
870 S.W.2d 329 (1994)
Gregory Joseph STANUL, Jr., Appellant,
v.
The STATE of Texas, Appellee.
No. 3-92-619-CR.
Court of Appeals of Texas, Austin.
February 2, 1994.
Discretionary Review Dismissed May 18, 1994.
*330 E.G. Morris, Smith, Morris & Florey, L.L.P., Austin, for appellant.
Arthur C. (Cappy) Eads, Dist. Atty., James T. Russell, Administrative Asst., Belton, for appellee.
Before POWERS, JONES and KIDD, JJ.
PER CURIAM.
A jury found appellant guilty of murder and assessed punishment at imprisonment for seven years. Tex. Penal Code Ann. § 19.02 (West 1989). Appellant challenges the sufficiency of the evidence, both factually and legally, to support the conviction. He also complains of the jury finding that a deadly weapon was used in the commission of the offense. We will affirm.
1. Sufficiency of evidence
On June 15, 1991, emergency medical personnel were called to the apartment occupied by appellant, his wife, Ann Marie Stanul, and their son, eight-month-old Zachariah Stanul. They found appellant and his wife attempting to revive Zachariah, who was not breathing and had no heartbeat. Although medical treatment succeeded in restoring the child's heartbeat, he was unable to breathe without the aid of a respirator. Subsequent tests determined that Zachariah had no brain function, and he was declared dead on June 17.
The attending physicians testified that the child died as a result of severe trauma to the brain. This was confirmed during autopsy, which disclosed massive subscapular and subdural hemorrhages on both sides of the skull. All of the doctors testified that injuries of this sort are caused by the head striking a hard, immovable surface with great force. Dr. Dennis Schellhase, a pediatric critical care physician who treated Zachariah at Scott and White Hospital, testified that
[t]he medical literature and my experience would suggest that traumathe force required to generate that trauma, is consistent with motor vehicle accidents, being thrown from a car, falling from several stories or being battered. And those are really the three things that we think about when we see thosethat type of injury. And it requires more than just falling down. It really requires significant force to cause such injury.
Schellhase and Dr. Jeffery Barnard, the medical examiner who performed the autopsy, testified that in the absence of any evidence *331 that a child has been in an accident of the severity described above, the most likely cause of such an injury is child abuse. In his report, Barnard classified Zachariah's death as a homicide. Dr. Vincent DiMaio, a forensic pathologist who examined the medical records and the autopsy report, testified that the child
died as a result of massive blunt trauma. There's three ways this could occur. One, he could have been flung and impacted a hard flat surface. Two, he could have been swungusually by the feet they do itinto a hard flat surface. And less likely, the injuries would be due to multiple severe blows to the head, with the last being the least likely.
The medical witnesses agreed that the fatal injuries could not have been caused by bumping the child's head against its crib, by playfully shaking the child, or by an adult falling while holding the child in his arms.
Other evidence showed that Zachariah had been born while appellant was in Saudi Arabia serving in Operation Desert Storm, and that appellant had returned to the United States two months before the incident when the child was approximately six months old. A social worker testified that Ann Marie told her at the hospital that Zachariah cried around appellant. Two military colleagues of appellant testified that in a conversation two days before the child was injured, appellant told them that Zachariah's crying bothered him and that he had to get out of the house to keep from hitting the boy.
Appellant and his wife testified that the family spent most of the day in question shopping. After returning home, appellant placed Zachariah in his crib, bumping his head accidentally. The child began to cry, so appellant picked him up and played with him briefly. He then returned the child to his crib and joined his wife. Shortly after this, Ann Marie left to go to the post office. She returned five or ten minutes later, and laid down on the bed to take a nap. Before joining her, appellant decided to check on Zachariah. He found the child lying in the crib with his eyes half-open, not breathing. There was vomit on the sheet. Appellant picked up the child and called for his wife. As he turned to run from the room, he tripped and fell. He struck the floor with Zachariah under him. At this point, Ann Marie entered the room and began to administer CPR while appellant called for help. Both appellant and his wife testified to appellant's love for Zachariah and denied that the child's crying troubled appellant.
Also testifying on appellant's behalf were Byrom Donzis, a lecturer in sports medicine and designer of protective equipment widely used by professional and amateur athletes, and Steve Ingram, a biomechanical engineer and director of biomechanics at the Texas Sports Science Institute. Donzis testified that he and Ingram had developed a system for determining the force required to cause various injuries to the body through computer analysis of videotapes of such injuries made when they occurred. Donzis further testified that he videotaped appellant in his apartment as he reenacted his fall with Zachariah. Ingram testified that his analysis of this videotape indicated that the child's head would have been moving at a velocity of four meters per second, and would have received a crushing force of between 380 and 530 pounds when he struck the floor beneath appellant. Donzis testified that, in his opinion, this force was sufficient to cause the fatal injuries.
In rebuttal, the State called Dr. David Hardy, another pediatric critical care physician at Scott and White Hospital. Hardy testified that he had examined the medical records, the autopsy report, and the videotape made by Donzis, and was of the opinion that Zachariah's fatal injuries could not have been caused by a fall of the sort described by appellant and depicted in the videotape.
There was no dispute that Zachariah sustained severe brain trauma, nor any dispute that appellant in some way inflicted this injury. The contested issue at trial was the nature of the circumstances surrounding the injury. Appellant's theory was that Zachariah stopped breathing for some reason, perhaps sudden infant death syndrome or perhaps by choking on his vomit, and that the brain trauma was sustained when appellant accidentally fell with the child in his arms.
*332 The State's theory was summarized in this jury argument:
[T]he crying is driving him nuts.... He's crying. He's fussing. It is not an orderly universe for Greg Stanul any more.
And then they have a discussion about the bills. And then Ann leaves to go to the post office. And then I guarantee you, Ladies and Gentlemen, that little boy who was supposed to be down for his nap, started crying again. And Greg Stanul goes in there to stop the crying.
At the moment that he slams Zach on the floor, because I think the evidence supports that that is what happened, slamming him on the floor by his heels or by his body in some fashion, to create the arcing rotational deceleration forces that the doctors testified caused this injury, at the moment that he slammed Zach on the floor, he intended to shut him up. At that moment he intended it.
. . . .
The issue for you to decide is, at the moment when Zach's head hit the floor, did Gregory Stanul mean to hurt him bad. You bet. You bet he did.
The district court's charge instructed the jury to find appellant guilty of murder if it found beyond a reasonable doubt that appellant,
intending to cause serious bodily injury to an individual, Zachariah Thomas Stanul, commit[ted] an act clearly dangerous to human life, to-wit: by then and there striking the said Zachariah Thomas Stanul's head with his fist, or striking the said Zachariah Thomas Stanul's head with an object to the Grand Jury unknown, or by slamming the said Zachariah Thomas Stanul's head against an object to the Grand Jury unknown, thereby causing the death of the said Zachariah Thomas Stanul.
In determining the legal sufficiency of the evidence to support a criminal conviction, the question is whether, after viewing all the evidence in the light most favorable to the verdict, any rational trier of fact could have found the essential elements of the offense beyond a reasonable doubt. Jackson v. Virginia, 443 U.S. 307, 99 S.Ct. 2781, 61 L.Ed.2d 560 (1979); Griffin v. State, 614 S.W.2d 155 (Tex.Crim.App.1981). From the medical testimony in this cause, the jury could rationally find beyond a reasonable doubt that a blow to an infant's head of the sort alleged in the indictment and set forth in the application paragraph is an act clearly dangerous to human life, and that Zachariah's death was caused by such an act. The jury could rationally find from the other evidence that appellant committed that act. Given the nature of the act, the jury could rationally infer that appellant acted with the intent to cause serious bodily injury. Point of error five is overruled.
When conducting a factual-sufficiency review, we do not view the evidence in the light most favorable to the verdict. Instead, we consider all the evidence equally, including the testimony of defense witnesses and the existence of alternative hypotheses. Orona v. State, 836 S.W.2d 319 (Tex.App.-Austin 1992, no pet.). We will set aside the verdict only if it is so contrary to the overwhelming weight of the evidence as to be clearly wrong and unjust. Stone v. State, 823 S.W.2d 375, 381 (Tex.App.-Austin 1992, pet. ref'd as untimely filed); Orona, 836 S.W.2d at 321. In this cause, defense witnesses with expertise in biomechanics testified that the injury to the child's head could have been caused in the manner suggested by appellant. These witnesses, however, were not physicians and did not claim to have expertise with respect to the causes of brain trauma in infants. The medical witnesses, who were shown to have such expertise, unanimously testified that the fatal blow to Zachariah's head could not have been inflicted by an accidental fall while in appellant's arms. Further, there is no evidence other than appellant's testimony supporting the hypothesis that Zachariah stopped breathing before the injury to his head. We conclude that the jury's verdict is not so contrary to the overwhelming weight of the evidence as to be clearly wrong and unjust. Point of error four is overruled.
2. Deadly weapon
In answer to a special issue, the jury found that appellant used a deadly weapon in the commission of the offense, and this finding *333 was entered in the judgment. Tex.Code Crim.Proc.Ann. art. 42.12, § 3g(a)(2) (West Supp.1994).[1] Appellant argues in point of error one that a floor cannot be a deadly weapon within the meaning of Penal Code section 1.07(a)(11). Tex.Penal Code Ann. § 1.07(a)(11) (West 1974).[2] In points of error two and three, appellant further argues that if section 1.07 is interpreted to encompass a floor as a deadly weapon, the statute is impermissibly vague and denies him due process and due course of law. U.S. Const. amend. XIV; Tex. Const. art. I, § 19.
The State responds to these points by urging that the jury did not find that appellant used the floor as a deadly weapon. In finding appellant guilty, the jury found that appellant struck Zachariah's head with his fist or with an object unknown, or slammed his head against an object unknown. The special issue asked the jury if a deadly weapon was used without specifying the weapon.[3] The State concludes that in the absence of a showing that the jury necessarily found the floor to be a deadly weapon, appellant's points of error present nothing for review.
Although the evidence in this cause is ultimately inconclusive with respect to the precise manner in which appellant inflicted the fatal injury, the evidence strongly suggests that the injury was sustained when the child's head was struck against the floor. Dr. DiMaio testified that it was unlikely, albeit possible, that the child's injury was the result of blows to the head with a fist. Several of the medical witnesses referred to a wall or a floor as the sort of surface capable of inflicting the observed trauma. The wall in Zachariah's bedroom had no observable marks to indicate that his head was struck against it, and the State concedes that the child's room had no other large flat surface except the floor. In her argument to the jury quoted above, one of the prosecutors expressed her belief that appellant slammed Zachariah's head against the floor. Under the circumstances, we believe that it is appropriate to address appellant's points of error.
Since the adoption of the current Penal Code, whether a thing is a deadly weapon is entirely controlled by statute. Thomas v. State, 821 S.W.2d 616, 619 (Tex.Crim.App. 1991). As it applies to the facts of this cause, section 1.07(a)(11) defines "deadly weapon" as anything that in the manner of its use or intended use is capable of causing death or serious bodily injury. Penal Code § 1.07(a)(11)(B). While this definition appears to be open-ended, appellant argues that both common sense and case law require that a deadly weapon be a "weapon" and an "instrument." Appellant does not, however, define either of the latter terms. Ultimately, his argument is nothing more than an assertion that a deadly weapon must be an "instrument," that a floor is not an "instrument," and therefore a floor cannot be a deadly weapon.
Appellant cites several opinions in which an alleged deadly weapon was referred to as a "weapon," "instrument," or "object." Turner v. State, 664 S.W.2d 86, 90 (Tex.Crim. App.1983) ("the evidence courts normally look to in determining whether an instrument or object is a deadly weapon from the manner of its use or intended use is not in the record"); English v. State, 647 S.W.2d 667, 669 (Tex.Crim.App.1983) ("we assay the facts of a particular case to determine whether the manner of the weapon's use and intended use was such as to allow the jury to infer that the weapon was deadly"); Garza v. State, 695 S.W.2d 726, 728 (Tex.App.Dallas 1985), aff'd, 725 S.W.2d 256 (Tex.Crim.App. *334 1987) ("instrument that is not a deadly weapon per se can qualify as a deadly weapon"). In none of the cases cited, however, is it held that a thing must be a "weapon" or an "instrument," however defined, in order to be considered a deadly weapon.
Appellant also notes that courts often look at the size, shape, or sharpness of a thing in determining its deadly character. Brown v. State, 716 S.W.2d 939, 946 (Tex. Crim.App.1986) (knife); Compton v. State, 759 S.W.2d 503 (Tex.App.Dallas 1988, no pet.) (broken bottle); Garza, 695 S.W.2d at 728 (belt buckle); Jackson v. State, 668 S.W.2d 723 (Tex.App.Houston [14th Dist.] 1983, pet. ref'd) (ax handle). Appellant argues that a floor cannot be a deadly weapon because its size, shape, and sharpness are irrelevant to its deadliness. That size, shape, and sharpness are relevant criteria in determining the deadliness of some things does not mean, however, that they must be relevant in every case, or that something cannot be a deadly weapon irrespective of its size, shape, or sharpness. In any event, the floor's size and shape were relevant to its deadliness in this cause, since the medical testimony was that the child's head was struck by or against something large and flat.
Next, appellant refers us to section 46.01 of the Penal Code, in which various types of weapons are defined. Tex.Penal Code Ann. § 46.01 (West 1989 & Supp.1994). Each of these devices, appellant asserts, is an "instrument." Appellant also cites section 46.11, penalizing the possession or concealment of a deadly weapon in a penal institution. Tex.Penal Code Ann. § 46.11 (West 1989). Appellant asks, "How would the statements `he concealed his floor,' or `he possessed his floor' make sense?" These statements, of course, do not make sense. But because some deadly weapons are concealable instruments, it does not follow that every deadly weapon must be a concealable instrument.
Where a statute is clear and unambiguous, the legislature must be understood to mean what it has expressed, and it is not for the courts to add or subtract from the statute. Boykin v. State, 818 S.W.2d 782 (Tex.Crim.App.1991); Ex parte Davis, 412 S.W.2d 46, 52 (Tex.Crim.App.1967). It is constitutionally permissible for a court to depart from the plain language of a statute only if necessary to avoid an absurd result. Boykin, 818 S.W.2d at 785. Section 1.07(a)(11)(B) unambiguously states that anything used to cause death is a deadly weapon. We believe, contrary to appellant's contention, that it is not absurd to apply the statute as written.
The Court of Criminal Appeals has indicated that it does not read the statutory definition of "deadly weapon" in the narrow manner urged by appellant. In Turner, the court reaffirmed opinions predating the current penal code holding that hands, fists, and feet can be deadly weapons if used to cause death. The court rejected the defendant's assertion that only inanimate things can be deadly weapons under section 1.07(a)(11). 664 S.W.2d at 89-90. In Mixon v. State, 804 S.W.2d 107 (Tex.Crim.App.1991), the court adopted the holding of the court of appeals that an unknown object can be a deadly weapon in the manner of its use. This holding is inconsistent with the notion that a thing must possess certain inherent characteristics (for example, be an "instrument") in order to be a deadly weapon. In Thomas, the Court of Criminal Appeals pointed out that there are two types of "deadly weapons" as that term is defined by section 1.07(a)(11): those that are deadly by design and those that become deadly by their use. 821 S.W.2d at 619-20. The court went on to observe,
Whether a particular knife is a deadly weapon by design, a deadly weapon by usage, or not a deadly weapon at all, therefore, depends upon the evidence.
The same is, of course, also true of every other object in the world, including automobiles, telephone cords, bathwater, feather pillows, golf clubs or shanks.
Id. at 620 (emphasis added).[4]
Under section 1.07(a)(11), only a fire-arm is a deadly weapon as a matter of law. *335 Thomas teaches that whether any other thing is a deadly weapon under the statute depends on the evidence in the particular case in which the question arises. Thus, a thing is a deadly weapon in a given case if the evidence in that case shows that the thing was manifestly designed, made, or adapted for the purpose of inflicting death or serious bodily injury, or if the evidence shows that it was capable of causing death or serious bodily injury in the manner of its use or intended use in that case. See Holder v. State, 837 S.W.2d 802, 807-09 (Tex.App. Austin 1992, pet. ref'd) (unloaded BB pistol used in robbery was not shown to be deadly weapon in manner of its use); Taylor v. State, 735 S.W.2d 930, 948-49 (Tex.App. Dallas 1987), aff'd, 786 S.W.2d 295, 322 (Tex. Crim.App.1990) (where defendant poured gasoline in room occupied by her unconscious husband and ignited gasoline to enhance fire resulting in his death, fire constituted deadly weapon in manner of its use).
In this cause, the evidence shows that appellant, intending to cause serious bodily injury, struck the victim's head with or against something large, flat, and hard, probably the floor, with such force as to cause fatal brain trauma. The jury could rationally find that the floor was capable of causing death or serious bodily injury in the manner of its use by appellant and, therefore, was a deadly weapon. Cf. Parris v. State, 757 S.W.2d 842, 847 (Tex.App.-Dallas 1988, pet. ref'd) (sidewalk not deadly weapon absent evidence of purposeful use to inflict injury). Point of error one is overruled.
Points of error two and three are also overruled. When analyzing a statute for vagueness when no First Amendment rights are involved, we need determine only if the statute is impermissibly vague as applied to the challenging party's specific conduct. Arnold v. State, 853 S.W.2d 543, 546 (Tex.Crim. App.1993). Thus, it is incumbent on appellant to show that in its operation, section 1.07(a)(11)(B) is unconstitutional as applied to him in his situation. Bynum v. State, 767 S.W.2d 769, 774 (Tex.Crim.App.1989). We believe that a person of ordinary intelligence understands that death or serious bodily injury can result if an infant's head is slammed against a floor with sufficient force. We therefore conclude that section 1.07(a)(11)(B) gives a person of ordinary intelligence sufficient notice that if a floor is so used, it is a deadly weapon under the circumstances.
The judgment of conviction is affirmed.
NOTES
[1]  At the time of appellant's trial, murder was not an offense enumerated in article 42.12, section 3g(a)(1). Act of May 21, 1985, 69th Leg., R.S., ch. 427, § 1, 1985 Tex.Gen.Laws 1532, 1535 (Tex.Code Crim.Proc.Ann. art. 42.12, § 3g(a)(1), since amended). Effective September 1, 1993, section 3g(a)(1) was amended to add murder as an enumerated offense. Act of May 29, 1993, 73rd Leg., R.S., ch. 900, § 4.01, 1993 Tex.Gen. Laws 3716, 3718 (Tex.Code Crim.Proc.Ann. art. 42.12, § 3g(a)(1) (West Supp.1994)).
[2]  The Penal Code definition of "deadly weapon" is expressly adopted by article 42.12, section 3g(a)(2).
[3]  An affirmative finding that a deadly weapon was used may be made even if the weapon is not identified. Mixon v. State, 781 S.W.2d 345, 346-47 (Tex.App.-Houston [14th Dist.] 1989), aff'd, 804 S.W.2d 107 (Tex.Crim.App.1991).
[4]  We find the court's reference to bathwater particularly interesting, since appellant asserts in his brief that a body of water cannot be a deadly weapon under his reading of the statute.
