Musculature_and_Organization_of_the_Ventral_Neck_Student.pptx

Musculature and Organization of the Ventral Neck Mr. Vaudrey Objectives • Describe and identify the highlighted surface anatomy and bony landmarks for the neck. Understand the anatomic relationships that make these specific identifications relevant or important to this session. • Describe and iden...

Musculature and Organization of the Ventral Neck Mr. Vaudrey Objectives • Describe and identify the highlighted surface anatomy and bony landmarks for the neck. Understand the anatomic relationships that make these specific identifications relevant or important to this session. • Describe and identify the function, innervation, attachment sites, and relationships of the muscles covered in this session. Include superficial muscles of the neck, the supra/infrahyoid muscles that were highlighted for this session, and the prevertebral muscles. • Describe and identify the anatomic triangles and their subdivisions. Include their boundaries, contents, and clinical significance. Part I: Introduction to the Neck Introduction to the Neck The neck is one of the more complicated anatomical regions in the body because it serves so many disparate functions that all have to be able to function (some of them have to be able to occur simultaneously!) • Supporting the head • Movement of the head/neck • Swallowing • Breathing • Phonation Surface Anatomy of the Neck4 Bony Landmarks for Reference1,2 • Mastoid • Manubrium of sternum • Temporal bone • External occipital protuberance • Superior nuchal line • Mandible • Clavicle Bony Landmarks for Reference3 https://www.cambridge.org/core/books/sonoanatomy-for-anaesthetists/greater-occipital-ner ve/A455DEF09343F1B06CA3687906F5784F Bony Landmarks for Reference4 Hyoid bone • The hyoid bone is suspended in the neck by muscles between the floor of the mouth and the larynx. Landmarks of the Neck • Hyoid bone: C3-C4 • Upper border of Thyroid Cartilage and bifurcation of Carotid Arteries: C3-4 • Isthmus of Thyroid Cartilage: C4C5 • Cricoid Cartilage: C6 C3 C4 C5 C6 T2 T3 Part II: Ventral Muscles of the Neck Superficial Muscles of the Neck2,4 • Platysma • Superior attachment: Inferior border of mandible, skin, and subcutaneous tissues of the lower face • Inferior attachment: Fascia covering superior parts of pectoralis major & deltoid muscles • Action: Draws corner of mouth inferiorly and widens it in emotional responses (fear, sadness) • http://www.tavmd.com/wpcontent/uploads/2013/11/ platysma.png Superficial Muscles of the Neck2,4 • Sternocleidomastoid • Superior attachment: mastoid process (temporal bone), lateral half of superior nuchal line • Inferior attachment: manubrium of sternum (sternal head); medial third of the clavicle (clavicular head) • Innervation: Spinal accessory nerve (CN XI) Superficial Muscles of the Neck2,4 • Sternocleidomastoid cont… • Actions: • Unilateral contraction: • tilts head to the same side (laterally flexes neck) and rotates it so face is turned superiorly toward opposite side • Bilateral contraction: (1) • flexes cervical vertebrae so chin approaches manubrium • extends superior cervical vertebrae while flexing inferior cervical vertebrae so chin is thrust forward while head is kept level • extends head at atlanto-occipital joint • Respiration: can help elevate manubrium and medial ends of clavicles, assisting in deep respiration • Trapezius • Main action: Movement of the scapulae • (refer to lecture on muscles of the back for more specifics) Superficial Muscles of the Neck2,4 Suprahyoid & Infrahyoid Muscles Suprahyoid and Infrahyoid Muscles of the Neck • Suprahyoid Muscles • • • • Digastric Stylohyoid Mylohyoid Geniohyoid • Infrahyoid Muscles • • • • Sternohyoid Sternothyroid Thyrohyoid Omohyoid Digastric and omohyoid are both double-bellied muscles (meaning, they have 2 muscle bellies separated by an intermediate tendon). In the neck, the bellies of both the digastric and omohyoid muscles serve as important landmarks. So even though, functionally, we will deal with the suprahyoid and infrahyoid muscles of the neck later (in the Respiratory course), structurally, you need to know digastric and omohyoid. Suprahyoid and Infrahyoid Muscles of the Neck 2 Prevertebral Muscles Prevertebral Muscles of the Neck2 • Prevertebral Muscles • • • • Longus colli Longus capitis Rectus capitis anterior Rectus capitis lateralis Prevertebral Muscles of the Neck2 • Longus colli • Action: Flexes neck with rotation to opposite side if acting unilaterally • Innervation: Anterior rami of C2 – C6 spinal nerves • Longus capitis • Action: Flexes head & upper cervical vertebrae • Nerve: Anterior rami of C1-3 Prevertebral Muscles of the Neck2 • Rectus capitis lateralis • Function: Flexes head and helps stabilize it • Innervation: Branches from loop between C1 and C2 spinal nerves • Rectus capitis anterior • Action: Flexes head • Innervation: Branches from loop between C1 and C2 spinal nerves Scalene Muscles Scalene Muscles of the Neck2 • Anterior Scalene • Function: Flexes head, elevation of 1st rib during inhalation • Superior attach: Transverse processes of C3-C6 • Inferior attach: 1st rib • Nerve: Ventral rami of cervical spinal nerves (Cervical spinal nerves C4-6) Scalene Muscles of the Neck2 • Middle scalene • Function: Flexes neck laterally, elevates 1st rib during forced inspiration • Superior attach: Posterior tubercles of transverse processes of C2-7 • Inferior attach: Superior surface of 1st rib • Nerve: Ventral rami of cervical spinal nerves Scalene Muscles of the Neck2 Middle scalene • Interscalene Space • A gap between the anterior scalene, middle scalene, with the first rib as the floor. • Traversing through the triangle: • Subclavian artery • Brachial plexus Anterior scalene Brachial plexus Subclavian artery Scalene Muscles of the Neck2 • Posterior scalene • Function: Flexes neck laterally, elevates 2nd rib during forced inspiration • Superior attach: Posterior tubercles of transverse processes of C4-6 • Inferior attach: External border of 2nd rib • Nerve: Ventral rami of cervical spinal nerves C7-8 Prevertebral and Scalene Muscles of the Neck 5 Middle Scalene Posterior Scalene Anterior Scalene Part III: Triangles of the Neck Anatomic Triangles of the Neck4 The neck is divided into two major anatomic triangles by the sternocleidomastoid muscle • Anterior triangle • Posterior triangle Anterior Triangle4 • Anterior Triangle (Green area): Draw an imaginary line right down the midline of your neck from the middle of your chin to the manubrium then follow the anterior border of the SCM back to the mastoid process, then follow the inferior border of the mandible back to the midline of your chin. • The Anterior Triangle is divided into 4 subdivisions: • Submental • Submandibular • Carotid Anterior Triangle4 Practice Questions: What muscle travels from the scapula to the hyoid bone? Omohyoid muscle What muscle travels from the mastoid process to the hyoid bone? Digastric muscle These muscles are used to divide the anterior triang into the 4 subdivisions. Anterior Triangle – Submental Triangle (1)4 The submental triangle goes from the midline of the chin down to the midline of the hyoid bone. Follow the hyoid bone laterally and then follow the anterior belly of the digastric muscle back up to the midline of the chin. The floor of this triangle is the mylohyoid muscle. Contents: • Submental lymph nodes • drain the tongue and the floor of the mouth. Anterior Triangle – Submandibular Triangle (2) 4 The submandibular triangle is really just the area between the inferior border of the mandible and the anterior and posterior bellies of the digastric muscle. Contents: • Submandibular gland • Hypoglossal nerve (CN XII) • Lymph nodes & branches of the facial artery and vein Anterior Triangle – Carotid Triangle (3) 4 The carotid triangle is formed by the superior belly of the omohyoid, the inferior belly of the digastric and the anterior border of the sternocleidomastoid muscle. Contents: • Carotid artery • Internal jugular vein • Hypoglossal nerve (CN XII) • Vagus nerve (CN X) Anterior Triangle – Muscular Triangle (4) 4 The muscular triangle is formed by starting at the middle of the hyoid bone and drawing a straight line down the midline of the neck to the manubrium. Then follow the anterior border of the sternocleidomastoid muscle until you get to the superior belly of the omohyoid (at about the midpoint of the SCM). Follow the superior belly of the omohyoid back up to the hyoid bone. Contents: • Infrahyoid muscles • Thyroid and parathyroid glands • Interestingly, there aren’t any substantial vessels typically Posterior Triangle4 • The posterior triangle is formed by starting at the superior nuchal line on the occipital bone where the SCM and trapezius muscles meet and then following the anterior border of the trapezius down to the clavicle, following the clavicle medially till you run into the posterior border of the SCM and then following the posterior border of the SCM back superiorly to the superior nuchal line. • The posterior triangle is subdivided into 2 smaller triangles using the inferior belly of the omohyoid. • The Posterior Triangle is divided into 2 subdivisions: • Occipital Triangle • Omoclavicular (subclavian) Triangle Posterior Triangle – Occipital Triangle (1) 4 The occipital triangle gets its name because the occipital artery passes through it (along with the hypoglossal nerve). Content: • Occipital artery • Spinal Accessory Nerve (CN XI) This triangle is formed superior to the inferior belly of the omohyoid. Posterior Triangle – Omoclavicular Triangle (2) 4 The omoclavicular (subclavian) triangle is formed caudal to the inferior belly of the omohyoid, within the posterior triangle. Content: • Subclavian artery (specifically the third part of the subclavian artery). • External jugular vein can typically be seen crossing superficial to this area References 1.Schuenke, M. Atlas of of Anatomy: Head, Neck and Neuroanatomy, Vol. 1. 2nd Ed. New York: Theime Medical Publishers, 2016. http://www.thiemeteachingassistant.com.ezproxy.ad.bcomnm.org/Home/Collection/1. Accessed July, 2021 2.Schuenke, M. Atlas of of Anatomy: Head, Neck and Neuroanatomy, Vol. 3. 2nd Ed. New York: Theime Medical Publishers, 2016. http://www.thiemeteachingassistant.com.ezproxy.ad.bcomnm.org/Home/Collection/1. Accessed July, 2021 3.Moore, K. L. Clinically Oriented Anatomy. 8th Ed. Philadelphia, PA: Wolters Kluwer, 2018. https://meded-lwwhealthlibrary-com.ezproxy.ad.bcomnm.org/book.aspx?bookid=2212. Accessed June, 2021. 4.Gilroy, A.M., MacPherson, B.R., & Schuenke, M. Atlas of Anatomy, 3rd Ed. New York: Theime Medical Publishers, 2016. https://www-thiemeteachingassistant-com.ezproxy.ad.bcomnm.org/Home/Collection/1/90608. Accessed June 2021. 5.Netter, F. Atlas of Human Anatomy. 7th Ed. Philadelphia: Elsevier Inc., 2019. Atlas of Human Anatomy - ClinicalKey (bcomnm.org). Accessed July 2021.