Anatomy Notes - Appendicular Skeleton PDF

**[Exercise \#12 ]** **[The Appendicular Skeleton]** It is composed of 126 bones that make up the appendages and the\ pelvic and pectoral girdles.\ \ **[Pectoral Girdle (2 paired bones)]** The Pectoral girdle consists of the anterior **Clavicle** and posterior **Scapula**.\ The clavicle has two e...

**[Exercise \#12 ]** **[The Appendicular Skeleton]** It is composed of 126 bones that make up the appendages and the\ pelvic and pectoral girdles.\ \ **[Pectoral Girdle (2 paired bones)]** The Pectoral girdle consists of the anterior **Clavicle** and posterior **Scapula**.\ The clavicle has two end: **Acromial** (lateral), **Sternal** (medial)\ \ The Clavicle can be differentiated between left and right by looking\ at the **Conoid tubercle** found posteriorly at the acromial end of the\ clavicle. When properly oriented the conoid tubercle will always point downward and posteriorly. The clavicle acts as a strut.\ \ **The Scapula** is the wings of the human being. Each has two large\ processes, the **Acromion** an enlarged process found on the posterior\ surface, and lateral. The clavicle articulates with the acromion. The\ **Coracoid process** is a smaller beak-like process which is found\ anteriorly, at the base of which is found the **Suprascapular notch**,\ which allows nerves and blood vessels to pass.\ Also found in the scapula laterally is the **Glenoid cavity** a shallow\ socket which holds the humerus. [The shoulder girdle is very light and allows for great mobility for\ three reasons**:**\ ]1. The Sternoclavicular joint is the only attachment to the axial\ skeleton.\ 2. Loose attachments of the scapula allow sliding due to muscular\ activity against the thorax.\ 3. The shallow glenoid cavity gives little stability for the shoulder joint.\ **All the flexibility leads to easy dislocation**.\ \ **[The Arm ]** The arm is composed of three bones, the **Humerus** (upperarm), and the\ **Ulna** and **Radius** (lower arm or forearm). **[Humerus ]** The humerus is a long bone. At the rounded head or epiphysis is\ found laterally the **Greater tubercle**, and anteriorly the **Lesser\ tubercle.** Midshaft, the **Deltiod tuberosity** is found laterally, this\ is the attachment site of the deltiod muscle.  At the other end of\ the humerus there are 2 condyles, the **Medial Trochlea** (the spool)\ which articulates with the ulna, and the lateral **Capitulum** which\ articulates with the radius. These are flanked by **Medial** and **Lateral**\ **epicondyles**, the medial epicondyle has the **ulnar nerve** running in a\ groove beneath it, this is also called the funny bone. Anteriorly\ the medial **Coroniod fossa** and laterally the **Radial fossa** and\ posteriorly **the Olecranon fossa** allow room for the ulna and radius\ processes to move freely when the elbow is flexed and extended.\ \ **[The Antebrachium (the forearm)]** In the anatomical position the **Radius** is Lateral and the **Ulna** is\ medial.\ The Radius has an anterior radial tuberosity that is the point of\ attachment of the tendon of the biceps muscle. The radius also has a\ lateral **Styloid process** at the distal head (lateral).\ The Ulna has a **Coronoid process** anterior and lateral and the **Olecranon\ process** which is posterior and medial, these are separated by the\ **Trochlear notch** these articulate with the humerus. The radial notch\ articulates with the head of the radius. The ulnar **Styloid process**\ is an attachment point of the ligament of the wrist.\ \ **[The Hand or Manus]** [Three groups of bones:]\ 1. **Carpus** (wrist bones).\ 2. **Metacarpals** (bones of the palm).\ 3. **Phalanges** (bones of the fingers).\ \ [Carpal bones] There are eight carpal bones, two irregular rows of four bones.\ Closest to the palm and on the pinky side or medial side are the\ **Hamate,** the **Capitate,** the **Trapezoid** and the **Trapezium**.\ Beneath these and articulating with the ulna and radius are medial\ to lateral the **Pisiform**, which is on top of the **Triquetral/ Triquetrum**, the\ **Lunate** and the **Scaphoid**. All of these are bound together by\ ligaments.\ \ [The Metacarpals] These bones are numbered simply 1-5 from the thumb, \#1, to the pinky\ \#5. Heads articulate with the phalanges to become knuckles when the\ hand is in a fist.\ \ [The Phalanges] These bones are numbered in the same way 1-5, the thumb (pollux) \#1 and have\ distal middle and proximal parts, except for the thumb which has\ only distal and proximal parts.\ \ **[Pelvic Girdle ]** The pelvic girdle consists of 2 **Coxal** bones, the **Ossa coxae**, and the **Sacrum** and the **Coccyx (**usually included in the axial skeleton**)**. The bones are heavy and massive, and attach securely to the axial skeleton. Main function is weight bearing. Sockets for the femur are deep.\ [Each coxal bone is a fusion of three bones]:\ 1. The **Illium.**\ 2. The **Ischium**.\ 3.  The **Pubis.**\ \ **[The Ilium ]** **[\ ]**The largest of the pelvic bones, connected to the sacrum, comprises the superior/posterior portion of the pelvis. The **Ala** are two broad planes found medially. The Iliac crests are the superior margins of the Iliac bone (felt when you put your hands on your hips). The Lesser and Greater Sciatic Notches allow blood vessels and nerves to pass to and from the thigh.\ \ **[The Ischium ]** **[\ ]**The ischium comprises the inferior and posterior portion of the coxal bones. The **Ischial tuberosity** bears the weight of the body while sitting.\ \ **[The Pubic bone]** The Pubic bones are the most anterior part of the pelvis. The **Pubic ramus** and the **Ramus** of the **Ischium** form the bones that enclose the **Obturator foramen**, which allows blood vessels and nerves to pass. The pubic crest is found where the two pubic bones meet. It is anterior and forms the anterior/superior part of the pelvis. This also forms the pubic arch underneath. The **Pubic crest** links both parts of the pubic bone at the **Pubic Symphysis** (a fibrocartilage pad).\ \ The Ilium, ischium and the pubic bones fuse into a deep socket, the **Acetabulum** which receives the femur.\ \ [Comparison of the Male and Female pelvis]. Female pelvis is modified for child bearing and is wider, shallower lighter and rounder.\ The **False pelvis** is superior to the **Arcuate line** and supports the abdominal viscera.\ The **True pelvis** is inferior to the arcuate line.\ The **Pelvic inlet** or **Pelvic brim** is the opening from the **Sacral Promontory** and the arcuate lines. The female\'s is oval/wide, and the male is heart-shaped.\ The pelvic outlet is the inferior margin of the true pelvis. The female coccyx is projected more posteriorly than the males. The **Publc Arch** angle is larger in the female pelvis\ \ **[Thigh ]** The **Femur** or thigh bone is the heaviest and strongest bone in the body. Ball-like head articulates with the acetabulum. Small pit in the head is called the **Fovea capitis**, allows the entrance of a small ligament. The Neck is the weakest point and is usually broken when the leg is damaged.\ The **Greater** and **Lesser trochanters** lie between the neck and the shaft, with the **Intertrochanteric crest** inbetween. The **Gluteal tuberosity** is posterior and the **Linea aspera** runs below the tuberosity. Both are sites of muscle attachment. The **Lateral** and **Medial condyles** articulate with the tibia. The medial **Adductor tubercle** is a bump where the large **Adductor magnus muscle** attaches.\ The **Patella** is a triangular sesamoid bone enclosed in the Quadricep tendon. The patella guards the knee joint.\ \ **[The Lower leg]**\ Consists of two bones the **Fibula** and the **Tibia** (the shin bone), which is larger and medial, has **Medial** and **Lateral condyles** which receive the distal ends of the femur. The **Tibial tuberosity** is the site of **patellar ligament** attachment. The **Medial Malleous**, which is distal, forms the medial part of the ankle. The **Anterior crest/border** is right below the skin, and inferior to the tuberosity.\ The **Fibula** is a thin stick-like bone with a sharp anterior crest that terminates in a **Lateral malleous**, the outer ankle bulge.\ \ **[The Foot]** [Three groups of bones:] 1. **Tarsals.** 2. **Metatarsals.** 3. **Phalanges**. There are seven Tarsal bones, 5 Metatarsals, and 14 Phalanges. [Tarsal bones] The **Calcaneous** (the heel bone), lies beneath the **Talus** which bears the bodies weight, the **Navicular** is medial and the **Cuboid** is lateral, these are followed closest to the Metatarsals by the **Medial, Intermediate** and the **Lateral Cuneiforms**. [Metatarsals] The Metatarsals are numbered 1-5 from the big toe to the pinky toe. [Phalanges] The phalanges are numbered1-5 from the big toe to the pinky toe and have distal, middle and proximal parts, except for the big toe which only has distal and proximal parts. The bones of the foot are arranged into three arches, 2 **Longitudinal** (medial and lateral) and one **Transverse arch.** Ligaments hold the boned in place and foot muscle tendons hold arches together. Weakened arches are called **Fallen arches** or **Flat feet**.