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Surface anatomy of the male seen anteriorly and posteriorly.
Hey everyone! This is Nicole from Kenhub, and welcome to our tutorial on male body surface anatomy. In this tutorial, we'll be looking at the surface anatomy of the male body and although many aspects of the surface anatomy are the same or pretty similar between the sexes, there are a few differences some of which will be highlighting in this tutorial. Surface anatomy is, of course, important to know especially when you're conducting a clinical examination as surface anatomy will not only provide you with major anatomical landmarks but also will help you with diagnosis itself especially when you're engaging in activities such as auscultation, inspection, palpation, percussion, and function testing.
In addition to being bodily organs, landmarks can be formed by the shape of the underlying tissue and therefore can be considered to be a bony landmark which indicates a bony structure lying beneath it or a soft tissue landmark which indicates that muscle or some other kind of soft tissue is lying beneath it. And as we go along, we'll point out if a structure is a bony or soft tissue landmark or if it is indeed an external organ of the body.
Surface anatomy of the male body can also be divided into the anterior aspect and the posterior aspect which each can be divided into an upper and lower half and, of course, we'll begin with the upper part of each aspect before moving on to the lower half. But, of course, let's begin with the anterior aspect.
The first soft tissue landmark I want to talk about that's located in the upper part of the body is the sternocleidomastoid muscle whose outline is seen here highlighted in green. The sternocleidomastoid muscle is a superficially situated two-headed muscle of the neck whose sternal heads standout at sharply defined ridges forming a slight V-shape. And as you can see when examining your own body when you turn your head to the head or right, it can be easily visualized and palpated.
In male surface anatomy, the larynx is easily distinguishable. This is because the laryngeal prominence of the thyroid cartilage of the larynx in males is more defined. This surface projection of the larynx in males is what is more commonly known as the Adam's apple.
Next up is a triangular indentation inferolateral to the neck known as the supraclavicular fossa and as you can see in the image, this triangular depression is bordered by the clavicle inferiorly and by the sternocleidomastoid muscle medially. At the top of the shoulder is a bony protrusion which marks the position of the underlying acromioclavicular joint. This synovial joint which is commonly referred to as the AC joint which we can see in more detail in the image on the right here is formed between the clavicle and the acromion of the scapula.
The surface anatomy of the pectoralis major muscle is quite discernible especially in males. This fan-shaped muscle is a strong muscle of the shoulder joint that decisively shapes the surface anatomy of the breast in males. On the ventral aspect of the body at the lower aspect of the thorax we see the surface anatomy of the costal margin which is also sometimes referred to as the costal arch. This somewhat upside down V-shaped arch is formed by the medial margins of the seventh to tenth ribs and can easily be palpated or traced under the skin.
On the anterior abdomen, the surface anatomy of the tendinous intersections of the rectus abdominis muscle can also be seen. And as you can see in this image on the right, tendinous intersections are three, sometimes, four fibrous bands that cross the rectus abdominis muscle transversely.
Another fibrous structure whose surface anatomy can be seen is the linea alba. In surface anatomy, the linea alba can be seen as a longitudinal depression that traverses the umbilicus along the line of the abdomen. It runs from the xiphoid process to the pubic symphysis and separates the two parts of the rectus abdominis muscle which is this muscle featured on the skeleton over here. As we just saw, the linea alba transverses the umbilicus and the umbilicus basically represents a scar at the attachment site of the fetal umbilical cord and often is simply referred to colloquially as the navel or belly button.
On the anterior abdominal wall, we can see here a structure called the linea semilunaris – two bilateral curved lines seen highlighted in green. The linea semilunaris marks the fusion of the layers of the rectus sheath to the lateral aspect of the rectus abdominis muscles. So the lateral edge along here and to the medial aspect of the external oblique muscles – so along this line just here – and you can see the rectus sheath just here.
The penis – the external part of which can be seen here highlighted in green – functions not only as an organ of the male reproductive system but also as a part of the urinary tract. At the distal end of the penis, the corpus spongiosum expands laterally before narrowing to a tip which essentially forms a bulbous shape. This portion of the penis is known as the glans penis. The glans penis is covered by a double layer of skin and connective tissue that extends from the neck of the glans penis to just beyond the tip of the penis. This double layer of skin is known as the foreskin or the prepuce.
Also very easily distinguishable in male surface anatomy is the scrotum which is situated just posterior to the penis. The scrotum, essentially a sac composed of the superficial fascia of the abdominal wall internally and the skin externally – houses the testes, the epididymis and the dorsal portion of the spermatic cord.
Next looking at the surface anatomy of the lower limb it's quite easy to distinguish the contour of the anterior and lateral thigh which is formed by the underlying quadriceps femoris muscle. The quadriceps femoris muscle is a four-headed muscle that almost completely covers the femur and is one of the strongest muscles in the human body. On the anterior surface of the lower leg just inferior to the knee, a bony protrusion found on the anterior proximal surface of the tibia can be palpated and this is the tibial tuberosity. It is here that the distal part of the common tendon of the quadriceps femoris muscle, also known as the patellar tendon, attaches to the tibia as you can see here in this illustration.
Finally for the anterior aspect of the male, the dorsum of the foot is seen here highlighted in green. And the dorsum of the foot also known as the upper surface of the foot is important to take note of because it's in this region that the pulse of the dorsalis pedis artery can be palpated.
Moving now to the posterior aspect of the body, the first significant landmark that we're going to look at right now is this palpable bony protrusion which can be seen at the lower part of the back of the neck known as the vertebra prominens. This protrusion is formed by the long prominent spinous process of the seventh cervical vertebra, C7.
The trapezius muscle – the shape of which is highlighted here in green – can also be easily seen and palpated on the posterior aspect of the body. This somewhat triangular-shaped flat muscle functions not only to stabilize and secure the scapula at the thorax but also move it medially and rotate it outwards. Speaking of the scapula, the surface anatomy of the spine of the scapula can also be seen at the back. This protruding ridge of bone which is found on the posterior surface of the scapula separates the supraspinous fossa and the infraspinous fossa of the scapula and it's quite easily palpated under the skin.
Along with the spine of the scapula, the surface anatomy of the medial border or the medial margin of the scapula can also be easily palpated under the skin. This thin medial border of the scapula runs parallel to the vertebral column and as such can also be referred to as the vertebral border of the scapula.
Moving down the back, we can now see the surface anatomy of the iliac crest of the pelvic bones. In this illustration, you can see the iliac crest highlighted in green which is basically the superior border of the wing of the ilium that stretches from the anterior iliac spine to the posterior iliac spine. Just below the iliac crest, we can see a shallow triangular depression known as the sacral triangular. The sacral triangle overlies the sacrum and, in some individuals, small circular depressions known as the back dimples or the dimples of Venus can also be seen in the area of the triangle.
On the posterior aspect of the upper limb is a quite prominent bony protrusion known as the olecranon. The olecranon is the bony point of the elbow and forms the proximal posterior end of the ulna as you can see in this image on the right.
Moving now to the posterior thigh, the semimembranosus muscle occupies the medial aspect of the posterior compartment of the thigh where it can be palpated. This muscle is one of three muscles that make up the so-called hamstrings, the other two being the biceps femoris and the semitendinosus. At the dorsal aspect of the lower leg is a fleshy or meaty bulge that is commonly referred to as the calf. This posterior curvature of the lower leg is formed by the underlying three-headed triceps surae muscle and this muscle is comprised of two muscles namely the soleus muscle and the gastrocnemius muscle which merged to form a common tendon known as the calcaneal tendon which we'll talk about on the next slide.
As I just mentioned, the tendons of the soleus and the gastrocnemius muscles merged to form a common tendon which is known as the calcaneal tendon. You may already know this tendon by its colloquial name, the Achilles tendon. It attaches or inserts at the posterior calcaneus and it can easily be visualized and palpated at the inferior aspect of the dorsum of the lower leg as it forms a visible ridge.
So now we've come to the end of our tutorial and I just want to take a couple of minutes to quickly go through all the structures that we saw today. So on the anterior aspect, we saw sternocleidomastoid muscle, the larynx, the supraclavicular fossa, the acromioclavicular joint, the pectoralis major, the costal margin, the tendinous insertions, the linea alba, the navel, the linea semilunaris, the glans penis, the scrotum, the quadriceps femoris, the tibial tuberosity, and the dorsum of the foot. While on the posterior aspect of the male, we saw the vertebra prominens, the trapezius, the spine of the scapula, the medial border of the scapula, the iliac crest, the sacral triangle, the olecranon, the semimembranosus muscle, the triceps surae, and the calcaneal tendon.
That's the end of our tutorial. Thanks again for watching.
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