Video: Body surface anatomy

Have you ever had a sharp pain in your lower right belly, rushed to the doctor, and found they started pressing around your abdomen? They were probably checking for appendicitis -- specifically at McBurney’s point, the surface spot which the appendix lies beneath.

That’s a great example of body surface anatomy—where we use visible or touchable landmarks on the body to figure out what’s underneath. It’s essential in clinical practice for examining, describing, and interpreting the location and relationships of anatomical structures, and it also helps in reading medical images accurately.

In today’s tutorial, we’ll explore the anterior and posterior surface anatomy of the head, neck, and trunk, otherwise known as the axial body, plus the upper and lower limbs, also known as the appendicular body. Across these regions, we will identify three types of surface landmarks: bony landmarks, soft tissue landmarks, and external organs.

Let’s begin by looking at the surface anatomy of the anterior surface of the axial body, or in other words, the front of the torso.

Our first landmark is the larynx, or voice box, located in the neck over the esophagus at the level of cervical vertebrae 3 to 6. The larynx contains vocal cords and helps produce sound, as well as conduct air to the lungs.

The thyroid cartilage of the larynx forms the laryngeal prominence, commonly called the Adam’s apple. To feel your larynx, simply find your Adam’s apple.
On each side of the larynx lie the large sternocleidomastoid muscles. These muscles originate from the sternum and clavicle and insert on the skull. When you turn your head, these muscles form sharp ridges that create a slight V shape and are easy to palpate.

The clavicle, also known as the collarbone, is a thin, S-shaped bone connecting the upper limb to the trunk. You can easily spot it by taking a deep breath and raising your shoulders.

Just above the clavicle, between the sternocleidomastoid and deltoid muscles, is the shallow supraclavicular fossa. It extends from the sternal end of the sternocleidomastoid muscle to the medial edge of the deltoid muscle.

Moving down to the chest, the sternum is a flat bone consisting of three parts: the manubrium, body, and xiphoid process. The manubrium lies between the clavicles and features the jugular notch at its superior border. The junction between the manubrium and the body of the sternum forms the sternal angle, which aligns with the second rib and can be felt just below the jugular notch.

The body of the sternum articulates with ribs two to seven, while the small, pointed xiphoid process forms its inferior tip and can be felt at the base of the chest.

Lateral to the sternum, beneath the breast, lies the pectoralis major muscle, a large superficial chest muscle.

Both males and females have breasts, composed of fat, mammary tissue, and skin. At the center of the breast is the nipple. The pigmented area around the nipple is called the areola.

At the lower edge of the ribcage is the costal margin, formed by the cartilages of ribs seven to ten. This becomes more prominent when you exhale sharply.

Next is the rectus abdominis muscle, or “abs,” running from the pelvic bone to the xiphoid process and lower ribs, giving the abdomen its characteristic “six-pack” appearance.

Down the midline of this muscle runs the linea alba, a fibrous band separating the left and right rectus abdominis muscles. On the sides, the semilunar line, or the linea semilunaris, is a curved, tendinous band that runs along the lateral border of the rectus abdominis. It marks the lateral margin of the rectus sheath, and extends from the ninth rib cartilage to the pubic tubercle.

The umbilicus, commonly known as the navel or belly button, marks the scar of the fetal umbilical cord attachment and is easy to spot.

Below that are the anterior superior iliac spines, bony projections of the pelvic bones that you can feel by placing your hands on your hips and sliding your fingers forward.

The inguinal ligament extends from the anterior superior iliac spines to the pubic tubercle and can be palpated along this line.

In females, the mons pubis is a fatty area over the pubic symphysis covered in hair post-puberty. It’s part of the vulva, which includes all external female genitalia.

In males, the penis is an external reproductive and urinary organ, ending in the glans penis, covered by the prepuce of the penis, more commonly known as the foreskin. Just behind it is the scrotum, a sac of skin and fascia housing the testes, the epididymis, and spermatic cord.

Let’s move on now to talk about the posterior surface of the axial body, or in other words, the back of the torso.

At the back of the head is the external occipital protuberance, a bony bump. Just below, the C7 vertebra stands out with the longest spinous process, easily felt when you bend your neck forward.

Covering the back of the neck and upper back is the trapezius muscle, a large, diamond-shaped muscle you can easily palpate.

The scapula, commonly known as the shoulder blade, is a paired bone with three palpable landmarks: the spine of the scapula, which is a protruding ridge that divides the bone into the superior supraspinous fossa and the inferior infraspinous fossa; the medial border, which runs parallel to the vertebral column, and the inferior angle at its bottom tip.

Below the scapula lies the large latissimus dorsi muscle, which helps pull the arms down and back. Its lower border runs near the iliac crest, the top edge of the pelvic bone, palpable at the lower back.

Between these landmarks lies the lumbar triangle, bordered by the iliac crest, latissimus dorsi, and external oblique muscles.

The posterior superior iliac spines mark the back ends of the iliac crests and can be identified by the “dimples of Venus.”

Between them lies the sacral triangle, overlying the sacrum and sacroiliac joints. The sacroiliac joint is the articulation between the sacrum and the ilium, and it supports the weight of the upper body.

At the lowest point is the anal region, including the anal canal and sphincters, located just in front of the coccyx.

Now that we’ve finished with the surface anatomy of the axial body, let’s move on now and have a look at the surface anatomy of the limbs, beginning with the anterior aspect of the upper limb.

The upper limb connects to the trunk where the clavicle meets the acromion of the scapula, a bony point easy to feel on the shoulder. This connection is otherwise known as the acromioclavicular joint.

The shoulder’s surface is mostly formed by the deltoid muscle, a rounded cap over the lateral arm.

On the front of the arm is the biceps brachii muscle, a major flexor you can feel when you bend your elbow.

At the elbow crease lies the cubital fossa, a triangular hollow containing important nerves, as well as vessels, such as the brachial artery and veins.
The palm has two soft tissue prominences: the thenar eminence at the thumb’s base and the smaller hypothenar eminence at the base of the little finger.
Let’s move now to the posterior aspect of the upper limb.

The triceps brachii muscle is found on the posterior aspect of the arm. It’s a large three-headed muscle whose tendon inserts onto the olecranon, the bony tip of the elbow.

Moving down the arm, on the back of the wrist, is the radial foveola, a hollow visible when you extend and abduct the thumb. It’s commonly known as the anatomical snuffbox, after the historical practice of placing ground tobacco—otherwise known as snuff—into the depression and then inhaling it through the nose.

Next let’s move down the body to look at the surface anatomy of the lower limb, starting with the anterior aspect.

On the anterior thigh are the quadriceps muscles, a group of four large muscles that flex the hip and extend the knee.

Near the groin is the femoral triangle, a small area inferior to the inguinal ligament containing major blood vessels.

At the front of the knee is the patella, which is otherwise known as the kneecap. The patella is the largest sesamoid bone.

And just below the patella is the tibial tuberosity, a bony bump on the anterior aspect of the tibia.

The tibialis anterior muscle runs down the front of the leg and shapes the shin. This muscle aids in forming the shape of the anterior surface of the leg.

At the ankle are two bony landmarks: the medial malleolus, which is found on the inner ankle, and the lateral malleolus, which is found on the outer ankle.

Switching up to the posterior side of the lower limbs now let’s look at the gluteal region, commonly known as the buttocks. The gluteal region is shaped by the three gluteal muscles, especially the gluteus maximus. The region is separated by the intergluteal cleft, or – as you might more commonly know it as -- the “butt crack”!

The crease below the buttocks is known as the gluteal sulcus. It’s important to note however, that the gluteal sulcus is a skin fold, and not a muscle border.

On the outer thigh runs the iliotibial tract, a thick band of fascia that stabilizes the hip.

The back of the thigh contains the hamstring muscles, which include the biceps femoris, semitendinosus, and semimembranosus, whose tendons are palpable behind the knee.

Below is the popliteal fossa, a diamond-shaped hollow behind the knee with important nerves and vessels such as the popliteal artery and vein, and the tibial and common fibular nerves.

The triceps surae muscles, made up of the gastrocnemius and soleus, form the calf.

Their tendons merge into the strong calcaneal tendon, commonly known as the Achille’s heel. The calcaneal tendon attaches to the heel bone.

Before we finish this tutorial, let’s go over a quick clinical note. Remember McBurney’s point, the approximate surface location of the appendix? If you’re in hospital and the doctors want to find it, they might draw a line from the umbilicus to the anterior superior iliac spine. The appendix lies at the junction of the lateral and middle thirds of this line, so tenderness here may suggest appendicitis, signaling the need for further medical evaluation.

And with that, we’ve explored the surface anatomy of the human body! Hopefully you’ve learned enough so that next time you’re at the doctor poking around that sore spot on your belly, you’ll know exactly what they’re checking for! Don’t forget to learn more about this topic and consolidate your knowledge with our articles and quizzes at Kenhub -- see you next time!