Anatomy of the Forearm and Pelvis

Radius and Ulna in the Antebrachium

  • Description: The radius and ulna are the two bones that comprise the antebrachium (forearm).

Structure of Radius and Ulna

  • Medial and Lateral Attachment:
    • The medial side of the radius is connected to the lateral side of the ulna by an interosseous membrane.
Ulna
  • Olecranon Process:
    • A prominent structure on the ulna that fits into the olecranon fossa of the humerus when the arm is extended at the elbow.
    • Trochlear Notch:
    • Located at the proximal ulna, it provides a cup-like structure that receives the distal end of the humerus during elbow articulation.
  • Key Anatomical Features:
    • Radial notch of the ulna
    • Coronoid process
    • Ulnar notch of the radius
    • Styloid process of the ulna
Radius
  • Head of Radius:
    • Integral to the proximal radioulnar joint.
  • Radial Tuberosity:
  • Styloid Process of Radius:

Hand Anatomy

  • The palm contains five metacarpal bones, which are elongated and numbered 1 through 5 laterally, corresponding to the digits of the hand.
  • Phalanx Bones:
    • There are a total of 14 phalanx bones in the digits (fingers and thumb).
    • Digit 1 (pollex) consists of two phalanges:
    • Proximal phalanx
    • Distal phalanx
    • Digits 2 to 5 have three phalanges each: proximal, middle, and distal.

Bones of the Wrist and Hand

Carpal Bones and Joints

  • The wrist comprises eight carpal bones arranged in two rows and articulates with the scaphoid and lunate.
  • Articular Disc:
    • The ulna does not directly articulate with the carpal bones as it is shielded by this structure.
  • Metacarpals:
    • Form the palm of the hand.
  • Phalanges Composition:
    • Each digit has three types of phalanx: distal, middle, and proximal.

Bones

Carpal Bones
  • Groupings:
    • Proximal Row: Scaphoid, Lunate, Triquetrum, Pisiform
    • Distal Row: Trapezium, Trapezoid, Capitate, Hamate

Important Notes for Lab Activity

  • Do not use writing instruments to point at or touch bones, as any smears or marks can damage the specimen.
  • Materials Needed:
    • Articulated bones of hand
    • Humerus
    • Radius
    • Ulna
    • Sticks or pipe cleaners for indicating bones and their markings.

Pelvic Girdle Anatomy

Overview

  • The adult pelvis is formed by two os coxae, sacrum, and coccyx.
    • The term pelvic girdle refers exclusively to the os coxae, excluding the accompanying axial skeleton.
Acetabulum
  • Features two lateral acetabula for articulating with the femur.
  • Anteriorly, the os coxae articulate at the pubic symphysis.
  • Posterior articulation at the sacroiliac joint.
  • Pelvic Brim:
    • The upper border of the pelvic inlet marked at the anterior by a ridge of bone.
  • Obturator Foramina:
    • Openings facilitating nerve passage to the anterior leg.

Composition of Os Coxae

  • The os coxa is formed from three fused bones in late teenage years: ilium, ischium, and pubis.
  • Ilium:
    • The largest of the three bones, features include:
    • Iliac crest, anterior superior iliac spine, anterior inferior iliac spine, posterior superior and inferior iliac spines.
    • Auricular Surface:
      • Articulates with the sacrum.
    • Greater Sciatic Notch:
      • Nerve passage point from pelvis to thigh.
  • Arcuate Line:
    • Part of the pelvic brim located on the ilium.

Ischium Anatomy

  • Forms the posterior inferior part of the os coxa.
    • Key structures include:
    • Ischial tuberosity, ischial ramus, ischial spine, and lesser sciatic notch.

Pubis Anatomy

  • Forms the anterior portion of the os coxa.
    • Articulation:
      • The two pubic bones meet at the pubic symphysis, while the pubic tubercle marks the attachment of inguinal ligaments.
    • Extensions of the pubis include the superior and inferior rami leading towards the ilium and ischium.

Purpose of Bones of the Pelvic Girdle

  • To learn the os coxae and the key bony markings necessary for understanding pelvic structure and its function in movement and support.