Triangles of the Neck

Summary

Highlights

• Triangles help us describe and explore neck anatomy. 📏
• Landmarks like the sternocleidomastoid muscle are key for dividing the neck. 🗺️
• Posterior and anterior triangles have distinct contents and borders. 🗂️
• The submandibular and carotid triangles are important regions to note. 🏞️
• Triangles facilitate visualizing and mapping out the neck's complex structures. 🗺️

Key Takeaways

• Triangles make understanding neck anatomy easier! 🦴
• Landmarks are essential for identifying smaller structures in the neck. 🔍
• The sternocleidomastoid muscle is a vital divider for neck triangles. 💪
• The posterior triangle has important nerves and arteries. 🚦
• The anterior triangle is a busy area with glands and major vessels! 💉

Overview

Chapters

• 00:00 - 00:30: Introduction and Importance of Neck Triangles The chapter begins with an introduction to the anatomical concept of neck triangles, crucial for understanding neck anatomy. Dr. Morton, a noted anatomist, introduces the importance of these triangles in facilitating the description and identification of neck structures. The chapter sets out questions to explore: the relevance of neck anatomy to geometry, and the specific borders and contents of both the posterior and anterior neck triangles. The analogy of zooming into a map is used to explain how breaking down complex structures into triangles enhances comprehension and identification of anatomical features.
• 00:30 - 01:40: Using Maps to Locate Structures The chapter discusses the use of maps to locate structures, with a focus on a specific example in Utah. It demonstrates how maps, particularly labeled ones, can help identify highways like interstate 15. However, it also addresses the challenge of identifying locations on unlabeled maps, suggesting the need to rely on other features when labels are absent.
• 01:40 - 02:40: Anatomy of the Neck: Identifying Structures This chapter covers the anatomy of the neck by discussing how to identify structures using readily identifiable landmarks. It uses the analogy of geographical features such as the Great Salt Lake and the Wasatch Mountains, and how these larger landmarks can help in identifying smaller ones like the interstate i-15. This concept is then applied to anatomy by showcasing a picture of the head and neck to explain how larger anatomical landmarks can assist in identifying smaller structures.
• 02:40 - 04:00: Dividing the Neck into Triangles The chapter 'Dividing the Neck into Triangles' discusses how to identify various arteries and landmarks in the neck by using anatomical triangles. It emphasizes the importance of recognizing major muscles like the digastric muscle (both posterior and anterior bellies) and mandible to locate smaller landmarks such as arteries within the submandibular triangle. The use of the sternocleidomastoid muscle as a key landmark is also highlighted.
• 04:00 - 05:05: Details of the Posterior Triangle The chapter details the anatomical division of the neck into two main triangles, focusing on the posterior triangle. The posterior triangle is situated behind the sternocleidomastoid muscle. The significant anatomical landmarks forming its borders include the trapezius muscle and the clavicle. The chapter also mentions the roof and floor of the posterior triangle, which are comprised of deeper anatomical structures. This division is compared to notable geographical features, like mountain ranges and lakes, providing a vivid analogy of the neck's anatomy.
• 05:05 - 06:00: Contents and Structures of the Posterior Triangle This chapter discusses the structures and boundaries of the posterior triangle of the neck. It highlights the importance of the posterior border of the sternocleidomastoid, the anterior border of the trapezius, and the clavicle in defining this area. The chapter further delves into the anatomical details, emphasizing the deep investing fascia and the significance of rotating the head and zooming in to better understand the spatial layout of these features.
• 06:00 - 07:00: Deeper Structures of the Posterior Triangle The chapter provides a detailed exploration of the structures within the posterior triangle of the neck. Initially, the outline of the posterior triangle is identified, with the roof being the deep investing fascia. A thorough explanation of opening this fascia to reveal deeper layers is provided, illustrating the cut edge of the deep investing fascia. The discussion extends to describe the floor of the posterior triangle, identified as the pre-vertebral fascia of the neck. The narrative uses anatomical references such as the sternocleidomastoid and trapezius muscles to locate the posterior triangle. Overall, this chapter offers a step-by-step guide to understanding the anatomical structures that form and surround the posterior triangle of the neck.
• 07:00 - 08:10: More Details on the Posterior Triangle Structures This chapter delves into the anatomical structures within the posterior triangle of the human neck, specifically focusing on the layers and contents encountered during dissection. The deep investing fascia is cut to reveal the floor made up of the prevertebral fascia surrounding the scalene muscles. Key contents include cutaneous nerves emerging from the cervical plexus and the external jugular vein. The chapter aims to uncover additional structures constituting the floor of the posterior triangle, emphasizing the role of the piercing deep investing fascia.
• 08:10 - 09:20: Overview of the Anterior Triangle The chapter discusses the anatomy of the anterior triangle of the neck, focusing on key structures and nerves. It mentions the deep investing fascia, the posterior midline, and the sternocleidomastoid muscle. The cutaneous branches of the cervical plexus, known as Erb's point, are highlighted along with the external jugular vein. It also notes the presence of superficial cervical nodes. The description emphasizes the path of nerves emerging between the anterior and posterior triangles of the neck.
• 09:20 - 09:30: Subdivisions of the Anterior Triangle The chapter titled 'Subdivisions of the Anterior Triangle' explains the anatomy of the anterior triangle in the human body. It describes how the omohyoid muscle divides the posterior triangle into two distinct sections. The upper triangle is named the occipital triangle due to the presence of the occipital artery, while the lower triangle is called the supraclavicular triangle, which contains the suprascapular artery and transverse scapular artery. This chapter explores the scalene muscles' relationship with the deep investing fascia as they extend towards the skin, forming the floor of the posterior triangle.
• 09:30 - 11:00: Submandibular Triangle The chapter discusses the anatomy of the submandibular triangle, highlighting important structures and layers relevant to this area of the body. It starts by describing the prevertebral fascia that forms the floor of the triangle. Superficially, the spinal accessory nerve, also known as cranial nerve 11, is mentioned, which innervates the sternocleidomastoid (SCM) and trapezius (traps) muscles. Additionally, the presence of the transverse cervical artery and suprascapular artery is noted. The chapter concludes by mentioning deeper structures such as the splenius capitis, levator scapulae, posterior scalene, and middle scalene muscles, which become visible upon removal of the prevertebral fascia.
• 11:00 - 12:00: Submental Triangle The chapter titled 'Submental Triangle' examines the anatomical features of the neck, specifically focusing on the scalene muscles, the cervical plexus, and the brachial plexus. It notes the positioning of the scalene muscles and how the cervical plexus (roots from C1 to C4) and the brachial plexus (roots from C5 to T1) exit the neck between the anterior and middle scalene muscles. The chapter concludes by pointing out the potential visibility of muscles and/or nerves in the neck area.
• 12:00 - 15:00: Carotid Triangle The chapter describes the anatomical landmarks in the region of the carotid triangle, particularly focusing on the subclavian artery and vein. The subclavian artery passes between the anterior and middle scalene muscles, while the subclavian vein is located in front of the anterior scalene muscle. It also identifies a branch of the cervical plexus, the phrenic nerve, and mentions the brachial plexus. The chapter employs the metaphor of a mountain range and a Great Salt Lake to describe this anatomical area, aiding in visualizing the spatial relationships between these structures.
• 15:00 - 16:30: Muscular Triangle The chapter introduces the main anatomical features of the muscular triangle within the anterior triangle of the neck. Key borders and structures of the anterior triangle are highlighted, including the sternocleidomastoid muscle, the mandible, and the anterior midline of the neck. The description explains how these features delineate the anterior triangle of the neck.
• 16:30 - 17:00: Conclusion The chapter 'Conclusion' discusses the morphological divisions within the anterior triangle, focusing specifically on the four subdivisions: submandibular, submental, carotid, and muscular triangles. A detailed examination of the submandibular triangle is provided, including its borders, defined by the anterior and posterior belly of the digastric muscle and the mandible. Visual aids accompany the explanation for clarity.

Triangles of the Neck Transcription

• 00:00 - 00:30 okay we're going to talk about triangles of the neck and answer the questions what is the deal with a Natomas and geometry and what are the borders and contents of the posterior triangle and what are the borders sub triangles in contents of the anterior triangle hello everyone my name is dr. Morton and I'm the noted anatomist so why do we care about triangles well triangles facilitate descriptions of neck anatomy and they also help us more easily identify structures what do I mean by this well here's a map of the United States and let's use Google Maps and let's zoom in and zoom in and zoom into
• 00:30 - 01:00 the great state of Utah and zoom in a little bit more we're like hey look at this great little part where in central Utah and someone asked a question says hey what's this highway right here well on this handy-dandy map I take a look at that blue thing and I'm like oh that's interstate 15 or the i-15 done and done but what happens if the map is not labeled and someone says hey what's is highway right there now I don't have the label on that highway so I have to use other features on this map to
• 01:00 - 01:30 identify that so I look over and to the west and Mike well that's the Great Salt Lake and oh there's the Wasatch Mountains what is the only interstate with a major interstate highway going north through between those two structures that's interstate i-15 I know that so you use readily identifiable diet' Pula here's readily identifiable landmarks a big lake and mountains to help you identify smaller landmarks within so here we have a picture of some anatomy of the head
• 01:30 - 02:00 and neck and this and someone says hey what's his artery right there and you're like oh man this is unlabeled what do I do so let's look for our big lakes we got the digastric muscle posterior belly and digastric muscle anterior belly and then we have here is the mandible so then we know that's in the submandibular triangle that's definitely the facial artery we use readily identifiable landmarks to help identify smaller landmarks within so the sternocleidomastoid muscle becomes one
• 02:00 - 02:30 of our big mountain ranges or lakes that helps us divide the neck into two triangles the posterior triangle and the anterior triangle so here's this lateral view of the neck and you're like there's the sternocleidomastoid so behind it is the pole dear triangle and in front of it is the anterior triangle that becomes one of our big mountain ranges that we recognize sternocleidomastoid well let's go to the posterior triangle its borders or the sternocleidomastoid traps and clavicle and the roof and floor are the deep
• 02:30 - 03:00 investing in pre vertebral facist here we have a lateral view we find the posterior border of the sternocleidomastoid inter border of the traps and the clavicle and she there is the posterior triangle of the neck so similar here we have we rotate the head and then we zoom in more like sternocleidomastoid clavicle traps there's our posterior triangle of the neck there is this region within and so the borders are also the deep investing
• 03:00 - 03:30 fascist so we then to outline that and there's our posterior triangle so the roof of the posterior triangle is deep investing fashio now let's take a scalpel and cut along that and open it up so you see the cut edge of the deep investing fascia and the floor of the posterior triangle is the pre vertebral fashio of the neck so let's do that again that was fun here's our sternocleidomastoid in the traps so what's in between them that's the posterior triangle of the neck so the roof is this deep investing fascia so
• 03:30 - 04:00 now if we take a scalpel there and there in cut we then see that deep investing fashio is cut the floor is the pre vertebral fascia in this case surrounding our scalene muscles the contents of the posterior triangle are follows well though it pierces the deep investing fascia are these cutaneous nerves from the cervical plexus and our external jugular vein and the floor has a number of other structures we're going to cover so let's first do this piercing the deep investing fashio so there's our
• 04:00 - 04:30 deep investing fashion and they're right in the posterior midline posterior part of the sternocleidomastoid we have these cutaneous branches of the cervical plexus that branch out it's called herbs point of the neck and I'll talk about all those in a separate video and then we also have the external jugular vein piercing as well in that area we're also lining that as superficial cervical nodes so in this cross-section we see right there between the - as opposed to your triangle so watch as those nerves come out between her
• 04:30 - 05:00 scalings and pierce the deep investing fascia and go out into the skin now the floor of this is as follows well there's one of the muscles we see in the floor of the posterior triangle is called the omohyoid and the omohyoid is going to divide this post ear triangle into an upper triangle called the occipital triangle because that's where the occipital artery is found and then below it is the supraclavicular triangle where we have the suprascapular artery and transverse scapular artery in
• 05:00 - 05:30 that area let's now take a look again there is the pre vertebral fascia forming the floor and then skimming right superficially across it is a spinal accessory nerve or cranial nerve 11 which is going to innervate our SCM and the traps we also have the transverse cervical artery and the suprascapular artery now if we go deeper and remove that pre vertebral fascia we see our splenius capitis levator scapulae post your scalene middle
• 05:30 - 06:00 scalene and an tier scalene muscles additionally between our middle and an tier scalene we have the cervical plexus which are the spinal roots from c1 to c4 and the brachial plexus which is from c5 to t1 all of those plexus ease c1 - t1 or all exiting the neck between our anterior middle scalene so if you then see muscle and/or a nerve in the neck
• 06:00 - 06:30 coming between you can now use these as landmarks to determine what is what additionally the subclavian artery comes out between us and here middle scalings and the subclavian vein comes out in front of that was fun let's do it again let's zoom in so there is our anterior middle scalene so there's become our mountain range and our Great Salt Lake so between that we know that must be a branch of the cervical plexus specifically that's the phrenic nerve and then we know that that's the brachial plexus and below that's the subclavian artery and in front of the anterior scalene is the
• 06:30 - 07:00 subclavian vein now the anterior triangle of the neck is what we're going to cover next and its borders are as follows the sternocleidomastoid and the mandible and the anterior midline of the neck that's what makes our anterior triangle the neck and let's do it from the front there's our sternocleidomastoid our mandible and your midline that's what makes the anterior triangle and so there is mandible and your midline sternocleidomastoid there is our anterior triangle of the neck so the
• 07:00 - 07:30 anterior triangle is subdivided into four triangles so look at this picture and she submandibular triangle submental triangle carotid triangle and muscular triangle let's talk about the submandibular triangle first we know this triangle because it's bordered by the anterior and the posterior belly of the digastric is muscle as well as the mandible when we find that those three borders we find the submandibular triangle let's zoom in and switch out the pictures so there we now have one of
• 07:30 - 08:00 the major contents that fills most of the space of the submandibular triangle is the submandibular salivary gland and then the facial artery is exiting deep from the gland and the facial vein is superficial to the gland and then any lymph nodes in this area are simply called submandibular lymph nodes we remove the submandibular gland and you can see the facial artery and facial veins holding hands within this triangle there is the on the floor of the submandibular triangle as the mylohyoid
• 08:00 - 08:30 muscle and tucked right in back there is the hypoglossal nerve cranial nerve 12 going to the tongue so let's zoom back out and now let's do the submental triangle the submental triangle is bordered by the mandible the anterior belly of the digastric as' and our high weight bone and so we zoom in the major thing we see in there is submental lymph nodes the chin is the mental symphysis so below it is the submental triangle and the lymph nodes are submental lymph nodes you may also see some tributaries
• 08:30 - 09:00 of the anterior jugular veins so let's now go to the carotid triangle and we have the borders of the posterior belly of the digastric hist the superior belly of the omohyoid and the sternocleidomastoid that's what's making the carotid triangle so if we then look at this lateral view and see all right here is a view and let's focus in on triangular region and so in there the contents include our internal jugular vein the carotid arteries and our vagus nerve which collectively are within the
• 09:00 - 09:30 carotid sheath if we recall there's the carotid sheath and wrapped around the IJ are these deep deep cervical lymph nodes draining much of the limb from the head we also have the hypoglossal nerve cranial nerve 12 that will eventually get into the submandibular triangle and we also have the ancestor of a callus and other branches from the cervical plexus within this carotid triangle now the carotid arteries is what I just put but recall that the carotid arteries
• 09:30 - 10:00 really come from the common carotid artery and whenever we see the prefix common with the vessel we know it'll bifurcate and we have one of those branches as the internal carotid artery and its base as the carotid sinus and the crowded body which are Barrow and chemoreceptors respectively more on that in the vessels of the neck tutorial I should note also within this carotid sheath you're going to have the nerve to the carotid sinus and body which is from cranial nerves 9 and 10 we also have all
• 10:00 - 10:30 the branches off the external carotid artery that supplied the face and a lot of the neck all of those are branches that come off within this carotid triangle next we're going to go into the muscular triangle which is bordered by the omohyoid the sternohyoid and the sternocleidomastoid and within there is primarily the side of the thyroid gland and parathyroid gland and I didn't have any good pictures to show it and clinically it's not that relevant but it's in every single book so I included it but I don't
• 10:30 - 11:00 care for my students if they ever know that triangle so that my friends is showing all the triangles in the neck in a nutshell [Music]