Rectum
Rectum | |
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deep inguinal lymph nodes | |
Function | Store feces prior to defecation |
Identifiers | |
Latin | rectum intestinum |
MeSH | D012007 |
TA98 | A05.7.04.001 |
TA2 | 2998 |
FMA | 14544 |
Anatomical terminology] |
Major parts of the |
Gastrointestinal tract |
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The rectum (pl.: rectums or recta) is the final straight portion of the
Structure
The rectum is a part of the
Unlike other portions of the colon, the rectum does not have distinct
Blood supply and drainage
The blood supply of the rectum changes between the top and bottom portions.
The superior rectal artery is a single artery that is a continuation of the inferior mesenteric artery, when it crosses the pelvic brim.[8] It enters the mesorectum at the level of S3, and then splits into two branches, which run at the lateral back part of the rectum, and then the sides of the rectum. These then end in branches in the submucosa, which join with (anastamose) with branches of the middle and inferior rectal arteries.[8]
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Arteries of the pelvis
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Blood vessels of the rectum and anus
Microanatomy
The microanatomy of the wall of the rectum is similar to the rest of the
The lining of the rectum changes sharply at the line where the rectum meets the anus. Here, the lining changes from the column-shaped cells of the rectum to multiple layers of flat cells.[9]
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Cross-section microscopic shot of the rectal wall
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Dog rectum cross-section (40×)
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Microscopic cross-section of the rectum of a dog (400×), showing a high concentration of goblet cells in amongst the column-shaped lining. Goblet cells can be seen as the circular cells with a clear inner material (cytoplasm).
Function
This section relies largely or entirely upon a single source.(January 2022) ) |
The rectum acts as a temporary storage site for feces. The rectum receives fecal material from the descending colon, transmitted through regular muscle contractions called peristalsis.[11] As the rectal walls expand due to the materials filling it from within, stretch receptors from the nervous system located in the rectal walls stimulate the desire to pass feces, a process called defecation.[11]
An
The urge to voluntarily defecate occurs after the rectal pressure increases to beyond 18 mmHg; and reflex expulsion at 55 mmHg. In voluntary defecation, in addition to contraction of the rectal muscles and relaxation of the external anal sphincter, abdominal muscle contraction, and relaxation of the puborectalis muscle occurs. This acts to make the angle between the rectum and anus straighter, and facilitate defecation.[11]
Clinical significance
Examination
For the diagnosis of certain ailments, a
Body temperature can also be taken in the rectum. Rectal temperature can be taken by inserting a medical thermometer not more than 25 mm (1 inch) into the rectum via the anus. A mercury thermometer should be inserted for 3 to 5 minutes; a digital thermometer should remain inserted until it beeps. Normal rectal temperature generally ranges from 36 to 38 °C (96.8 to 100.4 °F) and is about 0.5 °C (1 °F) above oral (mouth) temperature and about 1 °C (2 °F) above axilla (armpit) temperature.[citation needed] Availability of less invasive temperature-taking methods including tympanic (ear) and forehead thermometers has facilitated reduced use of this method.
Route of administration
Some medications are also administered via the rectum (
Constipation
One cause of
Testing may be carried out to investigate the cause. This may include
In general however, constipation is treated by improving factors such as hydration, exercise, and dietary fibre.
Inflammation
- Proctitis is inflammation of the anus and the rectum.
- Ulcerative colitis, one form of inflammatory bowel disease that causes ulcers that affect the rectum. This may be episodic, over a person's lifetime. These may cause blood to be visible in the stool. As of 2014[update] the cause is unknown.
Cancer
- Rectal cancer, a subgroup of colorectal cancerspecific to the rectum.
Other diseases
Other diseases of the rectum include:
- Rectal prolapse, referring to the prolapse of the rectum into the anus or external area. This is commonly caused by a weakened pelvic floor after childbirth
- In the context of splenic flexureas a watershed region.
Society and culture
Sexual stimulation
Due to the proximity of the anterior wall of the rectum to the vagina in females or to the prostate in males, and the shared nerves thereof, rectal stimulation or penetration can result in sexual arousal.
History
Etymology
English rectum is derived from the Latin intestinum rectum[19] 'straight gut',[20][21] a calque[22][23] of Ancient Greek ἀπευθυσμένον ἔντερον, derived from ἀπευθύνειν, to make straight,[24] and ἔντερον, gut,[24] attested in the writings of Greek physician Galen.[22][23] During his anatomic investigations on animal corpses, Galen observed the rectum to be straight instead of curved as in humans.[22][23] The expressions ἀπευθυσμένον ἔντερον and intestinum rectum are therefore not appropriate descriptions of the rectum in humans. Apeuthysmenon[25] is the Latinization of ἀπευθυσμένον and euthyenteron[26] has a similar meaning (εὐθύς 'straight[24]). Much of the knowledge of the anatomy of the rectum comes from detailed descriptions provided by Andreas Vesalius in 1543.[27]
See also
References
- ^ Nosek, Thomas M. "Section 6/6ch2/s6ch2_30". Essentials of Human Physiology. Archived from the original on 2016-03-24.
- ^ "12. Colon and Rectum" (PDF), AJCC Cancer Staging Atlas, American Joint Committee on Cancer, 2006, p. 109
- ^ ISBN 978-0-387-24846-2.
- ^ Wang, Yun Hwa W.; Wiseman, Jeffrey (2023). "Anatomy, Abdomen and Pelvis, Rectum". StatPearls. StatPearls Publishing. Retrieved 24 May 2023.
- ^ a b Gray's Anatomy 2016, pp. 1146–7.
- ^ a b Gray's Anatomy 2016, p. 1137.
- ^ Sneh Agarwal (January–March 2012). "Anatomy of the Pelvic Floor and Anal Sphincters" (PDF). JIMSA. 25 (1).
- ^ a b c d Gray's Anatomy 2016, p. 1151.
- ^ a b c Wheater's 2013, p. 273.
- ^ Wheater's 2013, pp. 252–4.
- ^ a b c d Ganong's 2019, p. 492-4.
- ISBN 978-0-7295-3905-0.
- ^ Davidson's 2018, p. 17.
- ^ "Definition of ENEMA". www.merriam-webster.com. Retrieved 2020-07-04.
- ^ "Definition of SUPPOSITORY". www.merriam-webster.com. Retrieved 2020-07-04.
- ^ PMID 31680970.
- ^ a b c d e f g h Davidson's 2018, pp. 786–7.
- PMID 5717099.
- ^ Federative Committee on Anatomical Terminology (FCAT) (1998). Terminologia Anatomica. Stuttgart: Thieme.
- ^ Schreger CH (1805). "Synonymia anatomica. Synonymik der anatomischen Nomenclatur". In Fürth (ed.). im Bureau für Literatur.
- ^ Lewis CT, Short C (1879). A Latin dictionary founded on Andrews' edition of Freund's Latin dictionary. Oxford: Clarendon Press.
- ^ a b c Hyrtl J (1880). Onomatologia Anatomica. Geschichte und Kritik der anatomischen Sprache der Gegenwart. Wien: Wilhelm Braumüller. K.K. Hof- und Universitätsbuchhändler.
- ^ a b c Triepel H (1910). Die anatomischen Namen. Ihre Ableitung und Aussprache. Mit einem Anhang: Biographische Notizen (Dritte Auflage ed.). Wiesbaden: Verlag J.F. Bergmann.
- ^ a b c Liddell HG, Scott R, Jones HS, McKenzie R (1940). A Greek-English Lexicon. Oxford: Clarendon Press.
- ^ Kossmann R (1895). "Die gynäcologische Anatomie und ihre zu Basel festgestellte Nomenclatur". Monatsschrift für Geburtshülfe und Gynaekologie. 2 (6): 447–472.
- ^ Gabler E, Winkler TC (1881). Latijnsch-Hollandsch woordenboek over de geneeskunde en natuurkundige wetenschappen (2nd ed.). Leiden: A.W. Sijthoff.
- ISBN 978-1-4419-1581-8.
Sources
- Barrett KE, Barman SM, Yuan JX, Brooks H (2019). Ganong's review of medical physiology (26th ed.). New York. OCLC 1076268769.)
{{cite book}}
: CS1 maint: location missing publisher (link - Ralston SH, Penman ID, Strachan MW, Hobson RP (2018). Davidson's principles and practice of medicine (23rd ed.). Elsevier. ISBN 978-0-7020-7028-0.
- Solomon EP, Schmidt RR, Adragna PJ (1990). Human anatomy & physiology (2nd ed.). Philadelphia: Sunders College Publishing. ISBN 0-03-011914-6.
- Standring S, ed. (2016). Gray's anatomy : the anatomical basis of clinical practice (41st ed.). Philadelphia. )
- Young B, O'Dowd G, Woodford P (2013). Wheater's functional histology: a text and colour atlas (6th ed.). Philadelphia: Elsevier. ISBN 9780702047473.
External links
- Cross section image: pembody/body15a—Plastination Laboratory at the Medical University of Vienna
- Cross section image: pelvis/pelvis-e12-15—Plastination Laboratory at the Medical University of Vienna
- Anatomy image:7808 at the SUNY Downstate Medical Center
- Anatomy photo:43:11-0101 at the SUNY Downstate Medical Center