4. Basophils (β cells, 10%)

          1. Larger than acidophils

          2. Cytoplasmic granules are smaller and less numerous

          3. Types (Distinguished only immunocytochemically):

            1. Thyrotrophs

              1. Angular cells

              2. Secretions:

                1. Thyroid Stimulating Hormone (TSH)
                  (stimulates thyroxine (T4) and triiodothyronine (T3) from thyroid)

            2. Gonadotrophs

              1. Fusiform cells with eccentric nuclei

              2. Contain varying sized secretory granules

              3. **Located immediately adjacent to sinusoid

              4. Secretions:

                1. Follicle stimulating hormone (FSH)
                  - ABP in males, ovarian follicles in fem

                2. Leutinizing Hormone (LH)
                  - androgen in males, progesterone/ovulation in females

            3. Corticotrophs

              1. Large ovoid cells with eccentric, indented nucleus

              2. Produce a prohormone: Pro-opiomalanocortin

              3. Secretions (Pro-opiomalanocortin products):

                1. Adrenocortocotropic Hormone
                  (Glucocorticoids in adrenal cortex ↑)

                2. β endorphin
                  (Pain)

                3. Melanocyte Stimulating Hormone
                  (Stimulates melanin synthesis)

                4. β Lipotropin
                  (function unknown)

    2. Chromophobes (50%)

      1. Small round pale staining cells with little cytoplasm

      2. Non-secretory

      3. Few specific staining granules

      4. Tumors here are common

  3. Identify the components of the neurohypophysis

    1. Pars Nervosa

      1. Highly branched glial-like pituicites whose processes end in close association to capillaries. Serve a nutritive function.

      2. No secretory epithelial cells

      3. **Herring bodies diagnostic for vesicle bound hormones dilating the axon terminals

    2. Infundibulum

      1. Descending axons form the supraoptic and paraventricular nuclei of the hypothalamus gather in the infundibulum, collecting to form a tract called the hypothalamic-hypophyseal tract which terminates on the capillary plexus of the posterior lobe

    3. Median eminence

      1. Superior hypophyseal aa. (from internal carotid a.) anastomose here and form the fenestrated Primary Plexus

      2. Small, unmyelinated neurons come down from the hypothalamus and terminate on the fenestrated Primary Plexus

  4. Describe the two hormones that are liberated from the posterior lobe of the pituitary in terms of their origin, the hypothalamohypophyseal tract, their target organs, and their functions.

    1. Oxytocin

      1. Originates in paraventricular nucleus of hypothalamus

      2. Induces contraction of myoepithelial cells of the mammary gland resulting in excretion of milk from the secretory alveoli

    2. Vasopressin

      1. Originiates in supraoptic nucleus

      2. Promotes water absorption through the collecting tubules of the kidney

      3. Increases blood pressure by promoting contraction of vascular smooth muscle resulting in increased peripheral resistance

  5. Be able to describe the signals which trigger the release of pituitary hormoneds and their feedback regulation.

    1. First Order (oxytocin, vasopression)

      1. Neurohypophyseal (Posterior Pituitary) hormone (oxytocin, vasopression) feeds back on hypothalamus for negative feedback

    2. Second Order (Growth Hormone, Prolactin)

      1. Hypothalamic releasing factor stimulates release of pituitary hormone which acts on peripheral target tissues

      2. Plasma level of pituitary hormone feeds back to the hypothalamus or pituitary for negative feedback

    3. Third Order (Thyroid Stimulating Hormone, ACTH)

      1. Hypothalamic releasing factor stimulates release of pituitary hormone

      2. Pituitary hormone stimulates peripheral target endocrine organ to secrete its own hormone

      3. Level of peripheral target organ hormone feeds back to pituitary or hypothalamus for negative feedback

  6. Describe the overall histology of the pineal gland and the hormones produced by the pineal gland.

    1. Flattened conical gland attached to midline of superior surface of the diencephalon of CNS

    2. Encapsulated by the CT of Pia of the CNS which penetrates the parenchyma as trabechulae

    3. Cell types

      1. Pinealocytes

        1. Basophilic cytoplasm with long cytoplasmic processes which end in bulb-like expansions in close proximity to capillaries

        2. Small dense core vesicles similar to those in catacholaminergic neurons

        3. Large oval nucleus and **clearly distinguishable nucleoli

        4. Secrete Melatonin

          1. Released during dark cycle (inhibited by light)

          2. Radical scavenger and anti-oxidant

          3. May inhibit growth of some tumors

          4. May be involved in Seasonal affected disorder

          5. Helps regulate bio-rhythms

      2. Glial cells

        1. Resemble astrocytes of the CNS both structurally and immunocytochemically

        2. **Brain sand: small aggregates of calcium phosphate and calcium carbonate. Radiopaque.

Nerves And Vessels of the Neck - Hankin

Blood Vessels

  1. Describe the venous drainage of the neck.

    1. External jugular v. (Drains into subclavian v.)

      1. Retromandibular v.

        1. Superficial temporal v.

        2. Maxillary v.

          1. Pterygoid venous plexus (deep to mandible)

      2. Posterior auricular v.

      3. Anterior jugular v. (somewhat inconsistent)

      4. Transverse cervical v.

      5. Suprascapular v.

    2. Internal jugular v. (Unites with subclavian v. and becomes brachiocephalic v.)

      1. Continuation of sigmoid sinus (dural venous isnus)

      2. Inferior petrosal sinus (dural venus sinus)

      3. Occipital v.

      4. Pharyngeal vv.

      5. Common facial v.

      6. Lingual v.

      7. Superior/Middle thyroid v.

      8. Infeior bulb of Internal Jugular V. (Contains a bicuspid valve)

    3. What is the relationship between the internal jugular vein and the carotid sheath?

      1. The internal jugular v. is within the carotid sheath

    4. Where is the external jugular vein located?

      1. Superficial fascia

      2. Crosses superficial and oblique to SCM

      3. Empties into the subclavian v. just deep/inferior to the base of SCM

  2. Describe the branches of the external carotid artery.

    1. Superficial temporal a.

    2. Maxillary a.

    3. Posterior auricular a.

    4. Occipital a.

    5. Ascending pharyngeal a.

    6. Facial a.

    7. Lingual a.

    8. Superior thyroid a.

    9. Are there branches of the internal carotid artery in the neck?

      1. NO

  3. Describe the carotid body and carotid sinus.

    1. Carotid sinus

      1. Located at the dilation of the bifurcation of carotid a.

      2. Usually associated with external carotid, but can be on common carotid a.

      3. Contains Baroreceptors

      4. Reacts to blood pressure by decreasing heart rate via the afferent loop of the Glossopharyngeal n. (CN IX) AND vagus n. (CN X) AND cervical sympathetic nn. (probably have opposite effect)

    2. Carotid body

      1. Ovoid mass at bifurcation

      2. Contains Chemoreceptors

      3. Senses low blood O2 or high CO2, reacts by increasing rate & depth of respiration, cardiac rate & bp

      4. Innervated by the afferent loop of the glossopharyngeal n. (CN IX) AND vagus n. (CN X) AND cervical sympathetic nn.


Nerves and Plexuses

  1. Describe the cervical and branchial plexuses in the neck.

    1. Cervical plexus (ventral rami C1-C4)

      1. Motor nerves

        1. Superior root of ansa cervicalis (C1)

          1. Runs with hypoglossal n. (CN XII: tongue)

          2. Also runs with thyrohyoidn. And geniohyoid n.

        2. Ansa cervicalis (Goose Neck) is on the carotid sheath

          1. Sternohyoid m.

          2. Omohyoid m.

          3. Sternothyroid m.

        3. Inferior root of ansa cervicalis (C2-3)

        4. Other direct branches

          1. Deep neck mm.

      2. Cutaneous nerves, ansa cervicalis (C1-3), and phrenic nerve (C3-5)

      3. Ventral Rami: Innervate skin of anterior and lateral neck

        1. Lesser occipital n. (C2) Neck & scalp posterosuperior to auricle

        2. Great auricular n. (C2-3) Skin over parotid gland, posterior aspect of auricle between angle of mandible & mastoid pr

        3. Transverse cervical n. (C2-3) Anterior cervical region

        4. Supraclavicular nn. (C3-4) Neck and shoulder

        5. Brachial plexus (C5)

      4. Dorsal rami: Innervate skin on posterior head and neck.

        1. Suboccipital n. (C1)

        2. Greater occipital n. (C2)

        3. Third occipital n. (C3)

    2. Brachial plexus (ventral rami C5-T1)

      1. See Unit 1

  2. Describe the cranial nerves that course through and/or supply the neck.

    1. Glossopharyngeal nerve (CN IX)

      1. Afferent from tongue and pharynx

      2. Efferent to stylopharyngeus & parotid gland

        1. CN IX runs to otic ganglion before going to parotid

    2. Vagus nerve (CN X)

      1. Sensory

        1. Inferior pharynx

        2. Larynx

        3. Thoracic and abdominal organs

        4. Taste

          1. Root of tongue and epiglottis

      2. Motor

        1. Soft palate

        2. Pharynx

        3. Intrinsic laryngeal mm.

        4. Palatoglossus

      3. Parasymp

        1. Thoracic & abdominal organs

      4. Superior (Jugular) ganglion: General sensory

      5. Inferior (Nodose) ganglion: Visceral sensory

    3. Accessory nerve (CN XI)

      1. Not really a cranial n. since its spinal component immediately joins the vagus and becomes indistinguishable. Both excit via the jugular foramen

      2. Motor

        1. SCM

        2. Trapezius

    4. Hypoglossal nerve (CN XII)

      1. Runs with the thyrohyoid n. and geniohyoid n. as well as the superior root of ansa cervicalis (all C1)

      2. Innervates the tongue except for pataloglossus m.

      3. Spirals behind the vagus nerve and passes between the internal carotid artery and internal jugular vein lying on the carotid sheath. After passing deep to the posterior belly of the digastric muscle, it passes to the submandibular region to enter the tongue.

  3. Describe the cervical sympathetic trunk, its ganglia, and branches.

    1. Superior cervical ganglion (@ C1-2)

      1. Large ganglion posterior to Internal Carotid A.

      2. Postsynaptic fibers

        1. ICA plexus enters cranial cavity to supply cranial vasculature and other structures (ex. Iris of eye)

        2. Contributes fibers to external carotid a. plexus

        3. Gray rami to C1-4 spinal n. to cervical plexus

        4. Superior cervical cardiac n. to heart

    2. Middle cervical ganglion (@ C6)

      1. Smallest cervical ganglion (occasionally absent)

      2. Anterior or superior to inferior thyroid a.

      3. Postsynaptic fibers

        1. Gray rami to C5&6 spinal nn. to brachial plexus

        2. Forms periarterial plexuses to thyroid gland

        3. Middle cervical cardiac n. to heart

    3. Inferior cervical ganglion (@ C7)

      1. Usually (80%) fused with T1 ganglion to form stellate (cervicothoracic ganglion)

      2. Postsynaptic fibers

        1. Gray rami to C7-T1 spinal nn. to brachial plexus

        2. Inferior cervical cardiac n. to deep cardiac plexus

        3. Forms plexus on vertebral a. to cranial cavity

Root of the Neck – Hankin

Lymphatics in the Head and Neck

  1. Define the major groups of lymph nodes found in the neck?

    1. From superficial to deepcervical lnn.

    2. Drains into supraclavicular lnn. (usually)

      1. Accompanies transverse cervical a.

    3. Usually on the carotid sheath, not inside

    4. Drain into jugular lymphatic trunks formed by

    5. The left jugular lymphatic trunk joins the thoracic duct

    6. The right jugular lymphatic trunk joins the venous system at the right venous angle

    7. The thoracic duct empties into the left venous angle (where subclavian/jugular vv. meet)
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