the appendicular skeleton english
Embed Size (px)
Transcript of the appendicular skeleton english
The Appendicular skeleton
The appendicular skeleton consists of
Arm + Shoulder Girdle
Leg + Pelvic Girdle
• Os Coxa
Your body is your cheat sheet.
To remember what whole bones look like, think about where they are, and what they do – how they move.
Let’s start with some simple examples.
What’s This?Cranial or postcranial?
Axial or appendicular?
• Where is it? Upper arm (anatomically, the arm; the lower part is the forearm)
• What does it do? It rotates at the shoulder, and it flexes at the elbow.
• You now know everything you need to know to orient and side the intact humerus.
• The shoulder is a highly mobile joint, so logically its anatomy must permit free movement.
• The elbow’s motion is more restricted. It’s a hinge, with a limited range of motion, so its anatomy is consistent of that.
• This enables you to distinguish proximal from distal.
• The humerus is a long bone. It has a shaft, called a diaphysis, and two ends, called epiphyses.
• The proximal end is smooth bone that’s rounded, like a ball. This is called a head.
• The distal end has rounded projections of smooth bone where the humerus articulates with other bones. These areas of articulation are called condyles.
• Projections of bone next to condyles are called epicondyles.
• The head is proximal and medial.
• The condyles are distal, and the rounded one (called the capitulum) is lateral.
• The epicondyles are distal and the medial epicondyle is bigger than the lateral epicondyle.
• Now you can tell proximal from distal and medial from lateral.
• The proximal humerus has two rough projections below the head anteriorly. These are called tubercles (the greater and lesser).
• The distal humerus has depressions on the anterior and posterior surfaces. A depression on bone is called a fossa. There are two shallow ones anteriorly, and one deep one posteriorly.
• Head is proximal and medial.
• Tubercles are proximal and anterior.
• Condyles are distal and project more anteriorly.
• The olecranon fossa is deep and posterior, and there’s only one of it.
• The coronoid and radial fossae are shallow, and there are two of them.
What are these?Cranial or postcranial?
Axial or appendicular?
RADIUS AND ULNA
• Where are they? The radius and ulna are the bones of the forearm.
• What do they do? They flex at the elbow and they pivot right below it.
• This tells you what you need to know to distinguish the radius from the ulna, and how to side them.
RADIUS and ulna
• The ulna is the medial bone of your forearm. When you bend your forearm, you’re using your ulna.
• The radius is the lateral bone of your forearm. When you pronate or supinate your forearm, you’re using your radius.
Radius and ulna
• Remember, medial and lateral refers to being toward or away from the midline in standard anatomical position.
• So when we say “the radius is lateral,” we mean that it’s on the lateral side of the forearm when the skeleton is in standard anatomical position.
Radius and ulna
• Another way to remember the position of the bones is that the radius is on the thumb side of your forearm.
• When you rotate your forearm, your thumb moves. That’s your radius rotating around your ulna. The ulna stays still, the radius moves around it.
RADIUS AND ULNA
• Round head proximally
• Major articulation with wrist distally (large concavity)
• Ulnar notch is medial and distal
• Distal end: concave anteriorly, small tubercles posteriorly
• Olecranon process (hook for the elbow) proximal and concave anteriorly
• Makes minimal articulation with wrist distally (small head with styloid process)
• Radial notch is lateral and proximal
• The hand consists of carpals (the wrist), metacarpals (the palm), and phalanges (the fingers).
• We’ll skip the hand for now and talk about it in the Anthropology section.
Clavicle and scapula
• Where is it? Anterior part of the pectoral girdle.
• What does it do? Stabilizes shoulder joint.
• smoother superiorly than inferiorly
• thick and rounded medially
• broad and flat laterally
• anterior surface is convex medially and concave laterally. (You can feel this on yourself.)
• Where is it? The shoulderblade.
• What does it do? Articulation between humerus and torso.
• Point of triangle is inferior
• Concave surface is anterior
• Spine is posterior and superior
• Fossa for articulation with head of humerus is lateral
• Where is it? The thigh.
• What does it do? Mobile hip joint proximally, flexes at knee distally.
• Head and neck proximal and medial.
• Trochanters proximal and lateral/posterior.
• Condyles and epicondyles distal.
• Where is it? The kneecap.
• What does it do? Improves functionality of knee joint.
• Anatomical siding: anterior surface is rough. Superior/proximal surface is flat (you can feel this on yourself). Lateral facet is the larger.
• Siding trick: put on table with rough surface up and point away from you. It falls to the side it’s from.
• Where is it? Large bone of the lower leg.
• What does it do? Flexes at the knee proximally and at the ankle distally.
• On the medial side of the lower leg.
• Two flat condyles proximally. The medial is longer.
• Tuberosity anteriorly.
• The medial face of the anterior shaft is convex and lies close to the skin (you can feel it on yourself).
• The lateral face of the anterior shaft is concave (you feel muscle on yourself when you touch there).
• The distal end has an articulation for the fibula laterally and a malleolus (large bone projection) medially.
• Where is it? Smaller bone of the lower leg.
• What does it do? Stabilizes the lower leg and ankle.
• The fibula shaft is complex, so we’ll avoid the detail on that for now.
• To side, hold it with either end up with the articular facet towards you. The facet is on the side the bone is from.
• The foot consists of tarsals (ankle), metatarsals (arch), and phalanges (toes).
• It’s complex, so we’ll talk about it in detail in the anthropology section.
• The two os coxae, combined with the sacrum, make up the pelvis.
• The os coxa consists of three parts, which start out as individual bones: the ilium, the ischium, and the pubis.
• The pubis is anterior. The ilium is superior. The ischium is inferior.
• On the anterior os coxa, there’s a large hole. A hole in bone is called a foramen. This particular one is called the obturator foramen.
• One more word to learn: ramus. The obturator foramen is bordered by the iliopubic and ischiopubic rami. (Rami is plural of ramus).
• The ilium is large, flat, and curved. It makes up the crest of your hip.
• The ischium is smaller, thick, and very dense. Its inferior margin is marked by ischial tuberosities. You sit on them.
• The pubis is relatively gracile, and it’s anterior.
• Iliac crest is superior
• Sciatic notch is posterior and inferior
• Auricular surface (articulates with sacrum) is posterior and medial
• Acetabulum (articulates with femur) is lateral and opens anteriorly.
What to remember
• Know the names of the bones.
• Know where they are, and what they do. That will enable you to side them.
• How a bone moves is the biggest help to identifying it when you’re new to osteology.
FINISNext: the axial skeleton.