Anatomy
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Lower Limb
A 42 year old man presents to ED following a hip injury. On examination you note weak lateral rotation. Which of the following muscles is most likely to have been injured:
Answer:
The lateral rotator group is a group of six small muscles of the hip which all externally (laterally) rotate the femur in the hip joint. It consists of the following muscles: Piriformis, gemellus superior, obturator internus, gemellus inferior, quadratus femoris and the obturator externus. This group does not include all muscles which aid in lateral rotation of the hip joint: rather it is a collection of ones which are known for primarily performing this action. Other muscles that contribute to lateral rotation of the hip include:- Gluteus maximus muscle (lower fibres)
- Biceps femoris
- Psoas major muscle
- Iliacus muscle
- Sartorius muscle
Hip Joint
Anatomy / Lower Limb / Hip Joint and Gluteal Region
Last Updated: 10th April 2019
The hip joint is a multiaxial synovial ball and socket joint occurring between the head of the femur and the acetabulum of the pelvis.
Table: Anatomical Overview of the Hip Joint
| Joint | Hip |
|---|---|
| Type | Synovial ball and socket joint |
| Articulations | Head of femur with acetabulum of pelvis |
| Stabilising factors | Acetabular labrum, thickened fibrous capsule, extracapsular ligaments (iliofemoral, ischiofemoral, pubofemoral), medial rotator muscles (effectively ‘pull’ head of femur into acetabulum) |
| Movements | Flexion/Extension, Abduction/Adduction, Medial/Lateral rotation, Circumduction |
| Blood supply | Branches of obturator artery, medial and lateral circumflex branches of profunda femoris artery and superior and inferior gluteal arteries |
| Innervation | Femoral nerve, obturator nerve, superior gluteal nerve and nerve to the quadratus femoris |
Joint articulations
The acetabulum is formed by the fusion of the three bones, the ilium, the ischium and the pubis.
![By Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://mrcemsuccess.com/wp-content/uploads/2017/01/acetabulum.png)
Hip Joint. (Image by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
The rim of the acetabulum is raised slightly by the fibrocartilaginous acetabular labrum which increases its depth, improving stability of the joint. The acetabular labrum continues inferiorly as the transverse acetabular ligament which bridges the acetabular notch and converts the notch into a foramen for the passage of nutrient vessels and nerves.
Ligaments
The intracapsular ligament of the head of femur (ligamentum teres) runs from the fovea on the head of the femur at one end to the acetabular fossa and the transverse acetabular ligament on the other. It carries a small acetabular branch of the obturator artery.
There are three main stabilising extracapsular ligaments; the iliofemoral (the largest and strongest ligament), the pubofemoral and the ischiofemoral ligament.
- The iliofemoral ligament is anterosuperior to the hip joint, attached proximally to the ilium just below the anterior inferior iliac spine and distally to the intertrochanteric line of the femur. This ligament specifically prevents hyperextension and lateral rotation of the hip joint whilst standing.
- The pubofemoral ligament is anteroinferior to the hip joint, attached to the pelvis at the iliopubic eminence and adjacent bone and blending distally with the articular capsule. This ligament prevents excessive abduction and extension of the femur at the hip joint.
- The ischiofemoral ligament is posterior to the hip joint, attached medially to the ischium and laterally to the greater trochanter. This ligament prevents excessive extension and medial rotation of the femur at the hip joint.
![By Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://mrcemsuccess.com/wp-content/uploads/2017/01/HipLig1.png)
Intracapsular Ligament of Head of Femur. (Image by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
![Modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://primary-cdn.frcemsuccess.com/wp-content/uploads/2017/01/HipLig3-1.jpg)
Hip Joint Ligaments (Anterior View). (Image modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
![By Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://mrcemsuccess.com/wp-content/uploads/2017/01/HipLig2.png)
Hip Joint Ligaments (Posterior View). (Image by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
Blood supply
The hip joint receives its blood supply primarily from branches of the obturator artery, the medial and lateral circumflex arteries (branches of the profunda femoris artery) and the superior and inferior gluteal arteries. The articular branches of these vessels form a network around the joint.
Innervation
The hip joint is innervated by articular branches from the femoral nerve (anteriorly), obturator nerve (inferiorly), superior gluteal nerve (superiorly), and the nerve to the quadratus femoris (posteriorly).
Joint movements
The hip joint allows the movements of flexion and extension, abduction and adduction, medial and lateral rotation and circumduction.
Table: Movements of the Hip Joint
| Movement | Muscles Involved |
|---|---|
| Flexion | Sartorius, Iliacus, Psoas major, Pectineus, Rectus femoris |
| Extension | Hamstrings, Gluteus maximus |
| Abduction | Gluteus maximus, medius and minimus, Obturator internus, Gemelli, Piriformis, Sartorius |
| Adduction | Adductor longus, magnus and brevis, Gracilis, Pectineus |
| Medial rotation | Gluteus medius and minimus, Adductor longus, magnus and brevis, Semitendinosus and Semimembranosus |
| Lateral rotation | Obturator externus, Sartorius, Iliacus, Psoas major, Biceps femoris, Piriformis, Gluteus maximus, Obturator internus, Gemelli, Quadratus femoris |
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
