Anatomy drawings by Susan Dorothea White – tutorial notes by Dr. Brian Freeman

Anatomy is the basic science that deals with the structure of the human body. The term anatomy, which comes from Greek, means 'to cut up' or 'to dissect'

THE ANATOMICAL POSITION

The anatomical position is the body upright with the palms of the hands facing forward (see fig. 1). The anatomical position is the standard reference position for all planes, directions, movements, and descriptions of the body. Basic anatomical terms: names of structures are now standardised by international convention; many of these are in Latin or have Latin or Greek origins.

ANATOMICAL VIEWS

VIEWS: The standard views of the body are from front (anterior), back (posterior), above (superior), below (inferior), and side (from outside - lateral; from inside - medial).

Simple movement terms in anatomy

Fig. 2. FLEXION is bending any part and extension is straightening it out; adduction is moving a part towards (ad Latin: towards) the midline and abduction is the opposite (ab Latin: away); Supination is positioning the palm of the hand upwards or forward (as in the anatomical position) and pronation is opposite. Inversion is turning the sole of the foot inwards and eversion is outwards.

SPINE or VERTEBRAL COLUMN

Fig. 3. VERTEBRAL COLUMN has 7 cervical (neck), 12 thoracic (chest), 5 lumbar (loin), 5 fused sacral, and 3-5 coccygeal vertebrae. Note the natural curves of the spine in side view. The spine's curvature in the chest region is similar to that of the sacrum (concave to the front) and is described as primary curvature of the spine because it is present in the fetus. The curvature in the cervical and lumbar region is opposite (convex to the front) and is called secondary curvature of the spine because it arises after birth.

SKULL

Fig. 4. SKULL in side (lateral) view, indicating individual flat bones of the skull that meet at fibrous joints called sutures.

LOWER LIMB

Fig. 5. LOWER LIMB. Drawings A and B show positions of the bones in relation to flesh and where the bones come close to the surface. Feel (palpate) the following parts of your bones:

• thighbone (femur) at the greater trochanter,
• thighbone at the medial and lateral epicondyles,
• kneecap (patella),
• head of splint bone (fibula) on the outside of the leg below knee,
• shinbone (tibia) all along its front margin,
• anklebone on inside (medial malleolus of tibia),
• anklebone on outside (lateral malleolus of fibula).

The adductor muscles (including gracilis muscle) brace the femur to the pelvis and bring the thigh to the midline; the hamstring muscles at the back of the thigh flex the leg at the knee; the quadriceps femoris (four-headed muscle of the thigh) extends the leg at the knee.

C. Anterior view of right and medial view of left lower limb showing surface muscles. A striking landmark is the diagonal thigh muscle sartorius (after the Latin word for a tailor, who developed powerful diagonal bulges across the thigh by sitting cross-legged while sewing). The sartorius muscle attaches to the hipbone (at anterior superior iliac spine; ASIS in B and D). The muscle crosses the thigh, passes behind the inside of the knee and attaches to the shinbone (tibia). The sartorius muscle crosses two joints (hip and knee); it is important in kneeling (D) and in the yoga lotus position because it helps to flex the leg on the thigh at the knee joint and also to flex the thigh at the hip joint.

E. This shows the fleshy hamstring muscles of the back of the thigh. Feel in the hollow of your knee (popliteal fossa): you can 'flick' one stringy tendon on the outer (lateral) side of the hollow and two tendons on the inner (medial) side. The hamstring tendon on the outside of the knee hollow belongs to the biceps femoris muscle (two-headed muscle of the thigh). Of the two inside tendons, the one closer to the surface (more superficial) feels round and stringy - this is the hamstring from the semitendinosus muscle. The deeper hamstring is coarser and flatter - this is the tendon of semimembranosus muscle. Each of the three hamstring muscles attaches to the bone of your bottom (ischial tuberosity; B) that you can feel through the buttock muscle when sitting. The hamstring muscles cross two joints; they extend the thigh at the hip and flex the leg at the knee.

The calf muscle (C, E) called gastrocnemius ('stomach' or belly of the knee) has two bellies ('heads'). It is also a two-joint muscle because it crosses the knee joint and the ankle joint. When standing on your toes (plantar flexion), the muscle pulls on the heel bone via the Achilles' tendon (E). The aubergine (H) mimics the asymmetry in the shape of gastrocnemius muscle (dotted line in E; the lower dotted line indicates the offset positions of the malleoli at the ankle).

F. Inside (medial) view of right knee. The three tendons from the muscles semitendinous (st.), gracilis (g.), and sartorius (s.) merge together in the skin of the bone (periosteum) on the upper inside surface of the shinbone (tibia). The tendons spread out in a webbed pattern that caught the imagination of early anatomists because it resembled a goose's foot (G) or pes anserinus (Latin: foot of the goose).

UPPER LIMB

Fig. 6. UPPER LIMB. A, B. The movements of flexion and extension of your elbow can be felt using the thumb and first two fingers of the opposite hand, as illustrated. Place your index finger on the point of your elbow (olecranon of ulna), then your thumb and third digit on the inside (medial) and outside (lateral) epicondyles of the humerus. As you flex and extend the free forearm at the elbow, sense the movement of your index finger with respect to the fixed epicondyles of the humerus. Flexion of the free-moving forearm on a fixed arm brings a teacup to one's lips. Conversely, flexion of a fixed forearm on a mobile arm allows us the move the rest of the body with the arm, as in climbing a rope.

B. Bones of left upper limb, flexed at elbow, viewed from the front, showing the position of the bones for A.

C. Inside (medial) view of left upper limb in pronation. Note how the radius crosses over the ulna, carrying the wrist and hand with it so that the palm is facing inferiorly ('palm to the earth' as Leonardo wrote). On the other hand, when the radius and ulna are parallel (as in the anatomical position) the hand is supinated ('palm to the sky').

D. Pronation of right forearm (midway); outside (lateral) view. The point of the elbow (olecranon of ulna) is massive; the ulna grips the medial condyle (trochlea) of the humerus (in C and F) like an adjustable spanner (E). The ulna tapers distally to a small pen-like projection or styloid process (prominent bone on the dorsal side of the wrist). Conversely, the radius is small at the elbow and becomes more massive where it supports the wrist.

F. shows the main muscles of the upper limb that are involved in flexion and extension movements about the elbow. Triceps brachii muscle is an extensor of the forearm on the arm at the elbow; it has three heads (the lateral head is not shown in the drawing) that pull on the olecranon and other structures.

In front of the humerus, biceps brachii, brachialis, and brachioradialis muscles are all capable of flexing the forearm on the arm at the elbow. Note how the lower tendon of biceps brachii in F wraps around the pronated radius like a rope around a pulley before it attaches to the bone at the radial tuberosity. Thus, as Leonardo da Vinci discovered, biceps brachii is a powerful supinator muscle, as well as a flexor, of the free forearm. Feel your biceps in the action of using a screwdriver to turn a screw: as well as holding the forearm flexed, biceps supinates and applies a powerful torque to the screw.

SHOULDER REGION

Fig. 7. SHOULDER. A. The deltoid muscle covers the shoulder joint (A, B, D). The upper attachments of deltoid are extensive and include the shoulder-blade (acromion and spine of scapula) and the collarbone (clavicle). The lower attachment of deltoid is at the outer aspect of the humerus, about one-third the distance from the shoulder to the elbow. When dissected from its attachments and laid flat, the shape of the muscle is like an inverted triangle or delta; hence its name. The middle portion of deltoid (from the acromion of the scapula) is active when we lower a raised arm under gravity (as in A). The middle part also helps to raise the upper limb from the anatomical position (as in B); this movement is abduction of the humerus at the shoulder joint. The anterior portion of deltoid (from the clavicle) acts to flex the humerus anteriorly across the trunk, and the posterior portion (from spine of scapula) extends the humerus posteriorly across the back. The deltoid resembles an inverted knob of garlic (C) with the fleshy muscle bellies like cloves and the sites of the tendon attachments forming clefts between them. This pattern is pronounced in athletes and in Rodin's bronze sculpture of The Thinker.

Pectoralis major muscle: we can feel part of this muscle in the front (anterior) skin fold of our armpit (axilla). The muscle is shaped like a fan and has extensive attachments at the sternum, at the collarbone, and on the ribs (D, E). It passes over the armpit to attach to the upper part of the humerus.

The crossing of fibres in the pectoralis major muscle of the hanging arm in E resembles an opened fan (G): muscle fibres arising from the highest point on the chest (collarbone) pass in front to a lower portion of the humerus (b in E) and fibres from the ribs cross behind these to reach a higher point on the humerus (a in E). When the arm is abducted and elevated (right humerus in E), the muscle 'unwinds' as the fibres slide past each other near the humerus.

Pectoralis major muscle can flex and rotate the humerus in a medial direction. At the end of a hard race, an athlete uses pectoralis major as an accessory muscle for inspiration in the following way: the humerus is fixed by placing the hands on the hips and pectoralis major moves the ribs against a fulcrum on the humerus. The fan-like folding of the muscle is reminiscent of the overlapping skin-folds in the web between the thumb and index finger in F.

FOREARM, pronated

Fig. 8. FOREARM and right hand in pronated position ('palm to the earth') showing muscles, tendons, and fascia. The 'anatomical snuffbox' is a depression between tendons that pass to the thumb. Note that the bellies of the muscles that extend the fingers are situated in the forearm; the long tendons of the extensor muscles pass under the extensor retinaculum (wrist-band of fascia) like ropes under a pulley. An important landmark is the change in the plane of the forearm where the adductor and the extensor muscles of the thumb ('button-hole muscles') emerge from between other forearm muscles.

FOREARM: supinated

Fig. 9. FOREARM and right hand in supinated position ('palm to the sky') showing muscles, tendons, and fascia. The bellies of the muscles that flex the fingers and wrist are situated in the forearm and their long tendons pass to the fingers through a tunnel of fascia at the wrist (carpal tunnel). The muscles of the arm and forearm are covered by, and pull on, fascia. The ball of the thumb (thenar eminence) is composed of a group of small thumb muscles that help in gripping; The ball of the little finger (hypothenar eminence) is a similar group of small muscles that help to move the little finger.

TORSO or TRUNK

Fig. 10. TORSO showing surface muscles and bony landmarks (e.g., iliac crest; anterior superior iliac spine; greater trochanter of femur). All the muscles are covered by fascia (e.g., the sheath of rectus abdominis muscle; the iliotibial tract). The linea alba is a white stripe of dense fascia that runs like a zipper between the two rectus abdominis muscles.