LAB Notes#1 Ahmad Ar'ar Eslam 1 P a g e
Anatomy lab Notes Lower limb bones :- Pelvic girdle: It's the connection between the axial skeleton and the lower limb; it's made up of one bone called the HIP BONE (unlike the shoulder girdle which consists of scapula and clavicle, so two bones). This bone ( hip bone ) is actually a fusion of three bones : ilium, ischium and pubis as the upper figure shows. As we know, we have two hip bones (left and right), these hip bones connect with each other at two regions; anteriorly and posteriorly:- Anteriorly :- left and right hip bones articulate with each other via spmphysis pubis. spmphysis pubis :-The pubic symphysis is a secondary cartilaginous joint (a joint made of hyaline cartilage and fibrocartilage, it's not movable ) located between the left and right pubic bones ( between left and right hip bones, specifically at the site of pubic bones ). 2 P a g e
Posteriorly :- at the posterior region, the left and right hip bones don t connect directly, there is sacrum in between. Sacrum: The sacral region (sacrum) is at the bottom of the spine and lies between the fifth segment of the lumbar spine (L5) and the coccyx (tailbone). It consists of five segments (S1-S5) that are fused together. So, the left hip bone (left ilium) is connected with the sacrum by the left sacroiliac joint, same for the right hip bone (right ilium) which is connected with the sacrum by the right sacroiliac joint. It's clearly seen in the figure above. Sacroiliac joint :- SI joint is a synovial movable joint that is found in the posterior part of the pelvis, it's the joint between the sacrum and the ilium bones of the pelvis. 3 P a g e
Again, we are concerned with three joints till now, the symphysis pubis (anterior, not movable as its secondary cartilaginous joint), in addition to the left and right sacroiliac joints (posterior, movable as they are synovial joints). Note: cartilaginous and fibrous joints are not movable according to the doctor. After this overview (pelvic girdle in general, its bones and joints), now we will be talking about the hip bone and femur in details. Make sure you notice the figures as they are crucial for your understanding. Hip bone:- Upper part: iliac bone Inferior part: pubis Posterior part: ischium -These three bones meet forming the Acetabulum. Three fused parts:- Ilium:- - Anterior superior iliac spine - Anterior inferior iliac spine - Iliac crest - Posterior superior iliac spine - Posterior inferior iliac spine (check the figure above) 4 P a g e
- Gluteal lines: - these lines are found at the outer surface of the ilium between the origin of different muscles (Gluteus Maximus, Medius and Minimus). There are three gluteal lines; inferior, middle/anterior (both names are used) and posterior gluteal lines. (They divide the outer surface to four parts origin of muscles) (Check the figure below). Note: as you can see, the iliac bone is well-known to have a fan shape. 5 P a g e
Note: anterior superior and posterior superior iliac spines are connected to each other by the iliac crest. So after we talked about the outer surface and the gluteal lines, we will discuss now the inner surface:- In the inner surface, we can differentiate between two areas:- - Smooth area: it's the iliac fossa - Rough area: two parts (as the doctor said); A) Iliac tuberosity B) Auricular surface: the irregular, L-shaped articular surface on the medial aspect of the ilium that articulates with the sacrum, it's covered by hyaline cartilage. (It's an extended part of the wing (ala) of ilium that articulates with the ala portion of sacrum, so the alae of the sacrum (at both sides) join the alae of the ilium bones along with sacroiliac joints). 6 P a g e
Now, to make sure you have a clearer idea about the wing (ala) of ilium and its components, you can read the following extra but important clarification about it:- THE WING OF ILIUM (OR ALA):- It s the large expanded portion of the ilium, It presents for examination two surfaces (an external and an internal), a crest, and two borders; an anterior and a posterior. A) The external surface: its smooth, crossed in an arched direction by three lines the posterior, anterior, and inferior gluteal lines.(mentioned before). B) The internal surface: The internal surface of the ala is bounded above by the crest, below, by the arcuate line; in front and behind, by the anterior and posterior borders. As we already mentioned, it presents two areas: - (1) a large, smooth, concave surface, called the iliac fossa. Behind the iliac fossa is (2) a rough surface, further divided into two portions, an anterior and a posterior. (A) The anterior surface (auricular surface), so called from its resemblance in shape to the ear, is coated with cartilage in the fresh state, and articulates with a similar surface on the side of 7 P a g e
the sacrum. (B) The posterior portion, known as the iliac tuberosity, is elevated and rough. After we discussed the ilium, no we will discuss the pubis: Pubis:- - Superior ramus. - Inferior ramus (meet with the ramus of ischium to form Ischiopubic ramus). - Symphysial surface: the medial elongated oval surface of the pubis that faces and articulates with its contralateral partner by means of the interpubic disc, forming the symphysis pubis. - Pubic crest: at the superior border. - Pubic tubercle: at the lateral end of the pubic crest. 8 P a g e
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Before moving to the ischial bone, we will define what is called the pelvic brim. Pelvic brim: The pelvic brim is an oval-shaped bony ridge in the pelvis formed by components of the sacrum, ilium, pubic bone and symphysis pubis, and this line has different names at these components; At ilium: Arcuate line which is a medial border in the iliac bone. At pubis: Pectineal line which is ramus. a sharp ledge in the superior pubic Note: the pelvic brim divides the pelvis into true pelvis below and false pelvis above. 10 P a g e
Ischium: - Ischial tuberosity. - Ischial ramus. - Ischial spine. - Greater sciatic notch (above). - Lesser sciatic notch (below). (Sciatic notches are called foramen when covered by ligaments) Acetabulum: C- shaped region ( articular surface/lunate) + acetabular notch (+fossa) -The articular surface/lunate is smooth with hyaline cartilage to articulate with femur. -The acetabular notch is rough with fat tissue so that it can cushion the artery and don t compress it. 11 P a g e
Now we are done with the hip bone, let's move to the femur. Femur:- -Type: long bong; it has two ends and a shaft. Upper end of femur: - Head of femur (medial). - Neck of femur. - Greater trochanter (lateral). - Lesser trochanter (posteromedial) - Intertrochanteric line: between the two trochanters, anterior. - Intertrochanteric crest: between the two trochanters, posterior. - Fovea capitis: in the head, for the ligament and artery that supply the head of femur. Shaft of femur: - Anteriorly rounded - Posteriorly: has a sharp edge called Linea Aspera (two lines: lateral lip and medial lip of linea aspera, these 2 lips continue till reaching the supracondylar ridges). 12 P a g e
Lower end of femur:- - Lateral condyle (same side of greater trochanter). - Medial condyle. These two condyles are covered with hyaline cartilage to connect femur with patella. - Lateral and medial epicondyles above the condyles. - Adductor tubercle: above the medial epicondyle. Some general notes about the pelvic region: - Obturator foramen is covered with membrane. - The anatomical position of the pelvis is tilted forward, so to put it in that position, you should maintain the anterior superior iliac spine and the pubic tubercle in the same vertical plane. - Hip bone is a fusion between 3 bones, complete fusion occurs at age 23. 13 P a g e
Figures for revision 14 P a g e
Now we will move to the last topic: The Lumbar Plexus THE LUMBAR PLEXUS and nerves of lower limb: Before we define the lumbar plexus, let's have a look at these general notes: - We have 31 spinal segments. - Sympathetic supply in the MMS is for sweat glands and vessels. Why sweat glands are innervated by sympathetic nervous system? Because the sympathetic response as a whole unit increases the temperature of the body, so accordingly, it should activate the sweat glands to decrease the body temperature. 15 P a g e
THE LUMBAR PLEXUS: The lumbar plexus is a network of nerve fibres that supplies the skin and musculature of the lower limb. It is located in the lumbar region, within the substance of the psoas major muscle and anterior to the transverse processes of the lumbar vertebrae. The plexus is formed by divisions of the lumbar spinal nerves L1, L2, L3 and L4 (upper 4). Each one of these nerves gives 3 roots, except for the 2 nd, it gives 4 roots. These roots form the 6 major peripheral nerves of the lumbar plexus that descend down the posterior abdominal wall to reach the lower limb. L1: gives 3 branches; - Iliohypogastric nerve.(larger) - Ilioinguinal nerve.(smaller) - The first root of genitofemoral nerve. L2: gives 4 branches; -The second root of the genitofemoral nerve. THE FIRST ROOT OF THE: - Lateral cutaneous nerve of the thigh. - Femoral nerve.( the largest and longest of plexus' nerves) - Obturator nerve. L3: gives 3 branches, THE SCOND ROOT OF THE: - Lateral cutaneous nerve of the thigh. - Femoral nerve. - Obturator nerve. 16 P a g e
L4: gives 3 branches; THE THIRD ROOT OF THE: - Femoral nerve. - Obturator nerve. - The upper root of the lumbosacral trunk. Details about the nerves will be covered in the next theoretical lecture. That s all about the first lab, sorry for any mistake or anything missing. If there is anything not clear, don t hesitate and contact me. Wish you all a great start in the coarse, sounds tough from the beginning 17 P a g e